RE: Braking 101

["Perry, Christopher" <cperry@cotl.com>]

I read an article several months ago in European Car about a VW Cab that
had a tweaked VR6 in it.  They also upgraded the brakes (duh!) and
claimed that they could engage the ABS at 120 mph or so.  Thats damn
good brakes!
cheers,
chris perry

>-----Original Message-----
>From:	quk@isham-research.demon.co.uk [SMTP:quk@isham-research.demon.co.uk]
>Sent:	Thursday, April 02, 1998 3:33 PM
>To:	quattro@coimbra.ans.net
>Subject:	Braking 101
>
>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
> (The contents of this post will _NOT_ appear in the UK Newsletter.)