8P Clutch Issue (Fellow Technicians Welcomed)

[- Jrd -]

Hi lads,

Well i don't like to come on a forum with a technical issue when im qualified technician, feel i should work through and find it - usually do but i've hit brick wall really. Im not a person to fit parts and try, i want to diagnose/assess/and fix,replace.

Heres the issue:

Audi a3 2004 8p, 2.0TDI(BKD)
Bought it and clutch problem raised itself(flywheel was rattling anyway)

Gears hard to select, especially reverse being furthest throw. With clutch depressed in gear, 80% of time if you bring to bite point and back down or even holding depressed, you'll lose the pedal, bite point thumps in - not enough to stall car under brakes but bite point constantly moving up/down pedal making gear change a hassle to say least and look amataur driver. Sometimes pedal sticks on floor and need to pull back up. if you hover foot over clutch while driving - pedal will drop 1/3, if you flick accelerator pedal will force back up.

Diagnosis;

I initially put problem as slave cylinder, As flywheel had failed anyway - Fitted new clutch/flywheel/slave - LUK/Sachs.

No change. Despite many pressure bleeds no progress. Decided to fit a 2nd hand 2007 model clutch pedal/master i had - No change.

Now getting frustrated and could not find any leaks under pressure bleeding, Seeked advice from more experienced pal - he swore his life on it being master cylinder despite me fitting one - 2nd hand. Voiced my 100% doubts but fitted new sachs unit for his better judgement - NO progress.

Carried out extensively looking around the clutch hydraulic line, we managed to see 2 bubbles from the bleeding unit affixed before slave in line - despite despressing many times only 2, as part was fairly rounded from previous owner ordered VW unit - Which had been revised to a much better contruction - NO progress.

Only component left in the system that hasnt been replaced for new in the line itself/black plastic unit(fitted for change of direction?)

Would anyone like to solve this?

Thanks for reading and appreciate the advice, First time ive given up!

Jrd

 

[Elgy]

This one sounds like a toughy!!! Have you checked the input shaft in the gearbox for any play in the bearings. Its a long shot, but the only thing I can think of, is that if the input shaft was moving enough, it might be moving the clutch plate on and off the fly-wheel/pressure plate. That may be enough to cause the biting point to move.

I'm not suggesting this through experience, but its the only thing thats left that might effect the operation of the clutch.

Is there a self adjuster by the clutch pedal or is it all done within the hydraulics of the clutch system?

 

[murran]

in the line itself/black plastic unit(fitted for change of direction?)

as far as im aware this little round unit is a valve to limit the amount of fluid that can pass thru it.
for instance, you slide your foot sideways off the clutch when its down to let the pedal fly up, the valve limits the speed at which fluid goes back up the line so as to let the clutch in more progressivly than the driver obviously intended by his action with the clutch pedal.

this type of valve has been around for years in various guises. many people remove them in the motorsport/drifting world where viscious clucth actions may be required to put the car sideways with a "clutch kick". but because of the said "valve" insted of drivers intentions of jerking/shocking the driving wheels into loosing traction all you do is make the clutch slip!!

whether this valve is the sorce of you varying clutch bite travel problems i dont know. not come across this before!

hope i helped lol!

 

[murran]

as a "fellow technician", if you value your time off work, id try not to spend much time on here..... quite depressingly, ive found i can quite easily fill my evenings giving tech help on here!!!!! lol.

 

[- Jrd -]

Thanks for input lads, Can't say i tested input shaft for play and would require full strip to check now.

As for the "Valve", i see from your comments it has an actual operation then. Whether it is the heart of my issue is questionable.

I've priced up the complete line/valve 37quid minus any discount i get. I may end up replacing it then ive replaced the whole system for brand new....

Im fairly new to this forum but i too well what you mean murran, ive done same on other forums, annoys me sometimes because by time you get chill out time you go on forum then its time for ****** bed, i often reach for lappy as the mrs pushes it further away haha

 

[fuzion]

Jrd,

I have a similar problem with my S3 8P that with Sachs Performance Clutch which was fitted about 2 months ago. Pedal is quite hard (bit of kick back) normal for a DMF performance clutch no issue there all good and happy with that. But past 3 weeks the pressure point as raised substantially to where the pressure point is now near the brake pedal. Very unusual and can't figure out what is causing it.

(new clutch/slave/flywheel the whole sha-bang was fitted).

Gears are easy to get in, but now they are slowly getting harder.. very unusual! Has been recommended checking master cylinder and slave again to see if any issues but they both are fine!

Sorry to hi-jack as i am also baffled!

 

[chadvaliant]

Hi Jrd

Sorry to bring up an old thread but I was hoping you had some luck with your car because mine is doing similar things. (Audi S3 8P 2007 69000km.)

My pedal would only return about half way and so my mechanic started with the master, no luck, then did the slave/release and the flywheel and the clutch. Now all I get for my money is a vibrating clutch pedal and stiff gear changes. Also a strange droning noise at 2500rpm and a huge hesitation/power surge on acceleration.

Did you manage to find out what your problem was?

 

[simat]

Hi,

I've also got the same issue on a Audi 8P with the BKD engine and 6 speed transmission. The clutch pedal bite point rides up and down from near the top to half way down sometimes not always causing problems selecting gears. As the gearbox drive is on a spline into the clutch plate it must be the flywheel that is floating around pushing on the slave cylinder. I'm pretty sure it's not the DMF.

Another chap has 8mm of crankshaft float causing clutch problems
Jetta Clutch - crank free play

Now my question is can the crank shaft thrustwashers be changed with the engine in the car, i.e removing the sump and working from below.

Regards

Simon.

 

[rikia93]

Dear All

I have had this problem circa 7 months ago when I bought my 2006 2.0TDI BKD, I found that the biting point would move depending on how much power you applied through the throttle and at idle the biting point would be at the top and under acceleration it would disappear to the floor. Also reverse and first gear even under idle were incredibly difficult to engage!

On investigation it appeared to be that the D.M flywheel had begun to rock to forward and backward due to wear and age as it had done 90K, the car then went to my mechanic, who stripped the clutch and flywheel out which both needed replacing which was no surprise, however he found the input shat to the gearbox had begun to wear through the gearbox casing allowing more movement on the gearbox shaft and thus more travel on the clutch pedal.

The gearbox then went to be reconditioned which involved a new casing as it had worn completely through, but first gear and second the teeth on the gears were severely worn to the point they were amazed it was still driveable!

Rather a lot of money later for a new clutch, D.M flywheel and gearbox recondition all is now well !