[DeTomaso] Brake Prop- Valve / Dick Ruzzin

[Thomas Tornblom]

Later Panteras, with the fatter three piston calipers, has a piston area 
which is 2:1 (front:aft), which without a prop valve will provide twice 
as much braking force to the front, compared to the rear. Without a 
device that will equalize this difference somewhat you are basically 
only using your front brakes.

The shuttle valve has nothing to do with pad wear. It is a device 
designed to indicate a pressure difference between the different 
circuits in case of a leak in one of the circuits.

Disc brake calipers are self adjusting, and unless a pad suddenly falls 
out of the caliper, no normal wear will actuacte the valve.

Thomas


JDeRyke at aol.com skrev:
> 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
> 
> 
>
> 


-- 
Real life:   Thomas Törnblom             Email:  Thomas.Tornblom at Hax.SE
Snail mail:  Banvallsvägen 14            Phone:    +46 18 444 33 21
              S - 754 40 Uppsala, Sweden  Cellular: +46 70 261 1372