VetteArts

I have a C6 A6 (6l80e) 2008. Heartbeat Supercharged 8psi 602rwhp, pump fuel. Has 83k Km on it.

I already changed the solenoid pack, oil and filter but I still get gear stuck into 2nd or 3rd with check light on. There is slight slip when changing gears as well.

I am opening up tranny in few days and wonder if OEM (AC delco or GM, GM PP) parts will be good enough or aftermarket parts should be used. Not aware what needs replacement yet but like to do my research as I progress.

It is a weekend drive, Some street races at times, may do strip runs but not very important.

CI GS

Man, that really sucks. Are you sure it's not a tuning issue? I've only heard of these transmissions frying the 4th gear clutch pack.
It could be that the stuck in gear thing is because the shifts speeds are off really badly, or something like that. And the slight slip on gear changes could very well be a tuning issue. Remember that the TCM completely controls the A6 transmission, so it is possible that it's a tuning issue. Before you tear into it, I would see if I could send the tune to a competent tuner who does a lot of A6 tuning and get his opinion on the tune. There's not a lot of folks around that fully understands how these transmissions work.
Or maybe try sending a PM to someone like subfloor or realcanuck, who know a lot about building and tuning these transmissions.
Good luck with it and let us know what the end result is.

VetteArts

Did Tech II check and it shows, solenoid valve 5 stuck on. I know the 6l80e is strong enough to hold this level of power. And don't want to pull it down. My mechanic who did tranny tuning says it is mechanical after many deliberations.

I will give it a shot with the guys you mentioned. If you know of a tuner please let me know.

realcanuk

No simple answer as far as whats wrong right now. If a solenoid is stuck I suppose that needs to be changed but as mentioned the tune is key. If you want to send me the tune I can look and see if I see anything obvious in it. realcanuk@gmail.com

First thing I would do is make sure the oil is full, and add 1 quart extra. That seems to help with a lot of issues on these.

As far as rebuilding, if you are planning to stay at around 600 rwhp I would consider 2 options. Either a new trans from GM which should hold well with a proper tune and cooling, or if you have someone good to rebuild it then I would have it rebuilt with some upgrades, but don't have to go crazy.
If I remember right it is mid 2008 that they changed the front pump design. If yours has the old one I would change to the new one. Then change out the clutches and steels, add an extra clutch to 4,5,6 pack. Weld the drums (because it costs peanuts to do so), and add in all the performance parts that sonnax makes for the 6L80.

Again, the tune is key. You can build with all the best stuff, and a bad tune will kill this trans in no time.

Tons of info in these threads which is where I took a lot of ideas for mine, which is holding great.

http://forum.grrrr8.net/showthread.php?t=27486

VetteArts

I sent you the file. Thanks.

realcanuk

I get an error message trying to open it. Either it is corrupt or from a version of HPT that is old.

VetteArts

Thanks a lot for your help. Now that it is likely mechanical I will see repair options.

I wonder if 2009+ tranny will fit for the 2008? I might find a used one for direct replacement. Any idea?

realcanuk

I'm not sure but I believe using a different year can cause issues with the computer part of it. Different TCM softwares I think.

Hopefully someone who knows for sure will chime in.

VetteArts

Luckily have got used 2008 tranny. Will have it delivered and installed in few days.

Would the latest tune you sent me hold good?

realcanuk

I didn't look at it very thoroughly. I just changed a few thing that were obvious and might have caused problems.
I would consider getting it tuned by someone who knows those trannies and does it for a living. I do my own car but don't want to be responsible for anyone else's.

VetteArts

Got the whole thing down including drive shaft. The rubber coupler for the drive shaft (both front and rear) are completely damaged.. powder looking .

Any suggestion for after market? heard about the BMW ones but not sure what type. Problem is that I do not have much time to order aftermarket.

chpmnsws6

The Driveshaft Shop couplers

schpenxel

Lemforder brand if you go BMW ones. Don't get the cheapo knock offs.

VetteArts

Unfortunately the used tranny I bought is not good either.

Pulled mine apart and would change clutches and pistons mainly. However, I have been in contact with many shops for aftermarket parts and got this combo from transmission center. Sonnax do not have clutches now.

https://transmissioncenter.net/shop/...o-kit-level-3/

I will include pistons for 125$.

What do you think?

realcanuk

I would use stock clutches, with an extra in the 4,5,6 pack.

VetteArts

Do you mean, go stock all parts including clutches instead of this package? How would 4,5,6 pack be an extra!

Apologies but I am no expert in this.

realcanuk

I mean use stock clutches rather than the Alto's. Should also use all the available Sonnax upgrades, weld the drums, and upgrade the front pump to the later one if it's an 07.

VetteArts

It was a lot of work trying to figure out what is what in a 6l80. Can’t claim I know enough but hope to get it right.

Searching and talking to different venders after your advice, I guess what I need is the below from Sonnax. For the remaining parts, I need to buy stock ones.

456 Piston kit:
https://www.trutechtrans.com/Sonnax-...80-Basket.html

1234 piston:
https://www.trutechtrans.com/Sonnax-...80-Basket.html

Zip kit:
https://www.trutechtrans.com/Sonnax-...80-Basket.html

This spring which does not come as part of the kit:
https://www.trutechtrans.com/Sonnax-...80-Basket.html

Everything else will be factory. Am I on the right track?

realcanuk

Those are the parts I used from Sonnax. Clutches and steels factory. Better filter, front pump, and bushing from PTC. I also added a billet intermediate shaft but you could try sticking with the stock one if you like.

VetteArts

PTC being Power Train Transmission?