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Discussion Starter #1
I changed over to a new booster and dual master setup from SSBC on my 65. The brakes work but the pedal feels soft. Must push the pedal almost to the floor to stop. Do I need to adjust the rod that goes from the booster to the master cylinder piston? The pedal height is fine. Thanks
 

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Drum/Drum or Disc/Drum? In many cases, the new master lacks residual valves for the drum brake circuit(s). The Raybestos MC36440 ('74+ Maverick) is one of those examples.
 

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I just had SSBC brakes, MC and Booster installed. When attempting to install the single diaphram booster my mech said he was not at all happy with it (he described a very weak pedal). He ordered the dual diaphram booster, installed it and did not have any of the issues.
 

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Discussion Starter #5
Drum/Drum and the kit came with an inline residual valve for the drum setup. Does not feel like a booster issue. Feels like an adjustment issue or air in the lines but the brakes were just bled for the 2nd time. 3rd time might be needed....
 

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Did you change the location where the pushrod attaches to the brake pedal arm? If not, there is an adapter that attaches the pushrod lower on the arm, which helps with a mushy pedal. Lots of info on Mustang Steve's website.
 

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Follow this procedure. It will get you to the issue.
Let me know if you have any other questions-Greg
Before beginning the following procedure check to make sure brake pedal free play is approximately ½” and air gap from booster pushrod to master cylinder piston is approximately .015” and all bleeders are at the top of the calipers or wheel cylinders.

1) Disconnect brake lines from master cylinder. Install plugs in ports of the master cylinder. Use plugs with tapered seat as not to damage brass seats in master cylinder ports.

2) Once plugs are installed press and hold brake pedal down firmly for 30 seconds. Does brake pedal remain steady at the top of its travel and not move at all? If YES proceed to step 5. If NO continue to next step.

3) If brake pedal seems spongy or pushes back at you while being applied you most likely have air in the master cylinder. Remove the master cylinder and re bench bleed following manufactures recommended procedure. Re install master cylinder and re test using steps above.

4) If while holding pressure on the brake pedal it seems to “sink” or “creep” to the floor the master cylinder is faulty. It will need to be replaced. Bench bleed new master cylinder following manufacturers recommended procedure and re install. Before hooking brake lines to master cylinder repeat steps 1-2 to ensure proper operation.

5) Clamp off all flex hoses on vehicle. Use caution as to not damage hoses.

6) Press and hold brake pedal down firmly for 30 seconds. Does pedal remain firm and steady? If YES proceed to step 8. If NO continue to step 7.

7) If the brake pedal is spongy, soft or “creeps” down you have an external fluid leak or air trapped at a point between the master cylinder ports and the clamps. Repair any leaks or re bleed system and re test.

8) Remove one clamp and press the brake pedal. Take note as to how it feels. Re clamp that hose and remove one other clamp and take note as to how the pedal feels again. Work your way around the car testing only one brake circuit at a time.

9) Once you find the circuit that lets the brake pedal move the most you have found the problem circuit. Inspect the brake circuit in question for an external fluid leak, excessive mechanical movement of caliper pistons or wheel cylinders, or air trapped in the circuit. Take this time to make sure the brake bleeders are at the top of the caliper or wheel cylinder and all brackets are correctly aligned and in the proper locations.

10) Perform necessary repairs/adjustments and re bleed and re test as needed.
 

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Discussion Starter #9
Thanks for all of the info. Is there a measurement for the proper brake pedal distance from the floor? The height is adjustable and I just guessed.

So the rod from the booster to the MC should almost touch the piston (.015) when the brake pedal is not being pushed? The Pedal should move no more than 1/2" down before
the brakes begin to engage?

I bench bled the booster but I can check with plugs as suggested.

What tool do you use to clamp off the flex lines without damaging the lines?

Thanks again for the help.
 
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