Vacuum brake conversion on 87'

Just because the first one went 31 doesn't mean the next one will. I went hydroboost for about $200 and would do vac before I even considered a power master on anything I planned to drive. Front sheet metal and that nose is way to expensive to chance putting it into another in front of me that decided I needed a brake check.
 
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.
 
Run a 3/8 fuel hose for vacuum.
Do not use 3/8 fuel hose for vacuum. Use 11/32" vacuum hose. The 3/8" fuel hose will collapse from engine compartment heat under high vacuum conditions. I had a customer from So. Cal. who was loosing his brakes because the hose was collapsing while in heavy traffic and traveling through parking lots. He was using 3/8" fuel line for vacuum to the booster. Changed it to 11/32" vacuum hose and problem solved.
 
Hey thanks! I guess anything is possible, but your example is an exception to the rule. I've been running 3/8" fuel line on multiple turbo cars as vacuum for 20 years and never had that happen.
 
Just because the first one went 31 doesn't mean the next one will. I went hydroboost for about $200 and would do vac before I even considered a power master on anything I planned to drive. Front sheet metal and that nose is way to expensive to chance putting it into another in front of me that decided I needed a brake check.

Everyone has a preference to the system that feels right for them. The PM still gives you a few brakes before going out completely just like the hydro will if the pump, power steering pump or belt gives way. Best thing about vacuum is the simplicity.
 
Do not use 3/8 fuel hose for vacuum. Use 11/32" vacuum hose. The 3/8" fuel hose will collapse from engine compartment heat under high vacuum conditions. I had a customer from So. Cal. who was loosing his brakes because the hose was collapsing while in heavy traffic and traveling through parking lots. He was using 3/8" fuel line for vacuum to the booster. Changed it to 11/32" vacuum hose and problem solved.

Wow! An honest mechanic, now that's a rarity now a days. A BIG thumbs up.
 
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