after 2 bad rebuilt and one new powermaster unit kicked me in the nuts i installed a new booster and power brake system.installed an 87 ss proportioning valve ,although never researched if it was different than the turbo car counterpart.anyhow.even with new rotors,calipers pads and hoses and not the cheap stuff mund you,the front breaks constantly smoke when applied after pushing the car hard.adjusted the rears without any improvement and no nose diving showing unbiased apply pressure.on the lift the rear brakes are also slow to apply.installed a vaccum can and still no improvement.all new parts and the symtom to me is inadequate front apply pressure.any ideas.im fed up with a slow stopping car and my front pads smoking at every light .the calipers are not dragging for those of you who may be thinking such ,neither are the hoses .all new.any help would be appreciated.
ditched powermaster,cant get vaccum to work right.
- Thread starter chris718
- Start date
- Joined
- Jun 18, 2001
Smoking brakes are an indication of excessive heat.
Ummm, think about that for a second. If the pressure in the front was inadequate, how could you possibly smoke them?
How do you know they aren't dragging?
How hard are you trying to stop? With good tires, these things *MIGHT* stop from 60 in 180 feet with stock brakes. More than two stops from that speed in quick succession, and the stock brakes are smoke. The car car 10.25" rotors, single piston calipers, and weighs 3600lbs. If you're smoking the brakes at every light, either your calipers are dragging or you're working the brakes too hard.
the smoking is a sign of the friction pad slipping against the rotor,much like a piece of metal held against a grinding wheel,or rubbing your hands together.imo without a doubt the pressure applied to stop the brakes is inadequate.my 10 second ss with the same brake system and about 300 more hp stopped faster and without the heat.does anyone know how much psi shoulb be in the line under full stopping?im sure i could fasten a gage to the caliper bleed hole to check.
John Larkin
Sublime Master of Turbology
- Joined
- May 25, 2001
Sometimes pads come with stick-on shims for the puck to push against. Maybe it shimmed the pad so close that it is borderline dragging. Theory has it that the prop valve does not allow fluid pressure to the front calipers until the system reaches 75 psi. This is supposed to allow the rear wheel cylinders to activate first since they require more fluid movement. Just some random thoughts....
Red Regal T
Senior Member
- Joined
- May 24, 2001
Maybe you should go back to a stock proportioning valve.
What kind of vacuum brake system? Stock replacement or some kind of aftermarket system?
What kind of vacuum brake system? Stock replacement or some kind of aftermarket system?
have a stock 87 ss mastr cylinder ,booster and proportioning valve.pads have been changed several times.same results with delco,and wagner thermo quiets.these parts should stop the car with ease as the ss is virtually the same in the weight department and weight placement in the chassis .anyone using this setup?i understand the theory behind the introduction of the powermaster to a turbocharged vehicle due to the limited volume of vaccum generated with a positive pressure forced induction system inherent with turbocharging.what did the 78 79 regals that were turbocharged use for front brakes?the same system i have retrofitted,correct?i certainly think the proportioning valve needs to be investigated,but i want to measure psi in the front to be sure.anyone know the psi specs at full brake apply?
Red Regal T
Senior Member
- Joined
- May 24, 2001
A better question would be, why did GM put a vacuum brake system in the 89 TTA. To get a way from the PowerMaster, of course. Earlier turbo cars had the power steering related hydro-boost brakes. Turbo cars have the same vacuum as a non-turbp car, except while in boost. However, the check valve on the cannister holds vacuum in the cannister when boosting. There's just something wrong with your system. Perhaps with one of your new parts. Did you change the brake pedal?