Vacuum Brake Conversion

earlbrown

runs with scissors
Joined
May 26, 2001
Gather up all the parts you'll need. Don't forget a large jug of BRAND NEW brake fluid too. No reason to use some old stuff that's been absorbing water for years.

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First is removing all the Powermaster stuff.
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Standard safety stuff here... Make sure to depressurize the system (odds are if you're doing his is because you don't have any pressure in there. lol), And keep some rags handy to mop up any spilled brake fluid. It makes plastic look good but will eat up some paint!

Once the two electrical plugs are removed, take the two brake lines and two mounting nuts loose. I find that vacuum caps make great seals for the exposed brake lines.

Next, remove the under dash cover and remove the clip that holds the Powermaster rod to the brake pedal. It helps to have a second person under the hood to move the Powermaster but it can be done alone. After it's disconnected from the pedal, it can be removed.

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Then remove the adapter plate that converts from the 4 bolt mount on the firewall to the two bolt mounting pad for the Powermaster.

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This little part is the reason there's two different pedals. It causes the Powermaster to point down a few degrees and as a side effect causes the pin location on he pedal to be higher.

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While you're under there, remove the pedal as well.

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Install the vacuum diaphragm and master cylinder.

Notice the front and real lines have been swapped relative to the Powermaster. Front is not rear and rear is not front. Much like doggie style.Luckily, thanks to the additional spacing of the booster one of them lines right up. The larger of the two lines need to be curled up to mate with the front of the master cylinder.

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If you trust yourself not to kink the lines, it can be bent with your thumbs. If you don't feel that confident you need a tubing bender. Oddly enough the ones you can rent from the auto parts store wont' work. The one you need comes from a home improvement store like Home Depot. That one will go down small enough to handle the small brake lines. It can be found in the plumbing section.

Once the line is tweaked it can be attached to the master cylinder.



Once the pedal is out it can be modified to accept the new pin for the vac brake kit.
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Measure 1-1/4" down (center to center) and closer to the edge. That is the new location for the pin. Notice the edge of the pin is now parallel with the large flange on the Powermaster pin.
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Drill a 13/32 hole at that location. Then drill that hole out to 7/16" but ONLY go 1/3 of the way through. This is to get the pin started so that it can be pressed into place.

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Put the pin on position with the cotter pin hole facing vertically and miss the Powermaster pin. Then smack it in place with a framing hammer. ...or if you have an arbor press, press, or vice I guess that will work too :D
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Note: This is the "no weld / press fit" method. If you have a welder or a torch, feel free to start out and 7/16" and weld it.

Once the pin in installed the pedal can be put back in the car. Notice with this method the car can be returned to stock without having to drop the pedal again. You also don't have to lose sleep at night and feel shame knowing there's a Chebby part on your Buick!

Next is to run the vacuum line to the engine. Route the hose under the coil pack and tee into the PCV hose. Put the check valve before the tee. That way you'll keep from sending boost into the booster and it'll also keep boost from hitting the PCV valve. Bonus!
Another way is to get a aluminum vacuum block for the throttle body that's set up like a TTA with the vacuum port sticking out the side. I don't really care for how those look but to each their own.


Now that all the connections are made, all that's left is bleed the brakes and do a final inspection.

YICK!!
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Now is also a good time to toss the 30+ year old rubber lines and upgrade to stainless lines. Not only would it be a safety upgrade but a performance upgrade as well. Since the system is opened and needs bleeding, it would be the perfect time.

All you have to remove is the wheels and they're already off.
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WOW! What a great post.

I just recently bought the conversion set up.

thanks a bunch.

D
 
WOW! What a great post.

I just recently bought the conversion set up.

thanks a bunch.

D
X2 on the thanks a bunch. Getting ready to plan my next project after the swap of body bushings , and thanks to this post, this looks to be it!
 
I left the lines in the same place. They both lined up and went in no problem. I'll post a picture of what I did.

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Yes ordered a 87 regal brake booster and master cylinder from advanced auto. With 30% off coupon code it came to $109 delivered in one day. The brakes work great with Russell steel braided brake hoses so I assume I hooked up the lines correctly.

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Yes ordered a 87 regal brake booster and master cylinder from advanced auto. With 30% off coupon code it came to $109 delivered in one day. The brakes work great with Russell steel braided brake hoses so I assume I hooked up the lines correctly.

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Did you have to modify the brake pedal or did you pick one up from a salvage 87 regal??
 
I got a pedal from an 87 el Camino with no interior. I was in and out of the junkyard in 5 minutes.

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Took me 10 minutes to take out the pedal out of the gn and 20 minutes to get the new one in.

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Yes ordered a 87 regal brake booster and master cylinder from advanced auto. With 30% off coupon code it came to $109 delivered in one day. The brakes work great with Russell steel braided brake hoses so I assume I hooked up the lines correctly.

Sent from my SAMSUNG-SM-G920A using Tapatalk
Any way That i can bother you to let me know what part nimbers you ordered?
 
What happens if you didn't swap the lines when doing the conversion?
Other than different sizes, the reason for swapping the front/rear lines is because the front/rear sections of the reservoir are opposite between Powermaster and Hydroboost. Your brakes may work after connecting them without reversing them, but you will probably lose the necessary extra braking power of the fronts as your front brake line is connecting to the rear section of the reservoir, and vice versa.

Check out this series of 4 vids on YouTube documenting this procedure, which I found quite helpful too:

 
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Yeah I realized that someone had the lines hooked backwards on the powermaster so I didn't have to do anything.

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There's no rerouting necessary. Just tuck the plugs under the harness or let them fall where they will.
 
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