Projects Mild custom '51 Pontiac Chieftain

Yeah, there were a few reducers and spring rate differences but overall they were mostly the same.

Idle is 375 RPM. That's right on the verge of starting to creep. At that speed the torus is turning about 280 RPM. It'll start to move about 400 RPM.

I know the bigger V8 torus was trimmed to not creep until higher RPM, so you may find using a Caddy torus will work better for your Olds engine.

 

Pleasant morning, so again the car assumed the position.

Greased everything up whilst it was up, then started stripping the gearbox down.

Loosened a few bolts and the valve block fell off.

Poked about, decided to just polish the heck out of the moving parts.

Clank, all back together.

Result? Still doing the same thing so bah. It's driveable but awkward when it's hot.

Pulled the serapes out and washed them.

Next up, valve job.

 

Well, I appear to have broken something- I think I might know why.

I pulled the pressure regulator valve apart and now the box behaves like I would have my foot flat to the floor all the time.

Throttle modulator pressure hits the regulator. If it's losing pressure in the modulator circuit and/or getting line pressure where it shouldn't, that would cause this.
I'm going to try something tomorrow and see.

 

Side-note, Fatsco comes through again; new old stock pressure regulator.

That's on the way. That may improve things. If not, it doesn't hurt to have a spare.

 

Thanks for the continued detailed write ups. It is always interesting to check out what Phil is working on! Beautiful car sir!

 

Beautiful, no. I just photograph it from angles that the rust and dents are less visible. Hollywood smoke and mirrors.

One thing the Hydra-Matic book is unclear on is if the throttle valve bleeds pressure off, or if it allows pressure in.
Depending on what it does would explain what I'm seeing happening make more sense.

 

Hmmm.

I was gonna pull the cylinder head off and look at #3 intake valve.

That fell into "nope" when I realized I have misplaced my 9/16" ratchet wrench, a vital staple in the toolbox to perform that task (manifold tool).

So, after having drained the water out and refilled it, I decided to pull the pressure regulator out again.

Armed with the knowledge that the top piston is the one that does the throttle pressure modulation, I started to poke and shake the thing like a Maraca.

Result? The throttle piston gets stuck in the divot it has hammered for itself over the years. The bore was drilled, and has the standard twist drill bottom. The end of the piston was machined to a sort of Mayan pyramid sort of shape, which had hammered a slight dimple. It would wedge itself in the dimple- heat making it expand and the grip worse.

I spun the sharp edge off the piston end to see if that would alleviate the issue.

Result? Yes. Yes, it does.

I also tried putting it in the other way up- the manual shows the smaller piston as a symmetrical object, where mine is most definitely not.
It didn't work properly the other way up.

Put back in it's still acting up a little, because it's still all worn out so the replacement should fix the problems.

What a weird, weird issue.

 

I spy with my little eye Redline ATF. MMM the good stuff...(I'm guessing the transmission is saying)

 

Yeah. Wanted something with better hot-temp characteristics, it's about 20 weight so that's good.


The replacement pressure regulator arrived. This one still has the black coating on the regulator plug; mine was worn to streaks and silver.


It *seems* to be okay. I'll have to give it a thorough test later today.

Phil

 

Better now, adjusted the brakes up too.

Valve block still occasionally gets stuck but it's much better.

 

What this?!


It's been vacuum cleaned?


It's been washed and waxed?

Something's going on.

 

...or not. Was going to go to Mississippi today but that's been decided against.

Just goes to show; this year's Cruisin' The Coast was vetoed by my wife- the news has nothing of the cars, events, music.

The only thing in the news is bad driving, fatal wrecks and an overbearing police presence which is being ignored at every opportunity. One of the largest venues closed up it's parking lot and told people to go away.

Doesn't bear well for the city inviting the event back next year.

Edit: There was a guns-drawn standoff last night. Yeah, I'm feeling less bad about not going.

 

I did a little light reading last night.

I 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.

 

This is getting a little repetitive.

However, the DTV was getting stuck on the bench so that's definitely the problem; I didn't want to go hog wild today but cleaning it up made cold shifting imperceptibly smooth; hot it still sticks but can be encouraged to bump back with a blip of the gas.
I'll have a go at it again but now that I know what the problem is, repair is somewhat easier...

 

So like ukrainian people, you have made that firm decision, that losing the batle is not ann option.
Good luck!
Im sure you gonna get it to work like it should.

 

What brEad and Pontmerc said x 2 ....... you'll git-er-done right.

 

Absolutely. To quote a favorite paraphrase of mine:

So, again the car was jacked up, drained and dismantled.

You! Yes you, behind the bike sheds! Stand still, laddie!

That there, which I'm pointing to is the DTV. It recieved a close up inspection.

Hmm. It's been dropped. I missed that. You can see where the dimple has raised the edge either side of it. Maybe that's causing it to get hung up? Either way, it needs to go away. So, it was carefully ground down and polished.
One thing that I do not like is the way the spring feels- I think with heat it's partially lost some springiness.

Test drive- 4th changes properly. 1-2 is still getting hung up but it can be made change by letting off the gas. Getting somewhere.

Phil

 

At PhilA, progress is the most important product......Just keep it up and see what happens

 

Phil, I have to say that you have a definite talent for making the most arcane subjects interesting!

 

Well, progress is progress wherever it occurs.

I think for the moment I'm going to be putting the heavy lifting aside on the Chieftain and focus back on my OT car.

Cabin fan motor decided to quit this morning when I needed it, too. That was sub-optimal.

 

Hate when that happens

 

It's a generational thing.

The kids had homecoming tonight. I offered to drop them off in the Chieftain, because you know, old car.

No? Okay. Wife took them in the bug-splattered, filthy OT pickup truck.

I asked why later on.

"I didn't want my friends to think I'm poor because that's an old car".

Sigh

 

A chilly morning today, with a winter mass of cool air sweeping through the area. 53 this morning, tomorrow due to be 40.
Went get coffee and pancakes before work because I'd been up all night running maintenance upgrades.

The car still amuses me, the temperature dial set to LOW where it always sits and there's roasting hot air coming out a mile down the road.

The lady at the drive through window told me I was making her feel cold by driving the car on such a chilly morning (shush at the back, it's cold for here). I told her not to worry, that I had the fires of hell and damnation under the seat, and the heater works very well. I was warm.

What made me smile more was halfway home the air coming out was almost cold- the thermostatic control still works properly.
70 year old car and it's got better heater controls than a lot of modern vehicles. Makes me smile.

Plus today once the valves had freed up the gearbox was really smooth. One fix, therefore, would be to move house to somewhere where the climate is cooler. Go figure.

Phil

 

Really cool here in VT Phil. We need talented IT guys here also, of course you may have to source some studded snow tires to enable you to get over the hill to work

 

What's this "hill" and "snow" you speak of?

 

Ha! It has been said for years that if you flattened all the hills/mountains in VT we would actually be larger than Texas. That snow stuff is necessary to make you appreciate the other 3 or 4 seasons we have here. (the 4th of course being mud season)
This is what Gramps used to get around back in the day

 

Phil, total agreement on heater controls.......that car is sure "look'n good". Glad it was shifting better.

 

Rolled over 108,000 miles this morning. Heater was pouring out the warmth, 40 outside and easily 75 in the car.

We just have 2 seasons here. Hot-and-raining, then warm-and-dry.

The former is from March through to December, with the other season filling in the gap.

The gearbox was sticky this morning until it had cycled a full 1-4 then 4-1, then it behaved as per design spec. Once it warmed up, sticky again. Joy.

 

Phil, after all you have done would it be advisable to try one of the many transmission additives that are offered to alleviate the symptoms you are experiencing?
Or maybe just try driving it around going a little further than you have been.

 

Been there, tried those. So far the best has been the current iteration of a modern synthetic oil, which holds viscosity across a wider temperature range.
Honestly what I think I'm fighting is dissimilar metal expansion rates.