Hey Wacker, 2007 6.2 AWD Denali Yukon here, ~130k miles. Primary critical use will be towing around 8,000 lbs long distances through the desert and up long, steep grades in those temps.
As per your recommendation, went with a CDT Level 4 setup. Have built quite a few performance 4l60’s, TH350/400’s, etc. but this was the first 6L80. Because of this I checked everything multiple times every step of the way and tried to be as careful as possible. New GM pump and bellhousing (0.0015 clearance), new 1234/35R drum, new Borg Warner sprag.
Relevant modifications:
BTR Truck Norris Cam
3.73 gear change (from 3.42)
1800 stall converter built with Sonnax GM-RK-21 kit with triple element carbon clutch
B&M +2qt pan
External Derale filter setup with Improved Racing thermostat
No info on history prior to this, unfortunately. Overall, the transmission originally shifted ok, but was sometimes confused/inconsistent at lighter throttle, but this is probably typical I’m guessing. 2-3 flare on first takeoffs also, but much less with the new drum that has been installed. Pan was amazingly clean
New clutch clearances (**without a travel weight) were:
1234 - .063 (CD Spec .070 to .095)
35R - .043 (.050 to .070)
2-6 - .043 (.045 to .070)
L-R - .042 (.040 to .070)
456 - .058 (.050 to .070)
All wave plates were brand new GM. Clearances were probably on the tighter side, which now I know I should go towards loose next time.
HPTuners trans tuning was put back to stock, with just some modified shift/TCC MPH scheduling, slip elimination, and no lockup in 1-4. MAF curve is mostly dialed in and is roughly +5% to +15% over stock across the board. VVE and idle are works in progress but not far off. Car runs pretty good overall currently, no notable A/F or timing issues. Torque output numbers seem to be right, including TM during shifting, but if you could look at those please.
Potential issues after rebuild:
Single clunk noise sometimes after start. Might be the parking pawl rod, which is being replaced with a newer TSB unit when the TCU is swapped. The noise was traumatizing at first, but I gave up and don’t even hear it anymore lol
PWM or purging type buzz/hiss on most first cold or cold/warm takeoffs. Sometimes 2-3 seconds, sometimes 1 second on, 1 second off. Sometimes it does it on occasion when sitting at idle in gear, which can be a buildup noise, then stop…then buildup then stop…etc. Have a reman Dorman TCU that is going to be swapped in here shortly as maybe the solenoids are taking a dump? This is concerning as they may not be applying the appropriate pressures and destroying things??
Reverse seems to be a bit more idle load than D when coming from P/N. Clutches potentially dragging here?? ☹
3-4 often doesn’t feel very inspiring at part throttle, compared to 1-2, 2-3, 4-5, but is that kind of inherent due to the separate 4-5-6 drum? The car is not driven hard at all, so it may keep learning to be mushy. These transmissions seem to shift differently every minute of every day as they please! WOT/heavy throttle shifting feels like no issues at all through all gears.
Main overall concern is if there is any binding or harmful slipping and then the subsequent failure of the unit (in the desert in the middle of nowhere!) Completely paranoid of this to be honest! I logged with your Channel 6 config. Reset/Preset was done and was driven a few cycles before logging. First two takeoffs are light and then medium throttle in 1-2-3-4. Third is very heavy throttle in 1-2-3.
So can you please look at:
- Potential binding
- Harmful slipping/flaring (mostly 3-4)
- Torque numbers/TM
- Pressures
Also if any suggestions on anything to log or note before changing this TCU. Want to have good before and after data!
Thanks!