Re: rear disk brakes

[Steve Stegmann <stegmann@domain.elided>]

John,

I beg to differ with you here.  And hang on, the story is a bit
complicated.  It has two parts.  

First, You do want the fronts to lock up first.  This way the vehicle will
slide front forward instead of swapping ends.  Once the rears lock up, you
have to back off on the fronts to get the rear back in line so you don't
hit something with it. 

The second part of the statement is that when set up this way, the onset
of lockup is at a much higher absolute braking level than with the stock
setup.  You are stopping *much* harder before *any* lockup occurs. 

That's the problem with the std setup.  The self energizing rear drums
will lock long before the front disc are at maximum stopping power.  And
this prevents you from using the fronts to the level they can work.  This
has been mostly worked out in modern cars, but wasn't generally agreed on
in 1979.

The discs are *not* a self energizing design while the drums are. They
really don't work well together.

The factories continue to use rear drums as they need something simple to
provide parking brakes, on most cars.  Did you notice that the drums are
very small?  This is what they've done to make them work with the front
discs.  Since they're so small they can't lock up easily. No absolute
power. This was really discussed in the auto mags back in the '70s when
disc brakes came out. 

'Course if you're too young you wont' know any of this.  I remember paying
a "high performance" surcharge for having disc brakes on my '70 Mustang
which I bought new.  The insurance companies told us that we would crash
more with disc brakes.

Steve
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Steven A. Stegmann
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