81 vette: slip yoke and clearance

[Feltman]

Ok, I need a little help. One problem I created the other I inherited.

Engine and transmission is installed. I called the local drive shaft shop and asked them how I should measure . They told me to have the slip joint out 1" from the seal and then measure from center of u-joint cap from slip yoke to rear gear yoke. I measured 26" and that is exactly what they modified the driveshaft to.....Now when I installed the drive shaft (the measurement should of been 25 1/2 inches, the slip yoke has about 3/8 of an inch before making contact with the tail housing......Will the slip yoke move that much?

Issue number 2. Installed a bowtie crossmember and 700R4 transmisson (not from bowtie). Both venders shipped trans mounts and here is where the problem lies. The trans mount was too short, allowing the tail housing to "sit" on the top of the crossmember. I installed spacers and now the tail housing is about 3/8 above the crossmember.....will the transmission move that much?

Any help is appreciated

 

[KANE]

....Issue number 2. Installed a bowtie crossmember and 700R4 transmisson (not from bowtie). Both venders shipped trans mounts and here is where the problem lies. The trans mount was too short, allowing the tail housing to "sit" on the top of the crossmember. I installed spacers and now the tail housing is about 3/8 above the crossmember.....will the transmission move that much?

Any help is appreciated

I've done the 700R4 swap before. I used a tranny and xmember from Bowtie Overdrives. No real issues other than I needed to shim the xmember on both sides where it bolted to the frame. The tranny would buck on the 1-2 and hit the tunnel. 2 millimeters made a difference. I never had an issue with the alignment though.

What is the GM part number for your tranny? If you can post that- maybe we can figure out what car it belonged in and then understand why the cases is not matching up. Then, we might be able to see how we can help you. FYI- Bowtie uses 89-93 F-body transmissions.

 

[big2bird]

I remember shortening the driveshaft exactly 3" for my swap. Gave me the 1" slip joint clearance. In all actuality, it never really moves. However, my tranny guy insisted on the 1" dimension. If it bottoms out, kaboom..

I called and inquired about the different mount heights when I did my install. They insisted on my using their shorter mount to correct the geometry. I have had no issues.

 

[Feltman]

follow up

No problems with the mount nor the driveshaft (after 100 miles)...the bottoming out does concern me......I did post another problem I am having.....

 

[Hib Halverson]

With the C2 and C3 chassis, the "slip joint clearance" is mainly to allow enough forward movement of the slip joint to facilitate removal of the shaft for maintenance of replacement.

The "ideal" slip joint clearance is just enough to allow removal of the shaft.

The amount of fore/aft movement of the trans and diff in relation to eachother is very, very small.

 

[Feltman]

Thanks Hib........my comfort factor is now higher:L

 

[spikebot 81]

Feltman, If its any help I just replaced rear trans seal on my 81 yesterday. Although its a TH350 the yoke slid in aprox 1 1\2 inch. Drive shaft droped right out with no trouble.