Tcc locks then unlocks
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On The Tree
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Tcc locks then unlocks So this is a rebuild with a new converter. During the test drive I notice that the tcc, when commanded to lock, locks for about a second. The slip goes to zero, then goes right back to slipping the same rpm as before the lock was initiated. All while the computer says that it is commanded to be locked. It is as if it loses pressure almost instantly. If I command max pressure it shutters. Only out about 10 miles on it at the most. Literally right down from my house and back. What are your initial thoughts? I have to pull the transmission anyway to fix a front seal leak.
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From: BERWICK PA
Solenoid missing ? yes that and other issue pressure wise. Seen that on dyno more than a few times lol.
Thus since i have no dyno now I photo everything , not jus for me but customer too , That was i can look over all when done and double check again at end .
Thus since i have no dyno now I photo everything , not jus for me but customer too , That was i can look over all when done and double check again at end .
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Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
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Thread Starter
On The Tree
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that’s a great idea!
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From: BERWICK PA
Yes it takes up a little time but when you have that MOMENT of did i do this or that ? It's so nice to just be able to look at the photos and go WHEW!
I did or DAMN well Least I know. lol,
Then of course always the slight risk you will have a customer take something to someone claim you didn't do this or that of install that part or this one. But since you not only took photos or in my case i send them to customer as I build , It's pretty indisputable
I did or DAMN well Least I know. lol,
Then of course always the slight risk you will have a customer take something to someone claim you didn't do this or that of install that part or this one. But since you not only took photos or in my case i send them to customer as I build , It's pretty indisputable
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Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
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Thread Starter
On The Tree
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Yes it takes up a little time but when you have that MOMENT of did i do this or that ? It's so nice to just be able to look at the photos and go WHEW!
I did or DAMN well Least I know. lol,
Then of course always the slight risk you will have a customer take something to someone claim you didn't do this or that of install that part or this one. But since you not only took photos or in my case i send them to customer as I build , It's pretty indisputable
I did or DAMN well Least I know. lol,
Then of course always the slight risk you will have a customer take something to someone claim you didn't do this or that of install that part or this one. But since you not only took photos or in my case i send them to customer as I build , It's pretty indisputable
Well, I took the transmission back out put a new pump seal on a new tour converter clutch seal, swapped out another torque converter put a different wiring harness and TCC s solenoid in. And own solenoid. Same issue. No change at all.
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On The Tree
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Well if the video had sound you could hear the engine rpms change as the lockup hits. Hits then goes away running up the rpms until it is completely unlocked. Like a temporary pressure spike. How likely is it to be a bushing of some sort?
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On The Tree
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So I took the trans back out….again. This makes 5 times!! I took the pump out and the stator bushings are basically brand new appearance wise. I took a few input shafts and old statues out of the scrap bin to compare and both stator bushings in the new unit were in better shape and had less slip than any of the old parts. I double checked for cracks and teflon ring damage. Nothing. So I re vacuumed checked the pump. Perfect. So I too the valve body off and vacuum checked the tcc bore and valve. Perfect. Took it out anyway and it was “type two” according to Transgo. With a very large stiff spring holding the two valves apart. So I swapped it out for the Transgo tcc valve and blue spring. Vacuum checked better than before but only by 2-3 numbers. That could not have caused my symptoms I did not think. I am at a loss here fellas.
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Also one other test I ran. I forced the tcc lockup valve on while in park and dropped it into reverse. With the breaks engaged it should have stalled the engine. You could barely tell the load was a tad heavier than normal. Cycling it on and off showed very small load increases. Barley noticeable. That’s why I pulled it to double check the stator bushing.
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From: BERWICK PA
I actually ran into one doing what you have on the dyno and it was not the trans, its was our dyno converter , the plate was hyper extending basically it would apply firm then travel to far and vent itself , I had forgotten about it, You could actually see the pressure drop when the converter released
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Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
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Thread Starter
On The Tree
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new torque converter this morning, now it is worse than it ever has been. put my gauge on it and i have over 60 psi at idle. 240 psi when the solenoid is maxed. Near 100 psi idle in reverse that blips to 200 plus when your press the gas. Still no tcc lock up and arguably worse than yesterday.
Thank you to Mr. Frank for taking the time to listen to me ramble about this issue. He has givien me a few checks to run and seems to have pin pointed the issue. I will update later.
Thank you to Mr. Frank for taking the time to listen to me ramble about this issue. He has givien me a few checks to run and seems to have pin pointed the issue. I will update later.
Last edited by reubone; Aug 11, 2024 at 11:52 AM.
Thread Starter
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Well as Mr. Frank suspected, we had a converter charge issue. The tell tail sign was the slow to prime issue the really reared it's head the last time I was filling it up. Number 5 out of six attempts. It took about 3 start ps and shut downs before it primed enough to transfer any power through the transmission. I had initially thought that the pump was bad or I had broken the rotor but the pressures checked out fine. 65-70 PSI at idle, 90+ in reverse idle. 240 PSI max. SO I was really puzzled when the tcc still did not lock even with out any load on the rear tires. It was still up on jack stands. So out it comes for the 6th time and I built a different pump and installed it. The PR bore and boost valve both vacuum checked low so in went the transgo PR valve and the sonnax boost valve. That got everything up to snuff and in it went. Back in it went and presto chango, we have a working transmission for the first time. The other pump vacuum checked perfectly. All new components and cleaned. I still have no idea where to look to find the failure, but I intend to figure that out. Has me kinda spooked as to how to prevent this in the future. I would have bet money that the pump that was in there was working fine. I was dead wrong. Thanks again for all the help.
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From: BERWICK PA
Well as Mr. Frank suspected, we had a converter charge issue. The tell tail sign was the slow to prime issue the really reared it's head the last time I was filling it up. Number 5 out of six attempts. It took about 3 start ps and shut downs before it primed enough to transfer any power through the transmission. I had initially thought that the pump was bad or I had broken the rotor but the pressures checked out fine. 65-70 PSI at idle, 90+ in reverse idle. 240 PSI max. SO I was really puzzled when the tcc still did not lock even with out any load on the rear tires. It was still up on jack stands. So out it comes for the 6th time and I built a different pump and installed it. The PR bore and boost valve both vacuum checked low so in went the transgo PR valve and the sonnax boost valve. That got everything up to snuff and in it went. Back in it went and presto chango, we have a working transmission for the first time. The other pump vacuum checked perfectly. All new components and cleaned. I still have no idea where to look to find the failure, but I intend to figure that out. Has me kinda spooked as to how to prevent this in the future. I would have bet money that the pump that was in there was working fine. I was dead wrong. Thanks again for all the help.
Most likely you have a bad crossleak in the old pump. If you had a lathe I would say put halves on and you will see , But also look for dull spots on faces that will usually also tell the tale. But also something could be blocking the feed at the stator on with pump back.
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From: BERWICK PA
So this is a rebuild with a new converter. During the test drive I notice that the tcc, when commanded to lock, locks for about a second. The slip goes to zero, then goes right back to slipping the same rpm as before the lock was initiated. All while the computer says that it is commanded to be locked. It is as if it loses pressure almost instantly. If I command max pressure it shutters. Only out about 10 miles on it at the most. Literally right down from my house and back. What are your initial thoughts? I have to pull the transmission anyway to fix a front seal leak.
It's always important to include every little detail when posting asking no matter how seemingly unrelated. Converter feed oil is also lockup supply. So of you have an issue with converter filling slow it helps with determining a solution, We all do it at times even me, But it is important to include every little detail .
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