AARGH!!! Surely not the gearbox!

[Dezzy]

Originally Posted by HPsauce

Have you tried (as MJ says) Reverse first?

Reversing is fine

[HPsauce]

Originally Posted by Dezzy

Reversing is fine

Ah yes, missed this in the middle of all the other stuff.

Originally Posted by Davey Blueeyes

Reversing is fine.

[Davey Blueeyes]

Thank you all again for your camaraderie but that was a waste of time!

Mobile mechanic with VCDS cancelled me at last minute, offered to come Thursday. Told him to get lost, mainly as I still have it booked in for Wednesday at a localish garage for a scan. Can't get anyone to do it sooner and I am away to Sussex lunchtime tomorrow anyway. Two more days of agony!

Silly question, obviously I can get the car recovered to the garage (about 8 miles away) and wait forever while they sort out the million holiday makers we now have here with endless broken down family wagons or would it be okay to drive the 8 miles in limp mode? Does this make it more broken?!

Meanwhile I am getting the bus, in this heat, with all the holiday maker smells nature can muster. Not a happy bunny and off to scan latest leasing deals!

[MikkiJayne]

I suspect the code you'll see is 'output speed sensor implausible' or 'incorrect gear ratio', both of which require a rebuild. At this point I feel its pretty unlikely to be the F125 as that will throw a code as you select a gear, not when you try to move. What I think has happened is that it has blown the end off the 'A drum' thusly:



The bang when it does try to move is the TCU not getting the result it expects (movement) and just going 'f it' and throwing it in 3rd with full line pressure. If it reverses then it has enough fluid to drive the torque converter and clutches etc so I think its unlikely to be a fluid level issue.

At this point its going to make no difference to drive it in limp mode so I'd just drive it the 8 miles and see what they can come up with. Do they have VCDS or a generic scanner? If its a decent generic like a Snap-on it may tell you what the actual problem is. If its a cheapo handheld which just gives Pnnnn OBDII codes tbh its pretty much worthless. It would be more effective to post you my VCDS cable since I can live without it for a couple of days.

[Davey Blueeyes]

Hmm, well I certainly wouldn't want to bet against your experience and expertise MJ and I really appreciate you sharing that, it will help me pass the cold nights in the poorhouse!

Thanks again, a wonderful offer but I'm away until Sat now so might as let them read the codes. The reason it's going there is that they have VCDS (well they tell me they have?!)

[IT]

Originally Posted by MikkiJayne

At this point I feel its pretty unlikely to be the F125 as that will throw a code as you select a gear, not when you try to move.

I confess, this was my thoughts too, although would love to be proven wrong....

Limp mode is designed to get you to a garage without causing further damage, but its awkward stuck in 3rd gear, especially if there is lots of stop start traffic and particularly with the engine overheat concern.

At least an S8 stuck in third is better than an A8 stuck in 3rd... far lower final drive ratios lol...

[tintin]

I'd echo what IT and MJ have said: both Mark (Moltuae) and I have driven these cars - admittedly not in full limp mode - more than 200 miles each when it was pretty clear that both our respective gearboxes were suffering from the sort of terminal problem that MJ pictorially described so clearly above, so I also think you'll be ok driving it in limp mode for 8 miles.

In my case, mine was playing up for about a month before I decided to make the trip to Mackies for a full rebuild: from memory (not wholly reliable these days!) I made at least one shortish (a couple of miles) trip with it in full limp mode.

[Conan_the_Librarian]

I drove my PF S8 from Dorchester to Exeter in limp mode before the car died completely! Subsequently I found out it wasn't the gearbox at all but the alternator had self destructed. I was running on the battery and below a set voltage the TCU gives up and shoves the box in limp mode.

[johnny_quattro]

After having had a nose at the photo MJ posted, it reminded me of my gearbox woes which I've cunningly hidden in the Engine/Under the bonnet section here:

http://forum.a8parts.co.uk/showthread.php?t=7550

Your current situation as described seems to be very similar to mine - my A-drum has some of the top lip destroyed, which was discovered when it went to KSM in Carshalton, Surrey for a rebuild. I was able to select reverse no problem, and it went into limp-home mode aka thump mode upon selecting drive. The thread posted above contains plenty of pics. When my gearbox went 'bang', I drove it for 13 miles back home from Gatwick, and then 3 miles to Carshalton where it was going to be repaired. Auto gearbox man told me to take it steady and not rev it too much - seemed to be quite happy on the way back home. Traffic light starts were of a glacial pace, at best so I used my hazard warning lights to good effect.

I hope it's not terminal for you - it was the enthusiastic and caring response on this very forum that persuaded me to spend the money and get it sorted. I'd have only possibly experienced the exact same issue if I were to have gone out and bought a replacement car of a similar age.

Hope all goes well and keep us all posted.

[sarg]

Very similar symptoms to mine, which was terminal I’m afraid.

Had to reverse onto the scrappers lorry because reverse worked fine...

Still wish I’d repaired rather than scrapped though