re: metalmasters

[tedcrum@xxxxxxxxxxxxxxxxxxxxx]

> Date: Fri, 19 Oct 2001 07:50:12 -0400
> From: "Michel Drainville" <MDrainville@domain.elided>
> Subject: Re: Dustless Barke Pads
> 
> In all these discussions about different brand names, when people refer 
to
> PBR, they always refer to the Deluxe categorie. I never hear people
> commenting PBR Metalmaster pads.  Why?
> 
> I put Metalmaster pads on my E30, daily driver, and I feel that they
are
> just OK, nothing special on stopping power, when hot of course. When I
> bought them ,  I was under the impression that I would see a big
> improvement in stopping power, but it was barely noticable.  BTW they
don't
> dust at all and are quiet.
> 
> Michel Drainville
> 91 318ic

I have used the Repco/PBR/Axxis Metalmaster (bmxb and bmxb+) pads in
several applications several applications and I have never found them to
be wholly satisfactory.

The main problem is that the friction is low when they are cold, and it
rises rapidly with temperature. With such a material, uneven braking
during warmup is unavoidable: If on wheel develops slightly more friction
when you first hit the brakes, it heats more than the others. The heat
increases the friction (because the material works better hot) , causing
that wheel to continue heating faster... This keeps up until the brake
temperatures reach the range where further heating produces less increase
in friction.

The result is the chacteristic "wig-wag" on the first stop with
Metalmasters, especially annoying in wet weather. Don't count on warm
brakes; "The stop that saves someone's life is usually made with cold
brakes."

I believe that this phenomenon can also lead to disc warpage when one side
of a rotor is better cooled, since the vent slots reduce conduction
between sides.

And they squeak and groan.

The Best street pads I've used are the Ferodo metallics, but they are very
hard to get. There is a distributor in Florida, but he's lazy. Motorcycle
and VW applications go through more efficient channels.

- -- 
Ted Crum
1988 735i  5-speed
tedcrum@domain.elided

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