i have a 4l60e with a level 3 build to handle a lot of hp. the only problem is as long as i'm accelerating the car is fine but when i'm cruising between 15 to 50 mph or i slow done the trans starts jerking. if i speed up it stops or if i put on the brakes it stops. any ideas what this might be. i have a 408 with a trex cam i don't know if that will help solve the problem. any advice would be appreciated

 

Ok the jerking could be several things but what comes to mind most particularly if you have a large cam is the converter not unlocking this will cause a sensation very similar to a standard shift when slowing down in to high a gear without he clutch depressed ,
and based on the fact that it stops when you apply the brakes I would say thats what it is , You will need to have the tuning checked to see if the converter unlock parameters are correct (the speed at which it locks and unlocks)

 

my guess is gonna be cam surge

 

That sounds right that accompanied with the converter not being commanded to unlock at the proper time making it very noticable

 

thanks, that is exactly what it is doing. its like i'm driving a standard in to high a gear when i slow down. what kind of numbers should i be looking at for shift points. i have hp tuner is there any place that shows what kind of numbers i should have. i just have the stock 3.23 gears in it.

 

Im sorry but I cant help you there i dont have much experience with the tuning side , I would consider posting another thread that says (converter not unlocking on decel causing surging tuning help please)That may get some of the tuning guys attention