Bob Barry
08-02-2001, 04:32 PM
Scary has been holding its gears too long, so I wanted to replace the modulator and check the governor.
I bought a Fram replacement that was the same size as the original, but which didn't have a notch to hold the adapter insert (unlike a normal TH400 modulator, it doesn't plug directly into the side of the case, but has a 90º elbow with a roller inside it, and uses a curved adapter insert to transfer the motion of the modulator piston to the valve-body). The adapter is necessary to avoid interference with the front driveshaft.
So I tried the one from my spare AMC TH400 case, which happened to be much smaller. It looked a lot like the one on my Olds TH400, so I thought I might plug it directly into the case sans the adapter.
Unfortunately, the AMC TH400 case has a shaft that extends out from that hole further than a normal TH400 case, so a normal modulator doesn't seat far-enough in. I don't know if there is an aftermarket modulator that would be a direct plug-in, but that would simplify things under there.
Anyway, I used the smaller modulator on the elbow adapter; the real problem, though, was a sticking governor. Though it looked clean, the internal piston that the weights cause to move in and out was not moving, so it was holding gears too long. Now it shifts like it should.
Anyone have any details about that rod that sticks out further on AMC TH400's? Is that removeable, so that a regular modulator could be used directly?
I bought a Fram replacement that was the same size as the original, but which didn't have a notch to hold the adapter insert (unlike a normal TH400 modulator, it doesn't plug directly into the side of the case, but has a 90º elbow with a roller inside it, and uses a curved adapter insert to transfer the motion of the modulator piston to the valve-body). The adapter is necessary to avoid interference with the front driveshaft.
So I tried the one from my spare AMC TH400 case, which happened to be much smaller. It looked a lot like the one on my Olds TH400, so I thought I might plug it directly into the case sans the adapter.
Unfortunately, the AMC TH400 case has a shaft that extends out from that hole further than a normal TH400 case, so a normal modulator doesn't seat far-enough in. I don't know if there is an aftermarket modulator that would be a direct plug-in, but that would simplify things under there.
Anyway, I used the smaller modulator on the elbow adapter; the real problem, though, was a sticking governor. Though it looked clean, the internal piston that the weights cause to move in and out was not moving, so it was holding gears too long. Now it shifts like it should.
Anyone have any details about that rod that sticks out further on AMC TH400's? Is that removeable, so that a regular modulator could be used directly?