It so happened I took my car to the stealership for routinely inspection
last year, before starting my Xmas holiday - which I meant to fit some
skiing in. As I started driving up a winding road I could hear some kind of
brake noise - even without touching the brake pedal - on left bends. I tried
braking hard because I thought a bit of rust might have settled in, and all
of this was to no avail.
Since the stealer'd told me everything was fine after inspection, it took an
enquiring mind to get a torch and check the rear pads - which funnily enough
always wear faster than the fronts in my car, and there the culprit was, I
needed new rear pads. I carried on to the skiing resort making use of the
shortest gears possible and of as much anticipation as I was capable of, and
the next day I had my pads replaced.
When I mentioned this to the stealer and I said how appalled I was at both
their service and the fact that no wear indicator light turned on on my
board, he said that of course, only S's have that stock - which is not true,
either, as my father's A6 does have the little twinkly.
What about B6's? Do they get that stock?
AFAIK the handbrake never operates on disc-brakes (only on "drum" brakes or
whatever they're called in english). If you got disc in all corners there
will be a small, separate set of brakes to serve the handbrake. If the
handbrake was operating on the hydraulic disc brakes I guess a pressure drop
in the system over time would be very critical.
Rubbish. The handbrake draws a wire connected to a lever in the side of the
(disc) brake. Pulling the wire causes the piston to move outwards. I'm assuming
we're discussing the A4 or similar (have not bothered to check the start of this
thread to see if this is the case).
Careful with that word "never". Take off a back wheel one day and have a look.
On newer Saabs and lots of other cars, the handbrake operates a variant of drum
brake, even if the wheel in question is stopped by a disc brake.
('01 A4 Avant, '99 Saab 9-3, '83 Saab 900)
Actually, that's very often true (hence my fudging ;o), but not always.
IIRC, the 2CV (just to take an example) used an entirely separate braking
mechanism - two additional pads on the front wheels. c1937 or so.
Implementations vary.. when I fudge an answer, I try to do it properly ;o)
The design you're thinking of (a small mechanical drum brake at the center
of the disk) *is* used in BMWs, at least. However, the Audi design actually
*does* operate directly on the disks. It is a cable-actuated *mechanical*
system (separate from the hydraulics) that clamps the rear pads to the disks
by pushing on the pistons. Personally, I think it's kind of a stupid,
overly complex and expensive design, but that's what it is.
(Been there; done that)
Well, he was correct. Our cars do not have rear brake pads with wear
sensors. Only fronts do. That goes for both B5 and B6 A4, and I'm pretty
sure the S4 as well.
As far as why the rears wear out faster, I can think of two reasons:
1. The pads are thinner to begin with.
2. The rear rotors are not vented, which means they don't dissipate heat as
efficiently as the fronts do. Higher operating temperatures cause the pads
to wear out quicker.
Never my case. The only abuse I can think of would come as a result of
abrupt starts - thus involving EDS - which is not my case either, and the
occasional brief drifting session on a deserted icy car park, but both of
these should affect the fronts more than the rear as the brakes will need to
counteract a bigger front torque contribution.
And the rears have to put up with a lot or rubbish churned up by the front
wheels, and they often don't have enough work to do either, causing rust on
the discs and excess wear on the pads. The apparent paradox that the rears
wear quicker than the fronts is familiar to many Audi (and Golf GTI)
Well, my B5 is a 2001 and it definitely has front brake pad wear sensors.
As a matter of fact, I had new EBC Green pads put on today, and they had
wear sensor wires/connection that had to be plugged in after disconnecting
the plugs from the old OEM pads. I am looking at the EBC brake catalog as
we speak, and even for 95-99 A4s they have pads with wear sensors, although
slightly different connector shape. So, I'm 99% sure your car should have
I hear ya. I had pads replaced on all 4 corners today, and the rears were
worn out way more than the fronts.
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