I posted this in the transmission section, but got no replies, so here goes. I have two problems, or maybe just two symptoms of the same problem? Part one. Occasionally when started cold the car will not move in Drive. Always works right away in Reverse, but I sometimes need to put it in Drive, then give the throttle a good stab, and then it goes into gear. Acts fine after that. Part two. Made two passes at the track tonight. Both times when I shifted into 3rd gear it stayed in second. Fortunately it was 1/8th mile, so I only had to wind it to 5300 to cross the finish line. Acted fine driving home.
Transmission The TH400 in my car started doing this last year at Salem. Wouldn't "catch" when the car was cold, but by the time the tranny warmed up things seemed OK. By this spring it was toast. The torque converter front bearing was eaten up. I called TCI and they said "These things happen". I put in another tranny and converter and it's OK for now.
Talked with my uncle who is a trans guy. He stated that the reverse gear requires more hydralic pressure than the drive gears maybe the reason why reverse works over drive. He was stating that more times than not it is a seal problem usually hard seals on an older transmission. hard seals soften up after the transmission starts to warm up. but will get hard again after it cools down. just taking a shot at it. :beer
Thanks for the replies. Please, keep them coming. Mike Kurtz of Century Transmission (big 200R4 guys) was inside it recently and said the bands and clutches looked like new. (Trans was said to be recently rebuilt when I got it.) He did replace the intermediate sprag, which was toast(trans was actually still working OK) Some folks have suggested front pump. If Reverse takes MORE pressure, seems odd that it would work and not Drive? Is the "torque converter front bearing" in the trans or converter? If I am visualizing correctly, I would think that the "torque converter front bearing" would be the pump gears themselves. Or is there a bearing that the snout rides on before the gears? (I DO remember that the notches in the converter snout are what drives the pump gears.)
Nick, didn't you have trouble manually shifting my car last time out? Was it the same as what you are now having on your car? Just curious. Maybe you have lost "the touch"? :laugh: Give me a shout if you want to stick my spare converter on there. dewey
Dewey You think you are cute huh? HA!!! :moonu: No, it's nothing like the bizarre behavior of your trans... And, yes, whenever this comes apart to be fixed, I would very much like to put that one back in. :grin:
Nick what my uncle also stated was he doubts it is the pump because you are able to produce enough hydralic pressure to move the car in reverse. He thinks your problems are not in the convertor or pump but in the seals inside the trans. Let us know what you get figure out. maybe valve body seals...
I was always told by Mark DeConti (dcm422) that manually shifting a stock THM 400 is a no-no. It wears something out, can't remember what. PM Mark.
I sent Mark a PM earlier this morning asking him to check in here. Hope to hear from him soon. (By the way, I have been planning to re-install the kickdown for a while; just been lazy. Will be doing it now. However, I do like having "something to do" while going down the track. Kinda boring if you don't have to watch the tach and shift in a high 13 sec car...)
Can't get into too much detail right now (am at work), but manually downshifting has the potential to wear out the low reverse band when going to L1. Also, continued upshifting to 2nd can wear out the intermediate band that is used for braking the trans in L2. Mark
Thanks for stopping in, Mark. Looking forward to more of your thoughts on what it's doing. FWIW, I never manually downshift, just manually upshift on the track. Once I identify and solve the problem(s) at hand, I will install the kickdown, modify the governor if/as needed and be a good boy and race in Drive. Just need to fix it first!!!!! :rant: Thanks for the input, all. Can't wait to get this figured out.
This may sound wierd but try pouring a can of KW TransX in it. I've fixed several trans shifting problems with this stuff, it's the best I've ever seen. It fixes seals and cleans varnish off shuttle valves in the valve body that may be sticking. Give it a try, its a cheap fix and if it doesn't work your only out about 8 bucks. Dave Berry
Some of the things you mention are puzzling. In reverse, the rear band and direct clutch are engaged. So, they work. No shifting into 3rd would indicate a bad direct clutch. But, reverse works and it should be good. No engagement when cold could be a bad modulator or a burnt up forward clutch. Sometimes a bad filter will cause this as well. In rare cases, a burnt forward clutch could make the trans appear to not shift into 3rd as it may slip enough to make it appear to stay in second. First thing I would check is to make sure your gear selector is aligned to get all the gears. Mis-alignment could cause the no drive when cold (and other times) and then may not be aligned enough to move from 2nd to 3rd when the selector is moved. Next is the condition of the fluid and the filter. Bad filters are not that easy to see and sometimes just replacing them will correct problems. Try to get the metal screen filter as it is better than the paper (Dacron) ones. Sometimes the screen filters are found at Carquest. Auto Zone and Advance usually only have the paper one. If you find a lot of material in the fluid and pan, it is an indication that something is worn out. It will be time for a rebuild. It is hard to pinpoint exactly what is happening without seeing, hearing and driving the car. Again, start with the basics and proceed. As to manual shifting the trans, everytime you use either L1 or L2 one of the bands is applied in the trans. The L2 (intermediate) band is used for braking the trans in 2nd and the L1 (Low/Reverse) band in 1st. Going manually into the L1/L2 ranges and then hitting the gas slips the bands before they completely apply. Upshifting 1-2 manually engages the intermediate band before the clutch in many case. The direct drum rotates counter-clockwise in 1st. The intemediate clutch/sprag setup is designed to stop the rotation and shift into 2nd. Timing of the clutch/band is usually off and the band applies a bit quicker. It is small and not designed to take this abuse forever. Several units I have taken apart have had the band burnt black (or all the friction material is gone) and the drum is worn/scorched in the band area. This is a sure sign of just manually shifting the trans. A properly functioning kick down does a couple of things. First and foremost is no bands are applied. Second, it redirects kick down oil to the pump pressure regulator vavle to increase line pressure for firmer shifts. Lastly, there will be no guessing at when to shift as it should be consistant at a set RPM. Hope this gives you some things to go on and help you find the problem. Good Luck, Mark
