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Is there a definitive 'fix'

for gearbox problems on the C5 RS6 ?  Currently own a B5 RS4 but have always looked  longingly at these to join the fleet. Is there a proper 'fix it' and its done  cure for the box problems or is it a case of always likely to go again  

All slush boxes will die. They have friction material in them that, like a clutch, will eventually wear out.

All you can do it reduce the rate of wear by uprating certain componenents.

The only solution that I know of that gives you half a chance of getting a very strong box is the 517trans route, but the amount of faff involved in sending your gearbox to the USA is probably a deal-breaker for all but the most hardened enthusiasts. I know a couple of people that have done it.

Amanda did it I believe.

Any idea which 'certain components' those are?

I imagine the transfer box (the slushy bit) will eventually need refilling (?) or replacement.

But the other parts - all the clutch packs for example - do they ALL need replacing or is it just the 1st and possibly 2nd gears?
And the last bit - the valves and valve body - that sounds like the bit I can't possibly fix myself, unless it is simply replacing springs...?

I did find some repair kits for just a few 100 quid:


That one includes the plates.
This one is just the seals etc:

This looks like a good ref for a rebuild and points the finger at a specific part...

This might be of some use.

Couple of weak points on the box. There's a lot of torque going through some arguably undersized clutches. Possibly a weak 2p spring that causes hideous wear.

I believe that to uprate the slush boxes they increase the number of friction disks in the clutches, uprate the pressure on them by modding the valve body, some other stuff. Oh yeah, torque converter, too.

You could just get a valve body. I know other people that have done that, but hard to evaluate the effective it would have.

Never heard of anyone having a problem with the transfer box. Other than the everloving leaking output shaft oil seal, of course.

If you can rebuild / repair the box yourself then that's great. There's nothing particularly special about it. What causes most people a major headache is the cost involved in getting the engine and box out and finding someone to trust to do the box repair work.

IMO the best solution is to fit a ZF remanufactured box, preferably get Audi to do it so you get the 2 year warranty.

FWIW, I thought my auto box was falling apart some 40,000 miles ago (at 140,000 miles). However, after 3 consecutive fluid changes and 2 new filters it seems to have recovered. The shifting problems appeared to be caused by the amount of cruft in the filters and valves which was reducing the hydraulic pressure on the clutch plates. This was allowing them to slip under load. This may be what causes the subsequent failures, if left uncorrected. I am now at 180,000 miles and all seems well. No more error codes or limp home episodes. I think the key is to act early, but due to the awkward refill procedure and the feeling of dread regarding a tranny rebuild, maybe the tendency is to delay.

Just make sure that you follow the refill procedure which includes moving through the gears while monitoring the fluid temp.

180k on the original box ?? Nobody can argue with that. I do sometimes wonder about 'specialist diagnosis' with the fix you have just outlined it reminds me of when i had a L322 Range Rover which would start to play up. Took it to a well known transmission specialist who had it for 2 days... told me it would need a rebuild(this was a petrol model.ZF box..) i took the car away and did a bit of research on various forums.Upshot ? The radiator needed replacing as corroded and on these boxes the bottom few rows cool the transmission fluid  so without the cooling the box was overheating. Cost was about 150 v pprox 2k from 'specialist'.
Moral being do your own research and dont necessarily believe the first diagnosis.
Still damn tempting these beasts....

^^it's an awesome car. Own one while you've got the chance!

[quote="bigee:670015"]Moral being do your own research and dont necessarily believe the first diagnosis.[/quote]

Just as anti virus software companies benefit from the fear, uncertainty and doubt that is created by inadvertant false positives, I sometimes think that auto box specialists (inadvertantly or maliciously) stoke the fear of auto box failures. Similar for auto electricians and damp proof installers, etc. Online forums can also dwell on those that fail rather than the thousands that don't.

I previously owned a Lotus Excel and Esprit S4 Turbo for a decade, with very few issues despite the endless stream of fear, uncertainty and doubt about their reliability and the need for dealer/specialist care. After all Lotus had raided the Jaguar, Toyota Celica and Vauxhall Calibra parts bins, so a lot of parts were more robust and more easily available than you might think. I also now have a R53 Mini Cooper S that the previous owner was told had serious electrical problems and would require a complete loom replacement. It was cured by a new 60GBP battery - cars do very weird stuff when a battery gets old!

Don't get me wrong, there are some weak points on each platform that need to be monitored and that may need specialist repairs. I needed a local Audi trained specialist to replace the hydraulic cam lifters (for 1750 GBP) on my C5 S6, but VCDS helped me be sure that the cams lifters were the problem before the specialist was engaged.  

BTW, when my auto box finally fails, I reserve the right to forget I ever made this post

[quote="bigee:670015"]Still damn tempting these beasts....[/quote]

BTW, my C4 S6 and C5 S6 are my daily drives, mostly the C5 because its auto box is easier in the Leeds/Bradford traffic. I find them pretty robust.

I've done 40,000 miles in 3 years in the C5. As noted earlier, I spent 1750GBP replacing the dodgy cam lifters and, as a precaution, I also paid 1500 GBP to replace the cam belt, v belts, cam lifters, water pump, snub mount, seals, etc. Other than that, its just wear items (e.g. pads, tyres, hoses, CV boots) and the ATF Filter, an Electric Radiator Fan, 2 x Headlamp Range Sensors and the AC High Pressure Sensor. Still much less than the depreciation on a mid-range hatchback.

FWIW, I've had the C4 for 15 years and 70k miles. Other than wear items (such as pads, discs, tyres, hoses, boots, bushes and fuel lines) its had very few repairs. In fact, track rods, bearings and an alternator are all I can think of. Forum Index -> Audi S6 & RS 6 (C5) quattro
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