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Out of curiosity...6l90 swap possible?

12K views 15 replies 11 participants last post by  Shiterado 5.3 
#1 ·
So I know this is far fetched and prolly more complicated than it is worth. But I absolutely hate our 4l60 it's junk, truck falls on its face all the time. We'll luckily within the year I will finally be able to do whatever my $$$ allows (will have a new to me daily driver for commute). My truck will assume the duties of offroad/hunting truck (large heavy tires). So it had me thinking instead of a v8 swap why not just swap in the 6l90? It would give me a 4:1 first gear, should get the tires rolling better giving me better acceleration and combined with 4lo a realitively good crawl ratio.

The 4l60 ratios are:
1st-3.059
2nd-1.625
3rd-1
4th-.696

The 6l90 ratios are:
4.027
2.364
1.532
1.152
.852
.667

I think it would really help our motors out especially the guys with big tires.
But someone with more information on how these bolt up can you chime in and say yes or no on could we actually mate it to our engines and could we control the computer within the trans?
 
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#3 ·
Doesn't the 6L80 and 6L90 have an internal controller?
 
#5 ·
James, total harness or splice in?

This is an interesting thought or swap
 
#6 ·
I'm intrigued..

I can hardly understand though why GM chose to locate the computer inside the transmission case. If it turns out that the heat and vibration cause excessive failure, it's gonna be damned expensive for them and the owners.

I've posted it here before...

In the mid 90's I worked for a company in South Carolina that was spun off the old Union Carbide. They make capacitors.

Chrysler made an electronically-controlled front-wheel-drive transaxle for the old K models that mounted the computer inside the transaxle housing.
The company I was working for had a production upset that resulted in some below-spec capacitors being shipped. It was only for a single production shift, but quite a few thousands of those unreliable capacitors were shipped.

That Chrysler transaxle computer had 7 or 8 of these capacitors that cost about 45 cents each.

Those 45-cent capacitors caused many transaxles to fail under warranty.
Chrysler had to pull the transaxles and crack them open to swap-out those computers.
It was a debacle.


Sure, today the state of the art is far advanced, and I'm sure GM has tested hell out of those transmission controllers. Still..... Inside a auto transmission is not a friendly environment for electronics. Solenoids are one thing, microprocessors are a different thing altogether.
 
#13 ·
Not to burst your bubble but you may have some fitment issues and I'm not sure if the T-case will bolt up without an adapter. It will also be about 6" further back than with the 4L60E.

The 6L90's are pretty bulky compared to the 4 speeds. This is a 6L80 in the pictures from what I've read the 90 is a tad bit longer.



 
#16 ·
So I know this is far fetched and prolly more complicated than it is worth. But I absolutely hate our 4l60 it's junk, truck falls on its face all the time. We'll luckily within the year I will finally be able to do whatever my $$$ allows (will have a new to me daily driver for commute). My truck will assume the duties of offroad/hunting truck (large heavy tires). So it had me thinking instead of a v8 swap why not just swap in the 6l90? It would give me a 4:1 first gear, should get the tires rolling better giving me better acceleration and combined with 4lo a realitively good crawl ratio. The 4l60 ratios are: 1st-3.059 2nd-1.625 3rd-1 4th-.696 The 6l90 ratios are: 4.027 2.364 1.532 1.152 .852 .667 I think it would really help our motors out especially the guys with big tires. But someone with more information on how these bolt up can you chime in and say yes or no on could we actually mate it to our engines and could we control the computer within the trans?
I have the sort of same situation just in reverse I made an amateur mistake and bought a 2000 Silverado 1500 4x4 5.3L 4 speed trans, the motor is good and trans is good but it was a northern truck and the cab and frame are pretty shot and just feel they are not worth my time to fix cost for body work and paint would exponentially exceed the value and I’d be loosing WAYYY to much $$$ and time if I try to sell it as is so instead I was wondering if I were to get a 99-06 2500 originally had a 6.0 and I know that 5.3L and 6.0L are basically the same exact block 5.3-327 cu in’ bore and the 6.0 is 366 cu in’ bore and they have the same motor mounts. But I’ve tried to read up and do my research but I can’t seem to find anything about the transmissions everything I see is about replacing the 4l60 with the 6l90. The 6l90- bell housing is 6.74, main case is 17.84, case extension N/A, length to flange is 28.559, length to shaft is 28.559, engine block to lug converter is 0.853, length to extension housing is 30.542, engine block to mount N/A, center line to bottom pan is 9.196 4l60e-bell housing is 6.941, main case is 15.421, case extension is 4.433, length to flange is N/A, length to shaft is 26.941, engine block to lug converter is 0.853, length to extension housing is 26.795, engine block to mount 24.353, center line to bottom pan is 7.82 never did anything like this before so I’m not sure that all of those measurements matter but from what I’m understanding is the 4l60e is bigger in diameter towards the front but it is ab 2 inches shorter in overall length from head to tail the block to lug converter length is the same but the engine block to trans mount is unknown CAN ANYONE HELP figure this out???
 
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