New clutch slipping in 5000 turbo quattro

urq urq at
Mon Oct 15 00:28:33 PDT 2007

Ado's recommendation is a good one in that it allows you to know if the
problem is inside or outside the bellhousing ... although it might be a bit
difficult to test as you can't use the clutch if the slave cylinder is not
staked into the tranny ... but you could do the first part, to loosen the
bleeder to relieve any excess fluid between the master and slave.

Equalization port ... it’s the mechanism that allows more (or less) fluid
into the hydraulic circuit as the parts wear.  The clutch and brake M/Cs
each have an equalization port, it's a little hole in the master cylinder's
piston that runs from the supply side of the cylinder to the part of the
circuit that is conveying the force.  If the equalization port were always
open the brakes or clutch wouldn't work as any attempt to compress the fluid
would get bled out the hole ... but the supply side port is strategically
placed so that once the piston starts moving into the cylinder bore the port
gets blocked.  

What can happen is that the adjustable rod that connects the pedal to the
master cylinder can be set too long ... which means that the clutch pedal
stops before the piston has come far enough out of the bore to open the
equalization port.  If this is the case and you happen to have excess fluid
in the line the slave will never fully disengage the clutch.  If you fix
that problem by opening the bleed port on the slave, eventually the clutch
hydraulic system will not have enough fluid to fully disengage the clutch
and it will be difficult to get the car into 1st or reverse at a stop and
you might see grinding during shifts.  

Steve B
San José, CA (USA)

-----Original Message-----
From: quattro-bounces at [mailto:quattro-bounces at] On
Behalf Of Ben Swann
Sent: Sunday, October 14, 2007 3:52 PM
To: 'urq'
Cc: quattro at; 'Ben Swann'
Subject: RE: New clutch slipping in 5000 turbo quattro


I maybe don't understand the hydraulics fully on this.  I feel I did
everything in my
power to get the clutch right.  It almost seems like the master is putting
too much
pressure on the slave circuit and not allowing the pressure plate to clamp.
The car
needed a lot of sorting, but I have done enough clutch jobs, that I did not
expect this
sort of problem.

He has some sort of problem with a switch - a brake control like switch, but
if I noted
correctly, it was on the hydraulic booster - maybe clutch master, and really
did not
think about it at the time.  What else in the clutch hydraulic circuit can
cause this?
I really spent too much time and effort - 'bout killed myself trying to
maintain my
honor and complete the job despite things going wrong right and left.  I
encouraged him
to go back home so he doesn't get fired for not being back to work on time -
13 hours
drive back to Toronto.  He left basically not paying for the job I did.  I
certainly did
not feel I could justify asking him to pay me even if I feel I did the job
right.  This
really puts a bad taste in my mouth for trying to help folks in offering a
service that
when it goes wrong backfires in the worst of ways.

If I missed something that can be fixed without separating engine and trans,
it will
save everyone a lot of grief.

Equalization port?


-----Original Message-----
From: urq [mailto:urq at] 
Sent: Sunday, October 14, 2007 6:39 PM
To: 'Ben Swann'
Subject: RE: New clutch slipping in 5000 turbo quattro

... sure sounds to me like the clutch isn't fully disengaging ... half inch
of travel isn't enough.  I don't know what makes the difference ... I've got
two identical V8s ... one the clutch pedal is right at the floor and the
other is maybe halfway up.  They are supposed to auto-adjust.  Are you sure
the clutch master is returning to the point where the equalization port is
opening?  Perhaps there's too much fluid between the master and slave and it
can't get out at the master because the pedal stops before the master
cylinder is fully out.  The other possibility is that the return spring in
the slave is weak.  It would certainly be easier to replace the salve than
having to open it all back up again!

Good luck!

-----Original Message-----
From: quattro-bounces at [mailto:quattro-bounces at] On
Behalf Of Ben Swann
Sent: Sunday, October 14, 2007 3:02 PM
To: quattro at
Cc: 'Ben Swann'
Subject: New clutch slipping in 5000 turbo quattro

After two weeks and extensive work on fellows car – ‘ 86 5000 CD turbo
quattro ( Canada
Car), a sick sinking and  maddening feeling came over me when finding that
the clutch
was slipping with only moderate power levels.  I reluctantly did a clutch
job for him
prior to doing power adders – Supp. Injector, single-pass, 3” downpipe and
other mods.
So we were not even able to test and tune for greater power, and hope he
could make it
home alright

Clutch disengages completely with only about ½” pedal travel leaving another
2” all the
way to the floor.  Usually when I replace Slave Cyl. I’ve  had the opposite
problem and
clutch does not disengage ‘til almost all the way to the floor until
extensive bleeding
or the circuit.  I did bench bleed the slave and free air between slave and
but nothing with the master. 

We decided to do Clutch work after some test runs showed about 217 WHP and
slipping in 5’th gear.  Removal showed leaking real seal and oil on clutch
disk surface,
and release bearing was nearing end of its useful life – so the job had to
be done and I
feel I made the right call, even though I really didn’t want to do the job.
So R/R
included turned 5000 flywheel, nearly new disk(about 5000 miles of use and
surface/no glazing), decent looking pressure plate (better than what came
out). I had
ordered a new disk, but found out they are NLA.  Flywheel had ben lightly
turned, and at
least the disk I put in was thicker and not worn, glazed and shabby compared
to the one
I took out.   All was cleaned prior to install.  Also I replaced rear main
seal, and
release bearing along with the slave cyl – new parts.  The engine went in
painlessly with no jamming – I usually get some, so did not perceive any
problems.  Yes,
I did the job removing the engine rather than dropping trans.   Easier for
me and had to
service EM, turbo and other engine stuff, and front was coming off for the
’91 200
crossmember and intercooler install.

So after all that labor and parts, why would this clutch be slipping?  I
simply can not
afford to do this job again and am pretty much going to eat the clutch job
unless there
is a simple cure.  At least maybe I can advise what might prevent having the
job redone
with similar problem.

I am upset since I reluctantly agreed to do the job for him at rock bottom
price prior
to bumping the power in the car. The only thing I can really think of is
that perhaps
some grease from the shaft or somewhere flew up onto the disk.  That
happened to me a
long time ago in a Scirocco, and now always use the slightest of white
lithium in the
pilot bearing and release bearing, but actually now I’m hoping that it is
the cause
since that can be resolved with liberal application of  brake cleaner in the

I don’t have the car now as he had to drive back to Canada after advising to
stay out of
the power.  He’ll be back in order  to tune the injector controller and
enable other
tweaks.   Maybe there is something his local mechanic can check without
removing the
trans or engine to check.

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