hello i just recently put a 4l80e conversion into my 2004 ss silverado and every time i put it in reverse it gives a hard hit. has anyone ever had this problem? if soo can it be fixed? (i reflashed the ecm with the 4l80e file). it doesnt hit hard going into drive just reverse.

 

Was the unit built?

 

yes its rated for 1200 hp from finish line

 

one fast ss, does it do when the engine is cold and the RPMS are in a higher range? Was the shift kit installed in your tranny by any chance?

I don't mean to highjack the thread, but it sounds exaclty like what I am having after installing the TCI shift kit. Both in drive and in reverse. After the engine is back to 700-ish rpms, it is fine.

Frank, how bad are these 'hits' on the driveline parts? I am guessing it is the increased line pressure that pushes more violently the clutch pack assemblies?

Thanks!

 

exactly thats whats going on but not in reverse in drive its fine but as the revs up it does it but when i wait a min and let the revs come down its ok but its only in reverse thats what puzzles me. yes i do have a shift kit the tranny was completely rebuilt. the shift kit was from transgo HD. now for your tci shift kit i put one in my old tranny a longg time ago and yes your gonna feel that one. tcis shift kits are all out race kits they were desinged to hit hard all the time to lower your ets. when i talked to the guy at tci thats what he told me. your best bet would be a transgo shift kit. at part trottle the shifts are smooth but when you hammer it the shifts are hard and crips. i think the reson mine is doing what its doing is because the idle was rasied by the guy who tuned my truck..im going to bring it back to stock idle and see if that helps.

 

but in reverse** sorry

 

Well during a built and a shift kit on these units generally the cushion plate plates are removed from the direct clutch .And in addition a weaker spring is often used under the low sevo in the 2nd accumulator. Between these two and enlarging the feeds to the direct clutch you can end up with a somewhat agressive reverse engage. This is probably normal and should not hurt anything its one of those performance verse comfort compromises. You may want to ask finish line about it to but I have noted this issue with both built and shift kit installs on these units in the past/

 

Great, thanks for the quick reply!