iC5

I have an 01 A6 4.2L that lost reverse last year (all forward gears worked fine). It also, shortly after, developed shuddering and torque slam during acceleration as well as through the shift points and started screeching and whining. I have recently rebuilt my transmission using a ZF banner rebuild kit with the F clutch seal and have also had my TC rebuilt. I still have only have partial reverse and the shuddering along with all the same symptoms. It will start out driving fine but develop all the symptoms within 15 minutes of driving. I did not replace the valve body which I now assume may be the culprit, so I have ordered a rebuilt VB from a specialist in CA. Can anyone shed a little light here? Is there anything else I may have overlooked? Much appreciated....Dan

Redneck Truck

That's a shame. Manual swap would have been much easier. I don't know a good procedure for checking all of your wires for continuity, but if you can think of a way, I'd start there. Also, what trouble codes are these problems triggering?

I've got a complete spare automatic transmission that needs rebuilt, so if you get further into it and find you need parts or external accessories, buy them from me rather than overpaying at a specialty shop or dealership. I've got a good valve body, lots of little wiring bits and connectors, and the whole gearbox is probably good except for the torque converter (discarded) and the clutches.

AR15Texan

Is it possible it could be a faulty Torque Converter lookup solenoid or wiring to the TCC?

iC5

I installed a new tranny harness when the tranny was rebuilt and had the TC expertly rebuilt and bench tested in front of me. It's not throwing codes, I used the updated ZF banner (full rebuild kit). The notorious rear drum along with all hard parts and planets were thoroughly inspected and fine. It has to be the valve body. It's a FL car so there is no corrosion at all.

iC5

I installed a new tranny harness when the tranny was rebuilt and had the TC expertly rebuilt and bench tested in front of me. It's not throwing codes, I used the updated ZF banner (full rebuild kit). The notorious rear drum along with all hard parts and planets were thoroughly inspected and fine. It has to be the valve body. It's a FL car so there is no corrosion at all. I have a modified trick valve body coming on Wednesday from a specialist in CA. Can you PM (private message) your number I'll call you tomorrow to talk about the valve body. I have two 2001 A6 4.2's and the other is due for a tranny rebuild as well, clutch packs mostly, but I may as well give it a good going over. Pity, I was staying in Plano 3 weeks ago while visiting a client in Dallas. Thanks, Dan

mustangbuffs

I have a 2000 A6 4.2L. Yesterday it started doing the same thing. Reverse engages slowly and starts to backup when I release the brakes but then drops the gear after about a second. It feels normal until it drops the gear. All the forward gears work fine. Hows your car doing? I got in it today and it worked fine. Drove around until it got to normal operating temp., and again no reverse. Feels like it clunks into reverse then slips when I give it gas.

iC5

Hi, it's either one of two things; 1) The Valve Body (delayed or inadequate line pressure, worn bores and or worn springs) 2) The F clutch piston (rubber is deteriorating around the seal. Generally, when this happens, even if you VAG COM the transmission electronics you would come up without a fault, so it's a guessing game. I rebuilt the whole tranny so extensively (torque converter, oil pump, ZF updated banner rebuild kit, steels, drum and trick valve body) that I corrected the issue, but you don't necessarily have to do the same. Replacing the valve body is the easiest thing to try because it takes all of 2-3 hours to have it done. It is located above the tranny oil pan, has 12 bolts and is removed and replaced with the tranny still on the vehicle. More detailed information is available from sonnax.com, vbx.com (valve body express)although they don't have your valve body and revmaxconverters.com which has them for $399.00. If that doesn't remedy the problem, your tranny needs a rebuild and I assure you, "Take great care in finding the right rebuilder"!!! You only want to do this once. The F clutch piston is located at the rear of your unit in the rear of the drum and it along with the other pistons, clutch packs, bearings and seals should be replaced using the updated ZF 5HP-24A banner kit. The reverse gear operates at close to 200psi of pressure while the other gears do not. If there isn't adequate pressure, you lose or encounter varying degrees of no-reverse syndrome. I am including a photodocumented rebuild of our unit that describes in detail what I'm attempting to explain here and can be viewed at http://tomboynton.com/Audi.html. I hope this helps and please let me know if there is anything else I can help you with. Best, Dan

Redneck Truck

Is this your guy who wants my valve body ic5?

mustangbuffs

I got in the car and drove at highway speeds until the engine andy tranny heated up to normal. I then drove off the highway to a parking lot and tried reverse and it worked. I dont get it. Reverse was only working when the car was cold. Now it works fine. Im going to drive the car again today and see if reverse is still working.

mustangbuffs

ok heres a update. Reverse is still engaging. The only thing I notice is that it takes longer to engage than normal. I have to wait about 4 seconds for it to engage. It engages with a thud. Not normal I know. Im still probably going to need a rebuild. After talking with my mechanic about it he called one of his mechanic buddies that runs a tranny shop. Hes very familiar with Audi ZF transmissions and hes going to charge me $1500 for removal, rebuild and installation with a 6 month 6000 mile warranty. Apparently he knows exactly whats wrong with it as he has seen many Audis with the same problem. From what I see on these forums it is a known problem with the 4.2L A6.