Brake balance

[Nigel Fox]

My Live axle Zetec powered car is fitted with James Whiting Alcon 4 pot calipers on standard discs on the front and Peugeot 205 calipers on Fiesta discs on the rear. Mintex1144 all round.

Single comp master cylinder, Willwood bias valve in rears wound to maximum.

The braking is a bit disappointing. I can lock the fronts easily but suspect the rears aren't working very hard. 
The car is used for sprints and hillclimbs only.

The rear caliper piston area is only 25% of the front. Does anyone have a feel for what the front to rear ratio of caliper piston area should be?

[Richard Price]

Nigel,

take the guesswork out of it! 

Dual mastercylinders with a bias bar is the way!

you should have blat mail.

[Ivaan]

Nigel,

Richard done this for me on the R1 BEC and now with a disc conversion on the rear, she pulls up like a Caterham should. No front locking. The rears do a surprising amount of the braking effort.

If you want some photos let me know.

If you want a pair of matching Willwood master cylinders ( from memory 3/4" and 5/8" bores ) with integral reservoirs, I have a set you can have.

The only problem is that with two mcs, it takes twice the foot pressure to brake. But you soon get used to it.

Clive.

[Nigel Fox]

Clive,

Thanks for the reply, sorry I seem to have missed it.

Richard has sent me some pictures of his car and your car which has the same pedal box as mine. I am going to replicate that design.

I would be interested in your master cylinders, could you send me details?

[Ivaan]

Will do Nigel. I'll photograph them when next in the garage.

I should say that they are spare because I swapped to AP.

Because of the heavy pedal, I wanted to swap to smaller diameter and Willwood didn't go down to 1/2".

From memory, I think the AP one's are 1/2" and 5/8". I know they were about 4 times the cost!

Clive.

[Richard Price]

Clive,

if they’re AP racing CP2623 family, then the smallest they go are 14mm, so you’re likely to have the 14mm on the rear, and a 15.8 mm (0.625”) on the front.

1/2” remote reservoir cylinders are now available , so, if you still wanted to reduce pedal pressure further, you could go that way (I remember when we did yours, Rallydesign had them in their catalogues, but could not actually supply them!!)  

[Ivaan]

This is the current set-up. They are remote AP MCs with motorcycle reservoirs .

Nigel, I've put the Willwood MCs away in a "safe place", somewhere in the garage. I've hunted for them but the little blighters are hiding well. I'll take another look over the weekend.

Clive