Red_bull

Hello guys,

I have some brake issues and I have a trackday comming, so this issue needs to be sorted now else i can't take this car.

I have rear brake upgraded to disks, the cosworth onces. As rears locked i bought an eBay proportional brake valve for the rear. I followed instructions of a dutch Guy and fitted it like this:

4 outs, two front, two rear, on master
Front two go to left and right front brakes
One back on master is blocked off and other back goes as single line away from the master cyl. Then the proportional valve is fitted. Out from PV to the back. T-piece and to the brakes.

First it seems to work. Later started locking. Didn't react as expected on adjustments, so contacted the company. Reaction it might be broken we send a new. New fitted exact same issue. The eBay company has good feedback and start to doubt my set up.

Did i do the mounting on the master wrong? Is the pressure out of the master equal on all 4. Do i create a problem by blocking one?

Any feedback would be highly appriciated!

Red_bull

Had somebody at the car today and checked there is a 22mm master cylinder mounted and this is the brake pressure adjuster that i have





Nobody that has seen issues with these before?

simonmcf

iTrader: (1)

Maybe block off one of the front ones? My setup is same but not tested

Chas

This will sound backwards for sure, but if all else fails can you go back to an S2 drum setup or have things been changed too far?

nigel b

the pv might not have the adjustment you need
if it still locks with it on then it isnt restricting the line enough
you need very little braking on the rears with calipers

Red_bull

Yea i think if all fails that i have to, but it would be ashame of all the money that is put in!

Red_bull

It says it adjusts 60% and some many other people have it, so i don't understand why my setup does not work. What i have done today is the following

1. Handbrakecable was removed. Tried the setup and still locks the rear
2. had ferodo brakepads on the rear and standard on the front, so put my set of ferodo on the fronts aswell, still locks the rear
3. bleeding front brakes. Little little air came out, but no difference

saterday i will test the PV on a braketestbench (RR type) to see if it makes any difference. I have ordered a willwood prop valve as back up plan

Does anybody know how much the standard prop valves of ford reduce? I mean the two that are mounted in the front. i still have a set laying around, but also i'm not sure which is in and which is out. Does anybody know out of their heads?

I will also order cheap ass brakepads for the rear to see if that does anything

Anybody that runs the same set up as me? What brake cylinder do you use?

If i would go from 22mm to 25mm what difference would it make? i would say more fluid travels with less pedal movement, so that wouldn't make any difference to a front-rear distrubution.

Are there any brakecylinders with two different size pistons inside? Then it would be easier to send less fluid to the rear and create more brake power on the front

Red_bull

This sounds like i am running the wrong master cylinder. Googled a bit an a bigger bore size will give less pressure. However i don't understand why it would change the front-rear pressure?

Have checked what piston diameters i need to have to check that on saterday. Front needs to be 60mm for the 4x4 sierra/escosworth and rear 43mm for the cosworth 2wd or XR4x4.

Maybe i have an issue in my master cylinder, so will have a look if i can swap that one for another one.

I WILL GET IT FIXED FFS

Chas

To get the right pedal I suggest using the equation on Rally Design's PDF:

https://www.rallydesign.co.uk/pdf/de...pot_brakes.pdf

This was the case with when I had the Wilwoods on mine. Going to the Cosworth calipers gave me a much better pedal.

Red_bull

Issue is found! It was the brake bias adjuster. On to the trackday! Now mapping needs to be finished!