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-   -   RS6 Gearbox - No reverse (https://forum.a8parts.co.uk/showthread.php?t=14030)

ulfilias 11th April 2018 08:16 PM

RS6 Gearbox - No reverse
 
Hi there,

i was chatting to a helpful mechanic at the local garage and he said he was looking at my gearbox (A8 4.2 D3) as it was the same/similar to an RS6 he was having a problem.

He said that forwards was fine, but no reverse gear, which sounds a little odd when i've experienced limp mode with the ZF gearboxes.

He seemed a little stuck with some of the local gearbox places not being interested, so i said i'd do some digging. Irritatingly i've not got the model and year on me, but i'm guessing someone here at least knows the odd pointer.

Based Peterborough/Cambridge area

thanks,
Lee

Architex_mA8tey 11th April 2018 08:17 PM

Quote:

Originally Posted by ulfilias (Post 140048)
Hi there,

i was chatting to a helpful mechanic at the local garage and he said he was looking at my gearbox (A8 4.2 D3) as it was the same/similar to an RS6 he was having a problem.

He said that forwards was fine, but no reverse gear, which sounds a little odd when i've experienced limp mode with the ZF gearboxes.

He seemed a little stuck with some of the local gearbox places not being interested, so i said i'd do some digging. Irritatingly i've not got the model and year on me, but i'm guessing someone here at least knows the odd pointer.

Based Peterborough/Cambridge area

thanks,
Lee

Might possibly be F125 switch (gear selector on the side of the gearbox) problems as they often start with random red lights of doom on selecting reverse only

ulfilias 12th April 2018 12:11 PM

I think i'm going to go see if I can get a VCDS scan as It would surprise me if a small village garage has VCDS etc

From a quick look the F125 switch shows as an error code?

HPsauce 12th April 2018 12:14 PM

The F125 switch in itself is a very dumb mechanical unit so doesn't give any error information at all, but the ECUs take information from its state and do record errors as a result.

The common "early warning" would be the 01119 - Gear Recognition Signal error.

David's8 12th April 2018 01:27 PM

...and for some reason the switch seems to "react" to selecting reverse as if the change of the electromechanical contacts in passing between forward and reverse positions triggers the fault or, in some cases, "cures" it.

As HP says "Gear recognition signal" fault code is the usual indicator.

ulfilias 12th April 2018 04:11 PM

Just nipped down the garage to pass on Chester Autos number, but whilst there I had my VCDS in the car and did a scan.

It's a 1999 model with 98,500miles

It goes forward not problems, drives great.
Reverse gear selects on the dash and no limp mode or error flags.....It just doesn't move backwards! Apparently when it's really warm after a long journey etc it will slowly move backwards

VCDS shows nothing on the auto trans. Engine had a couple of lambda b1,s1 errors and voltage too low....a couple of errors on level, locks and headlight range....which since it probably hasn't been read in a while could well be old and it did have a low battery.

Adrian E 12th April 2018 04:31 PM

Sounds like it’s a genuine mechanical issue. Gearbox clearly thinks it’s working or it’d be flagging a fault. Might be fairly simple valve issue, but inevitably the box will have to come out to investigate properly. Not a fun job on a C5 RS - can be done without engine removal I believe but whether a local garage would want to.....

MikkiJayne 13th April 2018 11:39 AM

The C5 RS6 didn't exist in 1999 :Confused: Earliest models are 2003. Is it an S6?

Symptoms suggest one of the clutch drums disintegrated. Disconnect the gearbox ECU (under the driver's footwell carpet) and see if it goes backwards then.

If so it needs to go to Chester, Mackies etc for a new drum and full rebuild.

ulfilias 13th April 2018 12:00 PM

Quote:

Originally Posted by MikkiJayne (Post 140169)
The C5 RS6 didn't exist in 1999 :Confused: Earliest models are 2003. Is it an S6?

Symptoms suggest one of the clutch drums disintegrated. Disconnect the gearbox ECU (under the driver's footwell carpet) and see if it goes backwards then.

If so it needs to go to Chester, Mackies etc for a new drum and full rebuild.

I think you are right. S6 - I was guessing based on the mechanic mentioning it was the same gearbox/engine line as my D3 and due to a private reg no idea of the age, I only got that yesterday on a second look etc.
If i'm honest i'm not that up on Audi's apart from the 8's :ROFL:

It's not mine but i've passed on Chester and suggested calling them, they'll pass that on to the owner and we can hope.

Looks a nice car and doing a net search they got it for a good price, albeit knowing that it had a gearbox issue. I think they were thinking it was a simple garage job rather than what it'll end up being!

steamship 13th April 2018 02:14 PM

Quote:

Originally Posted by ulfilias (Post 140138)
It goes forward not problems, drives great.
Reverse gear selects on the dash and no limp mode or error flags.....It just doesn't move backwards!

I remember reading somewhere (last few months) of someone whose father forced the gear lever on a D2 A8 from the Park position without pressing the button, with the result that it wouldn't go in reverse. I'll see if I can track it down from Chrome's history, and if there was ever a follow-up to it.


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