nferrari

My 2003 S8 is having transmission problems - good chance I'll need to replace the tranny. I have access to a 2001 Audi A8 and am wondering if the transmission from an 01 A8 would fit an 03 S8. Thanks in advance to anyone who might know!

jfrahm

No, many parts are compatible but it's not a direct swap. I read that it would not even work with an S8 rear axle to sort out the gear ratio issue.

What is up with your trans? There is a valve fix that resolves a lot of problems and prevents the catastrophic breaking of the drum or blowing out of the F seal.

nferrari

First noticed an issue shifting the car into drive, especially from reverse to drive - accelerated in drive and the car would not move forward. Check engine light came on at this point and car went into limp mode. After the car idles for a few minutes, it will accelerate in drive. Mechanic indicated it was most likely a transmission issue and is putting new fluid and filter in. He is not confident this will resolve the issue.

I am very interested to hear more about the valve fix you indicated. Thanks so much for your response!

JAA 4.2

I have a spare trans for sale in the classifieds.

jfrahm

Yeah that's the main pressure control valve, the TransGo valve fixes this but sometimes you also want to change the lower valve body casting. There are a lot of threads on it, maybe you can do a search here and on the quattroworld site. The valve is about $50 and the casting about $175, and you need fluid, filter, gasket, and a torx bit you can use to finagle the two tight-clearance pan bolts out. Are you doing the work yourself?

Don't drive the car, the stuck valve can cause the pressure to spike and break internal transmission parts, necessitating a rebuild.

A directed google search like "site:audiworld.com/forums/a8-s8-d2-platform-discussion-8/ transgo" will help, likewise "site://forums.quattroworld.com/a8/ transgo" for the other forum.

-Joel.

SC_09iduA

I have a spare valve-body that can be upgraded to forego the need of the TransGo fix...it's essentially the D3 transmission VB that works better...My '03 teanny has been 100% better since the VB upgrade...If you want the VB Casing, I can ship it to you or to Erikson for you to send information to him for payment or whathaveyou...

TRANSMISSION 5HP24A Audi

Cost me about $75 for the casing, then $230 for the upgrade sent back to the house...then you need a new filter, fluid, and installation of the VB...for someone else to do the work, it will cost you about $800 or you can do it your self for faaar less...not hard, just need access and time. If you need the spare VB I have, lemme know, I'll sell it for what I bought mine for...

jfrahm

I personally would prefer a new lower VB and the TransGo valve to a VB modded for the oversize valve. That's mainly because I think the fiber seals on the TransGo are a better way to keep the bore from wearing and the valve from sticking. I could be wrong though.

Just putting in fresh fluid will probably not do anything other than make your wallet a bit lighter. There might be a little bit more lubricity keeping the valve free but probably not much. If it sticks good and then pops loose it's eventually gonna break something and that's $4K-$5K for a rebuild or the car is salvage. $300 DIY for the fix is a better deal. Not sure what a shop would charge. I'd be leery of using a shop that rebuilds/replaces these transmissions for this work as they want you to spend the $5K. A good indie shop might learn a new trick doing this and there are thousands of cars with the 5HP19 and 5HP24 that they could apply the fix to.

CarrHarris

Tozo over at Quattroworld is the man to do this job! He did my tranny and it works beautifully.

tozoM8

70% of the transmission that I rebuild has new fluid in it. Everyone is hoping that the fluid change will fix it. It makes it worse. Your shop knows that too, once it is worse they know that you most likely leave it there to fix it instead of towing it to another shop.

jfrahm

Some say new fluid does not wreck transmissions but I saw your pics of the sludge blobs inside the valve body that can get knocked loose with new fluid.