Thread: "Rev and Clunk" Issue ? 08 5.3L GXP

Originally Posted by J57ltr

This is covered in the tech tips, but as I recall it's the apply piston seal not sealing all the way and as you rev to take off the seal has more pressure behind it and it pops in and grabs and goes. My car does the same thing at times. I raised the trans pressure and that seems to help, I haven't had it happen since, but it only did it once in a while anyway. The fix from what I read was a rebuild.

Jeff

Exactly! Its the apply piston. Very common. Mine at 75k started randomly doing it. Talked with TEP and ended up ordering a trans from him. He said very very common for the delayed engagement. New trans sitting in my garage till the weather warms up to install it. You can try raising line pressure, shift kit, pcs, swap fluid, etc but in the end you need to drop the trans and fix it once it gets annoying enough. Just drive it till you get tired of it then rebuild trans.

http://www.gmls4.com/index.php?topic=2773.0