I installed a Transgo HD-2 into my truck last Spring and I love it. However, when I'm driving around when it's hot outside, and the trans gets to 170*~180*, it begins to come out of converter lockup or OD hard. ie: I'm driving down the feeder. accelerating to 50 or 60. Then, when I let off at my desired speed, the truck pops out of OD and the engine ducks down 2-300 RPMS, then all is well until I get back on the power. As soon as I let off again, it does it again. I'm leaning towards an issue with the OD band, because when I put the truck into 3 and lock out OD, it quits doing this. I'm thinking maybe the Transgo servo spring kit I put in is odd, and am hoping a proper Corvette Servo from Circle D will fix the issue. Thoughts or suggestions?

PS: I have an aftermarket Hayden cooler on the truck and this problem does not manifest until a certain temperature.

 

Stock stall or modded stall? I never knew what a hard lockup was til I went to a stall.
Anyway, that's not my point. I know there's a term, but that powering on / off is hard on some internal component(s). I can't remember which one(s), but IIRC, Vince @ FLT or someone more knowledgable than myself commented on it. I could guess, but I won't.

 

what kind of tq convertor? it actually sounds like the convertor is locking when the drop in rpm happens.

 

It's a stock stall, and the RPMs actually to clarify, the drop of 2-300 then comes back up, like the truck got loaded up for a second. It also will not behave this way if I put my transmission to 3, instead of OD. It just shifts 1,2,3 then all is normal.

 

Has anyone else had this problem? Mine is doing something like this too. Unlocks in light throttle in overdrive around 45/50mph, but you give it more throttle and you feel it lock back up and start gaining mph.

 

They are disigned to unlock when ever you let off the throttle completely. Then when you get back on the gas the rpm's will go up until the converter locks again.

 

Yeah but mine is unlocking under lite throttle. Give it more throttle and it locks up, give it more then that and it unlocks again since its under more load. BTW this is a stock 2006 ccsb 1/2 ton.

 

Before you put in the HD-2 did you have the trans line pressures tuned. If so go back to the stock settings. Also, you can change your OD shift points higher before it locks or change the TB opening to MPH. A good 20 minute drive cycle scan log would be a great help in sorting out your proplem.