4l80E question

[White Duramax]

This is in my wifes 07 2500 Suburban. I rebuilt the transmission about 3 months ago and installed a Transgo HD2 kit with the rebuild. Drove fine for about 3 months and one day it lost 2nd gear, would shift from 1st to 3rd. P0752 fault shift solenoid A stuck on. Replaced 1-2 solenoid, no change, dropped valve body and checked over- no issues. Pulled trans out and found outside lip seal on intermediate apply piston missing about 2" of the seal. I replaced the lip seal and went back together with it. Drove for 4 days and lost second gear again, same failure I think but I'm not sure why, any advice? The first time I used a feeler gauge when installing the piston, the 2nd time I used a 90 degree pick so I don't think I could have cut it the 2nd time. Thanks

 

[onebaddmaxxx]

you should be air checking the 2nd gear clutch when you replace it. Youll be pulling the transmission out again to repair it. Then when you have the rear gear train, center support and intermediates in, install your center support 12pt 3/8" bolt, then apply shop air thru the hole of the bolt and make sure you get a pronounced thud. if you do not, then your lip seal is still messed up. The hd2 kit is not that great in reality for the 80e. the spring loaded pressure relief will hang on you sooner or later and destroy the trans when it dumps all line pressure. At minimum weld/tap and plug the vb casting closed where you drilled the hole through it.

 

[Mike L.]

How much play was in your int. clutches? You might also have a damaged int. piston.

 

[White Duramax]

Thanks for the info. I put a used transmission in it for now to get it going until I have time to go thru this one yet again. I don't remember the clearance off the top of my head, I will inspect it all and see. Thanks