driveshaft install problems with body off

[Domenic T.]

Re: driveshaft install problems with body off

One of the Munci transmissions I rebuilt was sold to a customer and when I installed it the drive shaft didn't fit! I was the one who took the old trans out and was attempting to install the rebuilt. The slip joint went in to the marks that the seal made on it, BUT, that was as far as it went!
All looked good, but slip joint would not slide in enough to install drive shaft.
I removed the tail housing to see if there was something stopping the slip yoke from going all the way in, and all looked good. THEN I saw what looked like a slight twist in the splines. The main shaft had twisted splines. I got another off the shelf and bingo all worked just fine.
What I am trying to point out is make sure the old and the new slip joint slip in enough to install the drive shaft, because there are twisted (almost un detectable) flaws caused by mega HP and slicks that can twist a shaft.
If that's the only thing changed then make sure the slip joint slips ALL the way in the trans for drive shaft installation.

Dom

[Larry M.]

Re: driveshaft install problems with body off

One of the Munci transmissions I rebuilt was sold to a customer and when I installed it the drive shaft didn't fit! I was the one who took the old trans out and was attempting to install the rebuilt. The slip joint went in to the marks that the seal made on it, BUT, that was as far as it went!
All looked good, but slip joint would not slide in enough to install drive shaft.
I removed the tail housing to see if there was something stopping the slip yoke from going all the way in, and all looked good. THEN I saw what looked like a slight twist in the splines. The main shaft had twisted splines. I got another off the shelf and bingo all worked just fine.
What I am trying to point out is make sure the old and the new slip joint slip in enough to install the drive shaft, because there are twisted (almost un detectable) flaws caused by mega HP and slicks that can twist a shaft.
If that's the only thing changed then make sure the slip joint slips ALL the way in the trans for drive shaft installation.

Dom

I like how you think...............

See my post #16.

Larry

[Domenic T.]

Re: driveshaft install problems with body off

I like how you think...............

See my post #16.

Larry

Larry,
You type faster than me, LOL. Amazing, you found that also in a main shaft. here I was thinking I was the only one to think of that!
Can't wait to see if that's what it is.
Your friend,
Dom

[Sascha P.]

Re: driveshaft install problems with body off

I rebuilt the transmission. New gears, new mainshaft, new yoke. The new mainshaft has straight splines. Just now I went back into the garage and played with the olds mainshaft and the new/ old yokes. Turns out the new yoke has some kind of rubber damper inside, at the bottom. That makes about 0.5 cm difference compared to the old one.
The picture shows both yokes inserted into the transmission. The left one is the new one, the old on on the right. As you can see, none goes in completely. The new one of course still has the rubber bumper inside of it.
But, the old one, should it go all the way in? Is it possible that the mainshaft sticks out too far out of the housing?
20210103_140643.jpg

[Domenic T.]

Re: driveshaft install problems with body off

Back in the early days when I was working at a dealer some transmission yokes would chatter on the new cars, so the fix was to use very thick grease on the shaft and inside the yoke.

Dom

[Sascha P.]

Re: driveshaft install problems with body off

I guess that is what the bumper is for. But in my case it 'steals' even more space for movement ...

[Domenic T.]

Re: driveshaft install problems with body off

Sascha,
I think you are fixed. The fore and aft movement will be almost nothing as the differential only has a bumper and the twist is almost nothing. You will be able to push that in (I bet ) with a bit of force!
I would still use a bit of grease to minimize wear.

Dom

[Edward J.]

Re: driveshaft install problems with body off

Sara, The old slip yoke, shows you just how far it should slip in, if there is a rubber bumper I would try and remove it. Also you can try to rotate the yoke so the u-joint can slip by and under the yoke, then rotate the shaft into yoke, this will give you a little more space to work with. Also look see that someone did not over grease the slip yoke this will stop the yoke dead in in tracks. Your new yoke should slip just as far in as the old, the old yoke will ind. the movement,the reason for the slip yoke is so the yoke can slide in and out during the suspension travel. Another possibility could be the tail shaft bushing is not not pressed completely in all the way which will also will stop the yoke from slipping in completely.

[Sascha P.]

Re: driveshaft install problems with body off

Thank Dom,

I was afraid someone would so so :-(

[Sascha P.]

Re: driveshaft install problems with body off

Thank you Edward!

By now I think I will remove the rubber bumper inside the yoke. That will give me 5 mm more space (I am counting every little bit). Also, these days I am meeting a friend who also has a 73 corvette and I will measure a few things on his car.

[Sascha P.]

Re: driveshaft install problems with body off

Here is an update. The body is now back on the frame and I will try to fit the driveshaft now. Depending on how it fits I may have it shortened. I will update this thread once it is working.

[Danny P.]

Re: driveshaft install problems with body off

did you try lifting diff. with floor jack maybe pinion angle different or try dropping the leaf spring end bolts and release the spring tension see if that helps, you should have more then one inch of play for driveshaft travel something wrong somewhere , i attach my 63 driveshaft setup it has more then one inch of end play ,but should go on with body off or on, just a though Z06 PHOTOS 105.jpg

[Frank D.]

Re: driveshaft install problems with body off

My 63 driveshaft is out right now for balancing/U-joints and the slip yoke can be pushed in nearly until the flange hits the tailshaft seal of the original Muncie ALL kinds of room.

[Sascha P.]

Re: driveshaft install problems with body off

Just wanted to give an update. I took the drive shaft to a shop where they have shortened and balanced it. It now fits perfectly!

Thanks again for all thoughts and ideas.

Sascha