Question about 4L80-E Trans

timh975 · July 2, 2005

Hey guys, I'm not too keen on transmissions, my truck has the 4L80-E trans, and at idle when I take my foot off the brake, it just sits there and doesn't want to move. Actually if I'm on a slight incline, it'll roll backwards. Is this because of line pressure? It runs fine, just never had a truck that rolled backwards at idle. Is there anything I can do to stop it? Maybe a shift kit? I've got a 2500 mile drive coming in 3 weeks, want to make sure it's up to par. Just curious. Thanks!

JRW68 · July 2, 2005

Every truck Ive been in has done this some, ussually its related to the torque converter and idle speed. Thats not to say something is wrong but if this is your only sign or worry about the tranny, I wouldn't worry. Basically IMO, I would check the fluid level and quality. If those two are alright I wouldnt' be worried unless the tranny has been giving other signs of age.

What type of truck do you have. 2500 or larger I presume?

MrQuadrasteer · July 3, 2005

Mine does that too. I bet if you check, you'll find you have a higher than expected stall speed.

Mine will foot-stall to 2500rpm, flash to 2400.

I love it. No need for an aftermarket stall for now

rahtreelimbs · July 3, 2005

Does anyone have a 4L80E that has a slight delay going into drive and reverse?

timh975 · July 3, 2005

Yes, it's a 2000 GMC Sierra 2500 4x4 NBS, stock 4L80-E trans. I just did a trans flush on it last week, put Valvoline Durablend fluid in it. Fluid level is fine. I'm not too worried about it, doesn't slam in or out of gear, to be honest it shifts good. The lightest pressure on the gas pedal will get it to move though. It's just annoying when it rolls backwards on the slightest incline, don't want to roll back into the car behind me. When you say "Mine will foot-stall to 2500rpm, flash to 2400.", what does the difference mean?

MrQuadrasteer · July 3, 2005

If I mash the brake and gas, it'll stall to 2500rpm. If I let the brake go and keep it mashed, I usually get a bit of spin, but a really sweet launch

Since I can't really break the Revos loose on dry pavement, it's a decent stall indicator. Vehicles that over power their brakes and brake-torque (or whatever you call it in your area !!! I've heard it called a dozen different things !!), this doesn't work.

If I punch it from a stop, let go of the brake at the same time, it'll *flash* to 2400 before the truck actually moves. Makes for a decent launch, not but as sweet as loading it up first

Under light throttle, it'll move at lower rpms, of course, but it does have some noticeable slippage and stall It's definitely the *loosest* factory auto I've ever driven

Pretty cool for a factory set-up

JRW68 · July 3, 2005

rah... all the newer trannies have a "slight" delay... not like the older th350 and 700r4s which were primarily mechanical... I notice the delay going into reverse mroe than anything... but its normal. Keep in mind I describe this as a slight delay, its not slipping into the gear, the ECM just takes time to go through the shift process. Ide imagine this is a protective operation to some what prevent reverse drops into gear... all the NBS ive been in have had more delay than what Im used to on the older vehicles.

timh975 · July 3, 2005

I appreciate all the help you guys! Mrquadrasteer, I have the same Revo tires you have, so I know what you mean when you say you can't break them loose! Thanks again for everything.

F_L · July 3, 2005

Same thing on my 2000 3/4 Silverado. Used to take 1000 rpm just to get it moving. After putting in a Nelson tune, hooks up right away. Feel a bit of a bump when you drop it into gear now. Maybe that is part of the infamous Torque Management.