Brake pressure proportional valve

[nicholas garn]

Hi guys, I'v read alot on the forum on this subject but didn't find an end solution. The IVA states that:
Note 4: Hydraulic valves that only operate automatically and react to vehicle loading or braking forces are permitted (Load Sensing and Gravity valves) Manually adjusted valves (other than to permit presetting the automatic function of a valve) are not permitted to be fitted even if they are rendered un-adjustable.

I'm using disk brakes all round so has anyone else used a proportional (bias) valve to stop the rear wheels locking up before the front? I understand the reason for using an adjustable valve but the IVA have seemed to made life a little difficult

Any help on this as i'm starting to assemble my brake system this week.