I have a strange problem with my transmission. During highway cruise when the throttle is released and the vehicle is decelerating at 60-75 mph the torque converter clutch engages and disengages very quickly until the vehicle is below 60mph. This would occur 3-4 times in succession until the vehicle is below that speed. This occurs with the stock transmission tune, I have a 4l80 and 2900stall converter. Attached is a plot of the timing when this occurs - also strange. Please help!

 

Hi,
I think my 99 SS has the same problem. I dont know what is exactly happening in terms of the torque converter or gears....ect... The same thing happens, around 60ish MPH when I let off the throttle there is a quick jerk or it feels like the car quickly downshifed and quickly upshifted again. I think you described it the best in terms of the clutches engaging and disengaging. I dont know, could this be the converter locking and unlocking.
My 99SS has a 3500 Yank SS converter with prob. less than 12,000 miles on it and 40,000 miles on the tranny.
Any one else ever had this problem.

 

This is definitely the TCC disengaging and engaging. The first thing I checked was the transmission TCC but ruled it out because it was the stock tune for a 4l80.

 

TTT - anybody?

 

hey Jamesbond2509,
Does it do this only between 60-75 mph range. I noticed mine will start anywhere around 50mph and beyond. The higher the speed, more noticable the disengaging and engaging is. I was at the track today and talked to a lot of ls1 guys and they weren't sure what could be causing it.
For now, I have learned to drive it with the problem. I keep my distance form other cars on the highway because the disengaging and engaging problems only happens when you come fully off the throttle. So I try to stay partially on the throttle as much as I can. This way I can avoid the problem most of the times.

If you find anything out please keep me posted.