Can you remove the driveshaft by:
loosening its rear ujoint at differential, wrap some tape around the bearing caps, then lower rear end of DS
then pull (slip) the forward end of DS from transmission tailshaft

* when the driveshaft is slipped from tailshaft, fluid/oil will drain out of tailshaft; have a drain pan ready.

 

Sounds like driveshaft safety loops and a non-stock driveshaft yoke that does not unbolt.
That driveshaft could be a custom larger diameter version for racing, or with larger u-joints.
You should measure both the u-joints and the shaft diameter and see what you have.
If there is no removeable yoke at either end, you will likely have to at least loosen the rear diff, to give you some wiggle room, to drop the u-joint out. That one at least should still have a strap on u-joint. The frame back there gets in the way, so you have to slip it beside the diff. Then back, and hopefully you can slip the long front yoke out.
It may even have been put in while the body was off, or while the diff was out.

C3 driveshafts came in both 1310 and 1330 u-joint sizes. Someone around here should have the shaft diameter, but IIRC it was like 2-1/2"
If it needed driveshaft safety loops, all that could have been changed.

1310s were stock for many years.
Then around 71/72 they went to 1330s, at least on BBs.
With big motors, some guys even put 1350s in there.
Unfortunately the bolt together style of front yoke is tough to find in the factory 1330 size.


This is my dirty but OEM bolt-together trans-side strap yoke on my 72 4spd car.

 

Hello,

Yesterday, before I even started looking at the slip yoke U-joint, I removed the U-joint bolts on the differential and then tried to pull the driveshaft back to get the slip yoke out.
I just checked again on the car, but unfortunately there’s way too little clearance on the left, right, top, and bottom to move the driveshaft back far enough.
So, that approach won’t work.

Thanks for the photo. The U-joint measures 27mm (1 1/16") in diameter and 92mm (3 5/8") wide.

That means it should be a 1330.

At this point, I either have to force the needle bearings at the slip yoke in (if thats even possible, because there are some kind of pin locks (?) in the u-joints), cut it off, or partially drop the diff...
BR


thats the kind of pin locks i meant. seen someone heating the u-joint, so the locks burned down.
too dangerous at a car where the driveshaft is still build-in in my opinion.

 

Rear of driveshaft is disconnected then pushed forward into transmission, then drop out the driveshaft. That should make it come out.

This is a better way to install a pilot bushing or bearing. Maybe your steering wheel puller would work? You can borrow these gear pullers from many auto parts stores for free.


Much better to use a gear puller to gently press the pilot bearing or bushing into the back of the crank. Why use a hammer?

 

well, unfortunately it won't come out this way, because the slip yoke won't go into the transmission far enough, to drop the driveshaft.

 

Not surprised.
The darn rear diff crossmember gets in the way, unlike every other chevy on the planet.
Time to loosen or remove the diff.

Those bolt together trans yokes have become hard to find in the 1330 size.
Once you are sure of the spline count of your trans, you can look for one.

Which 4 speed?
Could be Muncie, or Saginaw or Borg Warner.
And the Muncies have two spline sizes.

Make sure you put the stock style Oilite bushing into the crank.
Not bronze, steel or roller. Those all have a higher failure rate.
The right ones are out there if you look hard enough.

 

In above p#23, the circled "pin lock" seems to be where manufacturer injected pressurized molten plastic polymer. Once cooled and solidified, that effectively locks u-joint caps in yoke. What's circled is actually a sprue or vent.
I would be Very hesitant to use any open flame in that area under car. But, perhaps the u-joint crosses must be severed and there's no alternative to open flame ? Head-scratcher ?

 

“Seems to be where the manufacturer injected pressurized molten plastic polymer.”

Exactly—that’s the phrase I was looking for, thank you. Basically, the yellow-marked part is the end of this plastic polymer, where it’s supposed to exit when heated i guess.

I’m thinking of trying to press it out—maybe start without heat, and if that doesn’t work, use a heat gun (no open flame). But im not sure about that at the moment.

After that, the plan is to rebuild the whole assembly into a bolted slip yoke—or at least a slip yoke without any plastic polymer inside, using just safety clips on the outside of the bearings.

I thought I would be able to get more done over the weekend, but unfortunately, this held me up a lot and will continue to do so for a while…

 

So, I removed the transmission today.

The release bearing wobbles quite a bit on the side that sits in the fork when you place it on the ground.

However, when installed in the fork and turned, the side that presses against the clutch runs smoothly.

There are also some wear marks on the side that contacts the clutch fingers.

The clutch itself looks fine, and the transmission play seems okay to me.

The clutch fork, though, has a bit of play in the up-and-down direction.


pivot ball in the clutch housing

clutch fork

 

The wear on the clutch fingers looks perfectly normal. Very good in fact.

Your pivot ball looks very good. Low wear evident. They get quite a pronounced wear-shoulder when worn, and make clicking noises you can feel. Yours still looks very smooth on the half-round top.

The clutch fork should fit on the ball pivot fairly snugly. You have to snap it on with the springs. It moves, but not rattle/move/up&down quite as much as yours does. But it will move some, or rattle, some unless everything is put together correctly. But I have never heard a rattle as bad as yours.

The springs often get bent during installation. If they are not bent too bad, you should be able to tighten them. Those spring clips are only there for installation, they do not do much in operation. The fork does not fit on the spring all that snugly, but it should pivot very freely once it is. But again you have to load it the way it would be in the car. When the ball is into the depression on the fork, then it should not move to much. You can't check it the way you did, every thing has to be assembled., and then use your finger instead of the linkage. Clutch, bearing, fork, finger pressure. It should be fine then. Put some grease on the ball too. The linkage has to be adjusted properly, or the fork will be real loose. And there are several springs on the linkage, do you have an installation drawing from an assembly manual?

The other spring has tangs which go around the lip on the release bearing. That one gets held very loosely, but it floats on the clutch fingers which holds it in position.

The throwout release bearing itself, I would put in a new one. They go bad often, and make loud squeeling sounds. For as cheap as they are, and as hard as they are to get to, just go with a new one.
But make SURE you get the short one, that is the correct height. The same as the one you have now. There are short ones and tall ones, and they often get mixed up.


I also found the clutch adjustment pages from the service manual.

 

thank you.

i took out the transmission and while rattling it out, the throw out bearing fell off when it was supposed to be still in the fork.

maybe thats the cause for my problem?
because when i putted the bearing back into the fork (not built in), i had a hard time getting it out again. had to use a lot of force to get it out again. so it had to be loose when built in.

maybe it was shaking on the fork and as soon as i depress the clutch, it gets pressed against the clutch pressplate and stopped rattling.

i tried to move the fork by hand when everything was built together, the sound didn‘t stop until i depressed the clutch all the way through by foot.
but anyways, maybe the bearing was loose on the inside. so moving the fork by hand didn‘t affect the bearing and it kept rattling because it wasn‘t in the right place on the fork.

or, worst case, pilot bearing.

perhaps i should by a new fork too?

the springs where missing a long time, i build them in some time ago.
and the z-bar wasn‘t adjusted at all.
did that too as good as i could.

just dont want to install everything again and hearing the same noises again.

 

To wrap up the thread:

I only replaced the throw-out bearing and the clutch fork.
I wanted to replace the pivot ball as well, but I had ordered a 1 1/2" one, while the car currently has a 1 3/8" pivot ball installed.
With the 1 1/2" pivot ball, the release bearing would never have moved away from the pressure plate again.

The car is running again without any noises, and I'm really happy I was able to fix the issue.
Thanks to everyone who put in the effort to help me.

I also changed the transmission fluid — there was almost none left in it. Good thing I did it; it was completely black and the drain plug had some corrosion/mildew inside.

You can now hear a click after about 2 1/4" of clutch pedal travel, which should mean that the bearing is moving far enough away.

Before I pulled everything apart, this click was only audible when you pulled the clutch fork back by hand, and as soon as you let go, it clicked.
That basically means the bearing was constantly engaged/spinning.
The old bearing also made noise compared to the new one, both when spinning it and when shaking it.

I hope everything is correct now. The pedal returns a bit stiff, but it should definitely be moving far enough away at this point.

pilot bearing has not much of a play and the bearing only is active when the clutch is pressed - for my understanding. because then the input shaft doesnt turn but the crankshaft does.
so the bearing is in motion then.
when driving everything runs at the same speed, input shaft and clutch.

and clutch seems to be new.

thanks again to everyone!