John,
Thanks for posting this.
I had Ferodo (asbestos) shoes on my 63 Porsche 356 vintage race car. The
front shoes lasted about for about 25 races (approx. 2000 miles). The
steel liners in the aluminum drums had several burnt and heat cracked
areas. I had a new set of Ferodos but based on reports from owners of
similar cars I had the shoes relined (riveted, not bonded) with
carbon-fiber material and the drums turned slightly (0.010).
It seems your comments indicate that I should continue to use asbestos
lining and that I may get even more heat cracking from the carbon-fiber
lining thereby "ruining ... precious original components."
Phil
John Hardy wrote:
>
> I read with interest the thread about brake lining materials.
> Unfortunately I lost a lot of messages during a massive e-mail clearout
> and may not be replying to the right list. Nevertheless.......
>
> Iv'e been manufacturing aluminium/cast iron composite "Allifin" brake
> drums for some years now and have found that there is one thing that is
> ignored by most. The material that the brake drum is made from. If it is
> cast iron (unless a special grade) it will not withstand high
> temperatures. If these high temperatures are generated by one of these
> high tech linings then surface cracking is probable. The problem in
> specing a lining is 2 fold.
>
> first. lining hardness
>
> If the lining is harder than the drum material it will wear it away
> quickly. This is obvious. A customer of mine was using a market leader
> in racing conditions and was getting through 2 pairs of front drums per
> season. He was pleased with the brake performance though.
>
> Second. Operating temperature
>
> Most new materials on the market and many old ones have an operating
> temperature incompatable with the characteristics of straightforward
> cast iron. They just run too hot. Surface cracking is endemic and
> ovallity is very common because, if Cast iron gets too hot it will not
> return to it's original shape on cooling.
>
> The problem is that manufacturers and suppliers are trying to apply
> space age technology to stonge age designs. If the right sort of
> material is used very good brakes are possible to achieve. Most of this
> has been caused by the demise of asbestos. If have CI drums and you can
> get hold of a non-metallic asbestos lining I suggest you use it! A lot
> of racers are suckered by high spec and high prices. They think that if
> something is expensive and Hi-Tech it has to be good. Not necessarily
> so.
>
> I have had a lot of business created by the damage caused to drums by
> these lining and really should be encouaging their use!
>
> The above opinions have been formed over the years by practical research
> and hand's on experience. I am not going to enter into any lengthy
> discourses or arguments with anyone. Nor will I comment on any
> particular make of lining except the ONE I recommend for my drums. The
> point is that I have found that the combination Of MY DRUMS AND THE
> LININGS I KNOW give excellent performance under all conditions and have
> neither the time nor the inclination to reaearch the hundreds of
> alternatives. I merely offer my experience on a take it or leave it
> basis in the hope that I might save someone from ruining their precious
> original components and get them to stop safely.
>
> John Hardy
> www.brakedrum.co.uk
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