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Looking for some advice or suggestions with a clearance issue. Just put the stock 350 back in my 1970 Cutlass Supreme. My original TH350 is in need of rebuild so I picked up a good 1975 TH350 and mated it to the engine for install. The installation went smoothly. Installed a new trans mount and crossmember but now when I try to install the stock driveshaft, the yoke is not able to clearance the tunnel. Tried it turning it in several different orientations. In fact, I can't even get enough clearance to be able to slip the yoke on the output shaft. I need the shaft/end of the trans to drop about 1/2 inch to get the clearance I need. Not sure what is going on. Could it be the body mounts are bad and the body has sagged enough to create the clearance issue? I believe the car has about 106,000 miles and I'm sure the body mounts were never changed.
The picture is of the two trans mounts I have. The one on the left was the original and only had the single bolt. The one on the right is the one I needed for the 75 with the two bolt holes. They both measure about 45mm in thickness.
I did try slipping the drivehshaft into the trans before I installed everything and it slid in fine with the normal amount of resistance.
I don’t know anything to speak of about which Transmissions were available for what years…
but I do know some Transmissions have a longer/shorter tail housing lengths.
I don’t know anything to speak of about which Transmissions were available for what years…
but I do know some Transmissions have a longer/shorter tail housing lengths.
could this be the case?
I believe I measured the tail housing lengths for both and they were the same but I'll double check. I have removed the trans mount and have the tail housing temporarily resting on a hockey puck on the crossmember which lowered it (the puck is thinner than the mount). I can install the driveshaft then jack the trans up and try to get the mount back in to see if the clearance resolved once the shaft is installed.
The crossmember is the original one that was on the car so nothing changed with that.
Temporarily remove the trans mount, lower the trans, install the driveshaft, raise the trans and reinstall the mount. Check for yoke clearance before driving.
I had the same issue with my TH350 shaft yoke clearance after installing a new aluminum driveshaft to replace my steel one, albeit some of my clearance issue was at least partly due to worn body bushings (which I've since replaced).
Here's what I replaced my stock height mount with and it was the perfect solution for me
Temporarily remove the trans mount, lower the trans, install the driveshaft, raise the trans and reinstall the mount. Check for yoke clearance before driving.
Thanks Joe. I am going to try this tomorrow. If I don't have the clearance, I'll either go with the shorter mount or try to see if the body mounts are severely worn.
I had the same issue with my TH350 shaft yoke clearance after installing a new aluminum driveshaft to replace my steel one, albeit some of my clearance issue was at least partly due to worn body bushings (which I've since replaced).
Here's what I replaced my stock height mount with and it was the perfect solution for me
Yes but the mount went in first, so I know that helped as well. Bushings were a definite improvement, the one under the right front floor was particularly all but completely crushed from age.
The bushings in my car had been replaced once in the 90's by a prior owner whom removed the body for a rotisserie resto, so they were at least 30 years old by the time I more recently did them.
Yes but the mount went in first, so I know that helped as well. Bushings were a definite improvement, the one under the right front floor was particularly all but completely crushed from age.
The bushings in my car had been replaced once in the 90's by a prior owner whom removed the body for a rotisserie resto, so they were at least 30 years old by the time I more recently did them.
Just to follow-up, I bought one of the shorter mounts (thanks 70sgeek) and installed today. Removed the puck I had in there and connected the driveshaft first. I did try the OEM mount first and did not have enough yoke clearance. Installed the shorter mount and now have enough clearance. Driveline angles are good. After I replace the body bushings eventually, I'll probably try to put the OEM mount back in and check driveline angles again.
