6L80e to Colorado T-Case Adapter

Save

atvspeed4

· #4 · Nov 13, 2019

OEMOBDII said:
Not sure yet. Won't be ultra-cheap, but will do best I can and just a pinch over what is costs me to help out anybody else wanting such. 3/4" plate of 6061 aluminum, CNC work to have both flanges milled out, thick wall 5" OD 6061 aluminum joiner tube (this alone is $70 just for the piece), correct length hardened studs and flanged nyloc nuts for both sides, then the cost of having it professionally all TIG welded up once I index it. Right now I am determining its length, and then to re-spline the 6L80 short 4x4 output shaft, or buy and re-spline the longer 6L80 2WD shaft to keep good spline engagement and make the T-case adapter slightly longer at the same time to put it in the exact same spot. I think the front and rear driveshafts can probably handle some slight length difference, so TBD, I have some final measurements to do on trans vs trans length comparison, taking into consideration the length of the stock 4L60e t-case adapter, and to obtain the maximum amount of spline engagement possible for the 6L80 output shaft into the T-150 t-case.

This looks to be plug and play from the small amount of info out there on this (member 400ss on EFI Live forum did a good write up a while back). Company makes a CAN bus reverse light output relay, and can direct hardwire the tap up/down shift control if wanted.

We drew one up and had it made. Ended up being around $900 our cost not including labor to make. Sounds like similar design. We ended up not making a run of them due to being so expensive. We have a resplined 6l80 output, wiring harness and adapter for one of our builds ready to go in but for the other build we are running a 6L90 and pass drop np241 with factory large 29 spline. Have been running that setup for over a year now and love the improvement over the 4l60

Save

O

OEMOBDII

Discussion Starter · #5 · Nov 13, 2019 (Edited)

I think I've seen your same name on YouTube? So you have had a 6 speed transplant up and running? This will be my first one. Slightly apprehensive and a few remaining questions, but should be doable. I'll PM you my number, I'd like to run a few ?'s by you if you wouldn't mind, pleaser and thanks.

My adapter costs are not totally out of hand. 3/4" plate of 6061 was scrap yard price (sorry, forgot), each flange CNC machine was $70 per, and the joiner tube seems about $70, plus TIG welding cost. I hope to add gussets around the tube to flanges as well wherever not in the way of a mounting stud, even though it will just be a short tube piece. Then plus output shaft machining ($100?). So, not entirely crazy. joiner tube will be almost 5" OD and very thick wall. I would have paid $900 rather than designing one though. Doesn't matter too much either way. Was your for an H3 I think or Colorado?

Save

atvspeed4

· #6 · Nov 13, 2019

There are a few of us with v8/ 6L swaps on the cousin h3 platform. I am one of the owners of Outfitter Design LLC. Wiring was done by Jamie who is a member here. The fabrication and install we did

Sent from my Pixel 3 XL using Tapatalk

Save

O

OEMOBDII

Discussion Starter · #7 · Nov 13, 2019

4

Here are some pics of my progress. CAD drawings, 3D print test fit, T43 OS "upflash" from 2007 to 2009 (my Colorado is 2009), and then read T43 with HP Tuners to see what is editable. All worked perfectly. We have commercial AllData subscription, 3D printer, and GM MDI/GDS 2 at my work, so used it all so far. Awaiting CNC guy to hand finished flanges back.

See less See more

Save

atvspeed4

· #8 · Nov 13, 2019

I can't remember what we had to do but there is some thing we had to change from factory alignment to work

Sent from my Pixel 3 XL using Tapatalk

See less See more

Save

S

Slowrider

· #9 · Feb 19, 2020

Any update on this? For you H3 guys who already have this what was the fuel mileage increase?

Save

atvspeed4

· #10 · Feb 20, 2020

Slowrider said:
Any update on this? For you H3 guys who already have this what was the fuel mileage increase?

I can't say because I went 6.0L at same time

Sent from my Pixel 3 XL using Tapatalk

Save

S

Slowrider

· #11 · Sep 4, 2021

Any update on this. I’m interested in the final cost for everything. I looked at TBMs website and their kit seems complete but I have seen in here a lot that they are non responsive.

Save

BamaJwall

· #12 · Sep 17, 2021

Would like to know price too. Just recently got a Lh9 4x4 colorado here. Never was and never will be a 4l60 fan. Just kills the aftermarket fun.

Save

KM Richards

· #13 · May 26, 2022

For us 2WD guys... will the 6L80e bolt right up to and LH8 or LH9 5.3L engine?

And, do ya think the original drive shaft could be used or is the 6L80e a longer tranny and the drive shaft would have to be shortened?

Save

S

Slowrider

· #14 · 8 mo ago

Looking at this chart the 6l80 2wd is slightly shorter. It also says the 4wd version is the same as the 4wd 4l60

GM Transmission Dimensions

A B C D D E F G H Trans Model Bell Housing Main Case Case Extension Length to Flange Length to Shaft Engine Block to Converter Lug Length to Extension Housing Engine Block to Mount Center Line to Bottom Pan 4L60/70 2WD 6.941 15.421 8.909 N/A 30.975 0

paceperformance.com

Save

KM Richards

· #15 · 8 mo ago

Wow! Good info, thanks!

Looks like the 6L80e would actually fit in my truck physically

Now, all I gotta do is research what it would take to re-program my ECM to work with a 6L80e

This would be great out on the highway. My7 current 4 speed isn't bad, but if I had 2 additional gears it would make highway driving at high speeds much smoother and should help with fuel efficiency since the engine should be at lower RPMs at 80 mph

Save

O

Op4Gunner

· #16 · 13 d ago

OEMOBDII said:
I’m making an adapter to bolt the Colorado T-150 t-case to the 6L80e trans, if anybody wants one. 3D printing the flanges now to test fit, then off to CNC them. TBMS non responsive.

View attachment 339918
View attachment 339919
View attachment 339921

Any updates on this conversion?

Save