[DeTomaso] Brake Prop- Valve / Dick Ruzzin

[ProvaMo.com]

When I changed my braking system on my Pantera, (Brake booster, master,
pads, stock calipers remained, brake proportioning valve, etc...)

I intentionally tuned the system to allow the rears to lock up just before
the fronts, (Yes I like to test for myself occasionally) and just like
physics implies, the car wanted to spin (OK did spin).  Then I tuned until
the fronts locked well before the rears (the other end of the range), then I
found what I liked and what the stopping distance measurements indicated
were optimal.  This was the fronts locked just before the rears.

I would not advise anyone to set up their braking such that the rears locked
first.  In a safe parking lot test with soon-to-be-tossed tires OK, for road
or track use, NO.  

Chuck



The setups that allow rear brakes to actuate first are wrong for almost all 
cars except the stock Pantera with 4-piston fronts and one-piston rear 
calipers. It is a special case, having rear calipers that are so small, they
cannot 
possibly lock the rear tires. In addition on a Pantera, the non-adjustable 
proportioning valve is plumbed to limit the large front caliper's pressure
output 
while allowing the rears to run at full pressure. To any performance fan,
this 
is utterly backward. Maybe it worked with the stock 185-70 front tires and 
225-70 x 15 rears but its been so long since I've seen a Pantera with such
small 
tires, I dunno. Some pro racers that needed more brake force on one end but 
were restrained by class rules from using proportioning valves, injected 
controlled amounts of air into the too-strong brake plumbing to allow such a
delay. 
The shuttle valve is used to turn a warning light on if shuttle travel in
the 
assembly- due to pad wear- exceeds what Ford thought was prudent. Pantera 
shuttles tend to stick internally, all but shutting off fluid flow to half
your 
brakes. If I thought I need an idiot light to tell me my brake pads were
worn, 
I'd use an AMC assembly that has a spring loaded shuttle which doesn't
stick. 
Your stock Mangusta has larger rear calipers and tires than a stock Pantera,

more rear weight bias and probably different handling. Bottom line: if you
do any 
of this, I suggest you throughly test your Mangusta's new panic-stop 
characteristics on a deserted access road with lots of run-off room if the
rears lock 
first and send you into a spin. Good luck and tell us how it all worked- J 
DeRyke


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