cosmicvette

Hi all,

Have been considering a 4 speed auto conversion but after driving an '08 vette last year for a few thousand miles I loved the 6 speed auto it had.

Has anyone seen this transmission in the flesh? How big is it, would it come close to fitting under a C3. Anyone else considered this swap? Also does anyone have any idea how complicated the electronics are (for the lockup converter etc), would it be possible to run it with a standalone controller like the 4L60E is when swapped into a C3?

I love the idea of a 4.027 first gear, it would make my lazy 2.73 rear-end gears the same as having a set of 4.4's behind my current TH400, yet the second overdrive in the 6L80 gives me a final ratio of about 1.8 ...........................the mind boggles.

Plus the 6L80 designation seems to imply it is built on the bullet proof 4L80 platform is this true? (unlike the 4L60E/700R4 which people have claimed are weaker than the venerable TH400 which I currently have)

Any info greatly appreciated.


cosmic

gerry72

You might not be aware of this, but this transmission is mounted in the rear of the car and mates directly to the differential. Only the torque converter is behind the engine. If you were asking the question as; "If I had unlimited funds and mad skillz, could I do this?", I'd have to say anything up to fitting a GE J-79 turbojet is possible if you want it bad enough.

If you went with a more conventional trans, like the 4L60 (e version of the 700R4) you'd enjoy most of the benefits with far fewer fabrication issues.

BillysRed1980

I thought I read somewhere that all the new GM transmissions were build on a "modular" platform, with separate bellhousings like the Manual trannies, so that they could go into all the different applications without specialized castings. Can anyone confirm this? If that were the case, then I suppose the swab could become a little more feasible.

gerry72

For the most part, that is true. But this is a big trans (tunnel and mount fabricating/modification) and the double overdrive will be an issue with a 2.73 gear, rendering 6th gear unusable. Again, anything is possible if you want it bad enough and are willing to do the work to make it happen.

ToniH

Hot Rod mag nov 2005 says: "distance from the front of the case without the bellhousing to the rear mount is about 29 inches, making the sixspeed about the same size as the popular 700R4".

The sixth gear gas a ratio of 0.67 which IMO is pretty close to 700R4's 0.7.

The box is connected to C6 Vette with an transaxle adapter. There is also a Gen III/IV small block bellhousing which can be adapted to Gen I/II smallblocks or even big block - according to Hot Rod.

Maybe you are talking about 6L90?

gerry72

I thought it was nearer to .5 on sixth. My mistake.

PaPaPork

Cosmic

6L80 and 6L90 applications (per wikipedia):

* 2006 Cadillac XLR-V
* 2006 Chevrolet Corvette
* 2006 Holden VE Commodore
* 2006 Holden WM Statesman
* 2006 Holden WM Caprice
* 2007 Cadillac STS
* 2007 Cadillac Escalade
* 2007 GMC Yukon Denali
* 2008 Hummer H2
* 2008 Pontiac G8
* 2009 Cadillac CTS-V (6L90)
* 2009 Chevrolet Silverado 1500 Series


I pretty shure not all these vehicles have a transaxle in the rear, so it shouldn't be a big deal to install it in a C3 like someone suggested...

Also, If You do care about weight and size of the transmission and you don't have huge power You can also go with 6L50 (or6L45). It is the same design as 6L80/6L90 but for lighter vehicles than the 6L80 and 6L90 (8000lb and 9000lb)
the ratings are:
5000lb GVWR
332 ftlb

1 2 3 4 5 6 R
4.06 2.37 1.55 1.16 0.85 0.67 3.20

applications:

6L50

* 2006– Cadillac STS-V
* 2007– Cadillac STS
* 2007– Cadillac SRX
* 2008– Cadillac CTS
* 2009– Holden VE Commodore / Holden VE Berlina / Holden VE Calais / Chevrolet Lumina
* 2009– Holden WM Statesman / Holden WM Caprice / Chevrolet Caprice / Daewoo Veritas

rip74

My 2010 Camaro SS has the 6L80. It is mounted to the engine, not to the diff. It doesn't look very bulky or bigger than the TH400 in the Vette but laying on under the car it's hard to tell. After owning the Camaro I really want to put a 6L80 into the Vette. It is so nice around town but has more than enough grunt down low when you need it. Vendors are you listening???

mrvette

SO with a torque converter, the 700 first gear is 3.xx and so who need more than that...?? 5500 lbs of Poncho used to launch pretty good with a lousey 3 speed and 2.5x first gear set...and a typical 273 rear....

so show me any great increase in performance over a 700 type animal...a 200 4r is a better match...

much less over a grand in electronic shift controller.....

PaPaPork

so Its confirmed - it shouldn't be crazy expensive to throw that in a c3. I would love to score the new 6.2 all aluminum vortec with the 6L80 out of a trailblazer SS or yukon denali.... That would make a very nice package, with paddle shift...

l88rocket

checkout TCI new 6spd auto. but you dont need all that 1st gear they put in them its like a 2.80 1st. if it was a 2.66 or so like the the 6 spd manuals it would be great. a 4spd over drive would be plenty with any motor combo. a 4l65e would be good option