Hey guys. Jesse here from True Blue Motorsport (aka TBM, TBMsport). First time forum member and poster.
So I've been made aware of this thread's zombie life and encouraged by a few fellow members to come on and establish some internet lure and fiction from useful real facts.
So, first some background info: When the 6L80 first came out in 2006 TBM was one of the first companies to recognize the future potential of this transmission and make it a core business focus for conversions. While Speartech has the distinction of being the first to retrofit one in a vehicle and offer a system to do so (GMT800 RWD truck) it came at a VERY high cost. Financially and functionally. Things like cruise control and speedometer were not guaranteed to work with their kit. And you were pretty much out of luck if you had a 4WD vehicle. This type of compromise has never been acceptable for TBM products and we continued to follow our path until a few months later we successfully converted our project 2007 Trailblazer 4WD with a 6L80. Cruise control worked. ABS worked. Traction control worked. No check engine lights or codes. And yes 4WD ranges worked in conjunction with the speedo and tach. We focused on this platform until this threads OP came to us with a desire to use our system for his H3. As you can guess, there were several compatibility issues known going in, and even more once involved.
Due to the limited knowledge that we had of the H3 at that time and the OP's own work/personal schedule, we were not contacted regarding any of the issues he had beyond simply helping him get the E67 ECM and T43 6L80 to communicate with one another. We reached out to him for some updated information and received no response. *shrugging* Therefore, we moved on to other vehicle platforms until such time as Levi contacted us. At that time we had some experience with the GMT355 Colorado/Canyon platforms and explained the still missing gap of knowledge transfer regarding the H3. Levi, decided to move forward and promised to give us as much detailed information as possible on the most minor of issues that he came across. And true to his word, we took the past nearly 2 years to perfect the system.
During that time, needless to say, a lot of speculations, assumptions and altogether different trans swap conversions details were posted on this thread and made for a lot of confusion. Further, due to the avalanche of emerging differences or anomalies with regards to the H3, Levi and I agreed not to muddy the waters on here any further until we had definitive explanations and/or solutions. Long story short, there were a LOT of bugs and details to work out which is why the OP likely did not follow back up.
So, let's get to the current state of affairs:
First off we have a new FAQ section created for general 6sp auto swap:
TBM 6L50/80/90 FAQs
Second, Recap of problems and TBM Solutions
a) 27 vs 32 spline output shafts vs input shafts. Yes, the 6LXX transmission all have 32 spline output shafts (like the 4L80). Hummer H3's have 27 spline input shafts. With GMT360 (Trailblazer) trucks we could offer a universal 32 spline input shaft (4WD) or our own in-house 32 spline input shaft (Torsen AWD) bc the input shafts were New Process units with separable internal components. H3's with the Borg Warner unit have a input shaft-planetary gearing cage unit. That plus a nominal amount of thickness on the wall of the input shaft makes a cost effective 32 spline option impossible. Further, this BW transfer case shares no relevant similarity with any other BW transfer case to scavenge parts from. Hence, the only option, similar to the GMT355s with they tiny Isuzu T120 unit required a 27 spline OUTput shaft for the 6L80. Like many, we did not want to take this approach, assuming that it would result in a weak point. We invested in custom HD (non-heat treated) output shafts being made at significant expense, only to discover that Rockwell strength of a cut down shaft was ever so slightly stronger than our the custom shafts. The process which GM uses to make their 6L80/90 output shafts produces an incredibly strong shaft well beyond the surface. Imagine that GM engineers and suppliers knows what they're doing vs the collective internet! So therefore we are more than comfortable offering this as an option. Particularly due to the torque multiplication work that the 4.03 gearing takes off of the shaft, let alone if you have a 4.10 transfer case. Just make sure you use graphite grease on the splines before installation!
b) Transfer case adapter. So this was another issue we needed to nail down. In summary, our proprietary GMT360/355 based transmission-transfer case adapter, while wide enough to mate with the BW unit, proved to have conflicting bolt hole patterns with our pre-drilled units. Additionally, the depth of the adapter was forcing the V8 H3 customer to modify their front AND rear shafts' lengths and creating some questionable overlapping engagement of input/output shafts. Unacceptable for TBM. So we needed to re-redesign our adapters. They will not come with no holds, but only dimples to keep cost down and keep them universally applicable.
c) Cooler lines. The 6LXX transmissions have cooler lines coming out of the bellhousing right about where V8 H3's cat's are located. Soooo, yeah, big problem. Fast forward. We now give our H3/GMT355 transmission systems a special angled connector to keep the lines running snuggly against the bellhousing and away from the cat.
f) Low range engagement, VSS, Tach, etc. There is no loss of low range functionality with 08+E67 system and the TBM T42-Interface Module/Harness bc the integrity of the OEM CANbus network is maintained. HOWEVER, yes, if you use our standalone system (aka. PCS 2650, Zero Gravity, etc) there will be some, say "added complexity". Speedo off. Reverse lights, Etc. That said, yes, we use the PCS 2650 as the basis of our Omega6 system, but what makes the TBM Omega6 system more than just a more expensive 2650 kit is because we provide all of the components and support to make sure you vehicle operates with full functionality. Sometimes this means added parts, programming calibrations, etc that we learned and gained from tackling 6L80 swapped 4WD vehicles 18 years. Because we were also the first to put a 6L80 behind an Atlas engine (04 TB 4200 I6 lifted off road rig, metal bumpers, pulling camping trailer) while developing the H3 kit, we learned some more A-HA Gotchas. Short and sweet. Things like Atlas engine vs LS engine trucks have different front prop shaft lengths AND angles/clearance issues. VSS signals coming from different parts of the drivetrain give different signals some of which have limitations based on drivetrain ratios and tire size and the PCS doesn't always like them. The short and sweet? Truck is running perfectly with all issues addressed AND with tap shifting getting the same fuel economy as before but flying up hills and conquering rocks/trails like never before. And it chirps the 33"s!
e) Torque converter stall speeds. It's one thing when you have a run of the mill big heavy 4WD truck with 2.xx low range and 3.73 axle ratios. It's another when you have compact heavy truck with big tires, 4.10 gears (at least stock), V8, AND optional 4.10 low range. We needed to expand our options for H3's because, as Levi reported, in 4.10 low range with a 6L80 4.03, the truck will almost pull through the brakes at idle. While this can be addressed with some ECM retuning of spark tables in his truck due to it being otherwise stock, that may not be an option for others. We've addressed that. V8's will need a different speed the Atlas motors depending on ratios and tire sizes. Moving on.
f) Dipstick & tube. Levi reports that the OEM 6L80 GMT900 truck dipstick/tube that we originally provided fits with a bit of muscling to clear some H3 unique underhood features. Yes an aftermarket flexible one is available. We will be offering an option mini-dipstick that, like more modern vehicles will be accessible from under the truck. Makes installation WAY easier. Seals tight just like anything else. And you can still measure your fluid when you do services.
g) Last but not least, reverse lights. So the H3's reverse light set up is based upon an older GM platform design that directly powers the Park Neutral Switch (PNP) and then subsequently the lights, review mirror came, etc. Unlike the newer generations which take their signal internally from the transmission's Internal Mode Switch (IMS) or CANbus language, this older set up means that once you remove the PNP from interaction with the transmission's manually rotated gear selection shaft, it's static/stuck in one circuit direction mode. Thankfully, from our work a few years back in being the first to swap a 6L80 into a new gen GTO (2004), we saw this type of system and created a new shaft lever and bracketry kit that relocates the 4L760's PNP to the 6L80. Now, your PNP engages the appropriate circuits just like the factory 4L60. V8 ALPHA NOTE: We are currently awaiting confirmation that this kit will still adequately clear the notoriously ill-placed catalytic converter. All other engine configurations are not a problem.
So, all of that cleared up (hopefully), YES, we have comprehensive, fully functioning 6LXX swap systems for the full Hummer H3 line. Atlas or LS engine. CANbus E67 or older PCMs.
