Does anyone have a clue what the signs are that the proportioning valve is going out? My vette will have great pressure after a bleeding and then a week later it seems to loose some. Until the brake warning light is back on. I am not loosing fluid so I don't think I have a leak anywhere. Trying to figure out if it could be the master cylinder or the valve. Any help would be great.

Thanks,

James

James this is a pretty common problem . It can be caused by rotor runout ,,, this causes the caliper pistons to fluctuate in their bores and introduce air into the system . Installing oring style pistons in your calipers will cure this problem .

G

I agree with 4webbers. My brakes would fail all the time. I could bleed them and
everything was fine for a while , then no brakes again. I finally realized that
the problem was only showing up after prolonged high speed driving ( prolonged
being anything over about 10 minutes of over 60 mph ). Three of my rotors were
over cut and my pads were worn. New rotors and pads, now everything is fine.