Great forum here and some great info and knowledge! Questions on an upcoming rebuild on a 6L80 in a 2007 6.2 AWD Yukon Denali. Hopefully some future headaches can be avoided, so any advice here is much appreciated! Plenty of 4L60 and other rebuilds previously, but this 6L80 is a new animal for me. I think there are probably others in the same boat looking for this info, so I’ve included part numbers to hopefully help someone else out as well.
Currently 130k, all original and working ok for the most part. Unknown service history but fluid was ok and has been flushed. Shifts can be a bit soft and/or confused or with minor flaring on occasion but overall nothing horrible to note. Using this time to learn/tinker with the trans tuning since there is no consequence ;)
Performance upgrades will be limited to basic bolt ons and a cam. Stock-sized 32” tires, with gears to be changed after this transmission hoopla to 3.73 from 3.42. This will be a daily driver but also used for heavier long distance towing (6-7k lbs) in the lovely summer temps through the CA/NV/UT desert. Building this for longevity and load tolerance rather than high hp.
Full rebuild very soon on this. After much reading of the great information here on 6l80etuning, it seems that even after a “proper” rebuild with no assembly mistakes, many problems come from bad tuning and/or untunable setups, some of which point to non-standard clutch configurations.
Current proposed recipe, please vet this list and comment and make suggestions if anything looks like it will cause problems later.
Converter - Had a core unit rebuilt with Sonnax GM-RK-21 (billet cover and triple carbon clutch), stall speed slightly raised
B&M 70293 deep pan + Trucool 40k cooler LPD47391
New GM bellhousing 24248031, cover 24248573 and pump/slide 24042371 24222668
^Pump clearances TBD
Sonnax 104534-HD pump spring
Transgo SK-6L80 shift kit (I liked the Transgo spring loaded check ball boost bypass vs Sonnax boost setup)
Transgo 6L8 CS-TCC clutch select and TCC valve kit
Sonnax 104740-09K compensator valve kit
Sonnax oringed plugs, center support seal kit, checkballs
Sonnax pressure switch repair kit 124740-TL30
Updated GM separator plate 24245720
Durabond TK-19B bushings
Sonnax SBK-G80 roller bearings
Hi-per Blue 4858 pistons
Later GM 3-5-R drum 24298742 (Should I weld this? I have a TIG handy and always try to find things to weld lol)
Borg Warner sprag 140747BW
Sonnax 4-5-6 apply piston 104960-01K
Sonnax 1-2-3-4 piston 104984-01
Sonnax 3-5-R apply ring 104548-01
^^This one I’m questioning as it removes the wave plate for another clutch and steel. Asking for clutch fill tuning problems here?? Not even necessary?
Raybestos Kolene steels STMGM06K
Raybestos Stage-1 red clutch set RCPS189
**or**
The Stage-1 plus switch in the Raybestos GPZ Z pac RCPS21 for the 3-5-R and 4-5-6 clutches (+ associated steels, plates, etc) Is the GPZ even appropriate in this application? (i.e towing instead of high hp) Non-OE spec clutch pack will have clutch fill tuning problems?? Maybe the Stage-1 red throughout are good enough here.
Just looking to get this trans running good and tight, tune out the TCC slip, firm up the shifting a bit and that’s it. Trying to circumvent being stranded out in the desert with a big, heavy trailer at any cost here. Really don’t want endless tuning battles with this transmission as that’s another project for another vehicle for another day!