Braking 101

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <08b601bd5e6f$c176a180$9e08379d@a-mikemi1.dns.microsoft.com> JoMi@msn.com writes:

> If that were true - why would people spring big bucks for 4 pot calipers,
> 330 mm rotors, carbon kevlar pads, etc...These things help for repeated
> stops as in track use, but what about that one time panic stop on the
> freeway? If I can lock up the existing brakes easily, what will be gained by
> the above?

Perhaps the ur-quattro is a special case ...

The original design used 6" tyres.  I posted the piece about the Germans
working out that 8" tyres would fit.

The brakes fitted to the ur-quattro are adequate/balanced for 6" tyres
using the compounds that were available in 1980.  Now we're running
them on 8" tyres using 199n compounds.  The tyres have a _DAMN_ sight
more stickiness than the original design - but the basic geometry of
the braking system has not changed, excepting the 20V's ventilated
rears and a few percent for the MB's swept area.

Ergo - if you're running an ur-quattro in stock form today - the tyres
are capable of a lot more performance than the stock braking system
will ever demand.  On a warm, dry road my MB ur-quattro will crash
stop from any speed without the ABS engaging.  The tyres are so
sticky compared with the 6" 1980 design assumption that the discs
aren't capable of locking the wheels.

So, for the ur-quattro at least, brake system enhancements make sense.

--
 Phil Payne
 Phone: 0385 302803   Fax: 01536 723021
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