boy-racer brakes (was: '77 Audi Fox Turbo)

[Douglas Frank]

"Beatty, Robert" wrote:
> 
> Its a mere matter of physics... changing from a stock brake to
> a Bira system or other advanced braking system will DEFINATLY
> make a difference in braking distance.

Sure, on the track... but on the street???  If your street car's
brakes are fading, then either something's wrong with the car or
else you're driving insanely.  Yes, bigger rotors will soak up
more kinetic energy, but stock ones ought not to fade in normal--
or even "spirited" street driving.

There is "pad fade," which is due to heat-soaking the rotors to
equilibrium with the cooling airflow; and there is "fliud fade"
which is due to accumulation of residual heat in the calipers, to
the boiling point of the fluid (or of water, if your fluid is
contaminated).

If, when your braking goes away, the pedal feels really spongy,
then you're boiling your fluid. Replace it with fresh DOT4.  If
on the other hand, the pedal feels firm as ever but you gotta
stomp it hard to get some action, then your rotors are roasting
(or they're wet).  Besides replacing overheating rotors with
bigger ones, another option is to try to improve the cooling
airflow.  Rules permitting, race cars nearly always have some
sort of homemade ductwork, and you could also rig up a spray
mechanism to mist the incoming air, cooling it before it hits the
brakes (don't spray water on the rotor!).

Bottom line, if your stock brakes can lock up the tires, that's
all the stop you're going to get with ANY brakes.  So spending a
Porsche Unit or more (1 PU = $1000 US) on quadruple piston
wonders is silly... on a street car.  Spend it on better rubber
instead, that doesn't lock up so easily... and *then* if your
stock brakes can no longer lock 'em up, *then* buy better brakes.

And, don't drill your rotors.  Drilling does nothing but remove
mass that would have soaked up more calories if you hadn't
drilled it... and it introduces stress risers too.

(Flame suit on... and this was about STREET cars.  Racing's a
different world.)

--
Douglas Frank Compaq Computer Corp. Algorithm (Al-Gore-ith-m, n):
An
ZKO           110 Spit Brook Rd.     arithmetic procedure,
repeated
603-884-0501  Nashua, NH USA 03062   until the desired result is
found.