Downhill rear lockup

[70 LS1]

I was driving the car the other day and was testing the brakes. I did this downhill and the rear locked up first. I know you always want the front to lock slightly before the rear, but that is for a level surface.

I know I need to add an adjustable proportioning valve, but how do you know where to set it?

This is for a street only car that sees no track time. 1970 Corvette C5 front and rear rotors and calipers.

[zbugger]

Try it on level ground. Even down hill, you prefer the fronts to lock first, but depending on the grade it may throw off your adjustments.

[70 LS1]

Try it on level ground. Even down hill, you prefer the fronts to lock first, but depending on the grade it may throw off your adjustments.

So do I adjust it so the fronts lock just before the rears on level ground?

[6'9"Witha69]

So do I adjust it so the fronts lock just before the rears on level ground?

Yes. It is actually a suspension issue (brake hop) causing this on the downhill as there is more weight transfer to the front. Set the brake bias on level ground. Set as much pressure as possible to the back so it locks the rears first. Back out incrementally until it no longer occurs.Play around with finite adjustments in that area. Done as far as brake bias is concerned. My brakes work great on level ground, no lock up ever and a real quick stop!! Downhill braking while downshifting will cause the rear to lock slightly. I prefer a loose car to a tight one so it doesn't bother me much.