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Discussion Starter · #1 ·
Hi,
A couple weeks ago my TH350 started slipping and shifting late from 2nd to 3rd. When I drained the ATF it was loaded with clutch material, which would explain the slipping.

I installed the engine and transmission myself last Summer, and the trans was a brand new TCI Street Fighter.

What would cause it to wear out so soon? The vacuum line did appear a little loose when I checked it, and the trans was overfilled somewhat. If the vacuum was completely unhooked I would expect the trans to shift harder than normal, not softer.

Thanks for any info
 

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Is your kickdown correctly adjusted? On TCI streetfighters the kickdown works like a TV cable, similar to the overdrive trannys. The kickdown controls line pressure and if not correctly adjusted you will experience pre-mature failure.
 

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The most common cause of automatic clutches going south is low pressure. Could be one of the piston seals was damaged on rebuild. If the trans got hot then the seals would have got hard and failed. Could be a cracked apply piston. Another area on 350s is the front drum bushing wears and takes the stator support with it. This was common on early 350s but TCI should have updated this part with a wider bushing. Clutchs don't usually wear out on there own. Look for somthing that causes low pressure
 

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One of the most commond causes of low pressure is an overfilled state allowing air to mix into the fluid reducing pressure.
 

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Discussion Starter · #5 ·
Okay, it sounds like it could be any of the things I was suspecting:

ocs408, I hooked up the kickdown cable myself on my Edelbrock carb, which seemed to not have as much travel on the linkage that the cable would need. No bother, I just hooked it up so that the cable was all the way pulled out when the throttle was maxed out. Maybe I need to extend the lever arm for the cable on the linkage? It seemed to downshift when needed, but like you say maybe the lack of line pressure from this killed it.

70 Elky, It was overfull when I looked at it; I didn't know that the level changes so much between hot and cold, and I filled it up cold. That might be it.

There is also a leak on the passenger side near the kickdown cable mount, which I've thought was probably the dipstick. Mike, where would the leaks you describe show up? There doesn't seem to be any leaking around the torque converter where it meets the trans.

I'm calling a trans shop tomorrow to get it fixed. I hate doing it because I don't trust anyone to work on my baby. Even if I screw it up at least I'm not paying myself $40 per hour to screw it up.

Thanks for the info. I'll ask them to look for clues when it is apart and try to do it right when it is hooked up again.
 

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Dave66, since you need someone to look at your trans I have a place for you. Since you are in the D.C. area I have a friend in the trans repair business, He is located in Lothian,Md(Waysons Corner) the address is 5463 Southern Maryland Blvd, ph # 301-627-4949. Several of my co-workers have taken theirs to him and are happy with the results. Tell him that Leo from Washington Gas sent you to him. He does bench work also, but you might need him to look at your adjustments. He is a GM man. OOPS I forgot to tell you the name of the shop, its TRI-COUNTY TRANSMISSIONS. If you want to, stop by here at Washington Gas on your way to his shop and I'll give you his card. I work the 3:00 to 11:30 pm shift in the fleet garage around in the back of the building, come to the gate and honk. Its at 4000 Forestville Rd.

[This message has been edited by chev64 (edited 04-12-99).]
 

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Dave, I ran into the same problem w/ my TCI. I personally don't like using the kickdown so I contacted TCI about it and they told me to simply pull the cable all the way out (just before the kickdown detent) and to lock it down. The result would be full line pressure all the time. The only "downfall" to this would be that the tranny would shift at a slightly higher RPM and a little firmer. In my opinion the downfall was actually an improvement.
 

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Discussion Starter · #9 ·
Well, the trans guy told me yesterday the torque converter crashed and took out the pump, the high speed clutches, and part of the drum. Anyone here have a torque converter blow up on them with a street car that wasn't raced much? I was told by Bill64EC that maybe the trans was what broke and the material from it subsequently wiped out the converter.

Hopefully this won't happen again!
 

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dave,
i've had to replace the trans im my 64 twice in three years,(th350).both used trans from friends of friends.this time i went to a pro.
he said that my problem was the cooling setup
trans oil was running too cool.trans oil needs to be above 125f.hope you have better luck with the rebuilt unit.let those pros handle the details.:-(
 

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Discussion Starter · #11 ·
Well, finally got it back this morning. Damn, Chevelles are cool aren't they?!? What a commuter car!

The trans guy showed me where the surface that the crescent-shaped thing for the pump rides on was all roughed up, which caused a loss of pressure, and caused the clutches to wear out. He also said the paint on the torque converter was all baked from the heat.

I think I should get a trans temp gauge at least to warn when things like this are happening before it gets out of hand.

Thanks again for the help guys.

------

Mike, it sounds like you were right - the bearing thing in the pump was all worn, but the trans guy said that was because the torque converter failed and got metal on that surface. Maybe it failed first???



[This message has been edited by Dave66 (edited 04-20-99).]
 

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It could be that the converter failed first but its hard to tell. I have cut them open before on a lathe. Somtimes you can see an obvious cause like the one way spag broke apart or froze locked,or a thrust bearing went south. Once a clutch starts to slip it only takes a few miles to burn up. It creates a tremendous amount of heat that will cook internal seals that will add to pressure loss that will create even more heat. So the best thing to do when your trans starts to slip is to find the problem before it trashes the whole trans. Pump failure could have been caused by the converter coming apart and the pieces going right into the pump.The bad thing about having a high dollar converter is it can be ruined if the trans comes apart and puts metal in the converter. No amount of flushing will clean it out.It must be cut in half an cleaned.
 
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