6L80 swaps
 

As I searched I did not find an all-inclusive thread speaking directly to the 6L80 and 6L90 transmissions. I thought it would be a good idea to start collecting information regarding GM's 6 speed transmissions, similar to the LSx swap thread. I know many people have questions so this would be a great place to begin answering them. If we get enough info, perhaps this can become a sticky.

The gear ratios for the 6L80 and 6L90 are:

1st: 4.027
2nd: 2.364
3rd: 1.532
4th: 1.152
5th: 0.852
6th: 0.667
Rev: 3.064

Output shaft
 

The 6L80 has 32 splines.
The 6L90 has 34 splines.

It appears as though the 2WD and 4WD trannies are similar in structure. The difference is in the tailhousing adapter; 2WD gets slip yoke while 4WD gets transfer case adapter.

Additionally, on the 4WD trannies, the bolt pattern is the 6-bolt, round GM pattern. This means any transfer case with this pattern should bolt-up with no modifications! :metal:

Also, Atlas makes 2 & 4 speed transfer cases with this bolt pattern AND both 32 & 34 spline input shafts. Nice!

computer
 

From what I've read these trannies use a TCM (transmission control module) that is located inside the tranny. It talks to the ECM (engine control module), they collaborate, and decide when to shift, how hard, etc. These parameters are programmable using a laptop however I'm unsure which software companies support this, such as HPtuners or EFI Live.

Also, the engine needs to be a Gen IV with a 58x reluctor wheel for the ECM to talk to the TCM.

As for aftermarket companies with harnesses and computers to control the 6L80/90, both Mast Motorsports and Speartech have them.

http://www.mastmotorsports.com/2010/...ponents&id=290

http://www.speartech.com/

gear comparison with other GM trannies
 

Why the interest in the 6L80/90? Gearing options!!! The 6L80/90's 1st gear is 4.027. This is the lowest GM automatic 1st gear available. Only manual trannies with granny gears are lower (SM420 is 7.05, SM465 is 6.55, NV4500 is 6.34 and 5.61, NV5600 is 5.63).

As a comparison, I calc'd the mechanical advantage in 1st gear over other popular GM slush boxes.

60% lower than a TH350
62% lower than a TH400 or 4L80
and still 32% lower than a 700R4, 4L60/65/70

I also calc'd the advantage in overdrive too.

n/a for a TH350 or TH400
12% higher than a 4L80
and still 4% higher than a 700R4, 4L60/65/70

For you drag guys, this means you should get the same launch (assuming no other mods) running 4.11 gears in your diff with a TH350, or highway friendly 2.50 gears in your diff with a 6L80.

For you 4WD guys, this means you should get the same crawlability running 5.13 gears in your diffs with a TH350 as you would 3.23 gears and a 6l80. However, if you ran 5.13 gears with a 6L80, to achieve the same 1st gear crawl you'd need 8.20 gears in your diffs, which I failed to find (7.17 seems to be the lowest gears you can get).

And besides the amazing 1st gear, you still have the best O.D. of any tranny too!:metal:

Re: 6L80 swaps
 

Thanks for posting this great info. :thumbs:

With a double overdrive, I would think a guy could still run a lower rear gear (3.73) for an awesome launch and still be able to cruise the highway at a reasonable rpm.

Re: 6L80 swaps
 

By the way, I'm no expert. I'm simply regurgitating what I've read. So please, if you have any pertinent, useful knowledge, or especially first-hand knowledge working with the new 6 speed trannies, please write-up. I would love for this to be a one-stop-shop for all info related to these newer trannies. I would love to learn more from you guys! Thanks!

Links to Pirate4x4
 

I thought I would post a few links to people on Pirate4x4 that have, or are in the midst of swapping a 6L80.

whypave's build: http://www.pirate4x4.com/forum/showthread.php?t=848143
95geo's build: http://www.pirate4x4.com/forum/showthread.php?t=824983
dookey's build: http://www.pirate4x4.com/forum/showthread.php?t=882928

And a fair warning - Pirate4x4 has different forum rules than 67-72. Therefore, there is more colorful language, bashing each other's builds, and they love the "bird smiley." However, if you can wade thru all that garbage, there is still some good tech in there.

Enjoy!

Re: 6L80 swaps
 

just a ? Thor,

is there a practical purpose for going with the 6 speed auto? I understand the cool factor, just wondering

Re: 6L80 swaps
 

With the additional gears, you should be able to keep the engine (needs to be a Gen IV engine - 58x reluctor wheel - computers need this info) in its powerband instead of a TH350 for example where you wind the engine up, tranny shifts gears, you fall below the powerband and engine slowly builds power again, wind the engine up again, shift into third, fall below the powerband, wind the engine up again and no overdrive(s) like the 6L80.

Also, the ~4:1 first gear is really low for an automatic. Should make 4-wheeling more fun as you have better crawlability, make launching from a stop more fun as you've multiplied the torque of your engine more, make towing more fun as it again multiplies the torque of your engine to get that massive trailer/boat moving.

And it has two overdrives. If you are running at the freeway's posted speed limit, I would guess the tranny would be in 5th gear (the 1st OD). But when you want to really go fast, in comes 6th gear (the 2nd OD). It's kinda similar to the T-56 manual tranny that came in the corvettes that allows some of those guys to get ~28 MPH on the freeway when they are in 6th gear (although the T-56's 6th gear is 0.50:1 while the 6L80 is 0.67:1).

As for cool factor, I guess that would come with swapping a tranny that many have not swapped before. However, that also increases the headache factor too.

Re: 6L80 swaps
 

I see your point and I guess if I were into crawling, that would be the trans for me. I love learning what other hobbyist are doing to make their project work better or more fun for them, Thanks Thor!

Re: 6L80 swaps
 

Well after watching the u tube of John Spears 2002 truck with a 6l80e in it he is running 3.73 gears and burning the tires through first 3-4 gears with that thing. Impressive. I am scared to see what mine is gonna do since I am runnign facotry original 4.56ers lol think I will just let the engine take off at the light rather than goosing it lol. that and of course get a set of wings and rear ailerons! :uhmk:

Sean

Re: 6L80 swaps
 

Definitely post up some pics and helpful hints when you do your install.

Has anyone else performed this swap yet? I see them on other boards but not here....yet. Anyone?

Or even if you are just considering it, post up what you know. Always good to learn more.

Re: 6L80 swaps
 

Hey Thor,
Yeah waiting on cash right now to get my tailhousing in place since mine is a 4x4 drive setup. Going to have a trans shop convert it to 2wd setup and have the comp reprogrammed this fall for 2wd mode functions.
Will be posting as soon as I get the housing in and on and the engine trans in and in place :D
Sean

Re: 6L80 swaps
 

Sweet! Are you running an L92 in front of it? Or other Gen IV? Using stock comp & harness? Man, I need some cash too. Let me know where you find yours. :lol:

Re: 6L80 swaps
 

hey Thor,
72 hours a week 52 weeks a years nursing is what pays for the wife the kid and three toys lol. Yeah running the l92 I got a steal on the combo for 1k with only 37000 miles, I found a place in euless nearby me that is going to build me a custom standalone harness for 750 he is a retired gm techie that owns a dyno shop :D.

Sean

Re: 6L80 swaps
 

$1000 for an L92 and 6L80? That is the best price I have heard, for sure! Nice score Sean! :metal:

Re: 6L80 swaps
 

Yeah I'll take one at that price 2 wheel 4 wheel heck 1 wheel if its a 1000 bucks
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Re: 6L80 swaps
 

Where to find a 6L80 (sourced from wiki):


2006 Cadillac XLR-V
2006 Chevrolet Corvette
2006 Holden VE Commodore / Pontiac G8
2006 Holden/Chevrolet WM Statesman/Caprice
2007 Cadillac STS
2007 Cadillac Escalade
2007 GMC Yukon Denali
2008 Hummer H2
2009 Cadillac CTS-V (6L90)
2009 Chevrolet Silverado 1500 Series
2010 Chevrolet Camaro

Re: 6L80 swaps
 

I've got a 6.2/6L80E out of a 2013 Camaro SS. It's got the funky looking triangle output shaft on tranny. I need to convert it to a slip yoke style like the 6L90E's. I found a kit that provides the necessary parts to do the conversion, but I have been unable to find anything talking about doing the actual swap. Can you DIY or does it have to be done at a transmission shop? Thanks in advance.

Rob

Re: 6L80 swaps
 

Pretty sure tranny shop cause from what I gather you have to change the input shaft that everything rides on
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Re: 6L80 swaps
 

I'd like to add that the 2011+ Chevy Caprice PPV uses the 6L80E (essentially the Holden Caprice rebadged). Since these are police cars, it stands to reason that they may show up in junkyards wrecked or damaged from police use. Keep your eyes open. I think V6 engines are offered. But I know the V8 engine RPO is L77 for the PPV (9C3 and 9C1). Same as the L76 that was in the G8 and Commodore but the L77 adds active fuel management (cylinder deactivation). Otherwise it's the same as the G8 engine, which is derived from the LS2.

I like the 6L80E in my PPV. When placed in performance mode, it is specially programmed to hold a lower gear on turns for engine braking and better control, kinda like you would do with a manual so you can punch it coming out of the turn (I hate conventional automatics that downshift at that time and then your tires break loose). This trans will hold lower gears in performance mode, even after you let off the gas. Unless you expect it, you kinda think it's stuck in a low gear until you realize that if you were driving a manual, this is what you do naturally. It's hard to explain. But cool nonetheless. And fortunately, can be turned on and off.

Re: 6L80 swaps
 

Any idea on what this might cost??

Re: 6L80 swaps
 

I've been contemplating this swap for a while. How much did that combo cost you if you don't mind me asking?

Re: 6L80 swaps
 

I paid over $8.5K for 6.2/6L80 out of a 2013 Camaro SS with only 135 miles on it....

Re: 6L80 swaps
 

No way to tell cause if you find a shop that will swap just the shaft it could be pretty cheap but I'm pretty sure with having it for down there gonna say it needs a rebuild to be safe
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