LS4- 6T70/6T75 Happening...for real!
 

Hey guys. This is my little slice of LS1tech. that I'm carving out to share the progress of putting the 6 speed 6T70/75 into my 08 Impala SS.



I know there has been a lot of internet chatter on it, but a lot of it has been scattered and partially correct...with a healthy sprinkling of internet trolls pissing on the idea from the clueless sanctity of their couch and keyboard. So, I'll start off with giving you the bulk of the accurate information and facts that I've gathered. This first post will be updated as new information comes out, so as to make for a quick and easy reference.

First a little background about me. I've spent the last 8 years learning the GM systems because I wanted to put a 6L90 in my '07 Trailblazer SS and didn't take to kindly to EVERYONE (including GM Powertrain division and training schools) telling me it couldn't be done, or that I would lose certain functionalities if I did. I wasn't buying it and was determined to prove them wrong. I have simply put out of my mind, the tens of thousands of dollars I've spent to gain the knowledge that I have (it happens easily when you don't have a wife or kids to worry about :cheesy:). After being the first to perform two successful 6 speed swaps on my two Trailblazers (07 Trailblazer 5.3L LS 4WD) and proving that I didn't have to give up cruise control, ABS, 4WD, etc I began to examine and explore almost other GM engine's adaptation of a 6LXX transmission; from old Pontiac V8's and Buick turbo V6's to Ecotec's, LT-1's...in every conceivable GM platform. Having provided tech support/parts/programming for a whole bunch of crazy one off LSX 6L80/90 project vehicles (wrapping up first Hummer H3 Alpha conversion), I wanted to spread the love with the transverse mounted and non LS-V8 groups.

I had planned to do a 4200 Trailblazer turbo 6L80 project, but sadly my '07 5.3L Trailblazer decided to dine on its bearings, so I decided to trade my '08 4200 Trailblazer for my new (to me) '08 ImpSS. As luck would have it, my father had an old Ford Galaxie he wanted to sell and that desperately needed to be removed from our family of cars and we traded it for a rust free, clean, well optioned '85 Pontiac GP [getting an 8.1L 496 and 6LXX]. My '99 Silvy (w/300K+ miles) is still working hard, but definitely reminding me it is tired [getting Gen III 6.0L LQ4 with 6LXX]. What's the point in telling you all of this? Because each vehicle has motivated me to make them their own first ever unique TBM 6speed conversion, starting with the ImpSS, because I have been greatly impressed by this car in the just the past 2 weeks of ownership. Also, so you'll understand if I don't get around to updating. :engarde:


:judge:Ok...to the 6T70/75 details:

1-The easiest conversions will be '07-09 because they use the 58X ECM system which is critical for the 6 speed transmission to network with. I'm eyeing an '06 GXP as a project car, to develop a cost effective solution for you '05-06 guys, but quite honestly, I think the cheaper way is to just swap the ECM, harness and engine to a newer model. Yes, there is a stand-alone system out there. No, it is not cost effective or readily/universally available because it requires custom and specific programming to YOUR car, transmission, driving style, engine components..PLUS the additional hassle of rewiring your existing harness so that your ECM and BCM don't freak out. So, we stick to GM systems and everyone plays nice-nice on your car's network. Plus, your vehicle is easily serviceable. Keep your ABS? CHECK! Factory Onstar and remote star still working? CHECK! TapUpTapDown (including ImpSS)....Optimistically HOPEFUL! :D Will I have to hack my harness and make a lot of one way mods to my car that exceed the value of the car? NOPE! That's not how I do things.:usa:

2- Fiero.NL has been a remarkable resource for helping establish some parameters on what can/can't be done for swapping into our cars. Unfortunately, because a Fiero is ancient technology compared to the LS4 W-body, there are a LOT of creative licenses that can be exercised when putting an LS4 in a Fiero compared. Beyond the similar engine layout arrangement, almost nothing else is transferrable or comparable. What works easily for those applications requires modifications to our application.
https://ls1tech.com/forums/ls4-perfo...version-3.html


3- The main issue of starter relocation is well documented. Two solutions (likely oil pan starter vs. unlikely custom case adapter) have been determined. I'm working on parts production within 3 months.;)


4- The 6TXX transmissions came in different engine bellhousing bolt pattern, torque rating, and case size configurations. That makes the initial hunt for the right one that fits our application quite a chore, not to mention the wave plate failure issues. If that weren't frustrating enough there are different TCM modules which will require specific reprogramming. More on this in the next month.

5- Critical key parts list (this will be updated as new information surfaces):
5a-TBMSport T42 (4speed) -T43 (6speed) interface module and harness. This allows you to keep 99% of your harness as it left the factory.

5b-GM OEM drivetrain parts. As GM saw fit to add the 6T70 to the Impala (with the 3.6 DOHC DI V6) in 2012, most of the drivetrain goodies are there straight from your local GM dealership or junkyard. Unfortunately, the transmission itself will not bolt up as the high feature V6 doesn't use our bolt pattern. Prior to that model year the only 6TXX transmissions that had our bolt pattern were weak Ecotec 6T45/50 transmissions. That would have meant buying two different transmissions to make one fit ours. But never fear!!:burn: I've found perfect fit. 2013-present Buick Regal (GS) and Malibu turbo Ecotec M7W-6T70 transmissions have our bolt pattern and higher torque capacity. Best part...as of now the transmissions are dirt cheap used! This makes the oil pan starter solution a win!! You're welcome! :jest:


5c-The engine cradle/frame. Sadly, I just discovered this problem today. GM used (at least) 3 different engine cradles for this generation W-body Impala/Lacrosse/GP. One for the pushrod V6's, one for our LS4, and another for the new 2012-14 Impala DI V6 for. As luck would have it, the mods that were made to accommodate our LS4 are different on the 2012-14 (passenger side). And the mods that allow the 6 speed transmission to fit are dramatically different from the 4T6X (driver's side). My current thought for a solution is to offer a bolt-in /weld replacement subframe component. The part of course would allow either transmission to fit, so that it doesn't become a one way mod. But until I have the two subframes side by side to measure and consider transmission contact/interference, I can't definitely say.


http://tbmsport.com/images/600_2008_...Mount_part.JPG


http://tbmsport.com/images/600_2012_...Mount_part.JPG


5d- Cross over pipe. The front cylinder banks will no longer have a liberally convenient space between the transmission and throttle body to funnel exhaust fumes.


Until next update. :cool:

Full Pics and details here:
http://tbmsport.com/projectvehicles/...ssfastfwd.html

Looking foward to it.

uh o i could be coming into small windfall because of a deer blatantly smashing my car up on purpose ,clearly deer fault and i don't think he is represented so i should win this case,if peta doesn't show up

I'm excited to follow the progress on the build.
Should be fantastic!

wow u think it could be don in 3-4 thou range

That's the target range. The subframe will determine where in that range the total cost is

Hello,

Do you have any updates or progress on the swap?

Thanks!

Mike

Is this dead?
I was hoping this would be the 6 speed swap that made it!

Hey this isn't dead. It's on hold. Work got crazy due to the loss of 4 personnel. I'm moving and a recent hit and run on my TBSS have conspired to derail the progress. :punch: Hopefully it'll be back on track in a couple of months.

Suck about the tbss - do you have any driving vids of the beast? Looking forward to more on this swap!

man,hope it gets back on track,fucking hit and runners,they everywhere

Following this thread

Ok. Update and crossroads for those guys who subscribed and encouraged me this far.

I've determined that the only sensible way to approach this is to make a new 6TXX case have that can accommodate the Northstar and GM Metric engine bolt pattern (3.8, 3800, 3.1, 3.4, 3400, LS4, etc.). I've got it all worked out and I've even found a source to make that happen for a reasonable project price of under $1k. BUT there are several other issues. Due to the taller and wider transmission case that LS4 motors will require the following:
-a change in inside exhaust manifold (possible custom)
-custom cross over pipe
-custom mini starter
-change in K-member
-axle shaft.

Of course after that physical fitment is addressed you're then looking at a TCM control module and harness situation that is going to run about $1500 and some calibration time for the specific engine (assuming you don't have an E67 LS4 vehicle). It is assumed that the GM metric V6's and N* engines will need to have all the same issues address to reroute exhaust around a different shaped transmission.

That said. As I've now determined what's necessary to do it, I'm not entirely sure it's worth the time and money to do it vs. investing in other more in-demand projects and requested parts.

Ah sounds like a snag in the easy-to-do and price department.
I think this would take off if the pricing/availability was comparable to a transmission rebuild (performance oriented).

I believe someone in this forum has completed something very similar to this. I know I have seen a successful transverse six speed on here.

Quick question
 

So, I have a 2013 Impala and I wanted to put a the LS4. Is recommended to keep my original tranny or replace it

Just wondering....

1) DO you have a wife and kids who require your attention daily?
2) Do you have your own fully functioning auto and fabrication shop?
3) Are you rich?

Because my guess would be 2 of those 3 would be REQUIRED... guess which two...

But... just my two cents = What would be the point of dropping in an LS4 with the original LS4 platform 4 speed automatic when you could just go buy a decent used LS4 Impala SS already together and running?

Plus, from a car sales perspective you would be killing the resale value of your 2013 by doing such a swap...

Not even sure how you would go about hooking up the LS4 to that 6 speed auto in your 2013.... this thread died because someone else threw in the towel... Can't say I'm not skeptical at this point when I read posts about this sort of thing.

Just curious if you've had any additional considerations for this project? I've been lightly researching a similar project for a Cadillac for different reasons, most as mod just to put the transmission that they should have used for better driveability.