I have a rebuilt 4l60e in my 2009 silverado, it has the sonnax 4l60e performance pack stage 3 performance built with the smart shell hd reaction shell kit, heavy duty 2-3 shift valve, 4th gear super hold servo kit, 2nd gear super hold servo kit, kevkar extra wide intermediate band, smart tech imput housing & heavy duty imput shaft, heavy duty reaction shaft kit, 2.84 imput carrier kit, it was rebuilt by the previous owner and this is all his information on it, since then I have put a 3200 stall fti converter in but that’s it. 1st gear pulls very hard and it will hold it to about 55mph, but when it shifts it feels like it loses all its power and will not climb very well. If you get to about 40 and are giving it medium throttle and then give it full throttle it stays in 2nd and it is SO slow. I swear 3rd gear with normal throttle is faster then full throttle 2nd. I have had it retuned twice and the tuner says everything looks good, just wanted to get some opinions on it.

 

My 1st step would be to check the band servo travel.

 

Can you do this with the tranny in the truck or do you have to drop it? sorry kinda new to transmission work.

 

You can do this in chassis but might be a little difficult. But can be done

 

Yes, it can be done. You most likely won't be able to be precise, but a ruler or tape measure should let you know if you are in the ballpark.

 

Does it sound like the servo pin is too long or too short?

 

A pin that is too short would allow the band to ship. I'm not saying that is the problem, just that is where I would start looking. Especially with aftermarket 2nd and 4th servos being used. I don't know the credentials of the person who assembled your trans.

 

It can be just teared D-seal at servo pistons
Once I teared it an mine(reinstall servo under truck ) and achieved slipping at full throttle