TCI Competition series TH350 Problems!

[HotRodGMC68]

I posted on here a while back about my tranny being stuck in high gear and having no clue why. I had the tranny torn down, inspected, and rebuilt.

Turned out that the direct clutch pack was burnt up along with the band. Also, the seals in the direct drum were shrunkin (from the insane heat that was in the tranny when the previous owner hot lapped it 5 times in a street race!) and was letting fluid blow by.

After installing and filling the fresh tranny yesterday, 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!

We're thinking that a crack inside the case or a porus area in a fluid passage could be the problem at this point but we've been wrong before!

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 new situation.

Thanks a bunch!
Kurt S.

[dartman]

Check the manual valve,make sure the "s" clip not bent. by putting it in low gear and making sure that the manual valve is level with the end of the valve body." i think,it's been a long time $ents i did a 350"

[Mark Yacavone]

First question is ; did you put a band back in it? Is this a full manual street transmission then? The band could be going on due to fluid crossing into that servo area, or
the intermediate clutches or even the direct drum .As long as the low/reverse and forward are both on, anything else applied will cause it to lock up.
You need to figure out what else is applying and why.

[njk53]

Make sure the governor is working freely

[HotRodGMC68]

Its a full manual valve body, There is no governor. The ports for it have been plugged off. Otherwise would've been a great thought. There most definitely is a band installed in it. Any ideas on how to find out what other components are being applied? (besides those that are supposed to be)

[Mark Yacavone]

The band is only there for 2nd gear braking . You can take it out,and remove the spring in the servo and replace it with some 7/16ths nuts/washers. You still could be getting feed to the intermediate clutches though, through that route, I think... (Russ Abrams , you there? )

A sticking governor will only hold it in 1st gear, not lock it up.
Here ,this will keep you busy for a while:

http://books.google.com/books?id=buw...age&q=&f=false

[dartman]

Originally Posted by HotRodGMC68

Its a full manual valve body, There is no governor. The ports for it have been plugged off. Otherwise would've been a great thought. There most definitely is a band installed in it. Any ideas on how to find out what other components are being applied? (besides those that are supposed to be)

http://books.google.ca/books?id=buwQ...%20350&f=false


http://www.tciauto.com/Instructions/...nt.aspx?cat=16

[dartman]

Originally Posted by HotRodGMC68

After installing and filling the fresh tranny yesterday, 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!

.

if the manual valve is out of adjustment.it could bleed into the 2nd gear passage and apply the intermediate clutch, it would lock up the transmission.

[HotRodGMC68]

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.

[ss3011]

Does the trans actually shift, from 2nd to third, or do the wheels just turn at the same speed. Even in third gear, intermediate clutch is applied. The 2nd gear roller clutch or sprag just overruns. If the trans locks up in 1st gear, then you have the forward clutch, low/reverse clutch, and either the intermediate clutch or the high gear clutch on. Suspect cross leak or a missing check ball. Most race trannies would not have the low/reverse clutch on in 1st gear. Street manual VB's put it on in 1st to give low gear braking. You should focus on figuring out how oil pressure is getting into the intermediate clutch or high gear clutch circuits, when you are in 1st gear. It is also possible your intermediate band is coming on, in low and holding the high gear drum, just like the intermediate clutch would be when in 2nd gear. Only thing is, it has low capacity and would probably start to slip if you got into the throttle, when "locked up" in 1st gear. When the transmission was rebuilt after being overheated, it is possible that some plastic parts, changed "shape" and were not caught or replaced during the rebuild. Those parts like an accumuator piston, or band servo, could be a source of a cross leak.