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Upgrading my 6L80e with a 6L90e QUESTIONS

Jorge Meza

Jorge Meza

Red Liner
Joined
Aug 12, 2020
Member Number
2698
Messages
25
Loc
South Georgia
I got a running 2011 Escalade but its already 149k miles to pull off drivetrain and transplant that to my 2006 Unlimited LJ.

At that mileage I think the 6L80e will go out sooner than later and if I'll have to spend $$ on a new/Rebuilt transmission a 6L90e is a better option.

So decided to upgrade my 6L80e with a new/Rebuilt 6L90e.

I know there are some variations on these 6L90e. Which one should I get??

I read I can transfer the TECHM in my current 6L80e to the new 6L90e to keep communications intact. Is this true?

Any advice I should follow before ordering a 6L90e??

Let me know guys/gals
 
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My advice is to build the 80...
Not sure why you're stuck on the 90... the 80 would be fine unless you're about to build something with 1k hp or more.
I can tell you this, the tail shafts will not swap, and from what my mechanic said, neither will any of the internals. You should just buy one, tear it down and see what matches up between the 2...
 
I thought the 90 was longer overall and tailshaft had a bigger spline count
 
It is and it does...32 spline on the 80 with round patten adaptor, 29 spline on the 90 (4wd version, 2wd is 36 spline) it is longer because it has an extra set of planetaries, so yes stronger, but not that much different in the long run. Which is why i say building what he already had would be the best option
 
I'm sorry guys I just realized my post is incomplete.

I got this escalade as a drivetrain donor for my 2006 Unlimited LJ. I'm running 1 Ton locked axles and 43" tires. I'm buying an Atlas and I need to make up my mind between a 6L80 or 6L90 is best before spending the cash.

A friend of mine who works at a Transmissions shop say the 6L80 has issues. I've read that a 6L90 is stronger.

I don't really care if the 6L90 is longer since I'll be ordering custom drivelines regardless.

*Original post edited.
 
Ask your friend which issues. I'm sure most here would like to know what these issues are, considering the 90 and 80 are damn near 75% the same, it would be nice to know which bits are problematic.
 
Jorge Meza said:
I'm sorry guys I just realized my post is incomplete.

I got this escalade as a drivetrain donor for my 2006 Unlimited LJ. I'm running 1 Ton locked axles and 43" tires. I'm buying an Atlas and I need to make up my mind between a 6L80 or 6L90 is best before spending the cash.

A friend of mine who works at a Transmissions shop say the 6L80 has issues. I've read that a 6L90 is stronger.

I don't really care if the 6L90 is longer since I'll be ordering custom drivelines regardless.

*Original post edited.
Click to expand...
I am not sure the juice is worth the squeeze here.

Only reason to swap to a 6L90E is weight rating and you don't have that problem.

You may have to program the ECM to work with the TCM, Yes, they use the same TCM type, inside the trans... so make sure the 6L90E TCM in the trans matches the ECM you have.

You also have to change the input on your Atlas.

All 6L80E problems I've seen are converter related. A decent converter matched to your cam shaft, gear ratios and tires size and they go forever.

if not, they heat up and burn up.

Same is true of any modern trans.

But hey, if you want to do it; If I were swapping trans, I'd go 8L90E.

With any of these, get a BIG fucking cooler.
 
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^^^this. The ATRA just released their March issue and it's got some good articles in 6l80e problems all related to the stock converter. There are a few other articles that pop up in regards to pump machining and fitting as well.

Basically get a good aftermarket billet or forged billet converter and your should be good.

March - 2022 Archives - Gears Magazine

GEARS March 2022. GEARS is designed to provide accurate and authoritative information in regard to the subject matter covered. It is distributed with the understanding the publisher is not engaged in rendering legal, accounting or other professional service. If legal advice or other expert...
gearsmagazine.com
 
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Funny thing is, i read it that the 90 also has this issue after 100k. The converters don't have a very flat surface for the clutch to ride against and basically disintegrates and takes the trans out.
I've used several of the jmbx converters in vehicles with over 100k and have not had a failure, or even discolored fluid. That would be survivor's bias though:laughing:
But you'd think with all the towing over 10k i do, and the hard miles would give me the same results as I'm reading about. I wish there was a way to compare driving habits(truthfully because people won't be out front with the abuse they put their vehicles through) just to see the difference between one of these converters has failed, and mine in my work truck with 268k that is absolutely bone stock(6l90e). Our 13 burb has just over 170k on it and shifts minty(6l80e). It also has done its share of towing, so no shortage of abuse on that either.
 
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