MOUNTING THE TH200-4R TRANSMISSION

11 November 2004

I'm using a TH200-4R transmission mated to the 248 with an adapter from Buffalo Enterprises. The adapter is made from .600" thick steel plate. It uses a 1975 Chevy 350 starter. The flex plate is custom made.

Click a picture to enlarge.

    Here the transmission is sitting on a floor jack to determine the correct angle for the rear mount. You might notice that the roof leaks at The Twin Oaks Garage. An excellent article about setting up your driveline can be found on the Classic Truck Shop web site. In short, the idea is to have the output shaft of the transmission parallel to the pinion shaft in the rear end within a couple of degrees.

This angle finder cost less than $20. Set like this on the yoke it shows the angle of the pinion plus 90 degrees. It is reading 87 degrees which means the pinion is sitting 3 degrees from level.    

A good place to measure the driveline angle is the starter housing. Ideally it is parallel to the crankshaft and the transmission output shaft. Here I've adjusted my floor jack to raise the transmission shaft angle to the same angle as the pinion shaft.     Now I'll need to set the rear mount to hold it at this angle.

I bought a universal crossmember from Classic Performance Products. For once, Lady Luck was on my side. I bolted the mount to the transmission and it met with the frame without having to build shims.    
The ends had to be welded on.

Then it was bolted to the frame. The angle is still right on.    

Next side mounts had to be built. At first I had them bolted directly to the sides of the frame but later changed them to mount on rubber pads.    

All the above work was done without the torque converter in place. Once I got it held in place with the side mounts I installed the flex plate and torque converter.    
UH-OH, we have a fouling condition. So I cut a little off the crossmember to give it some clearance but that wasn't enough. I had another problem. Lady Luck is paying me back for the freebie on the mount fit. Now the transmission fouls the back of the crossmember and lacks a bunch going on. Nothing I can't handle.

I thought about just eliminating that cross member since it had nothing mounting to it. But after further study I noticed the spring perches mount just forward of it and the cab mounts just aft of it. I decided to leave it in for reinforcement.     So I went to cutting. I lowered the center about an inch and a half.

And it all fits together nicely.    

    Here's the finished sidemount.

Here's the bottom view. I used the rubber mounts from a '56 Chevy 2-ton truck. Chevys make great parts trucks. They fit neatly into the recess of the spring perch.