audi 5000 tranny seal problems

[David Erickson <davide@Rational.COM>]

I recently bought a 5000S Avant with a blown automatic transmission.  I just
finished installing a replacement, and thought the information I learned in
the process might be of use to others on this list.  

First, there is a LOT of misinformation on this topic, from dealers
and from the independent shops and from the junkyards.  I wanted to know
what year transmissions could be installed in my car (an '84), and what
models of Audis/VW's came with this tranny.  I was told that I HAD to use
an 83-84 (by the dealer and by the junkyards), one of the independents
said I could use up through 87 but the locations of the oil coolers for
the tranny were different, and all of them said a tranny from a Quantum
or a 4000 would not work.  What I found out is that I could use a tranny
from a 4000 or a Quantum (I had to swap stub axles from the old tranny
to the replacement), and the oil cooler location did not make a difference-
either will install just fine.  I ended up with a tranny from an 85 quantum,
and it was identical with the original after making the stub axle swap.

I also learned what to look for in a used tranny.  This is not foolproof,
but one of the key things to look at is the color and odor of the atf.  If
it is clear red, things look good.  The normal mode of failure of these
trannys is for the pinion shaft seals to go, which allows the atf and
gear oil to mix.  Then either the differential bearings go out, or the
automatic stops shifting properly.  The automatic may be salvagable if
it has gear oil mixed in, but it would require a complete dissassembly,
and even then it is iffy.  This is also a good reason not to overfill the
atf or the differential, since you will then have gravity also working 
against you if any of the seals are marginal.  Note that you CAN replace
only the final drive or only the automatic transmission, instead of the 
complete assembly.  This might be justified in some circumstances, but 
the chances are that if the seals go, both components have been contaminated 
and you will have problems.

You may have trouble checking the atf via the dipstick, since the junkyards
have to drain the fluid (at least here in CA).  I just pulled the torque
converter off to find some fluid (the tranny has to be removed) or just
checked the odor (if there was gear oil in the automatic, the odor is
very perceptible).

I checked at least 10 transmissions, and only found three that looked
promising.  The one in the Quantum was the cheapest, lowest mileage, and
cleanest.  All the others had bad seals, so buyer beware!  The junkies
were quite willing to sell me a bad tranny with a 30 day exchange policy
(I could exchange it for another bad one).  If anyone else is looking
for a good tranny, let me know - there is one at Specialized Auto Parts
in Santa Cruz that looks really good, but isn't cheap ($800).

I replaced all the seals, as well as the crankshaft rear main seal.
All told, it took about 5 days work: a day to remove my tranny, a day
to find and remove the junkyard tranny, another day to replace seals,
and two days to get it back in and properly adjusted (and replace a
couple of motor/transmission mounts, service the car, repack the cv
joints, etc.).

Next project: lube and adjust the sunroof.  Suggestions welcome!

-Dave Erickson