driveshaft install problems with body off

[Sascha P.]

Hi all!
After almost 6 years I installed the engine and transmission back onto the frame of my 73 corvette with the body still off. However, when I wanted to install the driveshaft it did not fit between the transmission and the differential.
Up to now I could not find any information if that is normal, if the driveshaft can only be easily installed with the body on cause of the added weight and with that changed geometry of the drive system. I measured the driveshaft, it is 29.5 inches long (from centre to center of the u-joints) which I believe is correct.
What I am afraid off is that something else than the driveshaft could be wrong although I would not know what that could be. Transmission and differential sit tight in their spots.
Thanks for any hints, tips and ideas!

[Harry S.]

Re: driveshaft install problems with body off

Hi all!
After almost 6 years I installed the engine and transmission back onto the frame of my 73 corvette with the body still off. However, when I wanted to install the driveshaft it did not fit between the transmission and the differential.
Up to now I could not find any information if that is normal, if the driveshaft can only be easily installed with the body on cause of the added weight and with that changed geometry of the drive system. I measured the driveshaft, it is 29.5 inches long (from centre to center of the u-joints) which I believe is correct.
What I am afraid off is that something else than the driveshaft could be wrong although I would not know what that could be. Transmission and differential sit tight in their spots.
Thanks for any hints, tips and ideas!

Is the slip yoke attached to the drive shaft? If yes, mark the slip yoke and drive shaft. Seperate slip yoke from driveshaft. Push the slip yoke into the transmission as far as it will go. Attach driveshaft.

[Sascha P.]

Re: driveshaft install problems with body off

Hello Harry!

Unfortunately, that does not work. The slip yoke is new and has the same size as the original one. It is not attached to the drive shaft.
When I push the yoke all the way into the transmission the distance between tranny and differential is just the exact length of the driveshaft. With that, I cannot get the driveshaft in between the two.

[Michael S.]

Re: driveshaft install problems with body off

some thing does not sound right. try the old slip yoke. look inside the new one in case some thing lodged in there. the slip yoke should go in and then have to be pulled out a little to meet the shaft. it should not be bottomed out.

[Harry S.]

Re: driveshaft install problems with body off

Just a side note, did you have the slip yoke and the driveshaft balanced with new U-joints as a single unit. This is the way they showed up at St. Louis. If it's out of balance when your done, you will get a shimmy/vibration that will make you crazy.

[Sascha P.]

Re: driveshaft install problems with body off

I have also tried the old yoke, same result. The old and the new are exactly the same size, in and out. I was hoping that someone would tell me 'with the body on it will fit ... ' :-(

[Sascha P.]

Re: driveshaft install problems with body off

I have not balanced them, good point! I will look into that.

[Michael S.]

Re: driveshaft install problems with body off

can the engine/trans be shifted forwards? can the rear be shifted back?

[Sascha P.]

Re: driveshaft install problems with body off

Engine and transmission sit right where they should be, there was no problem installing them. I could only imagine that the differential is not right but, to be honest, it does not look like that either. I guess trying to move that back a little is the only solution although I would not know where to, so to say.

[Domenic T.]

Re: driveshaft install problems with body off

Did this all fit at one time, same parts, or was something changed other than the slip yoke?

Dom

[Sascha P.]

Re: driveshaft install problems with body off

I also changed the transmission mainshaft. But that has the same length as the old one.

The differential and driveshaft are the same, the original ones. The driveshaft did fit in the past, but I do not remember how well. I took it apart almost 6 years ago.

I changed the slip yoke because it was badly worn on its shaft and the transmission mainshaft because it was turning more in an egg shape rather than in a circle. That was the reason for the yokes worn marks I believe.

[Michael S.]

Re: driveshaft install problems with body off

if you had to replace the trany shaft you had this problem all along. get the specs on the driveshaft and see if yours is to long

[Sascha P.]

Re: driveshaft install problems with body off

The driveshaft should be 30.75 inches overall, mine is 30.78. That sounds about right I think. But, in the end, there is hardly anything else that a too long driveshaft. I have to do more searching on that.

[Larry M.]

Re: driveshaft install problems with body off

Is it possible that the transmission output shaft splines are twisted........and this does not allow the slip yoke to be pushed in all the way?? I would measure the cylindrical part of the slip yoke and then measure how much of this can be inserted into the transmission. And of course how much then is exposed outside of the transmission.

Hopefully this will allow someone to take some measurements on their own car or a spare transmission and see if your numbers are the same as what they get.

You should be able to install the driveshaft with the body on or the body off.

Larry

[Sascha P.]

Re: driveshaft install problems with body off

Thank you! I will do some measurements. Since I still have the old yoke and old transmission mainshaft I should get an idea if there is some off.