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1951 Pontiac Chieftain


PhilA

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17 minutes ago, PhilA said:

Nothing real to report. Over just been driving around in the Chieftain. It's been doing An Car duties well.

Fixed the heater fan the other day by giving it a gentle thump, one of the brushes must have gotten sticky.

Glad it's working now because a rainstorm blew in this morning; before work I went get coffee and sausage burrito from McDonald's. Sitting in the drive-thru the windows fogged up so I put the heat on the screen. At the same time I have got cool air blowing on me. 

Thats a feature modern cars lack- for down here where you need heat on the screen to clear it but it's far too warm outside to actually be running the heater.

 

Sometimes modern is not better.

That's one feature I miss from my Saab regularly.

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On 7/6/2022 at 2:25 PM, PhilA said:

Easily? I'd say moderate. The dark blue certainly. 

I'll keep putting it on- it's easy in terms of that, wash, spray on in sections and dry off with a microfiber cloth.

https://www.meguiars.com/automotive/products/meguiars-hybrid-ceramic-wax-easy-use-ceramic-wax-protection-g190526-26-oz

This is the stuff.

Phil

Actually, paint update. This ceramic wax stuff is not bad. The gloss has remained, through zero washes this month- all it's done is rain. 

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The rain globules on horizontal surfaces do dry in the sun and leave circles. 

It does cause the vertical surfaces to drip off well, and usually in one path, leaving the dirt in streaks where the water rolls down. The detailer spray took that off easily.

So, in terms of longevity and gloss retention? Yes. Better than the Turtle Wax carnauba stuff I had used before.

Five stars

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  • 4 weeks later...

Managed to get the torus drain bolt undone. In true fashion, hammered a smaller socket over it and got it to turn that way.

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Draining it down completely is possible this way. With it emptied as much as possible, I dropped the lower pan.

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Not bad, actually. The fluid was quite clean, not burned. A little friction material, and a few errant metal shavings from before the rebuild which must've been in oilways. They stuck to the magnet.

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Refilled with $115 of shiny new Valvoline ATF. Cold, it's a lot more delicate, changes gear almost imperceptibly. Hot, it's doing the sticky gears thing. I think I know what's causing it; I'll drain it down again and drop the valve block, I think I know what might be causing it.

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On 10/1/2022 at 2:48 PM, hairnet said:

sears catalogue :P

is there a pontiac man like wheeler dealers visited the cadillac man in usa?

pinto and type 9 obvs :D

 

TBH I don't know. Pontiac always sends to sit a bit in the shadow of the other GM marques.

 

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Stuck the car up in the air again. Graded all the grease points then set about taking the gearbox to bits again.

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Fluid drained, side pan off and valve block removed.

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I was going to block the throttle valves off but instead decided to polish everything up because a few valves were a bit rough.

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Buttoned it back up again. Net result, nope. Same old nonsense.

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Gave up with that and washed the serapes instead, they came up nice again.

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Tonight.

 

I had a thought on what the gears are doing, and how they do what they do.

There's an afterthought in the control of fluid pressure; at light throttle, there's a valve that keeps the pressure low because the additional clutch capability built in made for thumpy changes. So, the main line pressure was reduced, to be increased with throttle position. A secondary valve was added for reverse to bump the pressure way up to get the reverse cone to grab without slipping.

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So, I pulled the main pressure regulator out. I checked it and it was a little dirty. So, I cleaned it up and reassembled.

Now it acts up even when the gearbox is cold. 

 

Hmmmm.

I might be able to get another one (new) for not too much. Phone calls abound.

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Yup, just went for a test drive and it's behaving like I would have my foot flat to the floor all the time.

Ungood! 

I'm going to pull it apart again tomorrow when it's light, and check see the line pressure and all that jazz. Being as that part is linked to the pedal pressure, which in turn appears to be all jacked up... 

Ugh, this has so many moving parts, so many of which can cause this behavior.

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Pressure regulator softened the issues but when pinging hot it still acts up. However now it doesn't give you whiplash so that's a bonus.

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Vacuumed it out thoroughly. Fixed the fan so it doesn't hog the lighter socket. I can have the fan on and charge my phone at the same time now. Nice.

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Washed and waxed it too. 

Something's happening.

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I sat down with a little light reading last night.

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Sat down with the service manual and tried to condense 6 pages of sequencing into a single page where all the data can be viewed at once.
Then, I read something I had missed.

So, the sequence of gears is as follows, with the front and rear gears either locked (L) or in gear reduction operation (O).

1st: O, O
2nd: L, O
3rd: O, L
4th: L, L

So, with the gear selection valves at rest, it's in 1st. 2nd causes the first gearset to release the band and clamp the clutch.
3rd has to do a complex swap- it engages the rear gearset and at the same time operates an override valve which quickly dumps the front gearset into reduction again. That override feature is what I had missed, and it's important.
Fourth is simple, it keeps the 3rd gear selection but removes the first gearset override valve, locking both gears solid for direct drive.

So, if that override valve (called the Dual Transition Valve) gets stuck in the open position, it'll override any changes requested for the front gearset to change state. So, requested gears 1 and 2 are both the same as 1, and requested 3 and 4 are both the same as 3. The shift point between the gears occurs at the speed 2-3 would and with moderate violence due to the rear band just being slammed on and the softer engagement of the gear itself being down to the way the front gearset is engaged.

That's exactly what it's doing. Replacing the pressure regulator has helped because the additional line pressure it creates correctly now appears to be enough to jiggle the dual transition valve out of where it gets stuck, and sometimes get 2 and 4 to engage correctly.

I'll pull the valve block off again and investigate that valve, likely it's got a light score, burr or ridge that's causing that valve to get stuck when the block heats up and expands.

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Took the valves out again.

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That's definitely the problem. I didn't go hog wild with it but the compensator backs onto the shuttle which pushes the valve via spring pressure into place. Then it's getting stuck.

It got stuck when I tried it on the bench.

Cold, it's super smooth. Hot it's still problematic but can be encouraged to shift by blipping the throttle.

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20221009_160713.thumb.jpg.4aa86da7c1478f9f2bd6babdb8f83500.jpg

You! Yes you! Come here!

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Well, somebody's dropped that. (I think every damn part of this has been dropped at some point). Removed that and the burr. Improvement seen in that 4th changes by itself when it's hot now; 1-2 only if you lift off the throttle.

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It's late now, given up for tonight. However, that's a big improvement. I'll get to the bottom of it one way or another. It will gearbox properly.

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