Miata Mailing List: October 1998, Message #175

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Tom writes...

> It all comes down to this.  Pedal effort!  I can lock my
> stock brakes up at any speed, and I can modulate my stock
> brakes at any speed.  But a big brake kit and/or hi-perf
> pads can reduce my braking effort.
> 
> Do I find it easier to modulate the pedal when it requires
> 100 pounds of force to lock the brakes with a stock setup,
> or can I modulate the brakes easier when it only requires 30
> pounds of force to lock with a hi-perf setup?

I disagree.  I don't believe one can modulate the stock brakes at any 
speed.  Locking is one thing.  Once the rotors are not moving in the 
calipers, no heat is being produced.  This does not test the merits of 
good brakes.  As we all know, braking is not about locking.  It's about 
slowing rotor rotation.  This action generates *huge* amounts of heat.  
A small rotor will quickly get heat-soaked.  Once the rotor is full of 
heat, the heat travels to the brake fluid.  Once that reaches its max. 
capacity, it boils, doesn't compress, and brakes essentially fail.  This 
is on type of brake failure.  Another type of failure is caused by high 
temperature gases getting trapped between the rotor and pad.  This 
dramatically reduces friction.

All things equal, size is better.  Larger, heavier rotors will absorb 
more heat and reduce fade.  Brake pad size, from what I've heard from 
reliable sources mostly effects brake pade life.

If you think its easy to threshold brake your stock brakes at 100mph, 
try this:  Get stickier tires.  If, for some reason, you can still 
threshold brake, try a couple repeated stops.  It will not take long for 
you to notice that, no matter how hard to step on the pedal, your 
braking distance will get longer and longer and longer.  Very bad on a 
track.

As for the comment about better brakes requiring less pedal effort-- 
this is simply not true.  Better braking systems require high pedal 
effort (try a 911, Ferrari F40, or any racecar).  This is because the 
calipers used have small pistons to reduce pedal travel (easier to 
threshold).   The "downside" is higher pedal effort.  large pistons 
displace more fluid.  You need more pedal travel, but effort is reduced.  
It's basically a tradeoff.  One is geared towards performance, the 
latter is for comfort.

Shiv