Everyone’s fav topic: 6l80 issues

[Starkworks]

@NickTransmissions - I am beginning to wonder if GM removed the fast adapt learn from the 6L80. Tried another Autel scanner, the MaxiSys MS906 Pro. It doesn’t have the selection either.

 

[NickTransmissions]

@NickTransmissions - I am beginning to wonder if GM removed the fast adapt learn from the 6L80. Tried another Autel scanner, the MaxiSys MS906 Pro. It doesn’t have the selection either.

That screenshot of the scanner showing "line pressure reset" (or something like that) was likely the function you need. Call Autel tomorrow to confirm/deny tomorrow..

 

[Starkworks]

That screenshot of the scanner showing "line pressure reset" (or something like that) was likely the function you need. Call Autel tomorrow to confirm/deny tomorrow..

@NickTransmissions - I thought so too. It doesn’t have the car go through the test. I’ll call to confirm.

 

[Starkworks]

@Starkworks - Conduct a successful fast adapt relearn and take it for another test drive - that by itself may solve all the issues. If you do have to pull it back out and apart, do the following:

1. Replace all the bushings - do not reuse bushings in these transmissions, especially the pump stator and body bushings

2. Vacuum test the pump (not sure why you didn't test the pump with the valve body but you don't want to omit that step - this video will show you specifically how to do it and what your readings should look like)

3. Record and share your clutch clearances, pump rotor/slide-to-deck clearance and end play measurement - this is one of the most critical aspects of any build and one of the most common things I see w/DIY builds is folks not recording clutch clearances and end play measurements
- If your clearances are too tight, you will have partial tie-ups/bind-ups upon shifting - these, like all clutch-to-clutch transmissions, are sensitive to clearances

4. Air check all applied elements to confirm everything is working as it should

5. Take pictures as you go - don't skimp on this step as they may help you after the fact - ask me how I know!

6. If all of the above is done and you still have the same problems, replace the TEHCM - a brand new one from General Motors will run ~$1,050 plus core and programming.
- Sonnax reman TEHCMs are $550-$600 plus core and programming
- Street Smart Transmissions remans are $550-$650 w/programming (you give them your VIN so they program it to your vehicle)

@NickTransmissions.

I contacted Autel on 1/22. They said the device I have should have the fast learn ability. Tech had to escalate to software engineers across the pacific. Due to national holiday a response won’t happen for at least 14 days per Autel.

So while waiting, I decided to tear back into the transmission.

1. Replaced all the bearings.
2. Vacuum tested the pump, results below:

• TCC Control valve: 23
• Boost Assembly: 25
• PR Valve: 24
• CL Valve: 24

3. Working on clutch clearances with a dial indicator, will report back later today. Checked with feeler gauges

• 1234: 0.072
• 35R: 0.053
• 2-6: pending…clutches move, but the backing plate doesn’t jump very much. Wave plate pushing up?
• LR pack: 0.074
• 456 will check with dial
• Will measure end play as well

4. Pump clearances:
Slide to Deck:

• 0.015

Rotor to Deck

• 0.04

5. Will air check as well

---

 

[NickTransmissions]

@starworks,

Confirm the rotor-deck is .004? If so, it's high; needs to be .002 max.

Measure the 2-6 clutch with a dial indicator. Simply lift the clutch pack up against the snap ring and record the measurement. Do this at three different points but not where the clutch snap ring ends meet (reading will be higher simply due to gap at that location). Average the three readings, that is your clearance.

Did you calibrate your vacuum tester prior to gathering the above results?

Did you test the valve trains when they were dry or did you assemble them with trans fluid or WD40 then test?

Readings of 14-21 Hg is what id prefer to see on all working valves; 23-25 Hg may indicate binding due to being too tight in the bore.

You replaced the bearings? How about the bushings - did you replace those as well?