well, about six months ago, i bought an Audi A8L with a bad transmission, despite being advised otherwise by quite a few people. i removed the transmission, located the problem(s), overhauled it, and have been driving it since. i've been undecided as to whether to create a post or not, but have decided to go ahead with it. First of all, it's the 5HP24A transmission, made by ZF. The symptom it was displaying was a hesitation in shifting from first to second gear, then when it did shift, it would "slam" into second. the po said when driven for any distance, it would enter "limp mode". after removal, i purchased a complete overhaul kit (not from audi, go to a ZF dealer or distributor), and a service manual. it proved priceless. i had to fabricate quite a few special tools, but none of them were too terribly difficult. the source of the problem turned out to be a thrust bearing just behind the pump. the bearing had started disintegrating, and the metallic particles flowing through the oil had sliced several o-rings, thus causing the hesitation, then the hard shift. i tried to find a post of someone who had done an overhaul on one of these, but couldn't, so figured i'd let people know that it isn't unheard of. although, i will caution, if you are not familiar, and well versed with mechanic work, i'd reccommend not trying this. it is very complex. i'm posting pics, and i'll try to explain them all, hopefully in order. the first picture is basically the internals of the transmission, just no longer in the transmission housing, with the exception of clutch pack "F". it was still inside at that point. the second picture are the old clutches, and the tools i made to disassemble the clutch packs, along with a few precision instruments. the third is the bearing that went bad, and if you look closely, you can see some of the needles are missing. the fourth is one of the o-rings that got severed from the metallic particles being forced through the system, and the fifth is basically the same thing. hopefully everything loads up correctly, and maybe a few people will learn a little here. on a side note, if my memory serves me correctly, i paid $700 for the overhaul kit, $35 for the service manual, and $15 for the bearing. as for oil, the mobil 1 synthetic transmission oil is rated to be compatible. after a few more items, and the oil, i had a total of $1300 out of pocket for the overhaul. oh, and i've put over 5000 miles on it, and she is an absolute joy to drive. thanx for looking

 

maybe i should have put this into DIY. if so, toss it over.

 

Dear dgfreeze,

Great job and thanks for posting on your A8 transmission rebuilt. I have owned 6 Audi's since my first one in college which was a 1984 Coupe GT. Had a 4000S Quattro, Coupe Quattro, 90S Q, A4Q and a A6Q. I have done alot of repairs such as bearings, CV joints, control arms, shocks, exhaust, engine tune-ups and is pretty mechanically inclined. However, I have never done a engine or transmission overhaul.

I bought a 2000 Audi A6 4.2L V8 in anticipation on replacement of the aging A4. However, it has issue with the reverse (all forward gears are perfect) on the transmission which is also a 5HP24A. I have heard lots of issues with the F-piston failing causing the reverse and also 2nd to 1st gear downshift while in tiptronic mode. It apparently is the rubber de-bonding off the F-piston from the factory?

I am wondering how you jack the car up and how you were able to remove the transmission as I am thinking doing it in my own one car garage. Any special tools that is needed to disassemble the transmission or did you have the torque converter rebuilt or replaced? Thank you for your comments/advice in advance.

 

sorry bout the delayed response, but in regards to how to get the trasmission out, you just have to have 4 jackstands (i'd recommend the good, tall ones, not the cheap short junk ones) and carefully jack the car up, and put the jackstands under the body bumpers. as for special tools, there are a few bolts that have a torx style head on the cv shafts. if you don't have the tool for that, it's available at any advance auto for bout 10-15 bucks. now, the fun part is that due to it being an engine/transmission cradle, once you loosen the cradle, the engine needs to be supported by either a framework fabricated above the engine with chains suspending the engine, or a jack under the engine. the jack is easier to do, but far more dangerous, and quite frankly, a real pain in the a$$. i'd recommend suspending the engine from the top. now, for special tools, it all depends on how far you want to go with the disassembly. you will need something to gently pull the pump out of the bellhousing without damaging the shaft, and most importantly, the clutch "f" is the rearmost clutchpack, and in order to get it out, a press fit bearing must be removed. the catch is, there is no lip to pull on. i fabricated a tool that i was able to get below the bearing, turn to catch the bearing rollers, and pull out with bolt threads. if you look at the second to left picture that i posted, there is what appears to be a disc, with a shaft welded to it that sticks straight up. it's basically a "cog" shaped piece of steel, and a bolt welded to it. the cogs fit through the bearing, and catch the rollers. removing it allows you to get to the bolts that hold the "f" clutch pack in. believe me, it's not a job for a "bicycle mechanic". i just want people to know that there aren't any little german gremlins in there doin the shifting. but if you decide to go ahead with it, just remember, a digital camera is ur most valuable tool. take pics of everything, so you can go back and see how it was. good luck

 

If you can write up a procedure for doing this, definitely do so in the DIY section. If you can't get it to allow you to post in that section, write it up in the A8 forum and PM me a link to it, and I'll move it over. Great post and info so far - the tranny issues are what has had me shying away from an 8 but seeing that it can be redone at a reasonable cost may change that. Thank you for the info.

 

gimme some time to do that, but i'll try. i'm vacationing in florida right now, but once i'm back, and have a little time, i'll try to write up a somewhat more detailed post. i'm sure i'll forget a lot of things, but i'll do what i can.

 

Lol of course - I was hoping you'd be willing to do one when you were able and had the time. This could be very useful - the technical prowess of our membership is pretty good and I'm betting this is something that is not out of reach of quite a few potential A8 buyers on the forum. Thank you