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brakes

549 views 4 replies 2 participants last post by  poqman 
#1 ·
I purchased a 1967 Mustang 289 coupe recently.
The guy I purchased from said he had a power booster and brake pedal installed recently. The info. on the pedal tag indicates it is the correct pedal but there is absolutely no information to be found on the booster. I have done a 4 piston front disc brake conversion with a proportioning valve and master cylinder that came with the kit and kept the original distribution block and power booster. I did a complete drum brake replacement with new brake cylinders, shoes and drums and all new lines on the rear. I get good fluid volume at each bleed port.

The engine creates 19" of vacuum at the booster. I have adjusted the MC push rod with a push rod adjustment tool. Bled brake lines several times. Master cylinder was bench bled and then bled after attaching to booster using the tubes supplied with the kit after installing and any opening of the brake lines. The MC has a built in check valve. Following several you tube videos for testing boosters I believe my booster is good. I did not buy a new booster with my disc conversion.

I have a firm peddle and about 3/4" travel before becoming firm but still have poor braking. I have broken in the brakes by getting to about 40 mph and braking hard a number of times.

Purchased a brake cylinder pressure gauge set up to find what my pressure is and can not get above 300# on test gauge. I know that is not right.

When pressing on the brake pedal I get an eruption on the front MC chamber that goes to the rear brakes. The larger reservoir to the front does not erupt.

Added note. The is a large cupped washer that the push rod goes through in the booster. Is there a direction the cup should be installed?

Any help will be appreciated.
 
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#5 ·
The engine creates 19" of vacuum at the booster.

Purchased a brake cylinder pressure gauge set up to find what my pressure is and can not get above 300# on test gauge. I know that is not right.

When pressing on the brake pedal I get an eruption on the front MC chamber that goes to the rear brakes. The larger reservoir to the front does not erupt.

Any help will be appreciated.
I have 19-20" HG and that should be plenty.

I also used a pressure gauge and measured 1100 psi on the front and 800 on the rear in an emergency stomp of the pedal. 300 is way short of what you need. That is what I would focus on correcting. I think you need to measure at the MC and work your way around the wheels looking for the pressure restriction. Definitely check the distribution block for restrictions.

My MC also has an eruption on the rear brake side, so I believe that is normal.

Best of luck.
 
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