6L80 woes

BigBody79

BigBody79

Well-Known Member
Joined
Mar 30, 2005
Location
Lumberton
2011 Sierra SLE 5.3 LC9 4x4
145,000 miles.

developed a studder/shake speed it felt like it was missing. No codes or CEL.

when I pushed hard on gas it would go. But pushing easy at 65-70 it would studder. Same at lower speeds.

now it is slipping when I hit the gas. Got it home. Turn it off and back on it does ok for a bit but goes back to slipping.

what should I check? What’s the next step?

I’ve did fluid and filter this time last year.
 
New transmission :lol:

Last one I had to shit the bed has a pump or something let loose. Tech said there was metal everywhere in there when they pulled the pan. The good news is that it was under warranty, since the last transmission was put in less than 3 yrs ago, and that one was under warranty too, because it was only 2yrs old! See a pattern?
 
There is a known issue with them and the torque converter.

if you catch it early enough you can change the tc for an aftermarket billet one and flush it all good. Or you replace the trans
 
We bought a new one from GM.
When you look at the warranty difference and the modest cost difference it’s a no brained
 
BigBody79 said:
Did you have them put it in as well?
Click to expand...
we had a local shop do it, but whoever does it has to be able to program the new trans to work with the vehicle ecm or its a brick.
 
Do you know how much I should expect to be on the road again?

Since this transmission started slipping pretty hard should I even try to do the drain and fill 2x.
 
At work we swap in gm transmissions. My boss is friends with the shop foreman at the gmc dealer so we drive them in limp mode to him and he flashes them for us, any dealer and some independent shops or tuners could probably do it too.

Without programming you'll get a check engine light and only have reverse and third gears.

My uncle just bought one for my cousins truck it was $3400 just for transmission, he installed himself. that was with a little discount, he bought it under someone's account, he had a buddy who runs a shop program it for $100, this guy still has access to gm and his own tech2 scan tool.

Expect to pay a dealer $200 or so for programming.
 
Just be sure to drive it hard with the new trans so it will go out under warranty instead of just after. So far I'm doing pretty good on this truck, I've had 3 replacements and only had to pay for the first one!
 
BigBody79 said:
Do you know how much I should expect to be on the road again?

Since this transmission started slipping pretty hard should I even try to do the drain and fill 2x.
Click to expand...
Its been 2 years but we paid ~$3,500 for the trans and installation.

The issue as I understand it is a coating GM uses inside the stock torque converters that de-laminates and clogs/pollutes the transmission...
meaning even with a new trans strongly recommend a full system flush. We went a step farther and actually added an external cooler and deleted the factory one.

Not to hurt your feelins but march will be 3 years and the new one is slipping again. We had the tuner crank up the pressure and its helping, some...but its decision time for us.
 
Ron said:
Its been 2 years but we paid ~$3,500 for the trans and installation.

The issue as I understand it is a coating GM uses inside the stock torque converters that de-laminates and clogs/pollutes the transmission...
meaning even with a new trans strongly recommend a full system flush. We went a step farther and actually added an external cooler and deleted the factory one.

Not to hurt your feelins but march will be 3 years and the new one is slipping again. We had the tuner crank up the pressure and its helping, some...but its decision time for us.
Click to expand...

Well that doesn't really make me want to spend the money on a GM Transmission.
 
BigBody79 said:
Well that doesn't really make me want to spend the money on a GM Transmission.
Click to expand...
Thats why you buy the new one with the good warranty. Of my 4 trucks with 6l80's one is on its second and another is on its 4th. The other two are newer and so far, they are in their originals.
 
BigBody79 said:
Well that doesn't really make me want to spend the money on a GM Transmission.
Click to expand...
The GM one gets you a 3 year warranty.
The jasper [insert brand x here] has a 1 year warranty and it fails at year 2.
 
LBarr2002 said:
I shouldn't have read this thread. I have a '15 with 92k miles on it. It just drug my jeep cross country and back with no issues though, and its under warranty until 120k :driver:.
Click to expand...

Your lucky. His warranty was out at 60k, trans failed at 75k.
 
What about transmission oil filter? But a new one should get a aftermarket TC? What about warranty?
 
Most transmissions I’m seeing are either 12mo/12,000 miles or 36mo/36,000 miles.

I got 145,000 out of this one.

filter is in the pan.
Pan has no drain.
Exhaust has to come down to get to pan. Stripped another bolt trying to inspect fluid in the pan. Such a pain in the ass.
 
BigBody79 said:
Most transmissions I’m seeing are either 12mo/12,000 miles or 36mo/36,000 miles.

I got 145,000 out of this one.

filter is in the pan.
Pan has no drain.
Exhaust has to come down to get to pan. Stripped another bolt trying to inspect fluid in the pan. Such a pain in the ass.
Click to expand...
I was thinking more of a regularly serviceable filter
 
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