Changing the F125 - can it be easier?

[HPsauce]

I was just reading some new posts in this thread on RS246.com about a C5 RS6: https://forum.rs246.com/viewtopic.php?f=2&t=142156 (see page 3).
There is mention of a "mod" to make the job easier, which seems (to my untrained eye/brain) to consist of using different bolts and removing some surplus/unnecessary metal in a couple of places turning it into a "ten-minute job"!
Does anyone who has been "down and dirty" doing this horrible job have any thoughts as to whether there's anything similar that can be done to simplify the work on a D2 or is it just too different to a C5?

[steamship]

I replaced mine several years ago, following these instructions on the audipages site:

http://www.audipages.com/Tech_Articl...chreplace.html

It's very detailed and they specifically mention which bits are a PITA to do, or just awkward to reach. The only comment would be on point 6, where he says to use a small jack to support the transmission. If possible, either use a scissor jack or bottle jack, as they give a proper straight up lift, whereas a trolley jack (my only option at the time), isn't straight up. From memory, most of my time was spent on the top transmission mount bolt, (point 8) either getting it out or putting it back in again. Looking at the photo on the RS246 thread of the 'mod', I don't think you could do anything to make it any easier on the A8/S8.

[HPsauce]

Thanks Sean. MJ did mine the last time and she's obviously an expert at that job.
Previously I had a local VAG specialist do it and printed off those exact Audipages instructions to assist them.

[HPsauce]

And sod's law has struck again! The dreaded gearbox lights of doom appeared this evening on the way home, after I stopped briefly then reversed couple of feet to get space to drive off!

After I stopped again, turned the car off fully and restarted I could see the "D" symbol red background was flickering on and off intermittently, though when I went into Sport mode that stayed on solidly as normal, so I guess I can use it like that for a while... (fingers crossed).
I might try and see if it's useable in Tiptronic mode as I also have the steering column switches to make that easier to use.

My biggest problem, assuming I can get a new F125 switch, is finding somewhere competent to change it that's within a reasonable distance of South Bucks.

[tintin]

Originally Posted by HPsauce

And sod's law has struck again! The dreaded gearbox lights of doom appeared this evening on the way home, after I stopped briefly then reversed couple of feet to get space to drive off!

After I stopped again, turned the car off fully and restarted I could see the "D" symbol red background was flickering on and off intermittently, though when I went into Sport mode that stayed on solidly as normal, so I guess I can use it like that for a while... (fingers crossed).
I might try and see if it's useable in Tiptronic mode as I also have the steering column switches to make that easier to use.

My biggest problem, assuming I can get a new F125 switch, is finding somewhere competent to change it that's within a reasonable distance of South Bucks.

Don't assume it necessarily needs replaced.

Have you been using the car much recently? My recent experience over the last couple of years is that it can show the dreaded red PRNDS once in a blue moon, and that can disappear completely if the box is "actively used" via the stick shift or the paddles.

Though I think you may use yours more than I use mine...

[HPsauce]

I'll see tomorrow, but I have been using it occasionally.
It's definitely NOT detecting the D position properly (or at all most of the time) and that also looks as if it stops you using Tiptronic. It will currently go into S mode though.

I'll have a look at my diagrams of the innards and see if I can figure out the likely problem/breakage, but realistically I think it will need replacing.

[HPsauce]

I've got a busy day tomorrow as its my granddaughters 2nd birthday. But if I get a few minutes I'll plug VCDS in and see what contacts are operating as I move the stick - details on how to do that are in this post I made in 2020 with relevant information throughout the thread https://forum.a8parts.co.uk/showpost...0&postcount=23

First thing I'll do is see what code it's signalling when D is selected but D isn't highlighted on the DIS but I'll check all the stages.
It should start at 1000 for P then briefly 1100 (Z1) as it moves to R (0100) and 1100 (Z1) again as it moves to N (1110).
After N (1110) its then 1010 (Z2) in transit to D which should be 1011 and finally 0111 when in S.
(There can also, looking at the tracks, theoretically be a 1111 code between D and S.)

[briang9]

Originally Posted by HPsauce

My biggest problem, assuming I can get a new F125 switch, is finding somewhere competent to change it that's within a reasonable distance of South Bucks.

During my 14 years of D2 ownership I had mine replaced twice by my local trusted mechanic, not sure he found it all that difficult..then maybe I am lucky having someone very capable available, he kept my RS6 and Maserati going well for a number of years too and is currently doing a grand job of keeping the D4 running sweetly, his view is "they are just cars"

[HPsauce]

I recalled this post by MJ with some VERY useful tips: https://forum.a8parts.co.uk/showpost...&postcount=112

[HPsauce]

Originally Posted by HPsauce

if I get a few minutes I'll plug VCDS in and see what contacts are operating as I move the stick

Well I did that and everything seems to be working normally. I did of course have stored codes for implausible F125 signals in the Gearbox and ABS ECUs.

After a fair amount of wiggling of the shifter to try to look at "transitional" signals I did manage to trigger the red lights, but they went away on an ignition cycle, everything still looked OK and I couldn't recreate it.

I do wonder if there's a bit of "crud" in there that has just moved out of the way? I'll use the car locally for a while and see what happens.