UrS6 - Failing Clutch Symptoms ?

[Vorsprung durch Technik]

If anyone has any photos of the RHD C4 pedal box in situ and exposed on a car they were breaking, could they post a photo ?

The C4 30V is still here just so i'll get a photo tomorrow of the pedal box.

[macspring]

Great, thanks.

[macspring]

update, as mentioned new regular Sachs clutch fitted, gearbox back in, new slave cylinder fitted, along with new master cylinder. Pedal box is OK.

Eventually managed to work out where the screw is that secures the plastic shield cover underneath the ventilation tubing. Getting the screw out is pretty awkward.

So bled the system with a one man pressure bleeder I've had for a good few years, i.e. it works, but I cannot get a pedal.

The pedal goes to the floor and won't come back up by itself. When pulled up it pushes down by hand so easily it's hard to think it is disengaging the clutch.

Loads of stuff - starter and downpipes etc. taken off the car so can't start the engine to see if it is disengaging the clutch.

Has anyone else had this issue and what was the cure ?

With these cars from time to time they can be exasperating to say the least, and so right now I feel like touching it at this stage.

Thanks for any help.

[andy10v]

You can try gravity bleeding, open the bleeder a 1/4 turn or so, ensure fluid is dribbling out and just keep the reservoir topped up.

Alternatively get somebody else to push and pull the pedal.

Keep the faith, you will soon be

[macspring]

Hi Andy,

Why do you feel gravity bleeding might be more effective than pressure bleeding from the fluid reservoir at the top ?

Thanks.

[andy10v]

It has worked for me before with a couple of things that would not pressure bleed. I gravity bled the last ABY clutch that would not clear. Not sure why it works, my boss introduced me to gravity bleeding and it has come in handy a few times.

I do think moving the master cylinder at some point during the bleeding is helpful to dislodge air, then allow any air that has now entered the pipes to exit the system.

[diesel des]

The only way I have ever been able to bleed my clutch is by filling a syringe with fluid and injecting it into the clutch slave cylinder bleed nipple with the peddle full up. Air and fluid will bubble up into the tank so make sure it's not overfull. Try it I would put money on it...

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[andy10v]

Is the car at a funny angle trapping air in a high pocket?

I like the syringe method for bike brakes as it pushes the air bubbles in the direction of rising, never tried it on a clutch yet.

[newsh]

UrS6 - Failing Clutch Symptoms ?

That's the way we bleed clutches on dirt bikes, works a charm

I'd say you definitely have air in there.

Or you forgot the release bearing

[macspring]

Will try the syringe method tomorrow, and then the gravity method.

Now that it is mentioned, the car is slightly lower at the back. The rear axle stands are set lower.

Thanks for the replies, I post the updates.

[macspring]

This is the short version of what was involved in making further progress.

My description of my progress sounds straightforward, but it wasn't straightforward/easy to get to where I am now. See below.

Bled it by gravity and also in reverse direction.

Felt I'd got a pedal, so put it all back together and found that when I put the car back down on the ground and started it up while I had a pedal it was not enough of a pedal to disengage the clutch and select a gear.

After much grief and annoyance, I twigged the base of the RHD pedal assembly was cracked. The area at the rear of the flat plate that the clutch master cylinder mounts to.

As Dave has advised an old and therefore heavy clutch on a C4, the extra pressure needed to operate the clutch will break the pedal itself.

The RHD C4 cars break their pedal box, as described above.

My car had a squeaky clutch pedal about six months ago and I thought I'd fixed it with a dab of oil. With hindsight it was the start of the metal fatigue caused by continually pressing a heavy old clutch.

I need to make some sort of a metal plate to be able to bolt up to the base of the existing master cylinder mounting plate.

By doing so it effectively reduces the length of the threaded bar that comes out of the master colder. Therefore I need to have a longer clevis pin 'yoke' made up to as the necessary full travel of the clutch pedal to disengage the clutch is not lost.

If anyone knows of which car has a longer clevis yoke than a C4, I could order same from the relevant car dealer or get it in a breakers yard.

The other option is to make the threaded bar that comes out of the clutch master cylinder to be made longer, by being replaced with a longer 'factory' one, or doing a cut an shut modification to the oem one.

This problem with the RHD C4 pedal goal is an opportunity to make a bracket that strengthens the existing pedal box before it cracks ???

To all the C4 owners on here with a heavy clutch I would respectively suggest that you replace the clutch to avoid your RHD clutch pedal box breaking.

Hope you can understand what I'm trying to explain above.

Any questions let me know.

Thanks for reading.

[diesel des]

My peddle box also cracked with the stock old clutch many years ago. I welded a piece of steel to something in there and attached it with jubilee clips to the master cylinder to stiffen it all back up once pushed back into the correct position. Has been great ever since....

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[macspring]

Hi Des,

Never ending these cars, lucky they're addictive, but they sure can be trying, thank goodness for this forum though.

My pedal box broke exactly as per the photo Dave posted in post # 8 of this thread.

It is a weak point that got by Audi designers, when the spec'd the rhd pedal box. Hindsight is wonderful.

Gonna try and fix it with the master cylinder in place, don't want to have to drain the clutch/brake reservoir and lines again.

I know I sound like a crotchety old whinger, but much prefer driving the car than fixing it. When I went for a test drive after I'd fixed it to a fashion, one of the new'ish coils (months) blew living it on four cylinders.

[macspring]

Fixed it !

Back in love with it again.

Yes, I know I'm fickle.

God it makes you work for it though.

Made a metal plate to go between the pedal box metal and master cylinder to act as a 'gasket'. Then adjusted the clevis pin yoke out a bit to compensate for the thickness of the gasket so as the clutch pedal is still in line with the brake pedal.

As I had to disconnect the hard line out of the master cylinder, I had to re-bled the clutch again. Couldn't get a pedal, then got half a one and then a bit better, enough to drive it, and then after about two miles it came good by itself. Loads of brake fluid 'wasted', even though I'd clamped the flexible 'cloth' hose to stop fluid drawing down from the fluid reservoir.

Someone said theirs improved on quattro world and I thought yeah right, but he was correct. Don't rely on it though, brought taxi fare with me in case of an issue arising.

Now it has a new boost leak at high revs, but still goes well before that 'cuts in'.

Only the rear caliper to fix the handbrake on, and then onto changing the matrix to have a heater / de-misting for the winter.

That's why one needs three of these cars so you can always get to drive one when the other two are acting up.

Make one of these metal gasket plates and install them before the pedal box cracks.

If someone does a good one, it could be printed off as a template for each interested member wherever they are in the world.

[Michael S2]

Think i have a similar poblem with my S6.
A few days ago. I pressed clutch pedal to change gear and heard a crack/pop noise and felt some strange movement in the pedal.
Now my clutch pedal doesn't return fully. Bite pont is now near the floor. I wouldn't describe the cutch pedal heavy before or after this happened though . Certainly not in comparison to my S2 clutch.

I will get a proper look tomorrow, but reading above it sounds like the pedal box is hard to access on RHD? Or maybe the slave cylinder is broken?

Any pointers appreciated as always