6l90 replacement first mods

tonywannabefast

New Member
Joined
Apr 20, 2022
Location
Unicoi, Tennessee
Hey guys, new to the forum. Not sure how many of you guys have experience with the 6l80/ 6l90 transmissions but figured I'd see if anyone has any good experience with them on here. I've gone through it all with the 6l90 that was in my truck when I bought it used about six months ago (08 Chevy 2500 Duramax 4x4). Anyways, I decided the best route for me was to just scrap the old one and get a cheap newly rebuilt 6l90 from these guys, 6L90E Transmission Replacements | New, Used, & Rebuilt. However, it is not going to be put in stock. I would like the shop I'm using to "beef it up" a little bit per se so I don't have to worry about it going out again when I'm towing my camper or something which is approximately 8000 pounds. Any advice for anyone with first hand experience/ knowledge would be great
 
Put it back to stock, get it tuned.

They are notorious for converter shitting the bed due to the stock tune slipping the engagement clutch of the lock-up.

6LXX are actually really good transmissions in stock form, they just need the lock-up function tuned better.
 
They actually offered them in trucks too. I had to look it up and found a thread by Mike L from Inglewood. Not super common, but, as usual and same as the vans, they were severely detuned. Less than 300hp and mid 400s torque.
 
6L90 or MYD is a great trans unless you're pushing some serious HP no need to beef it. depending on the variant it came in everything from a ZL1 to HD gas trucks and Vans. I have one in my 2020 6.6 gasser. it's basically a modified 6l80. can't remember exact differences. I haven't heard of them having issues with converters but not saying their is not. they are extremely tough but not used as widley in the aftermarket racing scene from my knowledge due to weight and size depending again on variant. stock you can push out about 650hp reliably
 
DonYukon said:
6L90 or MYD is a great trans unless you're pushing some serious HP no need to beef it. depending on the variant it came in everything from a ZL1 to HD gas trucks and Vans. I have one in my 2020 6.6 gasser. it's basically a modified 6l80. can't remember exact differences. I haven't heard of them having issues with converters but not saying their is not. they are extremely tough but not used as widley in the aftermarket racing scene from my knowledge due to weight and size depending again on variant. stock you can push out about 650hp reliably
Click to expand...

Biggest reason they aren't used in a lot of swaps or racing is because they're massive and sorts heavy.

I agree, they definitely need a good converter.
 
Croatan_Kid said:
Biggest reason they aren't used in a lot of swaps or racing is because they're massive and sorts heavy.
Click to expand...
They need a pretty specific tuning knowledge too.
A lot more complex than simple solenoids like a 4l80 or similar gen trans.
 
Also, that too. One of the quickest ways to destroy one is with bad tuning. Good tuning and a good converter though? They can hold some power.

Most people don't want the headache with a swap or building an off-road rig.
 
Last edited:
Back
Top