75 P6 V8 - Bye, this car

[Clanger]

No, of course not. My usual P6 mechanic is too busy for it. I have consumed two bottles of brake fluid though. 

Surely that won't do you much good?  Probably tastes better than generic vodka though...

[forddeliveryboy]

If you're reusing the fluid which has dripped into a rusty baking tin there's no wonder you've got problems with the braking system, eh?

[Conrad D. Conelrad]

I'm not re-using the fluid! 

 

My car gets only the finest brand name 20w50, DOT4, AQF and GL4 from sealed bottles. 

[cort16]

Those roast potatoes aren't going to taste great.

Not tempted to create an access panel for those brakes like folk used to do on the xj6?

[forddeliveryboy]

I thought xj6 types with P6s just replaced the whole axle with a later Jag one.

[LC Torana]

It's dripping from or near the rear calipers, yes?  The lines are not wet, forward of there?

[Junkman]

It's dripping from the left caliper, specifically from the seal of the handbrake mechansim shaft,

the change of which requiring the caliper to be dismantled.

[danthecapriman]

I take it that seal comes with a recon kit?

I suppose it's taking the brakes apart that's the unpleasant bit of this.

[Junkman]

Taking it apart is not unpleasant. Everything that follows is.

[Junkman]

It depends on how seized and rotten the mounting bolts and bushes are.

The bolts are about 7 inches long and usually have a corroded allen head, so they love to round off and snap a lot.

The calipers swivel on these bolts/bushes, since they are mounted at an angle in relation to the discs, hence the pads are wedge shaped.

On Conelrad's car this shouldn't be an issue, since they were replaced just a few years ago when he got the car.

 

The story as far as I remember is that I overhauled two calipers, they went in the car and one refused to do its handbrake stuff.

It thus came out several times and was overhauled and checked again and again by me and Arnold, an old artist that had his

first exposure to P6es during his apprenticeship at the GMP motor pool in the Seventies. Although we both couldn't find a fault,

this caliper simply refused to react to the handbrake mech at all, no matter what we did. Rover P6, you know.

So it got replaced with a used caliper courtesy of the always golden hearted Steve Benyon, which just worked,

but never was overhauled. I think it's this caliper that's now pissing from the seal where the hand brake mech shaft enters.

The caliper has to be taken apart to replace the seal, since when you just pull the shaft out, which you theoretically can do in situ,

a little pushrod inside becomes dislodged and it will never go back together.

 

To basically understand how these calipers work, you need to imagine that the piston actuates a bellcrank, which pushes one pad

out and as a reaction the entire caliper swivels, so both pads grab the disc.

The handbrake mechanism is largely inside the caliper and actuates the same bellcrank via a little pushrod that overrides

the piston. Incorporated in the whole deal is also an automatic adjuster for pad wear, but I'm not mentioning that, since your mind

is already boggled enough without it.

 

The only thing I can say after having done this FOUR FUCKING TIMES in my life is that getting the rear brakes of a P6 from

fucked to working is an endeavour that makes the bloody moon landing pale in comparison, if that ever happened.

[Zelandeth]

Silly question that I probably should know the answer to:

 

P6 rear brakes...WHY?!?

 

Why the heck did they use this convoluted inboard inaccessible nightmare in the first place?

 

It makes the suspension on a Xantia Activa look user friendly.

[Junkman]

Why the heck did they use this convoluted inboard inaccessible nightmare in the first place?

 

Because they could.

[somewhatfoolish]

Silly question that I probably should know the answer to:

 

P6 rear brakes...WHY?!?

 

Why the heck did they use this convoluted inboard inaccessible nightmare in the first place?

 

It makes the suspension on a Xantia Activa look user friendly.

Unsprung weight is the answer; if your brakes are bolted to the rest of the car your ride quality is better..

[LC Torana]

It's dripping from the left caliper, specifically from the seal of the handbrake mechansim shaft,

the change of which requiring the caliper to be dismantled.

urgh.

[Junkman]

 

606781 are the bolts that always snap.

 

601953 is the seal that's leaking. It's actually a rubber ring and a stepped nylon washer, that's always borked and unavailable.

[SiC]

It's your lucky day! It is currently in stock.

 

http://shop.roverp6cars.com/epages/es146747.mobile/en_GB/?ObjectPath=/Shops/es146747/Products/601953&Locale=en_GB

[Junkman]

The inner workings of the caliper:

 

 

601922 is the little pushrod that falls out when you pull out 606783 from the previous post.

[Junkman]

It's your lucky day! It is currently in stock.

 

http://shop.roverp6cars.com/epages/es146747.mobile/en_GB/?ObjectPath=/Shops/es146747/Products/601953&Locale=en_GB

 

Getting the overhaul kits is never a problem. The problem is that they don't contain what's commonly borked.

[Junkman]

The calipers in situ:

 

 

 

The innards:

 

 

That translucent yellow bit is the nylon washer that's usually fucked and made from unobtainium.

 

Note that everything needs to be nicley painted, so they look good when you rolled your Rover.

[Zelandeth]

Unsprung weight is the answer; if your brakes are bolted to the rest of the car your ride quality is better..

 

Cheers!  Makes sense really.  Was sure there was a reasonable logical reason that they did it - even if it seems ill advised from a maintenance perspective.

[forddeliveryboy]

Unsprung weight is the answer; if your brakes are bolted to the rest of the car your ride quality is better..

Better grip too with the lower unsprung weight, better cornering with lower polar inertia and better wheel control under braking with loads transferred direct to the chassis rather than via the suspension.

 

But, cooling and servicing problems and incompatibility with ABS. Bit of a pita for a mechanic.

 

Of all the cars which used them from Audi and Alfa to Mercedes and TVR perhaps it was the 2cv which made best use of them with its low mass and easy accessibility. They were even fan-cooled.

[somewhatfoolish]

Better grip too with the lower unsprung weight, better cornering with lower polar inertia and better wheel control under braking with loads transferred direct to the chassis rather than via the suspension.

 

But, cooling and servicing problems and incompatibility with ABS. Bit of a pita for a mechanic.

 

Of all the cars which used them from Audi and Alfa to Mercedes and TVR perhaps it was the 2cv which made best use of them with its low mass and easy accessibility. They were even fan-cooled.

Easy access once you've removed the wings, the phlappy triangular bits that fill the gap between the bonnet and the wings, all the cardboard ducting that disintegrates if you so much as brush against it, and probably the airfilter as well. There aren't many fasteners holding the wings etc on, but if they're neglected at all they rust solid and are a colossal pain in the arse, because french.

[danthecapriman]

Couldn't you get the unobtainium nylon washers made up using a 3D printer? There's loads of little companies around now that will do it. Failing that some nylon rod turned down and cut to size with a lathe or similar?

[Junkman]

You could indeed.

[forddeliveryboy]

Easy access once you've removed the wings, the phlappy triangular bits that fill the gap between the bonnet and the wings, all the cardboard ducting that disintegrates if you so much as brush against it, and probably the airfilter as well. There aren't many fasteners holding the wings etc on, but if they're neglected at all they rust solid and are a colossal pain in the arse, because french.

Only if you're replacing discs. Pads take less than 10 minutes to replace (about 3 or 4 if you've done it a few times), handbrake pads perhaps half an hour including adjustment.

 

Front wings off and back on is under twenty minutes anyway. Sounds like you've been near a car which was slightly* knackered and hadn't seen any decent servicing in years, swf?

[Asimo]

Anyone with a lathe can make the nylon washers. 3d printing can make parts of approximately the correct dimensions but the mechanical and chemical properties will be completely different.

 

As for why inboard brakes?: the rear suspension design of the P6 does not have to cope with brake torque because the brakes are inboard. Neither does the suspension have to resist side (cornering) forces, that is done by the drive shafts.

 

The contemporary Mk4 Zephyr / Zodiac had a similarly stinking reputation for rear caliper woes despite the brakes being in the common position. MR2 handbrake / caliper issues made me hate that poxy thing. Handbrake via the caliper is a shit idea so Citroen used seperate handbrake calipers.

[Squire_Dawson]

This is precisely why I shy away from rear discs. It's just not conservative.

[Junkman]

The contemporary Mk4 Zephyr / Zodiac had a similarly stinking reputation for rear caliper woes despite the brakes being in the common position.

 

They are the exact same calipers.

The issue is not the inboardness of the P6, which is merely an inconvenience, it's them daft calipers themselves.

[somewhatfoolish]

They do look willfully complicated; it makes me wonder how terrible the rear calipers are on early P6s, it's often mentioned in buyers guides that it's a different system made of unobtanium and lubricated with unicorn sweat.

[Junkman]

That's why all of them have meanwhile been updated to the later system, which is equally shit, but at least you can make parts for it on a lathe.