Archive for AudiSRS.com The place for Performance Audi
 


       AudiSRS.com Forum Index -> Audi S4 & RS 4 (B6 & B7) quattro
hooblah

B6 s4 clutch or gearbox issue? Need help diagnosing!

Hey guys I've had my s4 for just over 6 months now, ive done a fair bit of maintenance on it but there's one thing that really let's it down with the driving experience and that's the gearbox. When I bought the car I was told the clutch had recently been changed, although there is no paperwork to prove this. Not sure what to make of that tbh.
Ok so back to the problem; The gears crunch sometimes unless I shift slowly. It's not all the gears, mainly 3rd/4th, but I've had it happen when shifting at high rpm into 5th or 6th. Surely all the synchros can't be worn out?
It's confusing me because the clutch is also a bit high and the biting point is quite vague. I often stall the car. But this could also be down to the dbw lag and/or my shagged snub mount causing excessive movement. I shall soon deal changede latter with a JHM remap and a poly snub mount.

I'd like to say f*ck it and change the clutch, fltwheel and gearbox in one go for peace of mind, but it pains me to have to part with all that money! If I could narrow it down and say yep it's definitely one or the other then I can sleep peacefully knowing what I have to do to fix it lol.

So is anyone able to help me diagnose this issue? It's driving me up the wall!

Just to add, I've already changed the clutch master cylinder and bled the system.
jockthedog

If your clutch isn't fully disengaging, the gears will crunch.

Your 3rd gear might be well worn by now. I dunno what material they use in the B6 box, or how you drive! How many miles on the box?

Think they are 3 part synchros in the 0A3 box

Sort the clutch first, I'd say.
hooblah

Im quite tame most of the time, occasionally give it a good thrashing. I don't slam gears, especially as it crunches! It's done 120k.
hooblah

Would anyone else care to input?
Ian_C

It will be the clutch and associated parts.  Known problem on the B6 B7 S4 RS4.  I'd change it with OEM parts including DMFW, cylinders and return pipe.  Thats what mine had with a 2k invoice!
hooblah

Thanks man. I was considering a single mass flywheel due to the rev hang. Is this advised and is anyone able to recommend anything?

I will be doing the work myself. Is it just a standard affair or is there anything in particular to be aware of, i.e. engine out job?
Ian_C

Audi quote 8 - 10 hours.  From memory I think 8 hours was on my invoice (Russell Automotive Centre, Hendon).  Yes, I think the engine needs to come forwards to split the longitudinal drivetrain layout (centre diff/gearbox/clutch/engine)

Personally, I'd stick with OEM parts, exactly as the car left the factory.  If you buy from Audi or TPS, at least you have some come back if something isn't right afterwards, even if you plan to fit it yourself.

I remember stalling my B6 when not paying attention - you think it has masses of torque, but actually of course it doesn't at 500 / 750 rpm!  Definitely don't want a lighter flywheel!
hooblah

Thanks Ian.
Can anyone comment in the rev hang issue? It's like there's no response from the engine when you rev it, then suddenly the revs shoot up and then come down slowly. Like a combination of very heavy flywheel and drive-by-wire lag.
Ian_C

Dodgy throttle position sensor?  Just changed the throttle on my B5, was about 90 quid new from Audi iirc
nickb834

could be a vacuum leak in the intake "plumbing" - my S4 did the same. air getting in somewhere it shouldn't?
hooblah

TPS checks out fine. No error codes.
If there was an air leak it would manifest itself quite quickly. I'm pretty sure there isn't.

So back to the clutch... Why is my biting point so high and lacking in feel? I can't pivot my foot to bring it up, I literally have to lift my whole foot off the floor.
S4Max

Not sure about the clutch issue but could the rev hang be caused by a faulty clutch switch located by the pedal. Actually the switch may not be at fault but because of the way your pedal is travelling it is activating the switch at a position that it doesn't like.

The clutch switch is not expensive but a bit fiddly so may be worth changing anyway. Have a read up on line there are plenty of write ups on the clutch switch. Mine has been replaced twice in the 7 years of ownership.
Ian_C

Re: B6 s4 clutch or gearbox issue? Need help diagnosing!

hooblah wrote:
When I bought the car I was told the clutch had recently been changed, although there is no paperwork to prove this. Not sure what to make of that tbh.
The gears crunch sometimes unless I shift slowly. It's not all the gears, mainly 3rd/4th, but I've had it happen when shifting at high rpm into 5th or 6th. Surely all the synchros can't be worn out?
It's confusing me because the clutch is also a bit high and the biting point is quite vague. I often stall the car. But this could also be down to the dbw lag and/or my shagged snub mount causing excessive movement

If there is no paperwork, sounds like the garage/private seller telling porkies to secure the sale.  Probably just a case of delaying the enevitable I'm afraid.

How many miles?
hooblah

He was quite adamant that it had been changed. Even a month after buying it I asked him again and he said it's been done so I don't need to touch it. I know the flywheel wasnt changed so i'll be doing that in the near future as it's done 120k.
I read something about the clutch line can also be a problem?
       AudiSRS.com Forum Index -> Audi S4 & RS 4 (B6 & B7) quattro
Page 1 of 1