GM 6L80 Transmission Information Thread

[NickTransmissions]

Hi All,

Since so many of us own at least one Tahoe or Yukon equipped with a 6L80, I figured I'd start an all-encompassing transmission thread with videos, links and other information as it relates to the 6L80/90 transmissions. I'll get it going with a tear down and inspection video and go from there. Hoping this can be an easy 'one-stop shop' for exchanging information, guidance and advice as it relates to 6L80 or 6L90 transmissions.

I'll update this first post with more over time and bump the thread when new stuff gets incorporated.

Feel free to post questions, comments, etc...

Note - Feel free to send me a PM as well but please provide your first name so that I know who I'm talking to - TIA.

2011 6L80 Teardown and Inspection

Special Tools Needed to Work on the 6L Transmissions

6L Transmission - Diagnosis and Troubleshooting, PT1 - Operating Fundamentals and Using Range Charts

Quick primer on TEHCM resistance testing:
> Review this article for the TEHCM testing procedures.

> Using a multimeter to test resistance for shift and pressure control solenoids (shift solenoids: 20-40 ohms; line pressure/clutch pressure control solenoids: 3-8 ohms).

clutch pressure control solenoid


shift solenoid


Pressure switch resistance (closed circuit): .7-1.9 ohms ( this is pressure switch #1 which sends a signal to the TCM reporting the status of the 3-5-R clutch reg valve in the valve body)


Pressure switch resistance (open circuit, pressure applied to switch) 11.5-12.9 kohms

> Use pencil eraser to put pressure on switch to open circuit
> Pressure switch resistance should drop back to .7-1.9 ohms or so when circuit is closed again (may vary a bit but should not be significantly different).

If any of those pressure switches are not reading like the above when you do this test, then the TEHCM is bad and should be replaced!

TSBs and other Tech Info
ATSG Manual
TSB - Cooler Bypass Valve
TSB - Pump and 3-5-Reverse Drum
ATRA - Intro to the 6L80
ATRA - Changes Over the Years
ATRA - TEHCM Diag, T&E
Installation procedures & fluid level check
GEARS Mag: Diagnosing CAN communication issues (no scan tool)
6L80/90 TSB - UU0073 Communication Breakdown Between Modules (including the TEHCM)


Parts List for Overhaul

PART	GM Part #	Notes
Paper and rubber kit		BW high energy or Raybestos Stage One unless full race
Clutch module
Kolene steel module for 3-5-R and 4-5-6 clutch packs
Factory steel module for 1-2-3-4, 2-6 and low reverse clutch packs
Bonded steel and rubber piston kit		OEM pistons are made by National Seal
Snap ring kit for the 3-5-R and 4-5-6 clutch pack return spring assemblies	24260139	Early spring kit listed will service all years
Snap ring for the rear sprag assembly-to-center support	24230752	Will retro to 2006-E2007 units
Snap ring for the 4-5-6 hub damper cover plate
38 element sprag clutch assembly	24248957	Will retro to 2006-E2007 units
GM heavy duty parking rod assembly (2017 and older)	24280048	12.5" for 6L80E and 14.5" for 6L90E
Factory bushing kit
Thrust bearing kit (only needed if trans overheated)
Sonnax billet aluminum 1-2-3-4 apply piston
Sonnax 4-5-6 piston kit		Optional but strongly recommended
Sonnax Zip Kit		Transgo Reprogramming kit is a viable alternative
Sonnax Oversized Clutch Boost Valve kit		Necessary if one or more existing clutch boost valves fail vacuum test or prove to be worn; requires Sonnax reamer and related tooling for installation
GM internal mode switch	24246427	Updated switch will retro to years 2006-E2007
GM wiring harness and speed sensor assembly		2012+: Application dependent and must match existing rear speed sensor design - consult dealer w/VIN
GM separator plate		Year/application specific - consult dealer w/VIN
GM TEHCM		Optional for later model units and strongly recommended for pre 2014 units; year/application-specific - consult dealer w/VIN
Sonnax pressure switch rebuild kit and tool		Purchase if intending to re-use TEHCM
GM TEHCM filter screen		Purchase if intending to re-use TEHCM
New Torque Converter		New converter should come w/ converter clutch thickness => .050"; billet cover required for heavy duty or high performance
Machine Work
Pump		Machine pump cover and body. Cut pocket to achieve .002 clearance between rotor/slide and deck surface
3-5-R Drum		Reinforce welds at the base of the drum (all years)
High Performance Options
Rear planetary carrier assembly with billet drive plate		Not needed unless horsepower exceeds 700HP or if vehicle is regularly raced
Sonnax 3-5-R high capacity apply ring		When installed and factory wave plate eliminated, this apply ring allows for an additional clutch and flat steel plate
Sonnax 4-5-6 billet clutch hub
Camaro ZL1 Converter		Great performance upgrade as these are significantly stronger than the stock JMBX converters that come w/the 6L80E
Raybestos Blue Plate Stage 3 friction module
Complete Raybestos Kolene steel module

 

[MWD_CTSV]

Thanks Nick!! some much needed 6L80/6L90 content for the channel.

 

[NickTransmissions]

You're welcome, @MWD_CTSV !

 

[Geotrash]

Having successfully rebuilt a ZF 5HP24 that had lost 1st and reverse on my workbench, this makes me feel like I could reasonably do a 6L80 now too. Only problem is I hate doing the R&R.

 

[89Suburban]

This is go great to have here Nick, much appreciated! Maybe do a thread here for the 4L60E here as well?

 

[NickTransmissions]

Having successfully rebuilt a ZF 5HP24 that had lost 1st and reverse on my workbench, this makes me feel like I could reasonably do a 6L80 now too. Only problem is I hate doing the R&R.

Nice work. Those restrictors between the channel plate and spacer plate are a blast to deal with, lol. I did a few '19s last year.

The 6L family descended from the ZF6HP26 (same with the ford 6R series of transmissions). Both were designed/built under license from ZF. You should be able to handle the 6L80 if you got through the zf5hp24.

 

[NickTransmissions]

This is go great to have here Nick, much appreciated! Maybe do a thread here for the 4L60E here as well?

Thanks, man! Ill start one later today.

 

[Geotrash]

Nice work. Those restrictors between the channel plate and spacer plate are a blast to deal with, lol. I did a few '19s last year.

The 6L family descended from the ZF6HP26 (same with the ford 6R series of transmissions). Both were designed/built under license from ZF. You should be able to handle the 6L80 if you got through the zf5hp24.

Do you mean these?



If so, it wasn’t too bad as I recall. The ***** was getting all of the packs to stack in place correctly for the final assembly. I did buy the special tool to compress the clutch packs, thankfully, or it would’ve been a real hassle to rebuild the individual packs. The failure in my unit was the A clutch drum. Wear in the pressure regulator bore caused pressure spikes in that clutch pack that eventually caused the snap ring groove to fail:



So I used Sonnax and Transgo parts to repair the regulator and upgrade the drum to a billet part. All new frictions, steels, bearings and seals.

I had no idea that the 6L80 was derived from a ZF design, but looking at the assemblies in the 6L80 from your video there are a lot of similarities. Thanks for sharing your knowledge - I’m grateful.

 

[NickTransmissions]

Do you mean these?

I had no idea that the 6L80 was derived from a ZF design, but looking at the assemblies in the 6L80 from your video there are a lot of similarities. Thanks for sharing your knowledge - I’m grateful.

You're welcome, man...

Nope, was referring to the valve body assembly in the ZF5HP19 - has literally 20 or 25 little restrictors that lie in their respective locations in the channel plate and will stick to the separator plate if you take it off without knowing to use a pick to unseat them so you know where they go. Each restrictor has a small orifice in the center and there's a bunch of different size orifices and would be damn near impossible to know where they went if you didn't keep track (unless you build those units every day).

Here's a few shots of the vb


Restrictors are at bottom right


Spacer plate lifted off channel plate to show all hydraulic circuit orifice restrictors

 

[Geotrash]

You're welcome, man...

Nope, was referring to the valve body assembly in the ZF5HP19 - has literally 20 or 25 little restrictors that lie in their respective locations in the channel plate and will stick to the separator plate if you take it off without knowing to use a pick to unseat them so you know where they go. Each restrictor has a small orifice in the center and there's a bunch of different size orifices and would be damn near impossible to know where they went if you didn't keep track (unless you build those units every day).

Here's a few shots of the vb
View attachment 400834

Restrictors are at bottom right
View attachment 400835

Spacer plate lifted off channel plate to show all hydraulic circuit orifice restrictors
View attachment 400836

Ah yes, I remember now. All different color orifice pieces, if I recall correctly. One of the kits I bought had them all in a little ziplock bag that mercifully also contained a color diagram of where they all went.