[s-cars] urS6 brake problem

[Fred Munro]

Hi Steve;

On the brakes, a couple things come to mind:
1. The RF splash shield is contacting the rotor
2. The RF caliper is dragging and has worn the pad(s) down to the backing
plate.

The rear rotor splash shields occasionally contact the rotor on my UrS4,
resulting in a continuous rubbing sound. Judicious application of a hammer
to a piece of wood inserted through the wheel solves the problem every time.
The front splash shield is much smaller so it's probably not the issue here.

Sounds like the brakes on the RF wheel may be dragging. My guess would be
the pads are worn out and the grinding is caused by the pad backing plates
contacting the rotor. If this is the case, the rotor will show signs of
overheating or be scored. The problem may be on the inside, so take a look
at both sides of the rotor.

Dragging brakes can be caused by the piston sticking in the caliper
(unlikely if you have new calipers), pads seized to the carrier with dirt
and/or corrosion, or a bad brake hose (swollen internally so it doesn't
relieve pressure back to the master cylinder after brake application). If
the caliper carrier pins are seized, the inside pad will wear out quickly.

Long pedal travel on the UrS cars is caused by the pads on one or more
calipers sitting too far from the rotors due to inherent weaknesses in the
brake design. The most likely causes are pads seized in the caliper carriers
and the e-brake cams seized or the e-brake not used enough to adjust the
rear pads. Seized caliper carrier pins will also cause long travel. I
service my brakes every fall and pedal travel on my UrS4 is only 1" or so
after service. It gradually increases over the year and goes back to 1"
after I redo the brakes.

As for the coolant leak, the most likely culprit is the after-run coolant
pump situated on the left side of the engine bay. These are plastic pumps
and tend to leak at the seam between the pump halves. They have been known
to fail completely, resulting in rapid and catastrophic loss of coolant.
Some listers with the older Type 44 turbos carry a 3/4" copper pipe elbow
and a couple of hose clamps to bypass the pump if it fails on the road. I
carry this "kit" in my UrS4.

HTH

Good luck with the brakes!

Fred Munro
'94 S4

-----Original Message-----
From: s-car-list-admin at audifans.com
[mailto:s-car-list-admin at audifans.com]On Behalf Of Steve Marinello
Sent: December 15, 2002 11:06 PM
To: s-car-list at audifans.com
Subject: [s-cars] urS6 brake problem


This is a multi-part message in MIME format.
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Okay...

The saga continues....So I'm driving this "new" '95 S6 sedan I picked up in
California back to New Orleans.  I check in tonight in Houston, as I've got
a business meeting in the morning.  I decide to go out to dinner and fire it
up.

Two things:

First, there's a puddle of coolant underneath...not big, but it's there.
There was a very small drip this morning in El Paso...a few tablespoons. The
source seemed to be at the back of the engine.  The system was slightly
overfilled by the PO and was still at max in El Paso and just above max when
I stopped on the road to check in San Antonio.  It is now slightly below
max.  Any ideas re. the source??  Heater valve?

Second, the bigger one.  When I started to back up, there was a NOT
wonderful graunching grind up at the RF wheel.  At first I thought it was
some of the damaged bumper cap (long story) snaggin on the wheel, but it
appears to be the brakes.  If I brake at all, hard in particular, the RF
grinds and continues to do so for a while after the brakes are released,
sometimes longer than other times.  The PO had 2Bennett replace the G60's
with new ones and it has cross drilled Brembo's with Mintex Red's.  Can't
see anything through the wheel, so I'll pull it in the morning and check.
Other than something jammed in somewhere, any ideas?  The pedal travel,
which was too long anyway, courtesy of an overzealous rotor turning (rear!)
and a flush and fill without getting all the air out, actually seems longer
than before and certainly feels, sometimes, like there is something jammed
somewhere.  I wonder if something is caught in one of the rotor holes?

Anyway, before I get into it in the morning (here's hoping my meeting
doesn't turn out to br at 8:30 a.m.), please send any ideas for what I
should look for in both cases.  Anyone got the p/n available for a heater
valve?  Doesn't AutoZone carry a replacement?

Thanks guys,

Steve
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