Still working out some of the bugs on my jeepster, one problem is that the tranny doesn't hold in park. It shifts fine. I haven't gotten underneath and checked the linkage yet, but barring that, what kind of a job am I looking at? Also if it is an internal problem what's it cost to remove/rebuild/replace a TH400? (gonna break it to the wife slowly)
If memory serves me correctly, the park "paw" is in the back of the tranny under everything, but not inside the rear housing/adapter. I think you can see some of it from the bottom when the pan is removed.
Double check the linkage. It should move fully to park position with some extra force.
When parked, there is a lever that moves over a grabs a cog type gear on the output shaft, thus locking the shaft to the case.
it is moved by a rod connected to the shifting shaft. This rod is spring loaded to the lock lever. That way if you hit park while still moving, you hear grinding before the lever grabs a tooth.
Has the tranny ben worked on lately? When I had my th400 rebuilt, the shop put the park linkage plate in backwards and it wouldn't stay in park on hills. You need to drain the trans, remove pan and filter. Find the metal cover over the parking gear plunger, it has two bolts through it and can be bolted in either way, common mistake to put it in backward.
Look for a th400 rebuild book at B&N or Borders and look up parking linkage and it discusses this in detail.
Just my .02
Hasn't been worked on to my knowledge, I just bought it back in June, and it's basically been sitting my garage while I rebuild the doors and get a hard top ready to put on it. The tranny didn't hold in park when I bought it. I contacted a website for trannies at http://www.quality-trans.com They have a question/answer guy. Chances are it's just a loose linkage, I have to disconnect the linkage and see if I can manually put it in park. If that doesn't work he said the parking pawl can be replaced without dropping the tranny, just remove the pan, probably the pawl return spring. WOW good news for once!
08-13-2002, 09:59 AM
TH400 not holding in park 
Linear Mode
