Well I got started on the install at 11am and finished at 3pm. First thing was to pull the headers in order to make room so I could get to all of the transmission pan bolts.
After the exhaust was pulled it was time to drain fluid. The stock oil pans on C4's didn't have oil drain plugs on them, so pulling the pan and letting it all out at once would be messy. Since I have a new oil pan going in I decided to just drill a 1/2" hole in the oil pan and let the fluid drain. Once fluid was drained and the oil pan was off I removed the valve body.
Next in the back of the transmission there is a hole for a shifting modulator. I didn't have one since my valvebody is a reverse manual already, but cars who use a C4 with the stock valve body will have a modulator with a vacuum line going to it. That is what shifted these cars back in the day. That hole is now where the Transbrake solenoid goes. Since the solenoid is push in and not screw in I had to drill out the existing threads. I kept stepping up the drill bit until the solenoid fit. It ended up being a 9/16" hole. The pin that you can see in the hole was for the modulator and had to be removed for the transbrake rod and spring.
After the hole was good to go and the solenoid was fitted I had to fiddle with the bracket that holds the soleniod in place. This is actually what took the longest and I actually had to fire up the welder and modify the bracket by welding a spacer on it. The rear band adjuster had to be tightened down to 10ft lbs and then backed out 3 full turns. once that was done the soleniod bracket was installed into the band adjuster bolt and tightened down. Then the soleniod was finally ready to go in.
After that it was time to install the new transbrake valvebody. This was one of the easiest things I've done to the car. There is a rod in the valve body that controls the shifting mechanism. You line up the rod with the shifting mechanism in the case and hand tighten a couple bolts. Move the shifting lever back and forth and insure that it is indeed engaged and the rod is moving back and forth with no binding. Once that is verified you tighten down the valvebody bolts to 80-100 inch lbs.
At this point You are ready to install the pan and fill with fluids, but I had a minor set back. When removing the trans temp gauge in the beginning I broke the temp sensor. the wire broke and the mercury leaked out. Unfortunately I have to have the gauge installed in the pan before I can fill the trans. I put a few bolts in the new transmission pan just to keep dirt out of the valvebody. I will order another sensor and when it comes in I'll have to start wiring everything up. Thanks for looking hope this thread can help someone in the future.

After the exhaust was pulled it was time to drain fluid. The stock oil pans on C4's didn't have oil drain plugs on them, so pulling the pan and letting it all out at once would be messy. Since I have a new oil pan going in I decided to just drill a 1/2" hole in the oil pan and let the fluid drain. Once fluid was drained and the oil pan was off I removed the valve body.


Next in the back of the transmission there is a hole for a shifting modulator. I didn't have one since my valvebody is a reverse manual already, but cars who use a C4 with the stock valve body will have a modulator with a vacuum line going to it. That is what shifted these cars back in the day. That hole is now where the Transbrake solenoid goes. Since the solenoid is push in and not screw in I had to drill out the existing threads. I kept stepping up the drill bit until the solenoid fit. It ended up being a 9/16" hole. The pin that you can see in the hole was for the modulator and had to be removed for the transbrake rod and spring.

After the hole was good to go and the solenoid was fitted I had to fiddle with the bracket that holds the soleniod in place. This is actually what took the longest and I actually had to fire up the welder and modify the bracket by welding a spacer on it. The rear band adjuster had to be tightened down to 10ft lbs and then backed out 3 full turns. once that was done the soleniod bracket was installed into the band adjuster bolt and tightened down. Then the soleniod was finally ready to go in.

After that it was time to install the new transbrake valvebody. This was one of the easiest things I've done to the car. There is a rod in the valve body that controls the shifting mechanism. You line up the rod with the shifting mechanism in the case and hand tighten a couple bolts. Move the shifting lever back and forth and insure that it is indeed engaged and the rod is moving back and forth with no binding. Once that is verified you tighten down the valvebody bolts to 80-100 inch lbs.

At this point You are ready to install the pan and fill with fluids, but I had a minor set back. When removing the trans temp gauge in the beginning I broke the temp sensor. the wire broke and the mercury leaked out. Unfortunately I have to have the gauge installed in the pan before I can fill the trans. I put a few bolts in the new transmission pan just to keep dirt out of the valvebody. I will order another sensor and when it comes in I'll have to start wiring everything up. Thanks for looking hope this thread can help someone in the future.
