Bought a beautiful 2000 A6 quattro with 4.2 v-8 and AT tranny 95k miles. Last owner sold it to me cheap because of the tranny issue. While the tranny is cool, its shifts great and never slips, after about 15-20 miles of stop and go it revved up betweeen shifts however I found that if I kept the PMs below 2000 while accelerating it would shift fine. I read forums and decided to attemp fluid change. Pulled pan, measured the fluid I got out (just shy of 7 quarts). Replaced filter, and added 7 quarts (not quite full 7 quarts before it started to run back out fill hole while running warmed up). The fluid was very dark and light sludge but no serious shavings or chunks compared to any other services I have performed on other rigs. I used the pentosin ATF-1, as recommended. Now the problem is still there just quite a bit different, the revs are much less before the shift takes place and seems to be a hard bang between 1-2 and sometimes between 2-3. After im in 3rd, no issues ever take place, accelerates and shifts fine from that point. I have to think one or more of those solonoids I saw on my valve body are malfunctioning/sticking but were slightly eased up with new fluid. Can anyone give me tips from this point? Can anyone tell me which if any of the solonoids would control the 1-2 and 2-3 shifts? Im will to try another fluid change but would like to be armed witha couple replacement solonoids when its aprt if thats possibly the issue. I have drove this car about 5000 miles so far and the problem doesnt get worse, just still exists.

Thanks for any advice.

 

You are working on a very complex mechanism and trying to use intuition to fix it. I suggest to save time and money that you ahve a ZF expert diagnose the problem for you, it will be worth the money. Hard bangs during shifts are often failed sealing o rings on the clutch drums dropping pressure between them, you can't easily fix this unless you have the book and tools.

 

Thanks for your response oldmots, but I have to say my intuition has served me well with other similar issues in multiple occasions. I have repaired many a vehicle that so called experts have claimed were not repairable such as this one without complete component replacements, Ive already repaired one item a local expert claimed needed a $1100 circuit system replacement on this particular vehicle (the blinker) by simply cleaning a connection. So please dont mind if I decide not to throw in the towel on your advice and pay a "expert" 5-8k to unbolt a tranny, install a new one with matching module. Lets see if any more advice is dispensed from intuitive Audi owners first or if I manage to use my own to solve it.

 

You are confusing diagnosis for repair. A thorogh diadnosis will be well worth the money in your case. There are eight solenoids, worth about $600, only testing will say which it is. The o ring and radial bearing that may be the problem are about $20. Knowing where to look is the trick.

 

I guess I should have told you that the local Audi dealer did complete the diagnosis, its was "needs a new transmission and TCM, 5-8K". Thats the reason I obtained the car so cheap. If I thought there was an honest and capable expert in my area that would actually conduct the tests your speaking of, Id be there.

thanks again.

 

The dealer may be essentially correct, if it is the o-ring or any other internal mechanical part, the tranny will have to be rebuilt. There are less expensive ways to do it though....the dealer is the easiest and most costly, gettign it diagnosed by an independent and then removing and rebuilding it your self is the cheapest. Then there are all the combinations in between. The choice is yours. I just saw a video of the repair of a similar problem in this car on the net somewhere, probably facebook, the rebuild kit has the needed parts and it costs $250.

 

Thanks again oldmots, I searched FB but will also try youtube, perhaps I can find it. I think another valid concern with diagnosis would be that the problem is intermitent and will not always rear its ugly head while conducting tests. I cleared the OBD codes so I wouldnt chase old ones and none have returned since then. Ill post any new developments but untill then I think its an neat little challenge and when its all said and done I may have to replace it all but as long as the wheels are turning, Ill keep trying.

 

I found the teardown pics on the Range Rover Forum, its for a 5HP24.

ZF 5HP24 teardown

This has no diagnosis element, just the disassembly to find the problem. It does explain how the
o-ring failure causes a low pressure situation that causes the tranny to bang from 2-5. It also took out the radial needle bearing between the clutch and hub due to lubrication failure.