[DeTomaso] Wilwood Brakes WTF????

eb0711 at kolumbus.fi eb0711 at kolumbus.fi
Fri Apr 19 05:03:20 EDT 2013


Now that you say this, your first sentence makes perfect sense to me. 
When I mentioned putting slight preload to the pedal rod in my Mustang 
system, I meant working against the spring pushing pedal back in the 
booster/master combo. When there's spring in the system pushing pedal 
back, it should retract pistons as well?
Now I'm beginning to wonder if my approach of putting slight preload to 
rod might not allow new fluid to enter the lines to compensate pad wear? 
RPV might still be the better way...

If the RPV limits travel at pad, it reduces required travel at pedal.

-Janne

4/18/2013 7:10 PM, Ken Green kirjoitti:
> 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?
>   
> Ken
>
>
> ________________________________
> From: Tomas Gunnarsson <guson at home.se>
> To: detomaso at poca.com
> Sent: Wednesday, April 17, 2013 11:49 PM
> Subject: Re: [DeTomaso] Wilwood Brakes WTF????
>
>
> Nothing. There's no mechanism actively retracting the pistons and that's
> why the valves are not needed. The only retraction you should see is
> rotor kickback and the flex of the piston seals. If you have excess
> kickback that's a problem in itself, nothing you "fix" by adding pad
> preload with valves.
>
> Tomas
>
> <-----Ursprungligt Meddelande----->
> From: richard bosch [theemonkey at yahoo.com]
> Sent: 18/4/2013 2:52:25 AM
> To: Tomas Gunnarsson
> Cc: detomaso at poca.com
> Subject: Re: [DeTomaso] Wilwood Brakes WTF????
>
> So what keeps the pistons from retracting too far?
> Just curious how it is designed without the valves.
> --- On Wed, 4/17/13, Tomas Gunnarsson <guson at home.se> wrote:
>
> From: Tomas Gunnarsson <guson at home.se>
> Subject: Re: [DeTomaso] Wilwood Brakes WTF????
> To: theemonkey at yahoo.com
> Cc: detomaso at poca.com
> Date: Wednesday, April 17, 2013, 2:08 PM
>
>
>
> No, I have disassembled both master cylinders and calipers down to bare
> castings and there are no valves.
>
> Tomas
>
>
>
> <-----Ursprungligt Meddelande----->
>
> From: richard bosch [theemonkey at yahoo.com]
>
> Sent: 16/4/2013 10:52:14 PM
>
> To: Tomas Gunnarsson
>
> Cc: detomaso at poca.com
>
> Subject: Re: [DeTomaso] Wilwood Brakes WTF????
>
>
>
>
>
>
>
>
>
> It could be that only the American cars have the valves in the master
> cylinders.
>
>
>
> Maybe Europeans have them in the calipers or distribution block?
>
>
>
> They have to be somewhere in the brake system or else you have a delay
> in the brakes being applied as the pistons would have a much longer area
> to traverse before they contact the rotor.
>
>
>
>
>
>
>
>
>
>
> --- On Tue, 4/16/13, Tomas Gunnarsson <guson at home.se> wrote:
>
>
>
>
> From: Tomas Gunnarsson <guson at home.se>
>
> Subject: Re: [DeTomaso] Wilwood Brakes WTF????
>
> To: theemonkey at yahoo.com
>
> Cc: detomaso at poca.com
>
> Date: Tuesday, April 16, 2013, 6:06 AM
>
>
>
>
>
>
> Must be an American thing. Euro master cylinders I've come across have
> no valves built into them.
>
> Tomas
>
>
>
> <-----Ursprungligt Meddelande----->
>
> From: richard bosch [theemonkey at yahoo.com]
>
> Sent: 16/4/2013 1:10:46 AM
>
> To: detomaso at poca.com
>
> Subject: Re: [DeTomaso] Wilwood Brakes WTF????
>
>
>
>
> Disc brakes require 2 psi residual pressure valves.Drum brakes have 10
> psi. valves.
>
> Most master cylinders have them under the flare seat  where the brake
> lines are screwed in thats why you do not normally see them or think
> about them.
>
> Without the residual pressure the pistons retract much further in the
> caliper and there is a delay while the piston has to travel further
> before it contacts the rotor.Not good as seconds count in braking
> distance!
>
> Mike's valves are "add ons" because his master cylinder does not have
> any valves built in.His valve pressure is correct as the pads did not
> drag on the rotors before the pad wear/cocked pad happened.
>
> Just what i have learned from playing with lots of cars  :  )
>
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