Replacing my powermaster

pkschul

Member
Joined
Jul 23, 2002
I purchased a vacuum pedal from a member here and the vacuum block from Kirban's just came in.
Now I just need a booster/master cylinder right?
Just want to double check that I'm getting the right part.
I'm looking to purchase this...
https://www.napaonline.com/en/p/NBB501243

Please let me know if this won't work.
 
They also sell one with a single diaphragm booster. Will they both fit? I'm assuming the dual diaphragm is better?
 
Just order a vacuum booster and master cylinder for a 1987 Regal, non-turbo, and it will be a simple bolt-on with the vac pedal.
 
Make sure you get the dual diaphragm booster. Singles only came on Monte Carlos in 81. And also try to get an aluminum master cylinder if you can. They don't rust like the cast iron's they've been peddling for the past 10 years. All the stockers on G-bodies were aluminum.
 
And, at no extra charge::D

Remove the powermaster system. This is accomplished by removing the 15mm nuts securing the PM to the firewall. They are located on each side of the brake pedal. There are four. Two on each side. Remove these, using a long extension, deep 15mm socket and ratchet. Unfasten the brake lines from the master cylinder and disconnect the booster rod from the brake pedal. Unplug the electrical connections from the Powermaster unit and remove it.

Next job is to swap out the powermaster brake pedal. In order to do this, you need to drop the saddle that the pedal is attached to. The four studs that held in your powermaster are the main fasteners that holds the saddle in place. After removing the PM mounting bracket, there is still one more bolt holding the saddle in place. Looking directly at the brake pedal shaft, the bolt is threaded vertically up at the top of brake pedal. Only the head is visible. You should remove the brake light switch and the other switch above it that rest against the brake pedal shaft. Though they appear to be threaded in, they just pull out from the saddle. Take a long 3/8" extension with a 13mm socket. The bolt is about a half inch left of the pedal shaft. Remove this bolt and the saddle will be free. You can remove the saddle completely and when you re-install it, make sure the booster bolt holes align with the holes in the saddle. You may have to tap them with a hammer to align. This makes easier to slide in the booster, especially if you're alone.

OK, now with the new brake pedal and saddle installed, you can install the booster. Make sure the pin is in the recess in the frontcenter of the booster. It can fall out. It just slides in loosely. Install the booster into the firewall and through the saddle and before fastening the 15mm nuts inside the firewall, attach the booster rod to the pedal stud.

Next, you need to bench bleed the master cylinder. Place it in a vice just tight enough to hold it in place. They should include fittings you can use to bleed the master cylinder. Fit a hose tightly over each of the bleed fittings and run the other end of the hoses into the reservoir. Fill with clean brake fluid and then use a rod to push on the plunger of the MC. This will pump the air and fluid into the reservoir. Keep pumping it until all air is removed.

When this is done, you can attach the MC to the booster, reinstall the brake lines and you may be done. If there was no air in your brake lines before you attached the new MC, you will have a hard pedal. If there was air in your lines, your brake light will probably be on, your brake pedal will be low and will pump up. This indicates air in your lines and you'll have to bleed all your wheels, working from the farthest wheel away, first, and so on. If you're by yourself, you can bleed each wheel cylinder by attaching loosening the bleeder cock, attach a hose to it, and submerge the other end in brake fluid. Pump your pedal gently at least 5 or 6 times. Close the bleeder cock and move to the next wheel. Keep the MC filled with clean fluid as you go from wheel to wheel. Another way is to gravity bleed. Just unscrew all the bleeders in all four positions and let the fluid drip out. Keep the reservoir full and when you feel you bled it enough, tighten the bleeders and check your pedal.

If you don't have a TTA vacuum block, you'll have to get your vacuum from the PCV vacuum hose. Purchase a 3/8" vacuum Tee from any parts store. Basically, cut into the pcv hose an inch above the pcv valve and install the T in that line. Run a 3/8 fuel hose for vacuum. Run it to the check valve on the booster. Charcoal filter is not needed. This will provide adequate vacuum for your vacuum brake system.
 
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Man I wish I knew about the aluminum master cylinder before I ordered. That's the kind of info I was looking for when I started the thread. Thanks. I'm not sure what rockauto is going to send. Anyway it should arrive today. I think I'll have all the parts now except I'll need a vacuum line. I should probably replace all the smaller vacuum lines off the block too. Anyone have vacuum line size specs?
 
I want to give Boxcars a big Thank You for his post from May 10th. I didn't realize at first but there are a lot of little details in there that I haven't seen other places. It saved me a ton of time I'm sure. I have my vacuum booster brake system stopping the car on a dime now. Thanks man!
 
I want to give Boxcars a big Thank You for his post from May 10th. I didn't realize at first but there are a lot of little details in there that I haven't seen other places. It saved me a ton of time I'm sure. I have my vacuum booster brake system stopping the car on a dime now. Thanks man!

Hey, great! Glad my post was able to help you out. :)
 
I want to give Boxcars a big Thank You for his post from May 10th. I didn't realize at first but there are a lot of little details in there that I haven't seen other places. It saved me a ton of time I'm sure. I have my vacuum booster brake system stopping the car on a dime now. Thanks man!


Not sure what you went with but don't use vacuum line to the booster. Unless you have a check valve, that hose will see boost. On my kits I send fuel line. That way I know it won't burst and fuel fumes from the intake won't compromise the hose.

Also if you're running around 30PSI or so, I'd recommend deleting the charcoal filter. Yes, the life of the booster might get shortened but it's worth it to avoid the risk of splitting that filter and only having 2 or 3 pumps before ending up with manual brakes.
 
I have done 100 or so vacuum conversions and will add my comments.

First of all do NOT use fuel line as 11/32" hydraulic pressure hose should be used. Also, the tee fitting must be brass, NOT plastic.

When changing the pedal, I have always just removed the pivot bolt, not the saddle?

As far a bleeding the system, I install the new master cylinder that has been bench bled, and leave the lines loose for 15-20 minutes as they bleed slowly on a rag. I then have someone slowly push the pedal until it is to the floor and tighten the lines to the MC.

Do this MC bleed 2 or 3 times and you should have a firm pedal w/o having to bleed the wheel cylinders.
 
I have done 100 or so vacuum conversions and will add my comments.

First of all do NOT use fuel line as 11/32" hydraulic pressure hose should be used. Also, the tee fitting must be brass, NOT plastic.

When changing the pedal, I have always just removed the pivot bolt, not the saddle?

As far a bleeding the system, I install the new master cylinder that has been bench bled, and leave the lines loose for 15-20 minutes as they bleed slowly on a rag. I then have someone slowly push the pedal until it is to the floor and tighten the lines to the MC.

Do this MC bleed 2 or 3 times and you should have a firm pedal w/o having to bleed the wheel cylinders.
 
I have done 100 or so vacuum conversions and will add my comments.

First of all do NOT use fuel line as 11/32" hydraulic pressure hose should be used. Also, the tee fitting must be brass, NOT plastic.

When changing the pedal, I have always just removed the pivot bolt, not the saddle?

As far a bleeding the system, I install the new master cylinder that has been bench bled, and leave the lines loose for 15-20 minutes as they bleed slowly on a rag. I then have someone slowly push the pedal until it is to the floor and tighten the lines to the MC.

Do this MC bleed 2 or 3 times and you should have a firm pedal w/o having to bleed the wheel cylinders.
 
I have done 100 or so vacuum conversions and will add my comments.

First of all do NOT use fuel line as 11/32" hydraulic pressure hose should be used. Also, the tee fitting must be brass, NOT plastic.

When changing the pedal, I have always just removed the pivot bolt, not the saddle?

As far a bleeding the system, I install the new master cylinder that has been bench bled, and leave the lines loose for 15-20 minutes as they bleed slowly on a rag. I then have someone slowly push the pedal until it is to the floor and tighten the lines to the MC.

Do this MC bleed 2 or 3 times and you should have a firm pedal w/o having to bleed the wheel cylinders.


Well, I haven't done a hundred changeovers to vacuum brakes, but I've removed well over 200 assemblies from G-bodys in boneyards, over the years, which most of them I sold here on this board. I don't have a problem with folks choosing to use 11/32" hydraulic pressure hose or a brass Tee, and it's probably good advice, but I've been using 3/8" fuel line and 3/8" plastic vacuum Ts on my own turbo cars for 15 or so years without a failure. Now, I realize, there's always a first time. :D Also, when I would take these vacuum brake systems in the junk yards, vacuum booster w/ check valve, master cylinder, and brake pedal, along with fasteners, I would just remove the pivot bolt, to remove the pedal, but if you were trying to install the vacuum brake pedal on a new installation with the saddle in place, it's almost impossible to line up the pivot bolt, through the saddle and through the pedal because A. you can't see it, and B. There's not much room, and C. People only have two hands. It can be done. I did it once, I think, but I wouldn't want to do it that way again. :inpain: Removing the saddle makes it a piece of cake. Don't forget, with the booster out, there's only one bolt holding the saddle in place. Hey Nick, maybe your vacuum brake install guys have been fibbing to you. :D
 
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Thanks for the comments. I picked up the line from a local NAPA. They didn't have vacuum line that would fit so I did end up needing to buy fuel line.
As for the plastic T, do you mean the vacuum fitting connected to the booster? I used the stock fitting that came with the booster which I do believe is plastic. I did the job all by myself so while I did bench bleed the master cylinder I couldn't pump the pedal while tightening the lines. I think it's ok though because I did bleed at each wheel. (The car had been sitting for 14 years after all)

Not sure what earlbrown is talking about re: charcoal filter. I'm running stock boost so I don't think it matters.
 
Thanks for the comments. I picked up the line from a local NAPA. They didn't have vacuum line that would fit so I did end up needing to buy fuel line.
As for the plastic T, do you mean the vacuum fitting connected to the booster? I used the stock fitting that came with the booster which I do believe is plastic. I did the job all by myself so while I did bench bleed the master cylinder I couldn't pump the pedal while tightening the lines. I think it's ok though because I did bleed at each wheel. (The car had been sitting for 14 years after all)

Not sure what earlbrown is talking about re: charcoal filter. I'm running stock boost so I don't think it matters.

Earl was correct. You do NOT want to use line that is specifically for vacuum. Like I said. I used 3/8" fuel line for my vaccuum and connected it to the plastic -- check valve -- that plugs into the booster. The charcoal filters were original equipment installed in the vacuum line before the booster check valve. Most guys get their vac brake systems in the boneyards and take the charcoal filter too. It's not necessary to use it.
 
Has anyonbe tried with tgfe current pedal?

I put my hydraboost in a while,ago and used the same pedal

I'm trying the held a buddy put in a vacuum or hydraboost in his car
Could not get the hydraboost to work will try vacuum setup



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