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A6 4.2L Still has no reverse???

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Old 01-28-2011, 12:16 PM   #1
iC5
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Default A6 4.2L Still has no reverse???

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
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Old 01-28-2011, 08:59 PM   #2
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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.
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Old 01-29-2011, 07:34 AM   #3
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Is it possible it could be a faulty Torque Converter lookup solenoid or wiring to the TCC?
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Old 01-31-2011, 06:13 PM   #4
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Originally Posted by AR15Texan View Post
Is it possible it could be a faulty Torque Converter lookup solenoid or wiring to the TCC?
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.
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Old 01-31-2011, 06:20 PM   #5
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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.
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
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Old 03-19-2011, 03:28 PM   #6
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Default Mines doing the same thing.

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.

Last edited by mustangbuffs; 03-20-2011 at 01:12 PM.
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Old 03-21-2011, 06:12 PM   #7
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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
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Old 03-21-2011, 06:19 PM   #8
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Is this your guy who wants my valve body ic5?
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Old 03-22-2011, 07:42 AM   #9
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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.
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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
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Old 03-22-2011, 02:34 PM   #10
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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.
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Old 03-22-2011, 02:39 PM   #11
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ic5 can you tell me who you got your trick valve body from. Thanks. Hows your car doing?
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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
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Old 04-05-2011, 08:27 PM   #12
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I am having the same issue with my reverse gear. I tried changing the fluid and filter but it still does the same. When it's cold, it doesn't engage as well when the engine is warm. Even it's warm it feels like that you need to rev the engine high to get the reverse going.

I would assume it's the F-piston rather than the valve body? I wanted to do it myself and just worried about getting the car high enough to remove the transmssion as I do not have a car lift.
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Old 04-06-2011, 01:11 PM   #13
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I am having the same issue with my reverse gear. I tried changing the fluid and filter but it still does the same. When it's cold, it doesn't engage as well when the engine is warm. Even it's warm it feels like that you need to rev the engine high to get the reverse going.

I would assume it's the F-piston rather than the valve body? I wanted to do it myself and just worried about getting the car high enough to remove the transmssion as I do not have a car lift.
most likely it is the transmission. Mine is kind of odd though. Mine works great when cold but slips a little when warm. It wasnt working at all for about a week and then all of a sudden reverse started working again. It still engages slowly but works! I dont get it. I havent even done the fluid and filter yet. Weird!
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Old 04-19-2011, 07:59 PM   #14
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most likely it is the transmission. Mine is kind of odd though. Mine works great when cold but slips a little when warm. It wasnt working at all for about a week and then all of a sudden reverse started working again. It still engages slowly but works! I dont get it. I havent even done the fluid and filter yet. Weird!
You mentioned that the transmission mechanic knows what's wrong. Is it the F-piston that he is chraging you $1500 to rebuilt?
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Old 04-25-2011, 08:20 AM   #15
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Hi, I've been out of the country for a while since my last post, sorry I couldn't get to the questions sooner. I've had 3 A6 4.2's and they have all had reverse issues. I beat the crap out of these cars indiscriminately and have successfully tackled every issue you can have with them I assure you all. In one case on my first one, I had replaced the tranny valve body which took care of it. In my second I had replaced the F clutch piston, which had severely deteriorated. The last issue I had that caused me to lose reverse in my current vehicle was the clutch drum that had a hairlike crack in it, I pulled my tranny out and re-rebuilt it 3 times but couldn't find the problem until I pressure tested the drum and found bubbles escaping from it. Replaced the drum and solved my problem. The bottom line is that these are the only areas of the tranny that would cause you to have irregular or total loss of reverse. The F clutch piston is the most obvious source of failure in these units followed by a bad drum and rarely a valve body, although it does happen. Dan
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Old 04-28-2011, 11:19 AM   #16
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You mentioned that the transmission mechanic knows what's wrong. Is it the F-piston that he is chraging you $1500 to rebuilt?
Yea thats what he is saying. But im not going to use this guy as I just found out he screwed another customer on a easy trans rebuild on a suburban. He didnt do crap to the trans except clean it to look like he worked on it. No way im going to give him my hard earned money for nothing.
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Old 04-28-2011, 11:23 AM   #17
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Hi, I've been out of the country for a while since my last post, sorry I couldn't get to the questions sooner. I've had 3 A6 4.2's and they have all had reverse issues. I beat the crap out of these cars indiscriminately and have successfully tackled every issue you can have with them I assure you all. In one case on my first one, I had replaced the tranny valve body which took care of it. In my second I had replaced the F clutch piston, which had severely deteriorated. The last issue I had that caused me to lose reverse in my current vehicle was the clutch drum that had a hairlike crack in it, I pulled my tranny out and re-rebuilt it 3 times but couldn't find the problem until I pressure tested the drum and found bubbles escaping from it. Replaced the drum and solved my problem. The bottom line is that these are the only areas of the tranny that would cause you to have irregular or total loss of reverse. The F clutch piston is the most obvious source of failure in these units followed by a bad drum and rarely a valve body, although it does happen. Dan
Thanks for the info Dan. What would you think would cause my reverse to stop working and now work again. although it still engages slowly when the car warms up.
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Old 04-28-2011, 11:23 AM
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