Torque Converter clutch failures

[Tom]

When my 200k mile 4L60E went out a couple years ago I went ahead and put a rebuilt torque converter in it as well. The lockup clutch in that lasted maybe 10k miles and then failed. It was a big name rebuild company that I shouldn't have gone with to begin with, so I replaced it with a TC from the local company my trans rebuilder recommended. I also replaced the TCC solenoid with an OEM part for good measure.
Well, 20k later and I'm getting the same failure. It starts as the truck shuddering after going down the freeway 15min or so and encountering a slight uphill. Eventually it unlocks, stays that way for a few min, then locks back up like nothing happened. I know it'll get worse as time goes on until it won't lock up at all anymore.
Besides confirming the trans is still getting a lockup signal when this happens, anything else I can check that might be causing this that's not a bad converter itself? My 98 GMC btw....

[AussieinNC]

Originally Posted by Tom

When my 200k mile 4L60E went out a couple years ago I went ahead and put a rebuilt torque converter in it as well. The lockup clutch in that lasted maybe 10k miles and then failed. It was a big name rebuild company that I shouldn't have gone with to begin with, so I replaced it with a TC from the local company my trans rebuilder recommended. I also replaced the TCC solenoid with an OEM part for good measure.
Well, 20k later and I'm getting the same failure. It starts as the truck shuddering after going down the freeway 15min or so and encountering a slight uphill. Eventually it unlocks, stays that way for a few min, then locks back up like nothing happened. I know it'll get worse as time goes on until it won't lock up at all anymore.
Besides confirming the trans is still getting a lockup signal when this happens, anything else I can check that might be causing this that's not a bad converter itself? My 98 GMC btw....

There are a multitude of failure points within the 4L60E convertor lockup system. IMHO, most failures occur from worn pump units, badly worn lockup and pressure valves, poor wiring connections and general pressure loss areas within the transmission.

Sure you can get a poorly built convertor, but for it to last 20,000 miles and then start giving issues tells me the convertor is the result of the situation, not the cause.

When you replaced the previously failed convertor, was the transmission gone through again ? Or did you just replace the failed convertor and reinstall?

Have you checked the power circuits responsible for the lockup process to apply?

I am usually around to answer questions however, it may take me a day or so.

[AussieinNC]

I just uploaded a diagnosis pdf for 4L60E transmissions....

See the post above yours for details.

It is a working document and I will update as and when needed.

[Tom]

Clinbarger rebuilt the trans. He posted a full review on here actually: http://67-72chevytrucks.com/vboard/s...d.php?t=812006

I spoke with him the first time this happened. He had tested the PWM solenoid and the tcc enable solenoid, but recommended replacing those before replacing the first torque convertor. I hadn't been happy with the balancing on that first TC along with the lockup problem so I did all 3 things at the same time, with oem solenoids.

[jjzepplin]

My TCI Towing Converter Lost the lock up clutch. Tampa Converter cut it open on a lathe in front of me and said it looked just like a stock converter. It was one month old. I had a fella they recommended go thru my trans "Built by me" and he said he only found a couple problems. I had Tampa Converter Build me a custom converter and it has been fabulous for many years, This was a 700r4. Yeah yeah. 700rs get a bad wrap. This was built with a bunch of internal goodies. Has been behind my 406 pulling hard for decades.