Competition Series TH350 problems!

HotRodGMC68 · #1 (**permalink**) 03-01-2010, 04:26 PM

I have a TCI comp. series TH350 that a picked up from a guy that had overheated it and was getting rid of it.

The tranny started out being stuck in high gear while still having Reverse, Neutral, and Park. No low or mid range. I had it torn down, inspected,and rebuilt. Found a burnt up direct clutch pack, strunkin drum seals allowing fluid to get by, and a burnt up band. Brand new clutches and steels, a seal kit, and a new race band were installed and it was buttoned up.

After installing and filling the tranny I ran it through the gears.. had Reverse, Neutral, high, and 2nd. But in first gear the rear tires would lock up as if it was holding two gears at once!

This transmission does NOT have a trans. brake. Does have a full manual, FWD pattern valve body. Has not been modified in any other ways than what TCI does when they build them.

I would greatly appreciate it if anyone could help out with this situation.

Thanks!
Kurt S.

Cameron@TCI · #2 (**permalink**) 03-02-2010, 01:13 PM

Kurt,

Check over you valve body gaskets. Make sure that you have the correct gaskets (match them to the seporator plate), and also check to see if the gaskets are still in tact. It sounds to me like it's a cross bleed.

Thanks,

HotRodGMC68 · #3 (**permalink**) 03-02-2010, 02:45 PM

Thanks Cameron! I will check the gaskets ASAP.

Is it possible that there is a crack or a porus area caused by the transmission being super heated when the previous owner hot lapped it, causing a fluid bleed somewhere in the case?

Cameron@TCI · #4 (**permalink**) 03-02-2010, 03:40 PM

Originally Posted by HotRodGMC68

Thanks Cameron! I will check the gaskets ASAP.

Is it possible that there is a crack or a porus area caused by the transmission being super heated when the previous owner hot lapped it, causing a fluid bleed somewhere in the case?

Kurt,

That's a possibility, but it will be hard to find.

Thanks,

HotRodGMC68 · #5 (**permalink**) 03-02-2010, 04:24 PM

Is there any chance it could be something I missed when I was rebuilding the valve body?

Cameron@TCI · #6 (**permalink**) 03-03-2010, 12:51 PM

Originally Posted by HotRodGMC68

Is there any chance it could be something I missed when I was rebuilding the valve body?

Kurt,

What part number is the valve body? It could possibly be a cross bleed with the high gear circuit. I really don't think that it's anything that you could have done with the re-installation of the valve body, except except a gasket issue.

Thanks,

HotRodGMC68 · #7 (**permalink**) 03-03-2010, 01:47 PM

The valve body is a 321000.

Cameron@TCI · #8 (**permalink**) 03-04-2010, 02:54 PM

Kurt,

Check the gaskets..

Thanks,

HotRodGMC68 · #9 (**permalink**) 03-05-2010, 10:49 AM

Here are some preliminary pressures we checked last night. The pressures noted are what I'd call an average. It has a lumpy idle so the pressure gauge needles were shaking about with about a 15-20 psi spread. All pressures were checked at idle.

Line pressure:
Park: 170(ish)
Reverse: 130-140(ish)
Third: 170ish
Second: 170ish
First: 130ish

@ 1/2 accumulator port:
No pressure measured in any gear

@ 2/3 pressure tap:
Third: 170ish
Reverse: 20-30ish (it was about a 10 second buildup to this)
No other gears showed pressure at this port.

I dont know if these say anything to anyone else, but we found it a little odd that the first was dramatically lower and made us think it was an indication of a bleed through with the pressure.

HotRodGMC68 · #10 (**permalink**) 03-15-2010, 01:18 PM

Okay, this weekend I dropped the pan, checked the manual valve- Was within spec.

Pulled the valve body and spacer plate and inspected the gaskets- all were okay and correct.

I installed a replacement 321000 valve body and tried it on for size... the results were almost the same. The only differences were that now instead of the rear tires locking instantly when it goes into low gear, they would spin for ~ 2 seconds in low gear (could watch the drive shaft and notice the RPM difference from 2nd to 1st) and THEN they would lock up. Also, if I gave it half throttle or better, it would TRY to turn the tires.

Any ideas??