sticky clutch weirdness

[sakimano]

I’m sure Audi a, know the problem b, know the solution c, know the cost of a recall

a, yes b, yes c, yes.

The topic has run since the car originally launched (I even uncovered an Audi workshop notice for this same issue).
They have never (and will never) offer a recall now as the car is far too old.
It's a design problem.

Seems the only way to fix is to change to an alternative clutch.

You mean an alternative flywheel, clutch and pressure plate.

[Timster]

Yes

[ArthurPE]

I’m sure Audi a, know the problem b, know the solution c, know the cost of a recall

a yes (they know it exists, their fix was a hose replacement)
b perhaps (see a)
c only if b is known, and it may not be

don't think it will take a fw, disc or pressure plate

this is a common problem amongst high powered, high reving v8's that use a OCS
do a google for over center spring sticking clutch

Audi did not design the fw, clutch assembly or pedal/hydraulics...LUK did

about a year ago I greased all the pivots and linkages up really well becasue it was sticking (I could make it stick at will, rev to 7-8 k while stationary, clutch depressed 2 or 3 times, and it will stick)
I then tried to make it stick, I could not
I can make it stick at will now, grease has worn off, I will grease it again and see if repeatable

I have a new hose (covered in heat insulating hose)
new slave
system was flushed

[ArthurPE]

cold start
let the idle stabilize
rev'ed the engine 2 times
pedal stuck

but depressed it the 1" and engaged gear, released (still stuck down) and the clutch engaged? car could be driven (still stuck down), no slip as far as I can tell

don't think it's the pressure plate because the clamping force, ie springs, are still strong, no clutch slip at all
acted the same at 7k miles as it does at 77k miles

not the following:
hose
fluid
heat
bearing guide
pressure plate
disc (can't see how that would do this
slave cylinder

this leaves
SAC mechanism (same exact set-up is used in the e46 M3 an it never stuck once in 150k miles)
master (but I think some have replaced this and it still happens)
flywheel (M# had one too, same mfg, LUK)
linkages

[sakimano]

I have a similar thread that I started on AR a while ago Arthur, and someone posted this on it yesterday....

Sakimano, I drive the 08 model and I used to have the same issue. I solved it by swapping out the fluid with this stuff two years ago:

[RS4pete]

Id been having sticking clutch pedal issues, yet after a flush from std Audi spec fluid to RBF600 it seems to have disappeared. I've tried VERY hard to recreate the circumstances during which i'd had problems and to date it's been fine.

I wonder if anyone with aftermarket brake/clutch fluid has had clutch issues?

[ArthurPE]

Id been having sticking clutch pedal issues, yet after a flush from std Audi spec fluid to RBF600 it seems to have disappeared. I've tried VERY hard to recreate the circumstances during which i'd had problems and to date it's been fine.

I wonder if anyone with aftermarket brake/clutch fluid has had clutch issues?

with engine warmed up and car stationary
put car in gear (clutch down obviously) and rev to 7-8k 2 or 3 times slowly, see if it sticks

[RS4pete]

Just gave that a try and it stuck down, worse than ever before. I wonder if bleeding the clutch with fresh fluid would help?

Incidentally, if i press the clutch pedal down slowly I get a creaking sensation through the pedal that can be both heard and felt.

[ArthurPE]

Just gave that a try and it stuck down, worse than ever before. I wonder if bleeding the clutch with fresh fluid would help?

Incidentally, if i press the clutch pedal down slowly I get a creaking sensation through the pedal that can be both heard and felt.

I don't think it's fluid
it's very confounding

my guess is crap/dust/debris on the bushing guide binding the return of the throw-out bearing, or hanging up on the lip
tolerance only get tight when hot from hi rpm's
????

[Coaster]

My car has recently had a new clutch, flywheel, master & slave cyls, clutch return pipe, release bearing and since then all is fine

[RS4pete]

I'd suggest to get them to perform the 'Arthur test' to recreate the issue.

[sakimano]

I'd suggest to get them to perform the 'Arthur test' to recreate the issue.

If you perform the Arthur test, and then just leave it in 3rd and run down after you hit 8000 (rundown to 7k,6k,5k etc till you're not speeding like crazy) , it won't stick and will be fine.

If you perform the Arthur test and push the clutch in once you hit 8000 and then coast, it will stick and get all crazy stiff.

Very odd.

[RS4pete]

Sorry i meant ask Audi to perform the static test and not the 3k-8k runs. But i guess anything to recreate the issue would be fine assuming Audi are prepared to do it!

Will be interesting to see what they say!

[Coaster]

so, just to recap; car warm, clutch out, rev engine, no sticking. Clutch depressed, rev engine, clutch should stick?

[RS4pete]

[quote} With engine warmed up and car stationary, put car in gear (clutch down obviously) and rev to 7-8k 2 or 3 times slowly [/quote]

This is what i did ... after fairly slowly revving to 7-8K three times with clutch depressed (Gear stick was in 1st) I took the pressure off the clutch pedal (as you would do to pull away) and the clutch PROPERLY stuck down.

Yet even with the clutch stuck down the car still pulled away fine, maybe it was just on the bit point? .... after pulling the clutch up and changing gear the clutch worked fine again.