[DeTomaso] Wilwood Brakes WTF????

[gow2 at rc-tech.net]

I think problems such as these are never full information or apples to
oranges discussions.  As was said many systems may incorporate a pressure
valve in the system already.

Having build a brake system from scratch for the MGB I originally went
with no pressure valve from the advice of others. What I found was the
return was way too much.

In the MG system it is un boosted so the master was calculated for optimum
pedal. These calculations included everything about 10 parameters from the
arm of the stroke to the size of the pistons. A master was chosen to
optimise the unboosted stroke.

What I latter found and so did many others is the lack of residual valve
meant a lot more un needed fluid return awhich cut my stroke in half.
Braking was all the way to the floor.

Simple residual valves solved this problem and made the braking system
about as optimal as it could be. As was also said, this also makes for a
quicker braking reaction and no my brakes do not drag.

I am rebuilding the brake system on the Pantera and runing all new lines.
The system in before was actually put in by Dennos Quella which
incorporates a dual master with balance bar. He in fact added a residual
valve on both as I am sure I will too.

Another thing to consider is it is often said these are for cars which
have the master bellow floor. Well, consider the height in an MGB or a
Pantera. In many cars this would be an elevation which would be very near
the floor of other cars!!!!!

Gary


>
> I find this residual valve discussion interesting. Through last 15 years
> I've been into the hobby, I've seen it come up in several discussions
> and it's always the same. Some people are very strongly opposed to using
> any in disc brake systems unless the master is below calibers. Although
> the only real life case against it, that I've ever seen anyone report,
> is the one where somebody installed one in series with existing drum
> prop valve which has residual valve already, and got the brakes sticking.
>
> I wonder where the strong opinions come from? Maybe it's not needed if
> everything comes together, but what is the big deal against? I'd really
> like to hear from someone who actually installed one and can trace pad
> wear or other bad behavior to it. Until that I'll personally treat this
> as "You should always eat your vegetables" type of discussion and feel
> sorry for anyone who dares to publicly confess using RPV with disc
> brakes with normal master location.
>
> I actually bought RPV's for my mustang (with 4 wheel Baer discs and
> aftermarket distribution block), when I wanted to increase pedal ratio,
> but not have any extra pedal movement to be able to still heel and toe.
> Fiddling with pedal ratio (one pre-defined, easy to use, alternate
> setting for pedal ratio) I noticed that when you set up the pedal
> pushrod to give zero lash or minimal preload in the pedal, the vacuum
> booster actually provides a little residual pressure in the system. If
> you preload little too much with engine off and brakes not dragging,
> when the booster kicks in, you suddenly have drag. At least in my case.
> Perhaps the vacuum seal in my booster is less than perfect over time.
> The car had been standing for a long time when I made the initial
> adjustment.
>
> Then I noticed that the higher pedal ratio still let the pedal too far
> down to mess my heel and toe and so I went back to old ratio and
> adjusted slightest preload without drag.
>
> I did not come to think of checking if it was only front wheels
> dragging, as I have prop valve to the rears reducing pressure there. If
> that was the case, then maybe RPV in the rear circuit could have gained
> me little something...
>
> -Janne
>
> 4/18/2013 3:45 AM, richard bosch kirjoitti:
>> 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  :  )
>>
>> _______________________________________________
>>
>>
>>
>> Detomaso Forum Managed by POCA
>>
>>
>>
>> DeTomaso mailing list
>>
>> DeTomaso at poca.com
>>
>> http://poca.com/mailman/listinfo/detomaso
>>
>> _______________________________________________________________
>>
>> Annons: Skaffa Spray Mail du också - Gratis, enkelt och säkert!
>>
>>
>>
>> _______________________________________________________________
>> Annons: Skaffa Spray Mail du också - Gratis, enkelt och säkert!
>> _______________________________________________
>>
>> Detomaso Forum Managed by POCA
>>
>> DeTomaso mailing list
>> DeTomaso at poca.com
>> http://poca.com/mailman/listinfo/detomaso
>>
>>
>
> _______________________________________________
>
> Detomaso Forum Managed by POCA
>
> DeTomaso mailing list
> DeTomaso at poca.com
> http://poca.com/mailman/listinfo/detomaso
>