Clutch will not disengage, pedal goes up but engine not engaging with tranny at all

[allroad_22]

Uh... One thing after another with this project...

So finally got all things put together, wanted to take it for a quick spin and noticed that as I was backing out the engine would engage and then suddenly slip. Then I put it into first gear and same thing, it would start engaging and then all of a sudden slip. After a couple more tries the engine would not engage at all, the clutch is acting as if it was pressed in.

I'm going a bit crazy on what it could be. I put in a new RS4 clutch with pressure plate, and also resurfaced the existing flywheel. There's consistent pressure on the pedal as I press and depress, makes me think that the slave cylinder is fine.

Frankly I can't imagine how this is even possible. Could it be that flywheel was resurfaced too much?

[swmic]

When they resurfaced the flywheel did they also cut the surface where the PP mounts? If not that distance may be too much for the PP to hold the disk. I'm sure others with more knowledge will chime in.

[julex]

^^, the mounting "ring" on the FW needs to be cut after resurfacing the friction surface so that the proper factory step up is preserved. Step up from FW friction surface to PP mounting surface.

When you were installing the PP, what was the gap between edge of "finger tight" attached PP and flywheel? It needs to be 0.1" if I remember right. Also, was the SAC mechanism clocked all the way back?

[allroad_22]

You two are likely right on the money. It has been a while ago (about 2 year ago) but I do remember the guy telling me they had to take some extra off to get it all smooth and it didn't look like they took off much if any where the pressure plate mounts... Now that I think of it more, it felt exactly like it barely locked up and then as i would give a little bit more gas it would slip, and once it slipped a few times it probably wore off that .001" that was barely making contact and wouldn't grip again.

Well, it could be worse, but the thoughts of getting rid of this project are raging through my mind...

[allroad_22]

So an interesting update to this, I just went back into the car and noticed that when in gear and clutch disengaged the speedometer is responding, so 1500 rpm in 1st = about 10mph, then in second its 20+, i didn't try anything after that.

[allroad_22]

yea, right side drive axle is busted, not sure how that happened, brand new axle... hope its just the axle...

[allroad_22]

i guess more than just "how it happened" (will find out later today), but I didn't realize that quattro is a fully open differential... I thought that Quattro had some sort of limited slip and that's why it was praised for traction in different scenarios... If this was ice I was stuck on with one wheel, I'd be stuck... Or is my differential not working properly?

[rollerton]

. If this was ice I was stuck on with one wheel, I'd be stuck...?

Exactly.

Just jack one wheel up off the ground and the car is crippled. Or have an axle fail. Luckily it's not too common, but it's the one weak point of the totally mechanical open-Diff system if you don't have a diff locker.
I always wondered if a VW Vanagon Diff Lock could be adapted. But...not worth it.

[allroad_22]

Well, i guess as long as its not a blown diff, i'll be ok. for now...

[allroad_22]

Well, i guess as long as its not a blown diff, i'll be ok. for now...

So, just a lesson learned on this, double check that you're installing right on right side and left on left side, or else you won't be going very far.

[julex]

Exactly.

Just jack one wheel up off the ground and the car is crippled. Or have an axle fail. Luckily it's not too common, but it's the one weak point of the totally mechanical open-Diff system if you don't have a diff locker.
I always wondered if a VW Vanagon Diff Lock could be adapted. But...not worth it.

There is a difference between having a wheel in air and one with axle disonnected. That difference is functional torque braking of brakes which is how our quattro system has ability to power car forward when one, or more wheels are effectively free spinning, being it on ice or in the air.

So no, when one wheel is in the air there is still torque going to other wheels because abs sensor detects that wheel spinning faster and applies torque braking by using brakes. Torque has to go somewhere and if that free spinning wheels gives resistance now, it goes to other wheels.

[julex]

So, just a lesson learned on this, double check that you're installing right on right side and left on left side, or else you won't be going very far.

Lol, awesome that this was something so simple to fix... simple in respect to having to take off the tranny that is