power master-Hard pedal, weak brakes...

[BOP4ever]

Just wondering if this was a regal thing or a problem with the power master...
Normal stops the brakes feel very good but in a semi panic stop the pedal just got hard and I could not lock up the brakes if I wanted to .... The brake light works and is not coming on and under normal driving everything seems fine bu liek I said panic stop and it just does not stop very quick...kinda feels like your not in control ...my 96 work truck would stop shorter from 60 mph...

I have a complete spare PM that came with the car new in the box... if that is the problem... could it be a rear brake adjustment issue ?

If I need to change the PM unit is there a step by step process and any pit falls or tricks to make it go easier ?


Thanks !!!

 

[wolfmann442]

Face it bud,your in the same boat i am in.Vaccum brake conversion!



http://www.turbobuick.com/forums/br...good-ol-powermasrer-problems-please-help.html

 

[FreeBoost]

It's probably just the accumulator.

 

[BOP4ever]

Can I change that without changing the whole PM unit ?
That is the little ball deal on the side right ?
It looks liek it screws on the side of the unit. I would assume you have to pump the brakes to discharge any pressure in the system then remove it ?

Can I buy those seperate or do I just have to rob it off my spare unit ?


Thanks

 

[carlsbadGN]

Yes, you can change the accumulator w/o changing the entire PM assembly. It is the ball attached to the side of the PM.

All you need to do is pump the brake pedal (with key off) about 12-15 times to de-pressurize the accumulator. The pedal will be very hard after all the pressure is relieved. Put a rag under the old accumulator to catch any drips then screw it out. Lubricate the o-ring of the new accumulator with brake fluid and screw it in, torque to about 15-20 lbs. After the new one is installed, pump it down (de-pressurize) a couple times to insure all the air is out of it.

If your brake fluid is old and dirty, or been in the car for a long time, you should replace it with fresh fluid before changing out the accumulators.

 

[BOP4ever]

So I should bleed the brakes first then change the ball with the one off my spare PM unit ? Can you buy the ball seperate ?
I guess I would need to bleed the brakes again after changing the ball as well ?
Any reason I can't just change the sucker and bleed it down one time ?

Weird It will hold 5 psi on the brakes, but feels weak trying to stop the car ...


Thanks

 

[FreeBoost]

So I should bleed the brakes first then change the ball with the one off my spare PM unit ? Can you buy the ball seperate ?
I guess I would need to bleed the brakes again after changing the ball as well ?
Any reason I can't just change the sucker and bleed it down one time ?

Weird It will hold 5 psi on the brakes, but feels weak trying to stop the car ...


Thanks

Bleed the brakes after. If you've never bled the brakes the bleed valves may be siezed in the slave cylinders. Pick a MityVac of some other vacuum bleed kit - makes bleeding way easier.

Kirban sells accumulators you might be able to find them else where - search the posts.

 

[carlsbadGN]

You only need to replace (bleed) the fluid once. I do it before changing the accumulator but I suppose afterwards makes no difference.

Since you already have the accumulator on the new PM assembly, just take it off and install it on your car. If that doesn't fix your problem, then you know to look for something else. If the problem is solved, change out the fluid. Take a close look at the brake pads and shoes while your mind is on brakes.

By the way, Kirban's sells recharged accumulator units and they are not particularly cheap.

 

[BOP4ever]

Thanks, I'll give it a try !
The Brake light has come on before intermittently, but the brakes never felt any worse , but right now the brake light is staying off but the brakes just feel weak...

 

[BOP4ever]

I swapped out the accumulators this evening after changing the oil. It is slightly bigger... I turned the key on and the motor came on and ran for maybe 20 seconds and shut off... the pedal felt ok maybe a bit spongy, but the brake light is staying on... I have not bled the system yet so I am hoping that is why....Is this normal ? I'll get it all the ramps and bleed the brakes tomorrow.

 

[FreeBoost]

Another trick that will stiffen up your brakes is replace your rubber brake lines with braided steel brake lines.

 

[carlsbadGN]

Go ahead and bleed the brakes, making sure to run enough clean brake fluid through it to flush the system. De-pressurize the new accumulator a couple times (or more) until you see the fluid coming out clear, with no air bubbles.

The PM motor running for so long is not a good sign and it may be giving up the ghost. There is a ton of posted material here on this issue and you can go to GNttype.org for more PM diagnostics. Good luck.

 

[FreeBoost]

Pick a MityVac of some other vacuum bleed kit - makes bleeding way easier.

If you use a vacuum bleed kit you won't have to run the pump.

 

[BOP4ever]

How do I bleed the rear ! I dont see any bleeder screws !!!
Feels like there may be a rubber plug or something above the brake line...