GM 6L80 Transmission Information Thread

[Foggy]

Parts I like specifically for high perf are

- Transgo Unbreakable pump ring kit
- Billet rotor
- Sonnax 3-5-R HP apply ring
- Sonnax 4-5-6 piston kit-Powerglide spec
- Sonnax 4-5-6 Powerglide spec billet steel hub
- Billet drive plate on rear planet
- Alto reds and kolene steel module

Its prudent to tig-weld reinforce the two other hubs as they can snap like the 4-5-6 hub under serious power/torque.

Also, I dont have a supercharged, cammed engine (I'm the OP) - perhaps you're referring to another member?

Yes, I was referring to the poster with supercharged tahoe ...
BTW, I did the billet hard pieces from CircleD as well. Had to send back my originals for
a big core charge !! i don't remember exactly what they were, been a while www.circledtrans.com/6l80-level-4-performance-rebuild-kit
This is the web page I looked up. This is what I have...
I see that they now have a new billet output carrier (planetary)... I would have
added this but it may not have been avail back then, it's $$$

 

[Jakkel667]

@NickTransmissions got 07 Denali 165k not sure history I just bought it last week previous owner bought at 130k in 2019 no clue on if it was rebuilt or not at some point. It shifts fine with temps under 140 hasn’t been over 153 since I’ve owned it. 140-150 it starts not shifting or shifts hard at higher rpm’s. Pull it down into manual shift. It’s shifts thru all gears with No slipping no bucking. I’ve searched and searched. It did have a code 0700 and cant remember the other but it was for solenoid 5? being off. When I first got it. Cleared the codes and no lights on since. Fluid is full darker red but far from black. Doesn’t smell burnt smells like trans fluid. Yukon sat about 2 yrs drove once every 3-4 months just to move it and take to the store. Till I bought it
I’ve searched and searched can’t find anyone with same issues. Any suggestions on where to start?

 

[NickTransmissions]

@NickTransmissions got 07 Denali 165k not sure history I just bought it last week previous owner bought at 130k in 2019 no clue on if it was rebuilt or not at some point. It shifts fine with temps under 140 hasn’t been over 153 since I’ve owned it. 140-150 it starts not shifting or shifts hard at higher rpm’s. Pull it down into manual shift. It’s shifts thru all gears with No slipping no bucking. I’ve searched and searched. It did have a code 0700 and cant remember the other but it was for solenoid 5? being off. When I first got it. Cleared the codes and no lights on since. Fluid is full darker red but far from black. Doesn’t smell burnt smells like trans fluid. Yukon sat about 2 yrs drove once every 3-4 months just to move it and take to the store. Till I bought it
I’ve searched and searched can’t find anyone with same issues. Any suggestions on where to start?

When you say "starts not shifting", what do you mean? It wont upshift at all, remains in a given gear? If so, does this happen at all speeds or just hwy speeds (or just low speeds)?

Sounds like it has internal leaks/wear in what is called the compensator feed system, which is reaponsible for mechanical governance and control of all applied elements inside the transmission. This means comtrolling the timing of application and release of all of the different sets of clutch packs that come on and go off to give you the six forward gears in notmal auto shift pattern...This system includes/touches nearly everywhere in the trans, including the TEHCM, valve body (compensator feed regulator valve, clutch select valves and springs, tcc regulator valve), torque converter itself, turbine shaft and pump stator sealing rings, piston dams in the 3-5-R and 4-5-6 clutch drums, etc. leaks in the comp feed circuit usually result in excessive wear to burnt clutch packs, depending on the location(s) and extent of the wear.

Diagnosis starts by plugging in a bi directional scan tool and taking it for a test drive with live transmission data and engine management sensor data being displayed. First step is to rule out things like TPS, MAF, CPS, CrPS, etc then confirm the transmission is being commanded correctly and responding correctly. Look at TCC slip speed, duty cycle, efficiency, shift speeds, etc.

Let us know what you find...

 

[Jakkel667]

When you say "starts not shifting", what do you mean? It wont upshift at all, remains in a given gear? If so, does this happen at all speeds or just hwy speeds (or just low speeds)?

Sounds like it has internal leaks/wear in what is called the compensator feed system, which is reaponsible for mechanical governance and control of all applied elements inside the transmission. This means comtrolling the timing of application and release of all of the different sets of clutch packs that come on and go off to give you the six forward gears in notmal auto shift pattern...This system includes/touches nearly everywhere in the trans, including the TEHCM, valve body (compensator feed regulator valve, clutch select valves and springs, tcc regulator valve), torque converter itself, turbine shaft and pump stator sealing rings, piston dams in the 3-5-R and 4-5-6 clutch drums, etc. leaks in the comp feed circuit usually result in excessive wear to burnt clutch packs, depending on the location(s) and extent of the wear.

Diagnosis starts by plugging in a bi directional scan tool and taking it for a test drive with live transmission data and engine management sensor data being displayed. First step is to rule out things like TPS, MAF, CPS, CrPS, etc then confirm the transmission is being commanded correctly and responding correctly. Look at TCC slip speed, duty cycle, efficiency, shift speeds, etc.

Let us know what you find...

It’s will shift but I have to get into it and let out then it will shift sometimes tonight it didn’t shift it stayed in 3rd till I pull in to manual and shifted it to 4th. So far low speed in town red light to red light.
I’ll have to find someone with a scanner that can do that.
I was going to start with maf cleaning throttle body cleaning plug wires check grounds and trans plug for corrosion. Ohio weather hasn’t cooperated to do the work no garage at the moment.
Like I said it sat for the most part of 2 yrs in Ohio weather. It’s very clean vehicle but wasn’t used much in last 2 yrs. They only put 30k miles on it in 4.5 years.

 

[NickTransmissions]

It’s will shift but I have to get into it and let out then it will shift sometimes tonight it didn’t shift it stayed in 3rd till I pull in to manual and shifted it to 4th. So far low speed in town red light to red light.
I’ll have to find someone with a scanner that can do that.
I was going to start with maf cleaning throttle body cleaning plug wires check grounds and trans plug for corrosion. Ohio weather hasn’t cooperated to do the work no garage at the moment.
Like I said it sat for the most part of 2 yrs in Ohio weather. It’s very clean vehicle but wasn’t used much in last 2 yrs. They only put 30k miles on it in 4.5 years.

Sounds like a good set of first steps...If you are a DYI'er, I'd invest in a good bi-directional scan tool. Snap On, Autel, Bosch, OTC/SPX all make decent ones. I have a few and they have paid for themselves many times over...

 

[Jakkel667]

Sounds like a good set of first steps...If you are a DYI'er, I'd invest in a good bi-directional scan tool. Snap On, Autel, Bosch, OTC/SPX all make decent ones. I have a few and they have paid for themselves many times over...

Yeah I have been thinking about investing in one. I do 95% of the work on my vehicles. Trans are not in my scope. Thanks for your input.

 

[Tall56Dog]

Nick,

Sorry if this has been asked and answered already. I have a 2020 Tahoe with the 5.3 and 6L80, currently 45K miles. No issues currently that I'm aware of, but I keep hearing about the problems with the Torque Converter going bad and then ruining the transmission. I had the dealer change the transmission fluid at 25K miles, and plan on having it done again at 50K miles. They didn't drop the pan, just did the flush. I used to work on helicopters and know how important preventative maintenance is.

I tow a small trailer occasionally, 3.73 rear end, nothing that works the truck too hard.

My question is, at what mileage should I think about having the torque converter changed to avoid it failing and ruining the trans?

Thanks

Terry

 

[91RS]

If it were mine, I’d go ahead and change it. You won’t know it’s gone bad until it’s too late and you’ll need a full rebuild or a unit.

 

[donjetman]

Nick,

My question is, at what mileage should I think about having the torque converter changed to avoid it failing and ruining the trans?

Thanks

Terry

The sooner the better

 

[NickTransmissions]

Nick,

Sorry if this has been asked and answered already. I have a 2020 Tahoe with the 5.3 and 6L80, currently 45K miles. No issues currently that I'm aware of, but I keep hearing about the problems with the Torque Converter going bad and then ruining the transmission. I had the dealer change the transmission fluid at 25K miles, and plan on having it done again at 50K miles. They didn't drop the pan, just did the flush. I used to work on helicopters and know how important preventative maintenance is.

I tow a small trailer occasionally, 3.73 rear end, nothing that works the truck too hard.

My question is, at what mileage should I think about having the torque converter changed to avoid it failing and ruining the trans?

Thanks

Terry

This:

The sooner the better