[DeTomaso] Wilwood Brakes WTF????

[MikeLDrew at aol.com]

In a message dated 4/18/13 9 10 58, kenn_green at yahoo.com writes:


> Isn't there a spring in the master cylinder that retracts the MC piston 
> and therefore also the caliper pistons?  I had assumed that the residual 
> pressure valve worked against the spring in the MC?  If you look at the 
> reservoir ports in the MC there should be a relationship between port position, 
> piston travel, and transferring fluid from the reservoir to the MC bore and 
> brake lines.  Somehow, adding the residual pressure valve allows more fluid 
> to enter the MC bore, otherwise, I don't see how you end up with shorter 
> pedal stroke?
> 

>>>The RPV doesn't have anything to do with the master.   It keeps 2 psi 
between the valve, and the calipers, to keep the pistons extended.   
Otherwise, rotor wobble (or whatever) forces the pistons back into the bores 
slightly.   When that happens, your FIRST application of the pedal first repositions 
the pistons into their proper location, and only then does braking take 
place.

I drove a JFZ Pantera for about a half hour without using the brakes; 
coming off the freeway offramp the pedal went almost all the way to the floor.   
I instinctively pumped the pedal, and on the second (somewhat panicked) 
application, the brakes responded RIGHT NOW, and practically threw me through 
the windshield.

That's what an RPV prevents.   With the RPV, the brakes respond exactly the 
same way, each time you use them, just like a conventional car (to include 
a Pantera with non-racing brakes).

Mike