6L80E Transmission Failure

kdixer · September 7, 2012

The 6l80 is a clutch to clutch design. As one clutch releases the clutch for the next gear set applies. These are multiple clutch packs. Sounds like a control module or fluid pressure issue to me. Each shift is controlled by a seperate solenoid that controls fluid pressure that applies the clutches. Either there is a loss of pressure in the entire system or the tcm is going hay wire. It is quite possible that the clutch packs need replaced at this point from excessive slipping, but they are not likely the cause of the slipping.

BlackRain · September 7, 2012

Surprise, surprise, the truck wasn't ready today. They put it back together and there's still a problem. It'll be another week.

I tend to agree that there is probably a loss of pressure in the entire system or the TCM has gone (as a matter of logic), given it was slipping in all gears and there were absolutely no error codes.... I was standing next to them when they ran the codes. It makes me wonder if there's a self-diagnostic on the TCM itself? It would have been a real tragedy if the internals were actually "okay", but just a bad TCM. (Keep in mind the fluid was clear and didn't smell burnt at all.)

I think I'm going to make a few calls on Monday to see if I can get a hold of some folks I used to know when I worked (in Oshawa - but not the Truck plant) at GM. That was many years ago. Funny, if I was still there, I would have driven it / limped it straight to the Quality garage - at least then I would have known that some "smart" folks would be looking at it. Not so sure about the guys working on it now.

Guess, I'll just have to drive my '85 IROC this weekend (which still has it's original 700R4).

BlackRain · September 14, 2012

Here's an update....

Got the truck back last night from the dealer. The stated cause of the problem was the 1-2-3-4 clutch piston was cracked. On test, the 1-2-3-4 clutch pack leaked during the air check of the transmission pump with valve body removed (wording from work order). They removed and disassembled the transmission and replaced the 1-2-3-4 clutch piston and clutches.

Put it all back together, installed, road tested and...the transmission was binding in 1st and reverse. Took it all apart again and the 3-5-R snap ring was broken. Replaced the snap ring and put it all back together.

Now...it shifts fine. Great. And, now the "but".... After I drove away I was so focused on the shifting I didn't notice until I was close to home that something didn't sound right. It "ticks" on acceleration and only on acceleration when there's a load, i.e., when I put it in neutral and rev it, there's no sound, and there's no sound on coasting. Sounds sort of like an exhaust leak or the proverbial baseball card on the bicycle wheel. The ticking doesn't seem to get louder and the frequency doesn't seem to be linked to RPM or speed - if it is, it only changes slightly.

So, I'm going back...

tazerbro · September 19, 2012

Here's an update....

Got the truck back last night from the dealer. The stated cause of the problem was the 1-2-3-4 clutch piston was cracked. On test, the 1-2-3-4 clutch pack leaked during the air check of the transmission pump with valve body removed (wording from work order). They removed and disassembled the transmission and replaced the 1-2-3-4 clutch piston and clutches.

Put it all back together, installed, road tested and...the transmission was binding in 1st and reverse. Took it all apart again and the 3-5-R snap ring was broken. Replaced the snap ring and put it all back together.

Now...it shifts fine. Great. And, now the "but".... After I drove away I was so focused on the shifting I didn't notice until I was close to home that something didn't sound right. It "ticks" on acceleration and only on acceleration when there's a load, i.e., when I put it in neutral and rev it, there's no sound, and there's no sound on coasting. Sounds sort of like an exhaust leak or the proverbial baseball card on the bicycle wheel. The ticking doesn't seem to get louder and the frequency doesn't seem to be linked to RPM or speed - if it is, it only changes slightly.

So, I'm going back...

I feel like my transmission also is occasionally slipping. Almost like a blip to the throttle and it doesn't know what gear to go in. It feels like a slipping clutch in a manual though...my truck is also BB tuned

James2014 · October 29, 2014

I'm James I have a 2010 Cadillac escalade with the 6.2 just went over the 100,000 mile I got the cold air intake throttle body spacer n a tune n my transmission just started slipping n sec gear (only in full throttle) n the trans temp stayed around 185-195 this point I installed a cam n headers with electric cut outs n a 2,600 circle d convertor. I took it to the trans place n they said I needed a full rebuild so I ok it n than they said I had a cracked 1-4-R drum so they got me a new one $2,800 n 3 days later I get my car back n it's still doin the same thing wat do ya think I should do I really don't wana go back me blow more money that I don't have

Colossus · October 30, 2014

First I have read about. There are A LOT of guys putting A LOT of power through them too. Google

Let's leave google out of it, they have enough problems as it is.

00Silverado4x4 · November 10, 2014

Here's an update....

Got the truck back last night from the dealer. The stated cause of the problem was the 1-2-3-4 clutch piston was cracked. On test, the 1-2-3-4 clutch pack leaked during the air check of the transmission pump with valve body removed (wording from work order). They removed and disassembled the transmission and replaced the 1-2-3-4 clutch piston and clutches.

Put it all back together, installed, road tested and...the transmission was binding in 1st and reverse. Took it all apart again and the 3-5-R snap ring was broken. Replaced the snap ring and put it all back together.

Now...it shifts fine. Great. And, now the "but".... After I drove away I was so focused on the shifting I didn't notice until I was close to home that something didn't sound right. It "ticks" on acceleration and only on acceleration when there's a load, i.e., when I put it in neutral and rev it, there's no sound, and there's no sound on coasting. Sounds sort of like an exhaust leak or the proverbial baseball card on the bicycle wheel. The ticking doesn't seem to get louder and the frequency doesn't seem to be linked to RPM or speed - if it is, it only changes slightly.

So, I'm going back...

Any further updates?

ChrisLS1Z71 · April 13, 2020

I have a 13 GMC Sierra with a Texas speed LS1 and nasty cam and a RevMax billet 2800 stall, makes a little over 400 to the wheels. I drive it daily and snatch a 14ft trailer around with a SxS and run 75 and 80 mph, not the first problem!