MartyW

I am needing some transmission help and I am sending out the Colorado Vette distress call. I have a 76 that was rebuilt recently with new engine and transmission. The transmission is a TCI TH350 that was assembled by a company in Denver CO (no longer in business - SPEED INNOVATORS, LLC). It was assembled with all manual valve bodies and a reverse pattern on the shifter. When I got the car it had about 600 miles on it and I have put an addition 1000 at the most so it is still pretty new.

About a week ago I started having problems with the reverse gear. I first noticed a problem when I picked up my car from getting repainted and when I put it in reverse it did not seem like it had as much power as normal. Started to notice over the next few days that it did not always feel like it was fully engaged in reverse....felt almost like a manual transmission and the clutch was half-engaged. I belive that it is getting worse and am now paranoid that the problem may be spreading to the 'forward' gears as well. It seems to engage in reverse better first thing in the morning when the car is cool or when it has been off for a while. The transmission fluid is not leaking and is at the correct level and of normal color.

Would appreciate any and all help I can get in diagnosing what could be wrong as well as finding a way to get it repaired. I know there are a few of us located in and around Denver CO and if anyone is willing to help or knows of a GOOD place where I can get it repaired correctly and at a fair price I would really apprecaite it. I really wanted to take a few 'drives' with some of the local colorado vette clubs and need to get the car ready for Vettes On The Rockies, so I would like to get this fixed soon.

Thanks again for any and all help.

MartyW

Come one now....I know there are transmission experts on this forum so someone needs to chime in. I have heard you guys talking about completely removing and rebuilding the transmission in one day so I know you guys can do this. I will be contacting TCI today and might talk to a few shops in Denver that service TCI transmissions, but I could really use your guys help.

lars

Marty -
We use one guy in the Metro Denver area for all our hi perf auto tranny stuff - he builds the trans for the racecars and the street cars, and he's very good. I used to teach automatic trannys at the GM Training Center, and this guy is the only one I trust. And his prices are very fair. Info as follows:

Arnold’s Transmission
303-477-0210
1 blk east of 29th & Sheridan
Guy you want to talk to and to do the work: Joe

Tell him Matt Farwell and Lars sent you.

Victor

I'm definately not a mechanic so don't take what I'm about to say as a fact, but I have rebuilt my own TH350 transmission and I have a little bit of sense of what might be going on.

It sounds like the friction material in between the clutch plates is starting to go. As the friction material starts to go, the more the plates will slide, causing more friction material to be lossed at a faster rate. I think the biggest causes of this would be either too much torque going through the transmission or the transmission overheating.

There are several different groups of clutches in the transmission and the low/reverse group is one of them. I'm not sure why the problem would be spreading. Maybe as the friction plates from this group deteriorate, more grit and debris is passing through the other clutch groups causing them to wear faster and prematurily? Just a thought...

If you think that the transmission might be overheating, make sure that the transmission cooler in the radiator is fully operational. You can also add an additional aftermarket one as well.

I would think your problem could be solved by a simple transmission rebuild but I don't have a clue how much a rebuild should cost as I did mine by myself. Just keep in mind when you get an estimate that Summit sells a variety of rebuilt TH350s for around $750-1,000 that have shift kits and other higher horse power enhancements added to them. If you want to do it yourself, a shift kit/rebuild kit complete with friction material will cost you around $100-200.

MartyW

I am gonna stop by a local shop this afternoon and have a transmission inspection so I can hopefully tell what is going on. Everything on TCI's site says that with any of their tranmissions you definately need a aftermarket transmission cooler. I am not sure how this was assembled and would not be suprised if there was nothing but the stock cooler in there. I have never heard any unusualy sounds when shifting and it is pretty much new so there has to be a reason if the friction material is gone. If it is gone - is this something that is easily replaced. I do not even want to consider a new transmission since this one is brand new and is listed as a very good transmission. This is the TCI Chevy Competition Full Manual TH350 which is listed on their website at $1300. It should not be failing in the first place, but even if it is...should not be that much to fix it. I am partially just trying to convince myself that this should be easy.

Thanks Again

lars

If the tranny is slipping going into reverse, the low/reverse clutch pack and/or seal is likely failing. The tranny has to be completely disassembled to fix this, so there is no "not be that much" scenario. Cost will be $600 if you have a competent shop do it.

MartyW

Cars goes into 1st gear fine. Only affected gear so far is the reverse. I was getting paranoid that the problem was spreading, but at the moment only the reverse gear is slipping. I just can't believe that a 2000 mile new TCI TH350 transmission can just go like that and need to be completely rebuilt.

CA-Legal-Vette

Based on this I'm wondering if the issue is in the valve body. I went through the diagnostics in the service manual yesterday and this came up a number of times. What I don't know is how valid the standard diagnostics would be in a reverse pattern valve body.

MartyW

The TCI website some has information regarding my specific transmission. It was setup with reverse pattern and manual valve bodies directly from them...not aftermarket. They list on their website the proper pressure readings for each of the gears. The TCI part# is 312000. I will be taking it by to be looked at after work tonight so hopefully I will have the specifics of what is wrong and hopefully some idea of what happened to it. Definately not normal wear that caused it to fail....its got only 2000 miles on the tranny.

MartyW

Ok, just got back from a transmission center. Guess the person I spoke with on the phone did not really know what a TCI TH350 transmission was. They were expecting some external linkage to be able to test a few things, but the TCI TH350 is entirely self contained with no external linkage. I did take it for a drive with the master mechanic there and he seems to think that it might just be a seal. He said that it is definately trying to engage, just not getting enough pressure to engage the gear. Since it seems to work fine when I first start it up if it has been sitting for overnight, he seemed to think it was a seal problem that once it starts to heat up it is losing pressure in the reverse gear. I bet this is something that a normal vette mechanic could easily do themselves, but I will need to get someone to repair it for me.

Guess I will have to try Arnold's Transmission like Lars suggested, but I already called tham and they are not open on saturdays and will be closed this monday. I live about 100 miles from Denver so it is kinda a pain to get the car down there to be fixed. Still just can't believe that a seal would fail in a transmission that is less than 2000 miles old. If excess heat could contribute to failed seals, then I think it might be a good idea to get a 'phat' aftermarket transmission cooler for the TH350.

lars

Marty -
Automatics are funny. I've had them fail randomly with less than 100 miles due to a small nick in a seal or other seemingly insignificant issue, so it can happen.

If you have a higher-than-stock stall on your torque converter, you want to run an external tranny cooler. It's not the tranny itself that generates the heat - it's the slippage in the torque converter. The TH350 does not like to get hot, so install a cooler if you're running a high-stall converter. If your converter is near-stock, the existing in-radiator cooler is OK if you don't run the car hard. But a cooler will prolong tranny life even with a stock converter.

Joe over at Arnold's has been building race trannys for decades, and he's very good at it. He shouldn't have any trouble with the TCI setup, since he does reverse valvebody conversions regularly. As you know, the tranny has to be disassembled to replace any seals, so he can give the whole thing a good look-over when it's torn down. If friction plates are not damaged at all, you may be able to get away with just a seal kit, but the labor effort will be the same regardless of internal damage. Joe's pretty good to work with, so I think you'll be in good hands.
Good luck!
Lars

MartyW

Thank you very much Lars. I will be calling Arnolds' this morning to see if I can drop it off there on Tuesday. The car does have a higher than stock stall converter. I belive the guy I bought the car from said it was also a TCI and was 3000 or 3500 RPM stall converter so from what you are saying that should definately have an after-market higher end transmission cooler. I'l tell Joe that you guys referred me to them. I hope it is something simple, but if not...oh well....will have to just have it fixed anyway.