Gearbox Rebuild - RS6 C7.5

[joshviiv]

Gents,

Thought I'd start a thread as its very difficult to find any info on gearbox issues in this car online. Hopefully this can help others in the future.

I'd only owned the car a few months, fitted it with catless DPs and a stage 2 tune from Evolve coupled with a TCU tune from SRM. On my very first launch at the dragstrip, gearbox went into limp mode - wouldnt shift out of first gear. Turned car off and on again, gearbox functioned fine, but i noticed a shudder when moving off from a complete standstill. Interesting to note, the car did not shudder when it was in either sport, or manual mode - only comfort.

Spend many many months trying to diagnose the issues - thought it might have been the gearbox adaptation values, it wasnt. Tried transmission and diff flushes, nothing worked, and no one could really answer my questions - locally, or through forums/Facebook groups.

Last week I spoke to the team at Auto Trans Australia - they are well known here for building strong transmissions, especially the DSG and s-tronic stuff. He told me straight away what he believed the issue was. The ZF gearbox has a pump in it that provides pressure to the clutches, this has burnt out (or begun to burn out), and its not supplying adequate clamping pressure to those initial clutches. Eventually, it will completely fail and the shudder will become present in both sport and manual modes too.

Now unfortunately, you can't just replace the pump, and those burnt out clutch packs - the whole transmission needs to be overhauled. The plus side, is that in doing this, they add some more clutches, increasing its resiliency and hopefully help with getting that extra power and torque to the ground.

Total cost to me will be approx $8,800 ex GST (AUD$), not including shipping it from Perth to Sydney. Probably wouldnt be much change out of $11-12K by the time i'm finished.

I'll update this thread with the information i get out of ATA, and my experiences once i get the gearbox in.

Wish me luck :D

[Akakios]

Gents,

Thought I'd start a thread as its very difficult to find any info on gearbox issues in this car online. Hopefully this can help others in the future.

I'd only owned the car a few months, fitted it with catless DPs and a stage 2 tune from Evolve coupled with a TCU tune from SRM. On my very first launch at the dragstrip, gearbox went into limp mode - wouldnt shift out of first gear. Turned car off and on again, gearbox functioned fine, but i noticed a shudder when moving off from a complete standstill. Interesting to note, the car did not shudder when it was in either sport, or manual mode - only comfort.

Spend many many months trying to diagnose the issues - thought it might have been the gearbox adaptation values, it wasnt. Tried transmission and diff flushes, nothing worked, and no one could really answer my questions - locally, or through forums/Facebook groups.

Last week I spoke to the team at Auto Trans Australia - they are well known here for building strong transmissions, especially the DSG and s-tronic stuff. He told me straight away what he believed the issue was. The ZF gearbox has a pump in it that provides pressure to the clutches, this has burnt out (or begun to burn out), and its not supplying adequate clamping pressure to those initial clutches. Eventually, it will completely fail and the shudder will become present in both sport and manual modes too.

Now unfortunately, you can't just replace the pump, and those burnt out clutch packs - the whole transmission needs to be overhauled. The plus side, is that in doing this, they add some more clutches, increasing its resiliency and hopefully help with getting that extra power and torque to the ground.

Total cost to me will be approx $8,800 ex GST (AUD$), not including shipping it from Perth to Sydney. Probably wouldnt be much change out of $11-12K by the time i'm finished.

I'll update this thread with the information i get out of ATA, and my experiences once i get the gearbox in.

Wish me luck :D

Your first launch and the transmission shows it's face, ouch.

Have you logged the pressures in OBD11 or VCDS?

Following this post as I will be pursuing the same path: transmission, diff and drive shaft are going to be overhauled/upgraded before any major power is thrown at it.

[NikolaZ]

Hm is it the ZF8 hp70 on the rs6 ? I have a ZF8HP55 on my q5 and It got rebuild in february. When I first got the car, the shop that serviced the Gearbox didn't put the filter on, which lead to a massive bang from 2nd to 3rd on full throttle. So Eventually when they opened it up all the clutches were toasted. New clutch packs plus refurbished torque converter and so far I haven't had any issues.

I noticed the other day that It is having a bit of a kick when hitting rev limiter and shifting to the next Gear. But only when I am performing a Launch with the "Launch Control" Other than that, when on S and in Dynamic haven't had issues.

No idea why shops around the world are charging that much for that kind of rebuild ?

I can actually check the pressures on my gearbox and share them here.

[joshviiv]

Its the ZF8HP90 in the rs6, same as the rs7.

To be honest, $8800 is pretty good considering the strengthening work being done - price up some weistec clutches for a c63s AMG and see how much they cost to build! It is tough in Australia too - no workshops where i live are capable of dealing with this transmission.

[zazzn]

Curious how much did it cost to rebuild, I'm getting crazy prices in the USA like 12000$ when a new one from Audi is 13k

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Are you sure I was told it was the 8HP55a