Projects Mild custom '51 Pontiac Chieftain

That's what the one I'm looking at is, custom alloy.
They just charge a fair bit. Any one off alloy welding here seems to be rather expensive.
At least I know this one has been measured and will fit; they've even got a photo of it mounted in a Pontiac with an I8.

 

Well, "dog on it", or 2 dogs..... Phil; hope you had a happy Thanksgiving any who. You will overcome; you always have

 

Look around really good. The Pontiac radiators are difficult to find.
Many say the 49-52 Chevys work. And they don't. Too short and too wide with brackets. 48-52 Chevy trucks are a little closer to core size only do not have the additional heater port.

 

If the exact fit aluminum radiator is too pricey, you could search for one by size and inlet/outlet, then modify as needed for mounting. I've taken this route a couple times with good results (mainly because a replacement wasn't available) but I have a TIG outfit. If you decide to go this route and don't know anyone with a TIG outfit close by, I'm about 2 hours from you. Hit me up.

 

I have a lift tig capable machine but no gun; nor do I have the skill to weld aluminum.

I can pick up a Shanghai Speed Shop rad for a Chevy, which is about 7" shorter, and has the outlets in the right place but the wrong size and direction.
The pump has no inlet for the heater return, so that gies straight to the radiator lower tank.

 

Courtesy of our very own @bchctybob I have a replacement Hydra-Matic valve block... From a Cadillac. Cadillac. Mm. Caddy goodness.


As unboxed. It's got grimy old Type A fluid congealed everywhere. Doesn't look like it's ever been taken apart- further disassembly and diagnosis may prove that false but either way it looks pretty good so far.


First things, pull the gear selector quadrant up out of the way, off the manual valve. Then, undo the 3 screws holding the quadrant detent plunger/double transition valve vent.


Front servo exhaust valve comes off the other side, then the 3 screws undo and the two halves separate. The plate is complicated but only fits one way; still, try to keep it the same way up.


On the lower half, the governor pressure valve cap comes off (top right) and the shift speed modulator block comes off (top left)- caution undoing that, it is spring loaded from inside.

That's enough for tonight, all the valves are thoroughly gummed up with congealed old fluid, so when the weather is better tomorrow will be getting a warm gasoline bath in the ultrasound machine outside.

Phil

 

If the radiator doesn't have a return line in the lower tank for the heater, you can put a T in the lower hose for the heater return. I did that for my 472 Cadillac in my 49 Buick.

 

Had a thought and bought a can of Berryman Chem Dip, apparently from 2018... Unless they didn't change their packaging (would hardly think they'd miss their centenary).

Phil

 

Cleaned the valve block. There was not one single shuttle that was free to move- old hydraulic fluid all congealed with time.

Cleaned down all the ancillary parts. I was wrong, somebody had been inside this before, because one of the valves was installed backwards. It was all jammed up and would have only worked in 1st and 3rd gears- likely why it was parked.
This is the block which has throttle valve pressure on- the shuttles push against the governor pressure, making the gearshifts occur at a higher road speed the more you press on the gas pedal.

This is the way round the valves go in the respective bores. Note the top and bottom ones can be swapped which is wrong- the bottom one has a flat and a point, the top two flats.

Once you remove the throttle valve, this pin needs to be pulled out. The 4-3 shuttle has a small hole in the end, push a screwdriver into it and then the shuttle can be removed. It has to be maneuvered through a gallery that it falls out of line and easily gets jammed.

Gently pull it out- it may need a push from the other side.

It's the last thing out and the first thing back in. Refitting is reverse of removal.

Fitted back in, you can see the pin in place.

Continued...

 

The double-transition valve has a spring behind it, that fits back in here. This valve is responsible for the rapid 2-3 gearchange where the transmission goes from clutch, band to band, clutch. If it gets slow or jams up it is responsible for the traditional Hydra-Matic harsh shift.

Next up, the compensator valve. Again, spring loaded.

This one adds additional pressure behind the servos to add additional clamping force to prevent the transmission slipping when you've got your foot in it. On the 8 cylinder versions (like this one) there's a second valve on the pressure regulator which reduces the system bleed pressure to about 60psi (down from the normal 80-85) to prevent the lowest clamping force from engaging too hard- the additional clutch material added caused snatchy shifts at light throttle.

Throttle valve/4-3 downshift shuttle. Free floats between the 4-3 blocker plug and the throttle valve.

Throttle valve, with spring that needs persuasion to sit in both cups.

Continued...

 

The smallest shuttle, but still important - throttle valve plug.

That should freely push from the other side and back, moving all three shuttles in the tube.

Manual valve needs to be put in next, after the front servo dump end block.

Throttle valve lever needs to be put down, then the detent spring block needs to be fitted, then the manual valve can be engaged with the quadrant as shown.

I forgot to take a picture, but the lower block needs the springs fitting as shown, the outer two shuttles are interchangeable, the center not. The governor pistons are all interchangeable, find the best fit for each bore- they should fall out under their own weight.

Both end caps on, and the plate is this way up.

All back together, ready to fit.

 

Does this one have less ware than yours? Valves move without sticking?

 

It's got some miles on it but seemingly fewer than mine has. It does move freely, the main changeover valves (that basically do all the work) are all lot more smooth to operate than mine.

All that's left now is to fit it and see.

 

Fingers crossed...

 

It's so much fun to read, cause it's so well written by Phil - at least for me, I really enjoy it.

Frank

 

Great tech again Phil! Always impressed how you have such a grasp on the tech nomenclature. Hope it solves the shifting issue for you.

 

Thanks, folks.
I got so involved with cleanup and reassembly (a lot of wiggling shuttles into bores and seeing how they slide under their own weight) of the main valve body I forgot to take photos! Time was getting on and a bunch of wasps and hornets were taking an interest in my presence- the hornets would only go if I managed to physically swat them away. Persistent things!

 

Hornets & wasps at the end if November? Up here those guys have been napping for a awhile now.

 

Here, they rarely sleep. We had a cooler snap, a week of weather in the 50's and 60's; one stormy hot day and one following humid in the 70's had them all wake up.

 

Hornets and Wasps????? So this is a thread about Hudsons? I'm confused...

 

New valve block is in.

It's still getting hung up occasionally. So, that's great fun.

However, one thing that is definitely better, in 4th it no longer chatters. I think it was partially engaging another gear at the same time.

Further investigation follows.

Phil

 

Thinking about it, 3-4 gets hung up sometimes also- that leaves it down to one thing.

The front servo is getting hung up.

Edit:
Bonus, it doesn't engage the parking pawl in reverse now, so that's two issues solved.
If I stamp on the gas pedal, that adds pressure to the compensator circuit, and that'll now often make it change to second.

So, that's what it's gotta be- the front servo is getting physically stuck. I think I can drop that out without having to remove the transmission.

 

No. Can't be.

Still looking, going through the manual.

 

Only thing I can think of with what it does is the governor is sticking when it gets hot.



Cold, it shifts really well.

 

Just thinking out loud here, isn't the band applied with a spring? The servo releases it? Since you said "stepping on the throttle", could the throttle pressure adjustment make up that difference?

 

The front servo is held off with a spring, but is activated in both directions by hydraulic pressure, both on and off.

The rear band servo is held on with a spring but again operated in both directions by hydraulic pressure.

In both instances, the springs merely assist and/or apply the rear band with the engine off.

Edit: Further to that, I didn't answer your question, sorry.
The compensator pressure which is added by stepping on the throttle does two things- firstly it is applied in progressive amount to assist in forcing the bands to engage. Secondly, it boosts the overall main line pressure from 60 to about 80-85 psi in the early stages of the throttle being opened, so that will vary the force on the parts too.

However, I looked at the way the 1-2 change operates. 1st is engaged when Drive is selected, by applying pressure to the servo only, engaging it and clamping the band on (and clutch off so the sun can rotate and perform ratio reduction).
When the 1-2 shuttle moves over, that is a single line of pressure to both the servo and the clutch.
The clutch will then engage, and a bit of physics is used for the servo- the other side of the piston is larger so the servo is forced disengaged, loosening the band and then the sun turns at the same speed as the input shaft.

If the servo was sticking, the clutch and the band would both be engaged and the gearbox would lock up solid (two gears at once).
It's definitely not doing that, so all I can surmise is that is not getting the instruction to change- either there's inadequate pressure to push the valve over against the spring or this is getting stuck in exactly the same way (not so likely).
Thus, my attention turns to the governor. Which was new 5000 miles ago. I guess new does not equate non-problematic...

 

On a complete tangent, it's time to pull the radio out and find out why it sounds like junk.

Could be the speaker cone has gone might be a bad contact. Let's find out.

 

Pulled the radio out because I was getting antsy about it.

Took one look and figured the problem.

Loudspeaker selection switch- crusty. Cleaned that up, now it's playing great.


Phil

 

Loudspeaker selection switch? Multiple speakers in 1951?

 

And Bluetooth, another thread about it.

https://www.jalopyjournal.com/forum/threads/1951-pontiac-radio-restoration.1193864/