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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