project 1951 Pontiac Chieftain

[PhilA]

Thoughts on gearbox operation.

 

In this gearbox, pressure is everything.

The faster the gearbox turns, the faster the oil pump turns, the higher the pressure.

The higher the pressure, the valves open and operate the next gear, and the next, and the next.

The throttle pedal position operates a pressure bleed-off valve.

Open the throttle and the valve bleeds off pressure, meaning the gearbox has to rotate faster to create enough pressure to overcome the spring tension in the valve body, meaning it changes gear later.

 

So, if I press on the throttle, engine speed rises, gearbox pump speed rises but I'm bleeding off pressure faster than it can make, resulting in no gear change.

Letting off the throttle closes the relief valve, forcing a gear change, the pulse of pressure knocks it into the second epicyclic position (third gear, with a very brief engagement of second gear). Pressing throttle again holds third because it requires less fluid bleed off.

 

In short, all the seals in the gearbox are shot, it's leaking fluid, not making the correct pressure in the valve block and not changing gear until high engine speed and a closing of the throttle pedal relief.

 

Gearbox overhaul on the horizon.

 

 

Phil

[Zelandeth]

Obviously sort the seals which are actually leaking - but worth a good fluid change and cleaning/replacement of the filters and running some good quality fresh fluid through it before pulling the whole lot apart.

 

Behaviour sounds very like what the box in my first Saab was doing - which had 20+ year old 115K mile old fluid in. Just changing the fluid in that made a massive difference. Still felt like it changed gear with a sledgehammer, but at least it would actually change up through the box on its own again at sensible points.

 

Especially true as it leaks, and you've no proof it's been topped up before with the right stuff...could have any old oil in just now.

 

Not saying an overhaul isn't a bad idea, but you might find it can be shuffled a few places down the to do list.

[PhilA]

It's meant to have Type A fluid in, but you can't get that any more, so any flavor of Dexron from II to VI can be used.

 

It's definitely got Dexron in it, it's a nice clean shade of red (checked the dipstick) and I recognize the smell. The floor has a little access panel under the carpet to get at the dipstick.

 

It's a recommended item because when the valve block gets all out of order it'll try to engage both bands and a clutch at the same time. Obviously that's bad, it happens on deceleration- where there's a fair bit of pressure in the system and that tends to destroy the first epicyclic band.

 

Complete, full overhaul kits are available, from external seals to full clutch/valve/seal/shim sets. The seal overhaul set is $179, which isn't really bad. I look at it this way, that's $2.67 a year or $0.0017 a mile for the lifetime of the gearbox so far.

 

Plus, if I want to drive it anywhere, I'll need to redo it. It's evidently been sat up for a while, me running it is making the ATF leak worse. It's dropped probably about a pint of fluid on the driveway and road so far.

 

One nice design feature- the oil pan on the bottom has a drain point, but the fluid coupling torus does as well. Rotate the torus round, locate plug and you can fully drain the gearbox of all oil in one sitting, there's none of the usual "well, the torque converter is full of the old oil and will need to be flushed several times" nonsense.

 

It's evident the engine has seen some reasonable work as it doesn't leak at all and holds decent oil pressure. It's even got new core plugs. The gearbox needs the same treatment, particularly as I do plan on actually driving the car places.

 

First up, electrical. Second up, steering, suspension and brakes. Third up gearbox. Fourth, rusty bits. Fifth, cosmetics.

 

Phil

[PhilA]

I am hoping that the "bodywork wins" you find are much fewer than I experienced:)

Good work on sorting the lights though - really good improvement, and satisfying to boot:)

I found the first few mig wire tails today! Front wings have been repaired down by the turn signals.

 

So, in general, it's been fixed by having metal let in. To exactly what standard, I have no idea but it's certainly not the standard American wire mesh and wob job.

 

Phil

[PhilA]

 

Two different failure modes of old bulbs.

 

Cleaned up the garage, tidied and cleaned the workbench ready in prep for taking off manifolds and adjusting valves.

 

Phil

[LightBulbFun]

20180908_163835.jpg

 

Two different failure modes of old bulbs.

 

Cleaned up the garage, tidied and cleaned the workbench ready in prep for taking off manifolds and adjusting valves.

 

Phil

 

I was not sure if I should explain why they failed the way they did (while I certainly enjoy lightbulbs I understand not everyone wants to hear someone yap on about them) but since you went through the trouble of posting pics ill do so

 

the one which failed all shiny black/silver, is generally how a incandescent lightbulb normally fails

 

over the life time of an incandescent lightbulbs light tungsten metal slowly evaporates from the filament ending up deposited onto the surface of the glass bulb causing it to blacken/go dark eventually as more and more tungsten evaporates away the filament gets thiner and runs hotter because of that forming hot spots in the filament, which eventually get too hot and fail blowing the filament open. (halogen lamps work on the princiable of using halogens/chemestry to re-deposit the evaporated tungsten back onto the filament reducing/eliminating bulb blackening so you have much better lumen maintenance over a bulbs life time and you also increase the life time of the filament as your putting metal back onto it)

 

the one which failed all white failed because air somehow leaked into the glass bulb causing the hot tungsten filament to react with oxygen in said air, turning into tungsten trioxide which is a yellow-white colour

 

hopefully this all makes sense 

[PhilA]

TBH I posted that picture for you

 

The filament on the white one must have been close to the envelope. Running 12V through it (it's rated 6.3V) make it hot enough to breach the glass- the green mark at the top.

 

The black one just went phut, about 2/3 of the filament is missing.

 

Phil

[LightBulbFun]

TBH I posted that picture for you

 

The filament on the white one must have been close to the envelope. Running 12V through it (it's rated 6.3V) make it hot enough to breach the glass- the green mark at the top.

 

The black one just went phut, about 2/3 of the filament is missing.

 

Phil

I had a feeling as such

 

yeah I have seen things get proper ugly when the filment somehow manages to touch the glass envelope of a bulb your one is fairly tame ( in the small 12V automotive type bulbs it normally is results in the glass bulging out and just melting/completely wrecking the fixture its in) 

 

the blackening during normal can also trap heat in which can also cause the glass bulb to melt and bubble up and wreck shit up much in the same way. (I have mostly seen this happen to the wedge type bulbs found in side repeaters etc)

 

also 6.3V? id go back and check if the last owner also has an old Vacuum tube radio missing its dial/pilot light 

[PhilA]

Yup, at least one is an old radio pilot light.

 

Surprising, bayonet.

Glass contact is normally at rated voltage though!

 

Phil

[LightBulbFun]

yeah in automotive applications you generally see bayonet bulbs even in the US

 

because a Bayonet bulb cant shake it self lose due to vibrations.

 

which means of course IIRC the dash lights on an MGB are Screw cap, because prince of darkness thats why...

[PhilA]

Had a bit of a clean up of contacts.

 

License plate light works now.

 

 

Moody shot for y'all.

 

 

Phil

[PhilA]

Does it have good working Wipers Phil? Epic Car loving the transmission selctor

https://youtu.be/T0WX-5gb18g

 

I found the correct pipe going through the bulkhead and hooked it up to the vacuum.

 

They.. try. I may need to adjust vacuum things, that was hooked up to the Big Yellowish Tank, hence why they tried a few times after the engine was shut off.

 

Further investigation. Probably perished seals (common theme!).

 

Phil

[PhilA]

Pictures later, but so far the largest clearance on the valves has been 44 thou.

 

FORTY FOUR

 

It's meant to be twelve thou cold.

 

 

Time to adjust!

 

 

Phil

[mat_the_cat]

over the life time of an incandescent lightbulbs light tungsten metal slowly evaporates from the filament ending up deposited onto the surface of the glass bulb causing it to blacken/go dark eventually as more and more tungsten evaporates away

 

You're mistaken - it's commonly believed that light bulbs emit light when actually they suck up darkness! So the blackened glass you can see indicates that the bulb is full of dark, and must be changed. Further proved by candles - when they are new the wick is white, but as soon as they have sucked up a bit of darkness, it goes black.

[LightBulbFun]

You're mistaken - it's commonly believed that light bulbs emit light when actually they suck up darkness! So the blackened glass you can see indicates that the bulb is full of dark, and must be changed. Further proved by candles - when they are new the wick is white, but as soon as they have sucked up a bit of darkness, it goes black.

 

no no sir

 

what your thinking of are Black Light fluorescent tubes 

 

[PhilA]

So, as I have said, I wanted to get the valve lash set up better than it currently is.

 

 

Started by propping the hood up with a piece of metal pipe for better access.

 

 

Something tells me that's not quite the original shape the factory bent that to. Regardless, it's off now.

 

 

Pipes and such coming off.

 

 

Undo the carburetor. Someone has put the wrong damn nuts on two of the studs. Those need to be replaced.

 

 

Couldn't get the distributor vacuum line out of the carb. Didn't fancy breaking anything so just sat it up top.

 

 

Discovered the rear bolt is through into the water gallery. Drained the water off.

 

 

Now that's a manifold! I think the last time we saw anything like this in the beige it was stamped BEDFORD.

There's a spring weighted thing on the exhaust too, need to see what that does later.

 

 

It just sort of goes on and on and on.

 

 

Tappet chest covers removed. Moderately clean inside which is nice.

 

 

And this is where I had to stop. I need to get a couple thin 9/16" spanners to adjust everything up. I'll probably end up pulling the plugs because it's difficult to turn the engine over. There's not enough room to put a socket in the crankshaft balancer pulley or anything.

 

As stated, the worst clearance is 44 thou', so I am guessing that the lash was set by looking at it from a distance and using uncalibrated eyeball.

 

Exhaust manifold gaskets need to be replaced really, so I'll keep an eye open for some.

 

Hopefully next update will be of a significantly quieter engine.

 

Phil

[PhilA]

Ignition switch arrived.

 

 

Please understand that the key fob it came with is just plain unpleasant.

 

But, that gives accessory plus ignition. Does anybody know which way up it should be? Key ridges up or ridges down? Research suggests ridges down.

 

Next up, starter motor button.

 

Phil

[PhilA]

 

This is quite an art.

 

 

Phil

[hairnet]

dancing spanners (sorry wrenches )

[Squire_Dawson]

Ah yes, side valve tappet adjustment. Not a job I relish. The spring flap in the manifold is probably a hotspot for rapid warming up. The beauty of a s.v. engine is that they run for longer periods without adjustment. Once you have done this you may never have to touch it again for years. They are also a lot quieter because there's no rattly pushrods or valve gear. The price to be paid is fuel economy and power per cylinder capacity as half of the combustion chamber is effectively wasted. New gaskets are essential. Good progress.

[PhilA]

Yes, but yours only has 8...

 

 

I hurt from laying over the wing so much.

 

Phil

[PhilA]

That's six done.

 

 

I'm getting the hang of it, but what a complete and utter Corbyn of a job it is.

 

I'll be glad to not do this again soon.

 

 

Phil

[PhilA]

The ignition switch lights up. The bulb even works...

 

 

Thought that's a nice touch.

 

Phil

[hairnet]

You slag c0rbyn and you have trump whether you voted or not

[Momentary Lapse Of Reason]

What is the version of "rule of nine" for a straight eight?

(rule of seventeen )

[PhilA]

I honestly don't see how you can accurately measure and set all of the valves running and hot, it took me 2 hours to do 6, cold and with the best access possible.

 

Phil

[PhilA]

You slag c0rbyn and you have trump whether you voted or not

Nah, you're too contemporary. The reason for that is the engine is already fitted with a Carter.

[Squire_Dawson]

Looks very clean in the tappet chest. The ignition switch light is a great idea and one I wish every car had, sometimes I really struggle in the dark.

[PhilA]

The engine has seen a certain degree of work already.

 

I was moderately content yesterday, my fingers smelled very familiar- old oil, dirt and that slightly brassy smell all combined together that you get in engines of this era.

 

More adjustment tonight, hoping to finish all the valves then Wednesday get the manifolds back on and fire it up.

 

I think I shall also invest in some degreaser. The suspension arms and engine cradle and front framework are all pretty grubby. The grease points are blocks of dirt, so that needs to be rectified.

 

I'm thinking possibly just to jetwash all that muck off but this engine isn't really what I would call watertight.

 

Phil

[PhilA]

I just ordered a proper oil can, one with a pump handle and solid spout and fine tip.

All the ones in the shops here are pistol trigger, you have to hold around the can to support it and have a floppy plastic pipe with a fat nozzle on the end. Bloody useless! This one has a real handle like a coffee mug and you pump the thing with your thumb.

 

A kind gift from my parents to help with the car. It does have a lot of places to oil...

 

 

Phil