Originally Posted by Bigkuntree007
My 83 cj7 has a turbo 400 mated to an AMC 304ci V8 and it won't shift into 3rd gear. Seeing as how it only has 3 gears this is a problem. I think it's a vacuum leak but after I checked all the hoses all I can think that it might be is either the brake booster or the the part on the transmission where the vacuum line connects. Any ideas?
One Quick Question,
When you stomped down on the throttle, did it go into 'Passing Gear', from 3rd to 2nd, or even 1st?
This is important, so think hard and let me know.
Anyway, if it didn't want to shift UP before failing, then pull the vacuum line off the vacuum modulator and put a clean vacuum line on the modulator and (Suck) on that line to see if the diaphragm is busted or not.
Take the Governor cover off and take the governor out, see if it's got some crap stuck in it that is keeping it from working...
Make sure your 'Kick Down' switch on the throttle pedal is working.
Without electronic kick down, the high gear clutch drum won't live long, and that means a rebuild.
Also a good idea to take the pan off and see if there is a bunch of clutch material in the pan.... change filter/fluid while you are there.
With TH 400s, when high gear goes out (Direct) it's usually kick-down not working or it's the governor not letting you get an 'Up Shift'.
If it's Kick Down, then the direct drive clutch pack is shot and there is NOTHING you can do about it without rebuilding the transmission.
That's about $250 for materials, rebuild kit, ect. and it's a pain in the butt to get out and back in... that's the bad news.
The good news is these things are so simple a monkey could rebuild them.
Tons of rebuild manuals and books out there, and as long as you follow the steps in the books, you will be fine.
Crud in the governor or the spool valve just inside the vacuum modulator port can be cleaned out, but if you are getting pieces of clutch large enough to jam up those spool valves, then start saving for a rebuild.
If it's just a popped vacuum modulator around $25 and half an hour fixes the problem.