Brake Failure :(

[NickSampson]

The other day i was going down the road and i hit my brakes only to feel an extremely hard pedal with barely any stopping power. The brake light has been coming on intermittently on hard stops for about a month. Im assuming my powermaster is crap, before i convert back to vaccum is there anything else that would cause this? After the hard pedal when i was limping home, i heard a whining and the power brakes came back but went out soon after. Any ideas?

P.S its a 1987 GN(we2) completely stock.

 

[87-WE2]

See stickies above about diagnosing powermaster issues. Sounds like the accumlator though.

 

[bison]

Brake light coming on continuously indicates accumulator is weak and or leaking check valve. Hard pedal out of nowhere indicated loss of power assist. Check the fuse. If it's blown the motor is likely shot. If not verify the pressure switch is functioning. If the motor runs continuously it's not good. If it runs against high pressure from a failing switch it's not good either. Following the flow chart will lead to the answer. Stuck check valve is often missed. Sounds like there are at least 2 problems with your powermaster.

 

[87-WE2]

Also note that if it is the accumulator, they're about $200. For a few $$ more (about $60), you can buy thebrand new vacuum setup from gbodyparts and convert it. Before doing so, verify you've got the vacuum from the engine though. I think you need about 15in minimum of vacuum to properly count on them. The vacuum setup works great on a streeter.

If you're looking for more holding power for foot-braking your launches, hydroboost conversion may be the way to go. Many swear by their hydroboost setups. As far as I know, there's no one selling a complete hydroboost conversion setup. I think if anyone were to offer one, they'd make a killing on them.

Then there's the S-10 manual setup. I don't know much about that one, but there's plenty of info on the board to search about all three different routes.

You can always buy a Cardone reman powermaster with a "lifetime warranty" too. The whole powermaster thing worried me so badly that i changed to vacuum without it ever apparently going bad. Still have it in a box just in case a future owner ever wants to go back to stock. I never will.

 

[Chuck Leeper]

IMO, with an 11" rotor, and the smaller diameter bore calipers, a 3700# car, vac brakes may be ok. A HB is far and above, the better choice.
But, unless the m/c is a 1" bore, [or even a 15/16"], manual brakes may not be the solution. The 15/16" bore will add psi, but at the expense of added travel on the pedal.
CPP offers a 2.75" bore caliper that will help.
Most aftermkt brake suppliers, such as MPB, etc, suggest 1200psi to get good brake performance. The HB on my 55 is operating at 2100.
Even at 48KPA vac, the 11" rotor, soft pads, 8"dual booster, 1 1/8" m/c, I got a miserable 6-700psi. That = worse than poor stopping.
Adding the 2 3/4" calipers helped, but was not satisfactory...
Bottom line: The 55, [at 3400-3500#], stops like it should w/ a minimum of pedal effort.

 

[NickSampson]

i did an ohm test on the pressure switch itself and the terminal closest to the firewall had no continuity with either of the other terminals.
Should i go buy a pressure switch or keep running tests?