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Grace, Pace and Space ..even more so than the Jaguar.


Bfg

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new purchase . . .

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^ mostly from Classic Car LED's ..but for the four indicator bulbs on the left hand side, which were much cheaper on ebay. I thought I'd give them a try as they offered a saving of £25.  The top left bulb is a high power (equivalent of 50w headlamp bulb) reversing light bulb.  It was expensive but CC LED's were out of that type and I wanted a very bright light to see what I might otherwise be reversing into.    The two bulb holders on the right I'll fit into the headlamp bowls, same as I did with my TR4, because although the wing-top side lights are bright enough with LED's they are so tiny that they are difficult for others to judge the distance of.  Headlamps are much more familiar to contemporary drivers.     

- - -

Otherwise, I've been feeding the seat's leather with Connelly Hide Care. . .

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The pot says to apply it sparingly, whereas I put it on liberally with a sponge and then shoe-brush it in to the creases and stitches, and the seat squab's perforations.  I used half a pot for the first application. It looks very dull because I've put it on and not polished it off yet. I'll leave the car parked in the sun to allow it time to soak in. Then I'll repeat it.  Only then will I polish it off and use an old towel to cover the seats for the next couple of weeks of driving.   

Pete

 

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  • 2 weeks later...

Jaguar Brakes - Part 1 of 10.

Morning all, I've been busy on other things but the Daimler is being used as everyday transport, which to be honest is not so many miles for a retiree, ie. someone doesn't have to drive to work and can walk to the local shop.  Still just over 850 miles since I bought this car at the end of October is not bad compared to most classic cars through the winter months.  Unfortunately however I'm having issues with the brakes. Being a motorcyclist I'm not very experienced with car braking systems.  I've been really very lucky with most of the old cars I've had and have rarely needed to do much more than replace brake shoes or pads, clean up the drums, clean up and re-grease cable connections for handbrakes, and bleed hydraulics. So this old Daimler is a learning curve for me. In the first instance it has disk brakes on each corner and it also has a brake servo.

I'll tell you what the symptoms are..   The brake pedal has always been very high.  With the servo, this car's brakes used to be incredibly good ..albeit with very little travel.  I had had to be very light and steady footed to avoid overly sharp braking. Then one day, after the car had not been used for two months, the brake didn't seem to work unless I pushed hard, and then it sort of released and locked the brakes on. Something was sticking, but then they were pretty much okay.  However this initial resistance continued but steadily got worse, insomuch as the initial began to happen every time I applied the brakes during everyday driving.  I thought using the car more frequently might ease up the problem but it got worse still insomuch as the brakes then started to not release, at first for just a second, then for longer and longer periods.  On the last occasion, when using the car to meet a friend to go out to lunch, I braked into a roundabout and the brakes locked on and didn't release. despite my having dropped into a lower gear the car was on the point of stalling as I tried to get out of the way of traffic. This was getting dangerous and instead of freeing up with frequent use it was getting worse.  

I could feel no pulling to one side when the brakes failed to release, so I assumed it was neither one of the front wheel calipers. And I'd not noticed either side of the back of the car dragging either.  The car wasn't using brake fluid, there were external no signs of incontinence (from the brakes) and the servo was clearly boosting braking performance. 

From those symptoms does anyone else think it might be the brake master cylinder sticking ?  

I didn't know any better, so that's where I started from. . .

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^ being a posh car the underside of the dashboard is closed off with a trimmed aluminium panel. Two trip reset cables go through that, one for the mileometer and the other for the timepiece (clock) and the tread on each was seized.  Under the trim was a wad of sound insulation that had to be ripped out to get to even see the linkage between the pedal and the master cylinder's activating rod's forked connection.

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^ There it is, with the pivot pin pushed in from the outside so the split pin was a sod to see or reach.   With that out the pedal is free to swing up and down.

From above, inside the engine bay, the master cylinder is . . .

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^ The brake master cylinder and all the pipe work looks in great condition ..as if they are not very old.  The brakes were reconditioned for a prior owner in 2021.

However that master cylinder is situated close to the battery and under the bonnet hinge / spring, next to a deep chassis structure, behind the screen-wiper motor, outboard of the clutch master cylinder.  It's out the way there.!   The brake fluid reservoir is very much more easily reached. It is the tall plastic bottle.  Inside that (with a torch shining from the side) the fluid is clear enough to see a gauze filter in the bottom and just a few bits of ???

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^ I used a syringe to very conveniently suck the brake fluid out of the reservoir, including the bits settled in the bottom, and transfer it to a jam jar. 

But I made a mistake here because the syringe had previously been used with oil.  Had I thoroughly cleaned it out before doing this I could have reused the brake fluid. As it is the few droplets of oil in the syringe, although clean oil, contaminated the brake fluid. I'll have to refill it with new fluid.

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^ with the fluid drained there was very little to dribble out when I disconnected the pipe connections from the master cylinder. Getting a spanner in was awkward but possible without removing the battery.  Getting to the nut, which bolts the master cylinder to the bulkhead, was even more awkward as its level is below that of the chassis rail. An joggled ring spanner worked.  Having accumulated an assortment of odd spanners over the five decades is an advantage over someone with even the finest and shiniest new 'standard' tool-sets.

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^ Even with everything undone, I couldn't lift the master cylinder out. I used a claw hammer to prise it up off its bolts and the rubber dust cover on its end out from a corroded aluminium spacer tube.  

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^ nothing obviously wrong here. The rubber piston seal wasn't leaking and feels to be supple.  The spring is good, and the bore of the (Girling) master cylinder is great, and so after I further dismantled to check things, I simply cleaned up I put it back together again.  

I did prime the master cylinder with brake fluid before refitting it, and then by blowing (yes, down into the reservoir) before tightening the pipe connectors, I managed to fill the pipe and master cylinder (again) with brake fluid, so although a tiny bubble may still be in there - I didn't need to piddle around bleeding the brakes.  

Trying it ..and the symptoms I started with are still there.  Disappointing but as I didn't find much wrong, not wholly unexpected.

Looking at things more positively..  It was only partly a failure, because a. I learnt how to do this (should the seal fail in the future), and b. I've eliminated a sticking master cylinder from the probable causes.  Admittedly, the oil contamination from my syringe, ..which I noted when the fluid was in the (otherwise clean) had me wondering.. if incompatible brake fluids had swollen the seals. But on reflection - I think I can rule that out too. 

Now I'll make a cup of coffee before writing stage 2, in another post.    Watch this page. . .

Happy Sunday despite drizzling weather outside. :wink:

Pete

 

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Brakes part 2.

Okay, not the master cylinder, and unlikely to be swollen brake caliper seals due to incompatible brake fluids or fluid contamination, I put to one side of my mind the brake servo because a. it was clearly working strongly, and b. because I know bugger all about them and reading the original manual just seems to blank my mind.   I don't know why that should be but I've started to read it three times now and there seems to be some sort of mental barrier, as if it is written in Dutch.?

My next step then was to go and get my trolley jack, a 20 mile round trip to the barn.  With that I could individually test each wheel for the brake not releasing.  I jacked up the front right wheel, so I could turn it by hand, and applied the brakes. It released before I got around from the brake pedal to the wheel. I started the car's engine so as to check it when the servo was at full power. Again no binding.  I hadn't expected it to be binding as I couldn't feel the steering pull to one side when it had happened before, but still I needed to follow a systematic procedure. 

I next jacked up the rear right wheel and again applied the brake. Nothing on the first try but it did stay seized on after I really stomped on the pedal.  Ah Ha !  I hadn't felt the tail dragging but then perhaps the braking and rear axle / suspension has anti-squat geometry ?  I don't know with looking into that, but I know that offside rear brake was sticking on after the pedal was released. . .

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^ With the wheel-arch spat and wheel removed, access is amazingly good. Beforehand I'd only thought of spats as streamline styling, but their usefulness in doing brake work is apparent. Again I was pleasantly surprised at the general condition of things down under.  The rear axle tie bars clearly would benefit from new rubber bushes but nothing horrid.

Having a closer look at the brake caliper and again applying the brake pedal to get them to stick I noted that the outer pad freed up again but the inside one was stuck.  The brake pads are all very thick ...as if nearly new,  and the disk itself is is great condition and again doesn't look to be very old.   For such an old car that's an unexpected bonus  :-)

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^ again working systematically I wanted to remove both brake pads to check each of their pistons were working and would push back freely enough.  I removed the locking / anti-rattle plate and tried pulling on the metal tab to get the first pad out.  It would rattle around away from the disk but otherwise it wouldn't pull out.   I couldn't push the piston away from pad more than a 1/16th of an inch. But I didn't know why ..as all other vehicle brakes I'd worked on I could retract the piston back into the caliper to free the pad..  Only when I did finally get it out did I see ; there's a tab on the caliper piston which interlocks / slots into a keyway (the metal plate) on the back face of the brake pad.  

Anyway, it took me ages to get the darn pad out because it was tucked in under the bridge between the top and bottom of the caliper's carrier. I tried releasing the hydraulic pressure via the brake nipple - That was a mistake.  And then I undid the four bolts to lift away the outside caliper, off the carrier. . .

Despite advice of a YouTube video, because of the external plumbing ; when the four bolts are released the caliper lifts away without any loss of fluid. I think most every other disk brake caliper I'd worked on was in two halves, which when pulled apart leaked fluid from their internal oil ways.  I like these Jaguar ones.!   Even just lifting the caliper away on loosened bolts enabled me to pull / slide the pad out.

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^ getting the inside brake pad out was just as difficult., but on this side it was because the piston was sticking and tight into the caliper. I did manage to get the pad out and then things suddenly became very much clearer . . . The brake's disk was offset to the carrier ..or more correctly vice-versa.   So, the sticking caliper was because the carrier, and therefore the caliper was positioned too tight to the disk, and with the nearly new (thick) brake pads and a nearly new (thick) disk - the caliper couldn't retract fully without sticking.  Why it should suddenly (after almost a thousand miles) happen ? ..I don't know but happen it did.  

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Looking from underneath it was clear that the carrier was offset to the disk and needed to be centralised.    Pulling the carrier bolts out, there was a shim, outside as if a washer.  It was far too thin to correct much but it did confirm my conclusion that the carrier needed to be shimmed to centralise it to the disk.  I found in my pot of old washers a couple that were a mm thick and of the right size (laying flat within the lid) and a couple of plain washers too, then Copaslip to aide future disassembly - I repositioned the carrier a mm further inward. 

Tbh., it could do with a bit more but it's much better than it was. The inside caliper has that extra mm to retract its piston, and the outside brake pad is less tucked under the carrier bridge and so it'll be easier to pull out again.

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^ all back together, now to bleed the pipe (after having unnecessarily trying to ease the hydraulic pressure by undoing the bleed nipple).  ^^ I saw this idea on a YouTube video, saying that a hand-spray head (in this case from a windscreen de-icer bottle) coupled to the bleed nipple pipes could be used to draw the fluid and any bubbles from the hydraulics.   As you can see it did draw some fluid up as well as some bubbles, but I suspect most of the bubbles came from around the fitting rather than from inside the caliper.  It worked though with sealant around the bleed nipple.   Good idea for one-man blood letting.   

When tried again the brakes now release.  Success B)  ..in part. . . 

I did the same, centralising the brake-calliper's carrier offset on the near-side rear wheel.  It didn't appear to be sticking when I pre-tested it, but as it was similarly out of alignment i thought it best to be corrected ..while I had dirty hands. 

Test driving the car around the block proved, while deliberately trying to provoke their sticking, that this part of the problem was now resolved, and has narrowed the remaining issue..   The brake pedal is still hard and then releases with a jolt rather than eases the brakes on in a gentile manner.  I might only surmise that there is an issue with the servo.  As I know nothing about these, I'll have to learn as I go. 

So, progress insomuch as the car is driveable, but it's still not right. 

While at it, with the rear wheels off, I sought to address the handbrake barely working. I'd not really noticed it until I went to visit a friend who lives on the side of hill and has a very short driveway onto a road with a blind corner.  A situation where a good handbrake would be most useful.   More of that in the next post. . .

Pete

Postscript .. please see part 5 (in a following post) which adds further important factors.

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Jaguar-Daimler Brakes - Part 3.  Handbrake not working.

I'll not go through this as I did it because I did as best I could to fathom things out ..but then had to, am still redoing things.  Instead I'll run through this as I might do if I were starting again with what I now know. 

Firstly to describe the handbrake system on these cars. Again it's not quite as I've ever worked on before. . .

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^ Firstly the handbrake lever is outboard, on the floor between the door and the driver's seat.  In a previous post I'd shown that I'd removed the door's arm rest so that I might more easily get my arm down to reach the handbrake lever.   Under the seat is a rod which comes in the drive-shaft tunnel just behind the plate under the gearbox mount.  The second photo shows its inboard lever arm ..with the handbrake on (lever fully up).  A cable then runs to the rear of the car (actually to a turn-pillar mounted on the rear axle (really weird ! :blink:). . .

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^ This is that turn-pillar, which as you can see is literally bolted on to the differential's rear casing.  The cable from the forward lever arm is the one at the bottom. It has a screw adjuster into the square block to adjust it's length.  That square block is swivel. so there's no twist in the cable however the rear axle may raise on one side of the car's suspension or the other, even if just one rear wheel is parked on a curb.   The lever arm on the bottom of the pillar transfers the pull of the handbrake cable to the top two transfer cables. The whole lot is oddly loose, deliberately so.. to allow for individual cable length and stretch, handbrake pad wear, and adjustment.  The spring on the pillar helps keep each of the cables in cable in light tension.

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^ each transfer cable goes out to the caliper's handbrake lever.  Again it's all oddly loose.  The pivot-hinge end of this lever goes onto the very end of a claw.  There are two claws, each with a handbrake pad, one on either side of the disk. These pivot / hinge off the brake-caliper carrier. The lever arm also has a ball ended 'adjustment bolt' (like a countersunk bolt in a very rounded off countersunk hole) across to it counterpart claw on the other side of the disk brake.  As the cable is pulled, the hinged-pivot lever pulls the adjustment bolt, which in turn pulls the other claw (and it handbrake pads) onto the disk.  As both claws are hinged from the calliper carrier, the handbrake pads equalise on the disk.  Heath Robinson couldn't have conceived a more fun assembly.! :boomer: Altogether these casting are not lightweight.   It no wonder Jaguar soon went across to independent rear suspension with inboard brakes.!

 

Going back to the front, under the car . . .

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^ one of the things I didn't realise, until I read a Jag forum post, was that the forward lever arm (by the gearbox mount) is on a spline ..and can be adjusted for angle relative to the handbrake lever inside the car. With the handbrake all the way off / fully released - the transfer lever pointed straight down.  This one was incorrectly adjusted (first photo). You can see, in the second photo, it had been in contact with the gearbox mount's plate.  ie. the lever would hit this stop before the handbrake was fully applied. I've now adjusted it (second photo) so the transfer lever starts off from being at an angle of about 15-degrees back.  When the handbrake inside the car is applied the transfer-lever then comes to the vertical ..maximising the take up of slack in the cables and the closure of handbrake pads onto the disks.  I don't know, but I may yet have to take its angle even further back.

The handbrake at the calipers . . .

I tried to see how it worked, and to inspect it by crawling under the car and using a torch to see what was what..  I must have been having a blonde moment.  When looking at an exploded diagram I saw how it was assembles and so when I re-visited the issue I simply took the claws / handbrake assembly off. . .

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Disconnect the cable's fork end and claw's the two pivot-bolts (through the caliper carrier) and the whole assembly simply lifts off.  This would have to be the easiest way to replace worn pads too, and at the same time to clean, check and re-grease the moving parts.  

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^ Under the cover and inside the pivot-lever arm is the handbrake's self-adjusting mechanism. If the lever is extended beyond a certain point the pawl engages against the sprung clip and is tighten on to the adjuster bolt.   The spring inside hooked onto the cross bar, retracts the pivoting lever arm to release the handbrake pads off the disk.   Not much to do in there aside from clean it out, check that all the parts are serviceable and to lubricate.

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^ putting the cover back on is a bit of a pain, because its pin is also the pivot for the lever, and the lever is being pulled by its internal spring. However you might see the geometry of this pivot (where the screwdriver is in the hole) relative to the adjuster bolt going to the the other claw.  I think this car's nearside handbrake is faulty in or around this pivot pin because the pivot-lever is always wide open. Given half decent weather I'll check that tomorrow.   Btw. to get the pin in, I rounded off its end with the angle grinder and then smooth file ..which made its passage through five parts very much easier.  

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^ you may have noticed these strange brass forks in a previous photo.  I thought it was an anti-rattle pin, they are sort of but more crucially those prongs are a crucial double spring ..to hold the (released-handbrake) pads off the disk. Each prong needs to be individually adjusted - relative to the tightened bolts so that when assembled the handbrake pads are each 1/16" off the disk. When the cable and adjuster screw is correctly adjusted this clearance will be less, but the sprung brass forks are then under slight tension.  It's all somehow ingenious but at the same time somewhat weird to me.        :bouncesmile:

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That's it ..I think, for handbrakes and rear calipers.    All I need to do now is to get the other side corrected. and then to sort the what's happening with the servo, and then to properly bleed the hydraulics.   

But that's all for today . I bid you a good Sunday.

Pete.

 

 

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Disc brakes  seem to have got less complex over time, unlike most other car systems.

I have no experience of this happening, but it is often said that brakes sticking on can be due to failing flexible hoses acting as non-return valves.

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@Bfg: Another possible cause of your brake pedal and locking on problems could be that the adjustment between pedal and master cylinder pushrod needs  to be relaxed a bit so that the piston in the master cylinder can clear the port to the reservoir (brakes off).  If the piston is prevented from retracting to this position, the brakes will still work but any heat generated at the discs will cause the fluid to expand, thus locking the brakes on until things cool down.  With the reservoir port in the master cylinder open (cleared by the piston), any expansion will simply push up into the reservoir when the brakes are released. 

No harm done by checking everything else though.

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Thank you all

The servo is a remote unit, and the master cylinder to brake pedal has no adjuster for it's length.  The manual recommends the pedal should have 1/4" float. Mine has 1/2".  The car's brakes act the same whether cold or after its driven 10 or more miles and around town. The fluid level is correct in the reservoir bottle, so neither too high nor too low.  I'm using DOT4 fluid as recommended.  

Cheers, Pete

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Jaguar-Daimler Brakes - Part 4.  Handbrake not working.

Okay back at it again today, addressing the nearside (RHS) handbrake, which was somewhat worse than the offside. . .

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^ As it was, the handbrake pads released but unevenly, and the pivot-lever arm, attached to the inboard jaw was already a good 20-degrees open ..even when the handbrake was off.  The consequence of this was that the cable length to the turn-pillar mounted on the differential was too long.  And because that pillar is allowed to tilt over (to centralise braking force to left and right hand handbrakes) this (wrong angle of the near-side pivot-lever arm) adversely effected the handbrake on both sides.   Disconnecting the cable and removing the two pivot-bolts that attach these claws to the caliper's carrier, I removed the whole handbrake assembly. . .

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^ After cleaning (..for ease of handling) and removing the covers the first part of the problem was that the return spring was stretched and too long ..by 6 or 7mm

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^ having no replacement and not wanting to wait for one to come through the post, I re-bent the one I had and cut off the excess. Reduced from 40mm non-tensioned length to 33.5mm.  It'll do but I'll order a new one. 

Next up was that pivot-lever simply would close down to the claw anywhere near as much as it does on the offside handbrake. 

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This arm is (pinned) pivots through the square block at the end of the claw. Oddly I found by turning that around and refitting the pin gave me an extra 4mm of closing (measured at the cable connector end).  Cleaning up of the rust and paint under it gave me a little more, and a bit of filing of the underside of the pivot-lever arm a little bit more still.  ^^ after cleaning out a bit more, fresh grease, inside cover & spring, then the handbrake's self-adjuster pawl refitted, it was ready for the outer cover to go back on. . .

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^ The brass prong (spring) needed removing, bending in a vice, and refitting several times to get the brake pads more or less equally open on either side of the disk.  And you can see the cable now appears too short by some 1/2".  In fact the cable was loose before so my effort resulted in perhaps 3/4" or better improvement. Sufficient to have to undo the adjuster screw ..on both sides of the car, each by half a turn.  The car's handbrake now works well, although I would have preferred less angular travel at the handbrake lever.  Still the handbrake holds even under first-gear driving load.  And then they free off again.!  

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^ To reduce the angular travel of the handbrake lever I can re-adjust the forward lever arm (by the gearbox mount) another 10 degrees on its spline.  The cable from this has an adjustment screw to take in the length.  It may help a little, but first I'll need to re-bed the handbrake pads in, because the incorrect fitting of the caliper carriers (without centralising spacers) has meant these pads have each worn skewed.  When the pads wear-in then the handbrake will be better still.  

Job done ..almost.     B)

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Jaguar-Daimler Brakes - Part 5.  Fitting brake pads ..an interesting feature . . .

 

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^ these disk brake pads have a thin plate with a slot in them (note the parallel gap between that slot and the pad) ..which are supposed to engage with a flat headed pin projecting from each piston (indicated by the red arrow).  They are more than just locating pins, and they are easily fitted wrong. How do I know ?  well . . .  

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This pad had been fitted without due care to engage the piston's flat headed pin in the slot.  So when brake pressure was applied the plate was dented in.   

What's it all about ?? . . .

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^  I've not come across this before but, if I'm reading the workshop manual correctly, its saying that piston's 'retractor pin' is coupled to a spring which ..when the brakes are released, draws the pad away from the disk by 8 - 10 thousands of an inch.  Other bits of the design are to accommodate brake pad wear.   As I say ..never heard of it before - but bloody clever those Girling folk.   

So. . . , if the pin is not engaged in the slot, or if the slot's gap is too big (uneven) ..perhaps because someone (me ! ..would I ever ??  :ph34r: ) tried to prise the piston back into the caliper, then the brake pads will not retract as they are meant to..  That equals brakes dragging (= heavier fuel consumption and less performance) and accelerated brake pad and disk wear.

Thought I'd share this, 

Pete

 

p.s. I was wondering what to do with the brake fluid I wanted to throw out, having replaced what was in the master cylinder and reservoir with fresh. I was adverse to digging a hole and pouring into the soil so (to me) the better option was . . .

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^ patio heating oil

Slow burning rather than flash or explosion. I half filled the thin with the old brake fluid and lit the paper towels I'd been wiping thing clean with, and dropped it into the fluid.  Nothing dramatic, but topping it up from my jam jar of brake fluid - it burnt steadily (despite gusty breeze) for hours.

 

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Next I'll have to work on the servo.. 

The fault my car has is that brake servo appears to stick at the top of the pedal and then releases suddenly with too much braking force (rather than a smooth and progressive action). . . I have disconnected the vacuum at the manifold, which removes the servo operation. The brakes pedal and hydraulics then work smoothly and progressively (albeit heavy without the servo to help).

As i have no experience of this I thought I'd ask ...  Can anyone advise what, if any, remedial work can be done on a Jaguar Mk2 or Daimler 250 brake servo, without removing it from the car.?

...or is that just too much hassle because of the very limited access.?

 

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Further to this, is there a way to disconnect the hydraulics and bung the pipe ends so as to minimise the amount of breeding.? I'm wondering if perhaps grease or brake bleed-nipple rubber caps would do this.? I can of course empty the brake fluid reservoir to minimise the head (height differential pressure) but I would be glad to hear of any useful tips before I start into this.
 
Is there a specific place to bleed the system after, just, the servo has been removed.?
 
Is the servo's control valve something I can pull apart myself and service or is it a job for specialists.?
 
Many thanks for your advice.
 
Pete
 
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Thanks Gents..

As an aside I happened to come across photos of my previous Daimler 2 ½ which I had c.2000-02.  It's an automatic but with a lovely (after several pots of Connelly's leather care) cream interior and walnut dashboard.  I used it for several weddings and with light cream coloured silk ribbon from the bonnet mascot to the top of the A-posts and fresh cut flowers on the back shelf - she looked gorgeous.  These photos (from before I had a digital camera) are from when I visited my friend Judith and her children in the west country. We drove around to see the extent of floods over the fields.  Twenty-years-on the children (triplets) would be all grown up by now. Shame I lost touch with them. Perhaps I'll look them up this summer when I go across that side of the country.   

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Jaguar-Daimler Brakes - Part 6.  woes of removing the servo ..

On 30/04/2024 at 10:15, Bfg said:

I disconnected the vacuum at the manifold, which removes the servo operation. The brakes pedal and hydraulics now work smoothly and progressively (albeit heavy without the servo to help).

So.. It's reasonable to conclude that despite the brakes seeming positively excellent when I bought and first used the car, there were issues.  Disconnecting the vacuum pipe to the servo turns it off.  The disk brakes still work fine, albeit a lot of pressure on the peddle is required to slow such a heavy car before the next millennium.  A friend and I went out for lunch, in the car, on Thursday and the unassisted brakes are really not so heavy as my size 13's might have feared, but of course watchful anticipation is needed ..to avoid that feeling of impending doom. 

Friday, the weather here was wet ..and then more wet, and then more wet still .. so I couldn't get on with another job (outside) as planned.  Instead I moved the car tighter on its nearside to the garage wall, and with half the boot-lid out in the rain, to gain garage working space - and I removed the front OS wheel so as to access the servo unit. . .

P1020869s.jpg.e900bc665eaebde71839795ebe760606.jpg    P1020870s.jpg.dd9e54b699869cc61c1e4c236092be3f.jpg   P1020873s.jpg.624f06b6570814922d5fa8f20d19eed4.jpg

^ These Jaguar Mk2 / Daimler 250's brake servo is behind that bulge in the inner wing.  It's a bolt on cover and besides that (to the front, under the headlamp) is the servo's vacuum reservoir. 

That cover has to come off to remove the servo, and it would have been much easier if there were a little clearance to get a socket on the nuts. The bulge is too close until I hammered a chunky screwdriver inbetween them. 

Inside the engine bay, the servo and its brake cylinder is located under the windscreen washer bottle.  I removed that and its bracket to ease access to the brake pipes. . .

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^ reaching down / working between the radiator (bottom left of photo) and its fan shroud, the water pipes (bottom right), and the rocker cover (right of photo), I disconnected the brake pipe from the top connection of the slave cylinder (above the left paper towel) and tied that (pipe end) up above the brake reservoir - so as to prevent siphoning.  I then removed the brake pipe from its connection into the end of the brake cylinder and from its connection into the brake pipe junction.  The reservoir hasn't been drained and even though the pipes are off, very little fluid was lost.

^ In the bottom right hand corner of this photo you'll see a small diameter (9mm) metal pipe coming up. The bottom of which has a jubilee clip securing a rubber hose. This is the vacuum pipe from the inlet manifold to the servo. I disconnected the rubber pipe from the metal one.  

^ Just under the brake pipe junction you can see the end of the master cylinder is shiny. that's where a saddle clamp was.  I doubt if that was original. I didn't look very old, nor is it really necessary..   The servo's diaphragm canister looks new, and I'd been advised that this servo unit probably was an upgrade or a later type. I don't know if this particular car was originally fitted with a servo or whether someone added it later on, perhaps when the brakes were recommissioned a couple of years ago.  Who knows ? and I'm not worried enough to pay out for a Heritage certificate to find out.

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^ The servo unit is held in situ, by three studs through the front flat-face of the under wheel-arch cover, the nuts are accessible via the gap between the bulge and the vacuum tank. The vacuum tank is supported by a bracket onto one of those studs (seen in first photo, after it was released).  Only with the three nuts off can the servo be pulled forward ..a bit into the engine bay, to release its studs from the cover, so that the cover can be prised off its studs on the inner-wheel-arch. To be honest I was not in the sweetest of moods doing this job - the pissing weather had stopped me getting on with something more pressing ..but even so this installation is a royal pain-in-the-arze.   Nevertheless after just one and half hours !!! ..it was almost off.

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^ It's a Lockheed unit, which judging by its condition has (aside from the cast iron master cylinder) been mostly replaced. Even after wiping clean (carb cleaner was wiping the black paint off), there is no evidence of pitting from 56 years of corrosion.

I've never taken one off before, nor even handled one, let alone pulled one apart. I don't know what this particular one was off nor what model it is should I need spares, but hey up ..in for a penny in for a pound-force..  here goes . . .

.. my next post..

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Jaguar-Daimler Brakes - Part 7.  mysteries of the servo ..

Having read and studied the issue of how a servo works, I could now sit down and write an explanation with diagrams.. however I happened upon the following YouTube video which is presented by a college lecturer in Auckland NZ which presents it so very much better than I could.  It's very long (50+ minutes) so I played it at x1.25 speed.  His (non-American) accent and presentation is clear to English speaking audiences. . .

 

^ Highly recommended to anyone who interested to learn, whether novice or experienced - it's a brilliant tutorial.

Pete

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Jaguar-Daimler Brakes - Part 8.  delving into my Daimler's servo ..

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^ the servo as removed and again after having been wiped clean. The studded end of the diaphragm canister is held on by a screw-clamped band, which once removed presented a very clean and supple rubber diaphragm. It had a smear of rubber grease over it which I've wiped off but I couldn't see how to pull it further apart. More disappointing was that there was no adjuster on the end of the pushrod.  In fact no pushrod could be seen, except by lifting the edge of the rubber up and peering inside.      I found another YouTube video which showed me how to get in. . .

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^ The rubber diaphragm sits over a plastic support, and when the rubber is (carefully) lifted / peeled off the support drum's central boss, I found a key.  The rubber usually holds it in place and with gravity and a little help of a wooden block tapping the support drum it dropped out. Having been fore-warned in said video, I was holding the drum against the pressure of the spring inside.

P1030005s.jpg.175caec0d1ebdd4a8f2ea29081f8d66f.jpg   

^ The assembly so far, with my showing how the key from the slot locates in a groove in the pushrod.   Still no adjustment though.

With those loose bits put aside, the pushrod didn't move. I checked again on forum and as far as I could make out that pushrod would be connected to / pushing the master cylinder that was bolted on to the canister. Pushing hard and it moved with a start..  This was the same feeling as I'd experienced through the brake pedal. Very stiff to move and then moving freely. Stop and it would stick again.  I was getting close to the issue that set me down this path.  Either the rod, piston or some other component was sticking in the bore.

It was time to pull the servo's master cylinder off the canister ..and have a look inside.

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^ having recorded the bolt pattern and location of the two plates relative to the vent, I separated the master cylinder from the canister. And then removed the sealing gasket and plastic plug.  I don't know what the crud is on the inside that plastic end plug.  It looked like corroded copper, but more likely perhaps it is rubber grease with brake fluid, discoloured by perishing rubber seal. 

Even with that out the piston was equally as hard to get to start moving.

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^ After I cleaned up the crud from inside (where the white plastic plug had been) I still couldn't see how to get into it.  I was expecting to find a circlip of some sort but the black face i could see was rubber.  With no other sign - I yanked hard on the pushrod and the piston assembly came out of the master cylinder.  The bore inside looked fine. 

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^ The cylinder's end-rubber-seal, spring locators and spring are all loose parts on the pushrod. They just slide or drop off to leave the piston assembly. Trying just this piston in the cylinder, with fresh brake fluid to help lubricate movement, the piston's seal (far right) still sticks as badly.  Clearly that had gone soft and sort of sticky ! 

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I looked to see how it was put together, and thought if I pulled it apart the seal would be released.  Nope it didn't.  The pin under the nylon-type sleeve simply holds the pushrod onto the seal holder. The larger diameter hole and the spring within the seal holder permit articulation of the pushrod - that's all.   I prised the seal out from the groove, cleaning and dried it, and photographed it under magnification ..but it has no part number moulded into it.   I needs to be replaced as this little blighty is the source of the Daimler's brakes sticking.

Searching on the internet, the moulded-in part number of this servo's diaphragm, I came across a pdf file, of a Lockheed parts catalogue / list. And from that and what remained of an aluminium parts number plate, I've found out the exact model of servo, together with the exact part numbers to replace its seals.  The reproduced catalogue is over-printed with an advert for Northwest Classics Ltd., Girling & Lockheed - brake and clutch hydraulic parts. Tel ; 01617992653    < website here > . 

I've phoned them up and order the seals I need.  Being a bank holiday, they'll most likely be sent out on Tuesday or Wednesday next week.  

The car's off the road, unless I re-bend connect the hydraulic brake pipes to circumvent the servo at the pipe junction. I doubt if I'll bother because I have plenty of other projects to get on with in the meantime. 

So that's it. Hopefully a new seal will slide smoothly in the master cylinder bore and all will be good to go. 

Aside from crawling under the car and getting filthy with dirt and brake fluid - It has been an enjoyable learning curve. 

Bidding you a good weekend with great weather.

Pete

 

Oh yeah,  p.s.   The pushrod has pitting which would make no difference to the piston seal but might be damaging to the end-of-cylinder seal (which stops fluid leaking out).  Unless Northwest Classics have one (new or good used) then I'll have to reuse this one. To ensure there are no hard edges to further damage the end seal I've rubbed it down with 600 and then 1200 grit wet n' dry, and polished it up again with Autosol    ..

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  • 2 weeks later...

Jaguar-Daimler Brakes - Part 9.  reassembly of my Daimler's servo ..

 

Hi y'all it's been some time, firstly because the May bank holiday delayed my getting replacement seals through the post, but also because I've been taking advantage of the sunny weather to progress my (long-neglected) trailer tent's build..  < here >. 

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^ Last night the weather pendulum swung and we've had rain here all day. That's okay because I could do with a change of topic and the Daimler not being on the road is somewhat disappointing. So., this afternoon, I got on with the Daimler's remote servo reassembly with new seals in its master cylinder. . .

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^ Servo master cylinder (repainted with POR-15) and old component parts.  Just two seals were required and the nice man at NorthWest Classics sent me some rubber grease too. 

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^ The lip seals are easily fitted (noting of course their orientation ..to keep the oil in the pipes and not into the servo's diaphragm canister). The pushrod and seals motion was checked to ensure that it now pushes in smoothly (the fault was that it didn't before. the seals were sticking within the cylinder).   The gasket was in good order to reuse. The canister drum goes on first and the three bolts over a doubling plate and tab plate subsequently refitted. The hole is there for air to flow between that side of the diaphragm and the control unit ..which controls the amount of atmospheric air getting into the servo, according to the braking force being applied to the hydraulics (via the brake pedal's master cylinder).

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^ with the servo's master cylinder clamped in the workmate's jaws, the spring is position ed and then the diaphragm support moulding. Pushing down on the spring until the pushrod with its seals are felt to move within the cylinder - the key (seen bottom right in the fist photo) is simply slotted into the support mounding and thereafter in to pushrod's groove.  The rubber diaphragm, when fitted, fits over this support moulding's top rim, and secures the key in place.

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^ The rubber diaphragm now fitted (seen here with its ring of raised-slightly pimples) before the top cover goes on.  The cover's orientation is obvious by the pipe connector to the control unit.  Second photo ; reassembled and ready to be refitted.   Then the bitch part of the job starts.. refitting it to the car. 

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^ I'll not go into specifics because this car's servo and its mounting without brackets is not standard, (it fits within the wheel-arch's protective cover, but it first needed to be fed through the inner wing's hole and then the cover fitted and then the servos' stud fastenings needed to go through that cover (having to do this blind because there's no direct line of sight). Then working on my own I needed to wedge the servo in place to hold it because the nuts go on from under the wheel-arch. Needless to say it would have been easier with two persons and the radiator out of the way.  As i say it's not a standard installation so I cannot really complain..   Note as fitted the control unit is at an angle below the master cylinder. This is to aid bleeding air bubbles out of it. The servo's vacuum pipes were now reconnected.

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^  Because the servo's master cylinder was dry of fluid I wanted to prime it and mostly bleed it before all the hydraulic connections were in place.  The red arrow points to the pipe from the brake fluid reservoir. This was connected to the servo's master cylinder.  The blue arrow points to the master cylinder's pipe connection to the car's brake pipes.  This was left off but the pipe connected to a bleed pipe, which has at its end a spray head. That can be thought of as simple valve. Pull the trigger and the air in the pipe is drawn out. (..obviously that spray head should be aimed into a jar as you do this ! ).  By reassembling in this fashion ; gravity fed brake fluid from the reservoir fills the servo's master cylinder and the pipe all the way to that (blue arrow) connector.  That pipe was then quickly refitted into the connector to the car's hydraulic braking system..  ^^ There's very little bleeding left to do, and that was done at the nearest wheel's calliper, that of the offside front wheel.  Again using the same bit of kit, the bleeding was easier even on my own.

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Washer bottle refitted, and the brake reservoir topped up with fresh fluid. This whole operation (dismantled 10 days ago) lost around 1/2" in level in that bottle).

Btw., when I asked on Daimler owners club and Jaguar enthusiast' Facebook pages about repairing the servo, it was suggested (..by all who replied) that they would buy and fit a new servo or else take the one I have to a specialist for rebuild.  Instead of £-hundreds., doing it myself cost two afternoons, and £11 for the seals + postage.  And, aside from this particular car's home-brewed installation, I've enjoyed learning how it all works. B)

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^ I'm now left with just two little jobs before trying it (in hopefully dry weather) and that's refitting the vacuum pipe to the inlet manifold (it was removed to test the brakes without the servo) and to refit the control unit's air intake filter (with spring) above.   This is different to the standard Jag servo, and the scanned Lockheed catalogue I have isn't exactly clear on this. It may be that it was not supposed to come off in my hand. Certainly its spring wasn't meant to go boing and shoot across the garage.  And so now I'm not sure there's not another component (a spring holder / guide washer perhaps ?).  Anyway.. the control unit is now upside down and at 45 degrees. And the small spring inside this would topple as it's refitted, so I've glued it in place, in the lid.  I might only hope it goes back together and works.!  I'm reasonably confident it will. ;)

That's it for this evening,  so I'll bid you a good one.

 

Pete

 

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That swollen seal reminds me of what used to be a common cock-up: using Lockheed fluid in a Girling system, or vice-versa. I think you could get away with it one way around but not the other and that caused the seals to go soft and swell. 
 

Big relief all around when universal fluid became the norm. Useful article for brake fluid nerds here:  https://mossmotoring.com/brake-fluid-for-classic-british-cars/

 

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4 hours ago, Asimo said:

Big relief all around when universal fluid became the norm. Useful article for brake fluid nerds here:  https://mossmotoring.com/brake-fluid-for-classic-british-cars/

Wow..  what an excellent article - Thank you for posting this link for us.  I'd recommend every-classic car owner-driver read it.

Tbh., as a dyslexic I would have had great difficulty reading it, but this morning viewed it in 'reader view' .. I then used audio (Susan) to read it for me, at a slightly quicker than 'normal' pace.   I've learnt so much, and although I've never experienced brake fade due to heat build up or water in the fluid, I am very conscious of corrosion, particularly within brake calipers and how pitting will prematurely destroy lip seals. . .

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^ I also noted the corrosion in the pushrod of this car's servo's master cylinder, which itself is odd when everything else (the canister, the master cylinder, the bore) looked almost new.

In truth, I'd never given brake fluid much thought before. I always use the recommended (DoT-4 on my old Norton, the Triumph and in this Daimler), and I'd certainly never stopped to think about bi-metal corrosion within the system, nor moisture ingress through rubber pipes.  

This car is due to be totally stripped down for its bare metal respray, and so the fluid will be replaced at that time (within the year), but in future I'll consider a total brake fluid change with flush every two years  as a necessity to help prevent caliper corrosion.   

I'll even give serious consideration to stripping out and possibly replacing every seal in the system, so as to swap over to silicon based fluids, not least because I have experience of damaged paintwork with traditional glycol brake fluids.  I wouldn't want that to happen, nor would it be economic to take the risk, with a freshly repainted car (including its engine bay).  I guess, I'll need to the same with the clutch fluid then too. The balance is that everything will need to be replaced or somehow cleaned out of the glycol , and I guess that means the pipes themselves. Those on this car were replaced just three years ago, so the decision is not so straightforward.

My Triumph doesn't have very good brakes (they're non-servo) and following my learning curve with the Daimler I have considered finding a small unit to fit to that car.  The fluids would have been replaced when the chassis change happened June '21 which again is already almost three years ago. Doesn't time fly when you're crawling under cars !

Pete

 

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Jaguar-Daimler Brakes - Part 10. !  - the Brake servo control unit .. aka, my prior delving into the Daimler's servo was in most part a FAILURE ..


The brakes (albeit with a heavier pedal) still wok fine (smooth & progressive) without the servo.  Indeed on Tuesday I used the car like this for a 150 mile round trip up to Downham market.  However, when I refitted the servo, reconnected the hydraulics and the vacuum, and tried the brakes (with the engine running ..and so vacuum to the servo) the pedal initially still felt stiff (sort of sticking) although much less so than before, and then applied the brakes heavily ..rather than smoothly progressive.  I tried pumping the brakes (as I had done before - which tended before to free them off) but this time the pedal got harder and harder until all was locked on.  OOPS.. big Not Going Anywhere  issue !

What do you do ?  Brakes are locked hard on with the car poking half way out of the garage ..even with the engine turned off - the car wouldn't move.  I couldn't pump the pedal, to use up the vacuum in the servo's reservoir, because the brake pedal was like wooden-block-hard at the top of its travel.

Quick thinking (..for an old fart).. I'll disconnect the servo's vacuum pipe to let air in, this will release the vacuum and therefore the brakes. Huh.., Not quite as easy as that - because the vacuum was firmly holding the pipe connections on. 

Next then, I reached down to the servo's control unit to prise off its top lid (inside of which is an air filter and the air valve (see below diagram, top right in blue) and manually tilted and lifted that air valve off its seat  ..and so atmospheric air pressure hissed back into the servo.  This balanced the air pressure on either side of the main diaphragm (LHS, solid black in the diagram), which in turn allowed its spring to push it back into its canister and retract the pushrod with its piston ..and release the brakes.  

The car is now rolling again..  But wot next..?   Well., I could just say something like "fck it" and buy another servo ..as most owners seem to do, or I could try to learn from my mistakes and take it all apart again.   Not liking to be beaten by something man has engineered, always glad to learn ..and my being a tight arse, I opted for the latter.  :unsure:

I didn't know why the car was having these issues, after all the brakes were reconditioned just three years ago and I've driven over a thousand miles since October with little or no issue.  But I'd determined ..  1. by pulling the vacuum pipe off that it was the servo being 'problematic'.  2. the servo's boost was working forcefully, but now not releasing when I lifted my foot off the brake pedal.  And 3. because the vacuum was not being released it must surely be a fault within the control unit assembly (sitting on top of the servo's slave cylinder in the diagram below, but hanging under it when installed on the car.)  
 
Clearly the air valve was not operating correctly / lifting to release the vacuum as the mighty size 13 eases off the brake pedal.  How is it supposed to be operated ?  

Let's have a quick back to basics, not least because most explanations say how a servo works and not what's happening when the brakes are not  being applied, nor do they really explain what's happening in the control unit . . .

        Lockheedservo-controlunitsoperation04a.jpeg.819535be49ab7066595a685371c51054.jpeg

A servo works by differences in pressure on either side of the main diaphragm (seen as solid black in the above diagram). And the diaphragm itself, made from stretchy rubber, works rather like your lips. Put a finger-tip inbetween your lips and suck ; and the finger-tip is pulled into your mouth.  It's surprising how much force your suck can put into holding the finger.  Likewise the rubber diaphragm in a servo distorts / is sucked towards the lower pressure, and the pushrod connected to it is similarly forcibly moved into the slave cylinder. 

Given the same amount of suction - the larger the diaphragm's surface area, the larger the force applied to the pushrod.   People often say ‘vacuum’ but like sucking your lips in - there’s not a ‘vacuum’ .. there’s just a difference / lesser air pressure within, than the atmosphere all around us. The suction taken from this car's inlet manifold may only be minus 5 psi (pounds per square inch) so hardly 'a vacuum' at all, but still  5 x 20 sq.inches of diaphragm surface area gives a useful 100lb 'boost' to pushing the slave cylinder's piston in (..the figures given are arbitrary but to help explain).

P1030258a.JPG.50f4dfec08f46534458f0ca50151033e.JPG  

^ The control unit also has a 'diaphragm' - but in fact this is simply a stretchy rubber gasket tight around a plastic valve-seat.   In the diagram - brakes are not applied - and you'll see it valve-seat is not closed to the 'air valve'.  So air pressure is the same on either side of it.

You may also note (in the diagram) that the 'air-valve' has a second seal within the top cap, which is to atmospheric pressure ..and it is closed.  So, when the brakes are not being applied ; the top-cap seal is closed to the atmosphere, and the vacuum / lower pressure is the same throughout the whole canister ..and the same low pressure is all the way through the external pipe (diagrammatically being shown over the top) and to the back of the servo's main-diaphragm.  The main diaphragm's spring holds it away from the slave cylinder, with its pushrod & piston retracted.

When the brakes are applied, the master cylinder (attached to the brake pedal) pushes brake fluid into the servo's slave cylinder.  Some of the pressure goes directly through to operate the brakes, (perhaps enough to take up any float between the brake pads and the disk &/or the brake shoes and the drums), and some of the pressure goes to operate this slave cylinder's 'lift-piston'.  This in turn pushes against the short plastic pushrod (seen in the photo) and the diaphragm stretches to move its valve seat to close against the air-valve seal. 

Progressively more brake pressure stretches the diaphragm-valve further, which goes on to move the air valve ..whereby the air seal in the top-cap begins to lift.  As it does so, the partial vacuum in the top half of the control unit ..together with that in the pipe and behind the main diaphragm.. is progressively released.

The release of its partial vacuum is the same as higher atmospheric pressure being allowed in.  It is this difference  in air pressure on either side of the servo's canister, even though only small in psi value, which bellows the supple rubber diaphragm towards the slave cylinder, As it does so, it pushes its rod and piston down the cylinder to close the fluid bypass hole in its piston (which is otherwise necessary - so the brakes work even if the servo fails) and to further pressurise the fluid to each wheel's brake-cylinders. 

When the brake pedal is maintained (rather than pushed harder), the drop in fluid pressure from the master cylinder allows the top-cap air-valve seal to close (spring reaction), but the diaphragm-valve remains closed. The state of pressure differential (between one side of the canister and the other) therefore remains same.  Likewise on the difference on either side of the main-diaphragm.  Because it is in equilibrium (against the back pressure of the brakes) - it remains where it is, as does its pushrod and piston, and the amount of pressure being applied via the brake fluid to each caliper.

When the brake pedal is eased off .. the fluid pressure from the master cylinder is released and the lift-piston no longer applies pressure ..so the elasticity of the diaphragm should cause its valve-seat to pull away from the air-valve.  ie., open.  This equalises the air pressure top and bottom within the control unit and so, via the pipe, to either side of the canister. (NB. the part vacuum is not lost to atmosphere as that top-cap air valve is closed. The low pressure its still contained within the canister) ..but, without the pressure differential - the spring between the main-diaphragm and the slave cylinder is enough to push the diaphragm back to its start position, together with withdrawing the pushrod and piston, and the brake fluid back up to the reservoir.

- - -

Okay, having worked out what was supposed to happen, I had clues as to why my car's servo didn't.  Either something in the lift-piston or air valve was sticking, &/or the diaphragm supporting the valve-seat had lost its elasticity.    Time to order a repair kit for the control unit and then to pull it apart . . .

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^ quite comprehensive service kits from peter at Northwest Classics for £50+p&p.    ^ ^ and the servo off the car again.

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^ under the control unit's plastic cover was the air-valve and the diaphragm-valve-seat.   ^^ and under the pressed metal carrier we find the lift-piston in its cylinder.

P1030231s.jpg.748ed9f629d3de44fb56b43cd3d38203.jpg    P1030235s.jpg.2121733dad7402e1bc4ac27fb671bc36.jpg

^ with the gasket removed, closer inspection revealed corrosion and a stuck piston.  In this position the piston would be holding the diaphragm-valve closed. ie. low pressure on one side of the canister holding the main diaphragm in its state of pushing the brakes on.   ^^  I hoped that pushing the lift-piston inwards would break it sticking and so then I'd be able to withdraw it. 

Huh.. fat chance !    Try as I might ..slamming it down against a block of wood (so as not to damage the gasket face) the darn lift-piston thing wouldn't pop out, nor even show any sign of moving.  And unlike illustrated in the diagram the fluid hole under this piston is a small pinhole into the slave cylinder ..whereby a piece of fine wire wasn't strong enough to push the piston out from underneath.   There was no way to grip, or thread into the top of that lift-piston.  I was stumped

. . almost. . .

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^ It's very easy to fall out of love with a classic car when you've got to refit / plug the servo's slave cylinder's back into the car's hydraulics, bleed the system (seen being do in this photo) to use the car's master cylinder to hydraulic that pissing little lift-piston out of its sodding little hole.!  hump :angry:  The metal control unit carrier is back on but its screw threads are a couple of turns undone so the piston is retained but free to move an extra mm out of its hole.

And then., take it all off again, hoping the lift-piston will now pull out, otherwise I'd have to do the same again with the metal carrier still looser . . .

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^ Yeah okay it happened, but for it taking an hour to do so I was successful*.     ^ ^ very gingerly with the grips, so as to not damage the lift-piston.

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^ I hate working on brakes.! always have, always will !     ^^ any wonder it was sticking !   The only question really is why ?  and/or..  why now ?

I guess the answer to the first question is that this bit of ferrous steel is in fact open at times to the atmosphere ..and its humidity.  Why now ?  might otherwise be.. why not before now ?

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  ^ No new lift-piston came with repair kit, so I cleaned up the old one with a softer-bristle power wire-brush and then 1200 grit wet n' dry.  I similarly cleaned within the bore hole.  Dry of fluid or grease, the lift-piston (without seal) now slides like a bobbin in and out of the hole.    ^ ^ new parts (left tray) and old parts.  Note the white plastic valve-seat need to be reused with the new diaphragm rubber. 

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^ I also went back to revisit the slave cylinder bore, which felt and looked okay, but I thought might likewise benefit from a wrap of 1200 grit around a round rod to clean out any stickiness. 

 

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^ And then to put it all back together again.  In the hope that red rubber grease would help prevent further corrosion.    ^ ^ a close up of the air-valve.     ^ ^ ^ The assembly of the control unit.

In practice there's not much to it, but for all that - it's actually a brilliant piece of design, made to necessary precision without anything at all being adjustable. That's impressive. 

Of course this is the servo (not original) presently fitted to my car.   Your own car's may be different in detail but I guess in most aspects it will be very similar in principle.

 

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^ Job done, and I've driven around the block and the brakes now work fine.  The brakes are freeing off and they are progressive. 

When I bought the car - the brakes were very high on the pedal and aggressive if at all heavy footed, but now (without being bled at the wheel cylinder) there two-inches of pedal movement before the servo really kicks in.  This feels more natural for around-town driving, but at the same time is not the race-car feel of brakes I was getting used to.  I am undecided as to whether to bleed the brakes to see if they revert to what they were before, or to leave them this bit softer.   I'll give it a few miles and then decide.  

Another cup of tea well earnt.

And I bid you a very good evening.

Pete

 

 

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On 25/05/2024 at 20:06, Dobloseven said:

I like the thinking that if something has been created by man, it should be repairable by man.  Well done again, you seem to be writing the book on these jobs.

Pretty much so, naturally it would be somewhat more of a challenge to fix something that been devised in CAD and shaped in CAM and assembled and 'for life' by robot machines. !  :(  I'm old-school and wonder about the way things are made nowadays.

My writing is many-fold selfish. .

  • The first is to sort my thinking out to to help me achieve some sort of fundamental understanding.  I long ago learnt (when I was a manager) that if I was to sensibly discuss, and perhaps even show anyone how to do, a job - then I first had to thoroughly understand not only the sequence of doing the task, but equally the whys and wherefores and the pitfalls. Then, as a former engineer, I am enjoy discovering how past masters solved creative engineering problems. 
  • Secondly my writing is a record / an aide mémoire for the next time I have to do the same or a similar job.  Ever more frequently I look back over my own posts to see what I did, &/or how far I got.!  
  • And thirdly because I am trying to teach myself how to write. It looks deceptively easy but when I read some other's work which I find clarifying or profound in insight, amusing, entertaining, or awesome in their so simple yet picturesque expression - I know it's tremendously complicated to write well.  After being barely literate for 50 years (blaming dyslexia instead of my own laziness) I'm now learning to write.  Perhaps learning such a skill / an art will ward off dementia for a few more years. 
  • Fourthly, at my age ..and having found myself more blessed than I rightfully deserve or have earned for myself - it is perhaps natural to become just a little altruistic. I might only hope that my sharing such practical experiences and my forever learning how and why ? will encourage others to ' have a go' and to enjoy doing so. It can be satisfying, if not fiscally rewarding. 

So many things I like ; have a used patina, were made with old fashion ideas of technology, with more tactile materials and man operated manufacturing processes. Many more are classic, vintage, or antique, are not mass produced and may even be hand-made. To me they have a tactile and visually interesting charm, and have fine details, even flaws which are their own ..but they have parts which are not 'throw away and buy another'.  There is a mindset to overcoming the frustrations and finally fixing something, perhaps even creating something new or a variation on what was. 

It saddens me to think of a future society when everyday populous gives up thinking through problems, in favour of buying disposable every things.  However for those who can - there are opportunities in recommissioning, restoration and even recreations.  As classic, vintage and historic 'anything'  become a valued commodity - their owners will pay for their repair and their everyday maintenance.  The business of exchange units is fading because the old hands are fast retiring. There's many an opportunity for you paper shufflers, computer form punchers, and dead-ended job drones to take over. Many a cottage / garage business is just waiting to happen. B)   ...but don't wait too long or else those who know 'how' will no longer be around to ask.

P.

 

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Amen & Bravo....

As an apprenticed fitter/techy/draughtsman (.. now 66) I see all of this through your 'prism', similarly finding satisfaction fixing -the- fixable >> and, yes, feeling a quiet desperation as Fixable is morphing into Ultrasound Welded = no seams/no screws/no chance 😕

Cap doffed 💯

🚙💨

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