Time for today's brake related question...Disc/drum combo

mvh said

When you adjust the PV (assuming you have an adjustable type, like on the 67-72 K-H brake package), you are changing the point at which the "kink" takes effect. This is not the same thing as changing the overall braking effect from front to rear, or rear to front.

So when people tell me they have converted to front discs, didn't add a PV, and don't have any problems with their brakes, I am guessing they just haven't tried a full range of braking scenarios from soft, feathered stop to hard high-speed braking to full-on panic stop. Because without a functioning PV, you aren't going to get optimal braking performance under all these conditions.

Click to expand...

Thanks for saying and explaining this. There is a lot to setting F/R rear brake bias that a simple adjustable prop valve won't do. To the OP, yeah, there is tons of real world experience and good knowledge in this area but a lot of shortcuts are taken with using adjustable PV's; they will typically give you the right F/R proportioning over a relatively narrow range of braking system pressure, and fall outside of a good proportioning range with higher or lower system brake pressures. If you always drive on flat, smooth, dry pavement, the tire traction is good over a broad range which will tend to cover deficiencies in brake proportioning; throw in a rough road/pavement and some rain or loose gravel with a panic stop situatoin, and all of a sudden you will find out what improper proportioning is, perhaps in a bad way.

I would follow this statement: "The non-adjustable PVs in the 73-76 A-bodies should be a reasonable match for the typical conversion setup ("slider" front discs and 10" drums). "