Wilwood proportioning Valve

[Miles]

39 minutes ago, grannyknot said:

How did you even that out, prop valve on the front?

Does not make sense. If high front bias a PV on the rear would make it worse

[JMortensen]

2 minutes ago, Miles said:

Does not make sense. If high front bias a PV on the rear would make it worse

Not if the prop valve was set to a lower setting than the stock one it replaced.

[calZ]

He didn't say prop valve on the rear, though. He said a prop valve on the front. 

[Miles]

1 hour ago, JMortensen said:

Not if the prop valve was set to a lower setting than the stock one it replaced.

  Some members just gutted the stock PV. Don't know how effective it was though.

Edited June 3, 2020 by Miles

[JMortensen]

As I mentioned on the previous page, a prop valve in the front is never a good idea. As brake pressure increases, the proportion of braking done by the circuit with the valve decreases. With a valve in the front, the harder you hit the brakes, the lower the percentage of front brakes you get. This is not good, because the harder you hit the brakes, the more weight transfers to the front wheels and off of the rears. So the wheels with less traction get an increasing proportion of the braking effort as you step on the brakes harder and harder. 



"Proportioning Modifications We could start this section by clearly stating that you should not modify your proportioning valve. But, what fun would that be? In all seriousness, making changes to the proportioning valve to effect brake bias should be left to those with the proper tools and measurement devices, but if you have tweaked your vehicle beyond recognition, this may be your only solution to restore a sense of proper bias to your braking system. We’ll start here with three of the most basic rules regarding proportioning valve installation and selection.

1. If you have the deeply-rooted need to install your own adjustable proportioning valve, be advised that they should NEVER be installed if the factory unit is still in place. Proportioning valves in series with one another can do nasty, unpredictable things!

2. If you have the deeply-rooted need to install your own adjustable proportioning valve, be advised that they should NEVER be installed in-line to the front brakes. The effect would be to make your vehicle rear-biased before you could say “terminal oversteer.” Front brake line pressure should always be left alone – only the rear pressures should be considered for proportioning.

3. In all cases, the basic brake system balance needs to be close to optimized to start with. This is the only way that a proportioning valve can be effectively utilized. You should never assume that simply adding a proportioning valve will address all rear-bias conditions, as even the best proportioning valves must be well-matched to the target vehicle."

https://www.apcautotech.com/getmedia/d958a29e-4ebf-41fd-931f-bf7e4451801b/brake-proportioning-valves.pdf

Edited June 3, 2020 by JMortensen

[madkaw]

On 6/2/2020 at 6:53 PM, grannyknot said:

How did you even that out, prop valve on the front?

I hate to even say because my memory is so bad . I followed the instructions and recommendations that came with the kit . I do a a proportioning valves between front a rear brakes - set up where my old parking brake was. I remember that I had to put most of the bias to the front . I run wildwoods all around . It’s not the big kit , just two puck 11” I think 

[Miles]

2 hours ago, madkaw said:

I hate to even say because my memory is so bad . I followed the instructions and recommendations that came with the kit . I do a a proportioning valves between front a rear brakes - set up where my old parking brake was. I remember that I had to put most of the bias to the front . I run wildwoods all around . It’s not the big kit , just two puck 11” I think 

Is this a race car? 

[Ben280]

It sounds to me like Madkaw has a prop valve installed in the rear circuit, and has it dialed all the way down. You can only "bias" a dual master cylinder system, otherwise you are proportioning the amount of force to the rear. This would be mostly in line with what OP had to do. 

 

Would be helpful to know the model Wilwoods you are using, as saying you are running Wilwoods all around is just like saying "I run calipers all around". If you know the MC size and the size of your pistons in the caliper, you can do some pretty simple math to tell you where you should be, and how much prop valve you need to throw at it. 

[madkaw]

This kit I bought 15 years ago was considered a street kit.

 

http://www.arizonazcar.com/brake.html