Couple of questions im not finding definite answers to. Im receiving a basically free 5.3/4L85E combo out of an avalanche from a family member. My car is already wired for a 4L80. Are the wiring the same on those two transmissions and would I be able to control it with a factory PCM?

 

exact same

 

Thank you much.

 

As far as i know, they only had the 4L85E option available in the very large box van. Really there isnt too much difference internally but a 5 pinion planet and a couple other minor things.

 

I hate the internet... There is no point to GM having the 4L85E......

The aftermarket support for 3L80/THM400 and 4L80E is amazing!

Why mess around with planetary gear sets that need not messing around?????

 

Factory th400 gearset from the 70's at over 1500 horst.
Other guys have them at higher power than that.
Planets are not at all a weak point on an 80e

Did 85e denote straight cuts? Because I have actually seen a thrust benefit from straight cut planets in BIG box trucks/grain trucks/etc

 

I was told it's a 4l85e. I havent yet laid eyes on it yet. A quick google search yielded this from Gearstar transmissions.... " You can find GM 4L85E transmissions in a number of vehicles, including the Chevrolet Avalanche, GMC Savana, Chevy Suburban, and GMC Yukon." Im just tossing this setup in the car for now to have a running vehicle while I finish building my other 5.3l and 4l80.

 

Moral of the story...there are a number of small internal differences between an 80 and an 85. As far as swapability is concerned...they're totally interchangeable.

 

Straight tooth gear sets were available for the 4L80E just as the THM400/ 3L80... Over-drive only came helical if I recollect correctly.

There should be NO thrust in the section with straight gear sets... Any thrust would be from outside forces and not the gear set.

If any of you guys run straight tooth gear sets and have thrust generated by the gears... You have a problem.

 

Hence the thrust benefit...no excessive wear on the output bushing (or bearing when I build one) due to thrust.
But...for a race car, most of the time it's not necessary.
4200 lbs running 9's...probably necessary...most other stuff it's a waste if you're trying to hunt down straight cuts

 

I only and very rarely use a straight tooth gear set in a problematic build (IE thrust issues).

I much prefer the additional contact/ shear strength of the helical gear sets.