The Stovebolt Site Forums The Shop Area Driveline Clutch problem

Got it in neutral and cover on. Started it up and yoke didn’t turn so that’s ok. But it grinds going into 2nd and won’t go into 3rd. Won’t go into 1st or reverse either.
I have the clutch adjusted almost to the end of the rod and seems to have plenty of travel.

Now what?

Doug

Doug,

Did you test the movement of the shifting forks with the shifter in the tower (move through all the gear switching ranges), before resetting it onto the transmission?

On the same thought, did you manual push the gear clusters through their motions to confirm nothing was binding and all gears where able to move through the full ranges?

It can be a tedious process and takes patience to push/manipulate the gears and then turn the input shaft to make sure everything is aligning correctly, but that is also something that should have been done before reinstallation.

If you did these things, the only other thing I can think of off the top of my head is the shift forks didn't go into the correct places on the gears when you put the tower back on. There's a good possibility that one of the gears moved during the install.

I know "that" can happen as I did it myself once or twice.

11/5/23 Update
Ordered the clutch from Summit.. dropped the old one out yesterday and got the clutch installed late yesterday.. This morning before work I got the tranny installed.. When I get home I'm going to check if it works.
I had a assistant push in the clutch pedal and it looks like it opened up so hopefully it works in practice.. we'll see.

Doug

11/6/23
Got time last night to try the new clutch out... failed again...

I'm starting to wonder if the PO the truck had changed something.. but I'm going to try some different.. I'm going to add a washer under the clutch to back it off the flywheel and see if that is enough to give it clearance to work.. it seems to be partially opening a gap but not enough to disengage the trans so got to try something different.. lol

Doug

If there is a noticeable gap with the clutch pedal depressed, that is the definition of "released" isn't it?
Sounds like you have a different issue going on.

What Carl said. When you take it back off, check to be sure the disk will slide freely on the transmission input shaft. If it hangs up, it can make the clutch still turn the gears when the clutch is depressed enough that the gears will grind when shifting. Putting washers under the pressure plate is just a bad idea band-aid.

Bent input shaft from installing trans from the top?
I always put them in from underneath. IDK....sounds odd.

11/7/23
Ok. Dropped tranny and clutch. Checked pressure plate on input shaft and it fit smoothly no problems.

I still have a 1/2” gap when I put the clutch and a 1/2” gap between the trans and bell housing when I install them.

Checked a spare pilot bearing on the input shaft and it fit fine.

So where in the world is this 1/2” coming from. I’m at a loss at this point.
I can’t remember ever having this much trouble with a clutch.

Doug

Are you sure the transmission is the one you think it is?

Do you have this clutch fork? https://www.ebay.com/p/1230557946
This rod? https://www.classicparts.com/1947-5...2oX2eEHZxSpRRp6yv6_dUCghXjIaAhtYEALw_wcB
This offset rod? https://www.classicparts.com/1947-5...jj7oJwPVspqRyOBvy5vvzN9z140aApJOEALw_wcB

Without these things the clutch back and forth motion is binding and not natural.

I am having trouble following as it seems that you have different problems at differnt time in this thread.
The latest seems to be a problem seen prior where the transmission will not fully engage the clutch and pilot bearing preventing the transmission from meeting up with the bell housing. I thought that one had been resolved with clutch disk alignment?
Previously you had it all together and it appeared the clutch was working but the transmission would not shift into all gears.

Prior to the latest clutch I believe you were installing the original clutch after it had been refurbished which should have resulted in the same stack up as the original drivable version except with a resurfaced flywheel and restored clutch disk lining that had clutch slippage and started this whole process.

Maybe you can recap what problems you have had, how they were resolved, and what the latest problem is so that we can help determine a path to success.

Guitplayer. Yes to all.
Back to the start. Original clutch was slipping so bad it wouldn’t climb a slight hill.

Tried a clutch from classic, Napa, advance and now summit. Got the old clutch refurbished just before the summit one came in. Changed out the pilot bearing and have a new throw out bearing that matches original.

On all of these the clutch goes on and comes about 1/2” from the flywheel. Nuts pull it down as they are tightened.

The trans slides in easily but stops about 1/2” from the bell housing. It pulls in when the bolts are tightened.

None of the applications released the trans.

This is where I’m sitting after almost two months of work.

Doug

Edit: looked up flywheels and half of them had raised edges for the clutch. Looks about 1/2 inch or so. Is this what I’m looking for or should what I have be working. Really confused now.

Have you put a dial indicator on the crank flange and the bellhousing to check for alignment? If the clutch is centered to the crank center line, its very possible the bellhousing is not aligned and so the trans gets so far in until the alignment mismatch prevents it from going any further. I am assuming you have made up a pair of pins to slid the trans on. A stock trans install is indicative of this kind of misalignment.

Just as an FYI, dial indicating the bellhousing is a big giant pain the the backside, big one, but sometimes a necessary evil.

That's normal. You're compressing the pressure plate springs by tightening the bolts.

That's NOT normal. Measure the distance from the face of the pilot bearing area to the back end of the splines on the transmission input shaft, and also the distance from the pilot bearing face to the rear of the disk splines with the clutch installed. The second measurement should be smaller than the first, or the input shaft will force the disk into the flywheel. Have you compared the length of the splined disk hub with the clutch disk you removed? [on edit] I see that it's the original disk]
There's also a possibility that you don't have the pilot bearing deep enough in the flywheel, which would cause the bearings in the transmission to bind up when tightened that last 1/2", although that 1/2 inch should only occur on the first tranny installation, as it would tend to push the pilot bearing deeper. The second time, the transmission should be much closer to mating up with out the bolts installed. Normally, the transmission will be able to be pushed home by hand without any bolts tightened.

Dragsix's comment about bellhousing alignment is especially important if you're mating a different bellhousing than what was originally on the engine. The procedure is in the shop manual, and the lateral runout limit is 0.008 inches. The bellhousing should also be within 0.010 inches of parallel to the block.

Your flywheel should be flat across the entire back surface, but probably has a groove between the disk and the surface where the pressure plate bolts on.

Without me rereading the entire thread, did your truck ever run ok prior to the clutch slipping?

Are all of the major parts still the same...engine, bell housing, flywheel and transmission.

Was the trans input shaft ever taken out?

Like Kevin already mentioned, put a straight edge across the bell housing opening and measure to the pilot bushing. Them measure from the face of the trans to the front end of the shaft splines...what are those measurements?

Put the trans in without the clutch disc and see if it slides right up to the bell housing with out using bolts...it should.

Mike B

My 59 had a SM-420 in it with this bell housing.
I switched to a M-20. Same bell. Shorter drive shaft.
Sorry it might not help,
but yeah that tran should just slide all the way without much effort.

I agree with Kevin regarding the clutch install being normal and the transmission install not being normal. Whatever is holding the transmission away from the bell housing is probably creating the release problem - as you draw the transmission to the bell housing with the bolts you are deflecting or binding something that is preventing the clutch from releasing normally.

Are you sure that you are installing the clutch disk in the correct orientation? If it is reversed the hub will run out of spline on the input shaft and get held against the flywheel regardless of the pressure plate releasing it.

Pulling the transmission in the last 1/2" using the mounting bolts is a bad idea. It's a good way of breaking the transmission ears off.

11/9/23 I agree with you both.

I did a check this morning. I have everything off so I put the tranny in to see if it would go all the way in without the clutch installed. Nope. For whatever reason it didn’t want to seat all the way in the pilot bearing.

I’ve got another pilot bearing I could install. Is that my option.

First picture is the gap I’ve talked about

Second picture is how far the shaft goes into the pilot bearing.

Doug

Pilot bearing is too far in.
Wrong length input shaft or its bent?
Just guessing. Disregard.

Doug, Maybe do a test fit of the extra pilot bushing onto the input shaft by itself (uninstalled in the crankshaft). Maybe the input shaft is boggered up or the inner diameter of the bushing is wrong???

Measure the depth of the hole in the crankshft from the flywheel face and estimate where the input shaft transition to the spine is relative to the flywheel face and do the math.

Is it possible that the transmission input shaft got moved forward when you were working on the back end of the transmission? The picture of the shaft engaged into the bushing looks like it would be close if your mounting gap was eliminated. I do not recall what locates the input shaft but maybe a snap ring got out of place and the shaft moved forward and can not go back to its correct location.

I believe that the snap ring on the input shaft bearing is toward the front of the bearing, If it were installed toward the rear, I don't think the input shaft collar would fit on, so that would be a pretty obvious oops when assembling the tranny.

I don`t know if I wouldn't just pull that engine and start over. When I recently did my 235 it was out and was able to get a good eye at most things.

You have an incorrect pilot bushing. There's a bushing with an oversized OD that was intended to be used on crankshafts that were originally mated up to a Powerglide automatic. If you pound one of those bushings into a crankshaft with the proper diameter counterbore, it shrinks the center hole so the trans input shaft has to be forced into position. Then the clutch won't release. I've encountered that several times while sorting out a botched do it yourself clutch installation. Yank the pilot bushing and install the right one. The transmission should be an easy slip fit.
Jerry

That makes the most since Jerry. Just how do you tell if yo have the correct pilot bearing.
The one I have left slips on the input shaft easily.

I’m going to Harbor freight and pick up a good caliper to measure a few things. The one I have is cheap and doesn’t have a dial counter on it so I have to guess how many revolutions it makes.

Do you happen to have a part number for the correct bearing.

Doug

Jerry's thought that your pilot bushing has been swaged too small makes good sense. Another option would be to ream the one in place to the correct size, but that would require a reamer.

HA! Good luck. That has to be a classic oxymoron. HF and "good" in the same sentence. Although their digital calipers are probably as good as what's available on Amazon.

National Bushing - PB656HD
You don`t want a bearing

Highlighting this comment because it is important.

The bushing you have installed almost certainly slipped on easily before it was installed. The problem is that there are different diameter holes in the crank. When you press the larger bushing into the smaller hole, it compresses and the ID shrinks enough to bind up on the transmisssion shaft.

You need the ID and the OD to both be correct for the combination of transmission shaft and crank hole.

The ID of the hole in the crankshaft and the OD of the bushing shouldn't be more than a few thousandths different, with the bushing being maybe .002" or so bigger than the hole it's going into. More press fit than that will shrink the ID and require reaming. A VERY careful trim with an expanding reamer in the bushing that's there now will fix the problem, but buying the reamer would cost several times what the right bushing does. DO NOT USE A DRILL BIT! They don't make perfectly round holes. Fortunately, I've got a set of those reamers that I've been using for 50-something years.
Jerry

I’ve had need of a small hone for a while. This just may be the time to find one.

Doug

"but buying the reamer would cost several times what the right bushing does"...? I have had to drive in 3 pilot bushings recently and they have not compressed the I.D. of the bushing. I get the feeling something else is going on here.

There's no issue as long as the bore size in the crankshaft is correct. If the bore is too small for the OD of the bushing it would compress the ID of the bushing.

I think I get it . But would not the wrong OD indicate the wrong bushing? I mean the force to get it past the bore would be alot to change the ID.

A "little" is a whole lot when you are talking about the relatively tight clearance between OD of the end of the input shaft and the ID of the pilot bushing.

I am trying to learn...seems silly to have the right bushing designed but
when installed the ID changes making the bushing useless?

It is because it is the wrong bushing. The OD is larger that the hole in the crank, so when it is pressed in, it shrinks the ID just enough to bind.

11/18/23
Hone came in and I spent a couple days running the honer in the pilot bushing then bringing the trans up and fit checking it. Finally got to the point where it slipped in all the way yesterday. So yesterday afternoon I got the trans installed.

Clutch still doesn’t release. Lol

So I’m going to finish installing the rest of the drive line and see what I get.

Doug

Well, at least you found/fixed one problem.

Dorman 690-034 is the pilot made to convert a Powerglide engine to manual. The stock manual pilot is about 1.09 OD. The Dorman is about 1.06 OD. The Powerglide equipped engine did not require a pilot so in their infinite wisdom GM did not ream the hole in the crank for one. Never imagined that idiots like us would want to mate a 3sp to a Powerglide engine. My 235 came from a known Nomad with Powerglide. The 690-034 was the pilot that converted the Powerglide engine to the 3sp tranny.