Hello,

Re: 1985, F-250HD, 4x4, 460ci, XLT Lariat

Just purchased a CPP Master cylinder and the HydraTech Hydro Booster combo.

The CPP Master Cylinder has an internal proportional valve with adjustment for Rear Brake Pressure and Maximum allowed rear brake pressure.

I am running disc on the front and drum on the rear. I know the drum brakes can not take the same pressure as the Disc but what is the maximum break pressure I should allow to the rear drums? I don't want to be blowing out the cylinders. Note that I will be removing the rear load sensing proportional valve that is connected between the truck bed and rear axil via a pair of half moon arms. I understand these are prone to problems and don't work very well. So the rear brake line will run directly from the CPP Master Cylinder to the rear brakes

Does anyone have any advise on adjusting the proportional valve? The end application for the truck will be pulling a trailer

Thank you for any advise

Rgds

nonrev

 

The brakes will lock up before you blow anything out(unless you have a rusted line which is common). So the best thing for you to do is get everything installed and then do a road test. Slam on the brakes and see how easily the rears lock up. You can then adjust it down or up depending on your needs.

You will find empty they lock up very easily, and loaded not at all. That's the reason the factory put that gizmo on the rearend housing, but like you said some of this stuff was not very dependable.