Has it been done in a GMT800, specifically an 03 and later? I drive a 6 speed Ford F250 for work sometimes and the vast improvement in driveability with the 6 speed over a 4 speed 4L60/4L65 can't be dismissed. Not looking to blaze trail on this, or reinvent the wheel if it's a major undertaking. It was just something I've wondered about as opposed to having the 4L60 built. Thanks in advance.
6 speed Auto conversion
- Thread starter mattt
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Joseph Garcia
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My initial thought is that is would be a challenging swap, as the 6 speed (and maybe the 4 speed, as well) is computer controlled (computer inside the transmission), and this would have to be matched up with the truck's other related computer control systems.
Folks on this Forum with much more direct knowledge than me on this topic will chime in.
Folks on this Forum with much more direct knowledge than me on this topic will chime in.
TollKeeper
Full Access Member
I have been looking at this a lot myself. There are a few that have done it, but at major cost. The tail crossmember is in the wrong location to support the trans. The driveshaft is to long? or short? (cant remember). TCM does not shake hands with the rest of the modules in the truck without reprogramming because of VIN's, and looking for a specific TCM that isnt there.
And then because of the way the way the final drive is on the 6L80, you would also have to regear the front/rear diff.
The next issue is that the 6L80/6L90 will only talk to a 58x crank trigger. You have a 24x.
And then because of the way the way the final drive is on the 6L80, you would also have to regear the front/rear diff.
The next issue is that the 6L80/6L90 will only talk to a 58x crank trigger. You have a 24x.
swathdiver
Full Access Member
time and money better spent building a bullet proof 4l60, unless of course you have quantities of both to spare.
The swap can be done. If I remember correctly, the mount is not much different from a 4l80e mount (going off fuzzy memory). I know it has been adapted to the the autotrac transfer case using a factory adapter as well. Controlling it is a challenge. When I took the Holley EFI training course a couple years ago and the 6L transmission came up. They said they do have 6L transmissions running with Holley control but as of then (right before covid hit) they had no release date or plan for a release of it.
There is this controller that has been used many times for a swap like this and I am really considering it. I just want more people to iron out the daily driver related bugs first.
There is this controller that has been used many times for a swap like this and I am really considering it. I just want more people to iron out the daily driver related bugs first.
GM 6L45E 6L50E 6L80E 6L90E TCM2650 transmission controller harness
GM 6L50E, 6L80E 6L90E, Transmission Control Module. TCM-2650 transmission controller GM 6L45E 6L80E 6L90E transmission controller and wiring harness.
www.zerogravityperformance.com
This company offers a GMT800 swap kit as well. They are gaining popularity in the trailblazer ss community for 6L80 swaps. They seem to offer good results in that community but they are expensive.
Their old website here has tons of useful information about the transmission as a whole:
Their old website here has tons of useful information about the transmission as a whole:
Yeah the price is a huge shocker. I am hoping as more people figure out the electronics side of the transmission, the controllers will start to come down in price.
I agree with him on everything except the 60e part. Before I spent any money on a 60e, I would swap in an 80e instead. The upfront labor IMO pays off in the end of never having to worry about even a built transmission failing.
Tonyrodz
Resident Resident
Big $$
