Slipping clutch when hot-Fixed!!! :-)

[Mark Rosenkrantz]

One of the reasons the clutch system needs bled at least every 2 years...
and often is left ignored.

Mark Rosenkrantz

On Fri, Apr 22, 2011 at 10:36 PM, L DC <ldc007usa at yahoo.com> wrote:

> The slipping clutch problem that my 87 QSW had been having over the past
> year which only got worse as time went by has been solved, and I'm glad to
> report that it was not the clutch itself going south.
>
> Clutch Master Cylinder (CMC) was the culprit!!!
>
> Last Saturday, I spent nearly all day trying to get a possible fix on the
> issue and I finally did with the install of a brand spanking-new Ate CMC and
> fresh Ate Racing Blue brake fluid.
>
> I first tried to flush, bleed the troubled CMC but could not get the fluid
> to free flow even when vacuuming or pushing fluid through it using a brake
> bleeder gun I rented. The CMC acted as if it were plugged.
>
> I decided to remove the CMC from the car and diagnose why it did not allow
> for fluid to be fed through it. I took the whole part apart.
>
> There are two ports/orifices located just below the rubber grommet holding
> the plastic tube through which fluid is fed from the brake master cylinder.
> One of these ports, the smaller one, was completely plugged. I can see how
> it can get easily plug when I learned that it has the diameter of a small
> sewing needle. I actually took a need to unplugged what appeared to be
> rust-like hard matter. Would this be the RETURN/Stabilization port a couple
> of listers mentioned? I would imagine the fluid expanded with hot
> temperatures off the engine and radiator fan causing the fluid to expand and
> with the return port/ stabilization been plugged it had only one way to go
> and that it the slave cylinder. I also imagine it was using the very same
> fluid stagnated all this time in the line since it was not free flowing to
> back to the reservoir?
>
> Anyway, I put the CMC together and back in the car and although I got it to
> flow more fluid through than before taking it apart, I could not get it to
> bleed completely, causing the clutch pedal to sink to the floor without
> returning on its own to its up-resting position.
>
> Trying to bleed the sucker for more than 30 minutes to no avail, I got
> fed-up with it and removed it from the car, yet again, and replaced it with
> a new one as aforementioned.
>
> By contrast, I was able to bleed the new CMC in about 10 minutes.
>
> Since this is my daily driver, I took it to work this past week and saw
> some heavy, stop-and-go traffic with ambient temperature as high as 90*F and
> high-speed fan kicking on and off quite frequently and the clutch did not
> slip at all, even when putting it in 5th gear at 1K RPMS and sinking the gas
> pedal to the floor.
>
> Cody, could your car be or was suffering from the same issue?
>
> Anyway, I'm glad it was not the clutch itself and that it still has some
> life left to it.
>
> I going to see if I could build some sort of heat-shield for the CMC and
> brake master cylinder while I'm at it to prolong their usage.
>
> Tom, it so appears that the problem is what you described initially below.
>
> Thanks for every ones'' input again.
>
> -Louis
>
> --- On Sun, 3/27/11, Tom Leppke-Hennig <printhead at usinternet.com> wrote:
>
> > From: Tom Leppke-Hennig <printhead at usinternet.com>
> > Subject: Re: Slipping clutch when hot
> > To: quattro at audifans.com
> > Date: Sunday, March 27, 2011, 1:06 AM
>
> > Re: Clutch hydraulic fluid expanding due to heat, causing slippage: That
> > is possible IF the return port isn't getting uncovered in the clutch
> > master cylinder. This is normally due to an incorrectly adjusted push
> > rod.
>
> > Just as others have said, though,I don't think that is what is wrong,
> > here. The way yours is acting is how they act when the friction material
> > gets thin with mileage. The diaphragm spring loses preload (travels
> > further), and then is aggravated when hot. The steel in the spring loses
> > its ability to provide clamping pressure due to heat.
>
> > You need a new clutch.
> >
> > _______________________________________________
> > quattro mailing list
> > http://www.audifans.com/mailman/listinfo/quattro
> > http://www.audifans.com/kb/List_information
>
> _______________________________________________
> quattro mailing list
> http://www.audifans.com/mailman/listinfo/quattro
> http://www.audifans.com/kb/List_information
>