The Stovebolt Site Forums The Shop Area Driveline Clutch problem

I see no mention of a powerglide engine?? (The Powerglide is a two-speed automatic transmission designed by General Motors. It was available primarily on Chevrolet from January 1950 through 1973)

A "Powerglide engine" would be a 235 built expressly for a Powerglide transmission which did not use a pilot bushing. The difference is the crankshaft was drilled but not finished to accept the pilot bushing needed by a manual transmission.
My 57 235 is one such engine. The crank was drilled but not reamed for a pilot, therefor an undersized OD pilot had to be installed in order to mate the 3sp clutch shaft to the crankshaft.
Sorry for the confusion on my part.

Thanks!! Is that what engine we are dealing with here?
His trans is SM-420..?

Not sure if that is what he is dealing with but his truck has been a challenge from the beginning and no telling what the actual parts installed are.

11/20/23
It has indeed been a challenge from the get go.
But I installed the tranny and the ujoint yesterday and put the beast back on the ground. If its not too cold tomorrow I’m going to fill the tranny and ujoint with fluid and put the cover back on the transmission. Then it will either drive or die.

Doug

I think it’s time to throw in the towel with the local parts place and send the parts that worked to HRClutch in Bensalem, Pa. They will rebuild the parts you took off and then you can reinstall exactly what you had to begin with.

http://hrclutch.com/

I’ve been following this thread and I believe he already had his original clutch rebuilt. His pilot bushing was binding up from being driven into the crank and may still be dragging on the input shaft after he honed it out. Possibly the clutch will release with everything reassembled, but there’s a possibility that the bushing will gall on the input shaft if there isn’t enough clearance.

Klhansen. What you said. At this point I’m going to hope running it some will free up any latent friction on the bushing.

Now on to some info. The u-joint needs fluid also I believe. I had run across that reference somewhere but can’t find it now. Anyone know how much oil goes into it.

Doug

Put a half pint in the plug near the rear and the rest of a quart in the fill plug in the main body of the tranny. There’s a passage between the two sections of the transmission, but that half pint provides initial lubrication.

[on edit] that’s for the three speed transmission. I forgot you had the 4-speed. The service manual should cover that for the 4-speed.

Doug... the pic shows the input shaft not going into the pilot. That cannot be the correct pilot.
Read the code on the pad behind the distributor. Post that code and we can determine how that engine was set up.
How hard was the pilot to install? Was it easily tapped in or did you have to drive it in? Somehow that pilot became too tight if the input shaft does'nt fit with no clutch in the way. That is where your 1/2" gap is coming from.
"If it don't fit don't force it"
Drawing it up with the bolts binds the pilot to the input shaft and running it like that will create heat friction that will ruin either the pilot, input shaft, or both.
Pull that pilot and find the correct one. Measure the diameter of the hole in the crank and the diameter of the input shaft. Compare that to the pilot bushings that came with the other clutch kits you bought. OD should be in the neighborhood of 1.09"
The gear grinding you are experiencing probably comes from the binding of the pilot which does not allow the transmission to fully disconnect from engine torque when the clutch is depressed.

I couldn’t find a reference for how much oil to put in the u-joint housing in the manual. I ran across it somewhere but can’t find it now.

Doug

Is there even a fill plug in the u-joint housing on the 4-speed? If so, I'd put 1/2 pint in there, maybe a little more for prelubing the u-joint. The rear bearing on the 4-speed is directly between the u-joint housing and the main case, so excess would run thru the rear bearing into the main case. Then put the rest of 6 pints in the main case. The service manual specifies 6 pints to fill the 4-speed. On the 3 speed, the u-joint is further from the main case, which is why the manual says to add gear oil to the u-joint area. Maybe it's not critical in the 4-speed because lube will get thru the rear bearing quicker so it provides lube to the u-joint sooner.

Should be a small plug in the housing my 54 has one as well as a older parts I have has one

Yep. Mine has the same plug and that was what I planned on using.
Thanks for the info.

Doug

12/2/23 after putting everything back together the clutch still didn’t work. There was 1/16 inch where the shaft was a tight fit. That must have been too much. So walked away for a few days. Besides it was cold here in Alabama.

Anyway it is wet but 70 degrees so took the torque tube/u-joint down and got the trans on the floor today. Leaving the clutch in for now. Next day I have some time I’m going to ream that pilot bushing until the trans slides on and off with no friction.

Doug

The right bushing cost $8.88 , why not pull the wrong one out?

'Cause he almost has the wrong one reamed oversize enough to fit. After 2 months and 5 clutches.

Can you ream the bushing with the clutch in?

I betcha Doug can.

Sounds like the shaft fits cept for a 1/16th of an inch.
Its my suspicion that the input shaft is bent from raising the trany up from inside the cab.
But i don`t know much, still learning. thanks

Nah, out through the floor is how it's supposed to come out. Did it that way all the time when I was younger. Now I put a tire on a piece of plywood under the tranny and lower it down with a rope doubled around the tranny. Pull it out, lower it down and drop it on the tire. You can't bend that input shaft. He simply has the wrong bushing.

Hey thanks! I lowered mine down on a few card board boxes with some dense foam on top of a piece of carpet and slid it.
Im learning.

Input shafts are as tough as woodpecker lips. One might break with enough force applied (tens of tons) but I've never heard of one bending. I've been known to suspend a heavy transmission with a cable come-along attached to a long 4 X 4 post resting of the window openings of the cab. An 8-footer allows both doors to be open for easy access to the inside.
Jerry

You are right. I just cannot imagine...

Bearing retainers, on the other hand, are notorious for breaking the snout off with just a little twist, even the weight of the transmission hanging without support on the input shaft- - - -they're cast iron, and very brittle.

12/8 update
Had a couple days of not freezing weathe so dropped the tranny and clutch and backed the pilot bushing out with a 3/8 inch tap. So far that has worked every time. I gave up on the pullers.

So what I’m doing now is honing the ID of the new pilot bushing. I suspect the hone couldn’t get to the very back of the bushing.

The one I took out was .606. The new one was .586. That’s ID. Got the new one out to .605 and will work on it a bit tomorrow to finish it up. Then I’m going to work on the OD. Don’t remember the readings but I’ll post it tomorrow.

Then I’m going to compare how proud the original clutch surface is to the one from Summit racing.

Then I’ll see what to do.

Doug

I’m lowering the trans down to a small moving dolly so I can move it around. I’m a professional at taking it down and reinstalling everything now.

12/9/23

Have the pilot bushing ID to 6.025 so that should work.

Still have a little work on the OD. About 5 thousands

Put the original clutch (rebuilt) next to the new one from Summit.

The distance from the pressure plate surface to the mounting flange on the original is .1205 and the new one is .1825.

Pictures also show a slight difference in clutch thickness.

I’m going to go in with the original when I’m ready to go

First pic is my dolly I got from harbor freight for like $4 on sale.

Doug

Ps: I bet anyone pulling the trans through the floor was dealing with a 3 speed. The 4 speed is much bigger and weighs about 150 pounds I think.

I get those HF moving dollies for the casters on them. Way cheaper than buying the same casters from HF.
I wouldn't try to pull even a 3-speed up thru the floor. The acesss is just too small, and then you'd have to drag the tranny out the door. Dropping it down using an engine hoist is the way to go.

Evidently not. If he got it right the 1st time. Or the 2nd. or the 3rd.
I get mine right the 1st time.+ I don`t know what I am doing. Down from underneath. Its not Brain Science. Or is it?
A muncie 4 speed is lighter than that sm-420.
I would not put a engine lift inside my finished cab. What about the legs underneath.
Maybe Apaches are different. I don`t see ANY videos or mention of doing it this way. I`ll keep doing mine
the way of success. Good Luck Doug. You`ll need it.

The method of using an engine lift is only using it to lift and support the tranny for installation and removal. You still drop the tranny to the floor. The boom doesn’t touch anything in the cab. I’ve used this method and it works great on AD trucks. I dropped my tranny on a cheap HF dolly to pull it out from underneath the truck. Your TF may be be different where this method won’t work.

Possibly, .

With all that reaming the ID with a tool ill-suited for the purpose and now reducing the OD to "fit", I will be very surprised if it runs concentrically true. Next question will be "where's the vibration coming from?"

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