Mc/pb ???

[jspd234]

Hi all, do i need a proportioning valve when I use a cv mc/pb on my 72?

[EasyE]

I'm not the final authority on brakes, however from what I've read if you have disc front/drum rear then you DO need a proportioning valve. If it's disc/disc, then you DO NOT need one. The intent of the proportioning valve is to keep the front discs brakes from engaging until the shoes of the rears have made contact with the drums. Read the paragraph on proportioning valves at the bottom of this link for more info:
http://www.classicperform.com/How/How-M ... p-Work.htm

However, if it's disc/disc then you should install bias valve (such as this one from Wilwood: https://www.summitracing.com/parts/wil- ... /overview/). The bias valve adjusts how much braking force is applied to the front and rear brakes and if adjusted properly will equalize the braking force preventing the rear from braking loose under heavy braking.