funky brake pedal - Vintage Mustang Forums
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post #1 of 13 (permalink) Old 04-25-2019, 01:32 AM Thread Starter
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funky brake pedal

Hey guys, new to the forums and here to ask what you all think of my brakes. My car originally was 4 wheel manual drums that I put a CSRP SN95 cobra style front discs along with their brake booster and master cylinder. As soon as I did the swap the pedal felt weird. The pedal has an exceptionally long travel and doesn't seem to start grabbing until the end of the pedal travel, but once it does it feels good. The car would stop and since I was 17 and just wanted to drive the car, I ignored that the pedal felt like crap. Then later I bought a 9" with drum brakes on it, and still after putting that in, the pedal sucked. I would tell people about it and they all said it sounded like the rear shows weren't touching the drum, so i adjusted them, did nothing. then I got the SSBC rear discs and installed those, still same pedal So after that I decided I really needed to figure this out since Im planning on putting a stroker in my car and would like it to actually stop. I took the master out and bench bled it, then put it back in but blocked the 2 ports, and I had a firm pedal! So then I tried blocking off the front and still had a hard pedal, so it had to be a problem with the front brakes right? Nope, I tried changing the calipers, braided flex hose and nothing. then today I replaced the T for the front and then I had a solid pedal for the front with the rear blocked off! so we already decided the rear is solid right? Wrong, I then hooked the rear up, and after bleeding The pedal felt bad again! I'm pulling my hair out over this, I never have had this hard of a time with something as simple as brakes. My master has a 1" bore FWIW and yes I tried adjusting the push rod from the booster. So is it possible that its the master?? That's all it could be at this point I feel like but I have thought that about everything else too. Thanks in advance
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post #2 of 13 (permalink) Old 04-25-2019, 01:49 AM
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What year Mustang and details?

What are your using for a proportioning valve? Have you tried an adjustable one?

1969 Mach-1 Mustang
460 / C6 / 9"
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post #3 of 13 (permalink) Old 04-25-2019, 06:03 AM
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Welcome to VMF.


Same story, different chapter. There are many, many stories exactly like yours on this forum. If you're 20 years old or thereabouts why do you think you need power brakes? Switch to manual brakes and your problems will disappear.
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post #4 of 13 (permalink) Old 04-25-2019, 07:08 AM
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Also, are you bleeding the brakes in the correct order? It should be passenger rear, driver rear, passenger front, driver front last.
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post #5 of 13 (permalink) Old 04-25-2019, 07:31 AM
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I had the same issue when I had power front discs installed on my wife's 65 I6 200 convertible I bought from Summit Racing. The pedal would travel 3/4 of the way to the floor before engaging. Turns out the MC wasn't properly bench bled before installing it. I removed the MC, bench bled it put it back on, bled the brakes again. That brought the pedal back up to brakes began to engage about an inch of travel and after about three inches was at a complete stop.


Another reason you have so much travel the rod between the pedal and MC is too short. You can buy an adjustable rod.



Let us know what you figure out and welcome to VMF.
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post #6 of 13 (permalink) Old 04-25-2019, 09:34 AM
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One other thing. It's possible to put the calipers on the wrong side so they will never be bled and the bleed valve will be positioned so not to get rid or a pocket of air in the caliper.
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post #7 of 13 (permalink) Old 04-26-2019, 04:30 AM
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Did you change your brake pedal to the power brake pedal when you did the original swap?
The manual brake pedal has a different mounting point which gives it a longer pedal travel when compared to the power brake pedal.

69 Mustang Fastback... in pieces since 2009.
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post #8 of 13 (permalink) Old 04-26-2019, 08:59 AM
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Originally Posted by steferg View Post
Did you change your brake pedal to the power brake pedal when you did the original swap?
The manual brake pedal has a different mounting point which gives it a longer pedal travel when compared to the power brake pedal.
Pat at Master Power Brakes, the folks who make the booster kit I put in my '66, told me the pivot point of the pedal has nothing to do with excessive pedal travel before getting a hard pedal. He suggested turning the booster pin out one turn, and if it doesn't help, it has to be air in the system. It didn't help, and I'm in the process of bench bleeding the m/c yet again.
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post #9 of 13 (permalink) Old 04-30-2019, 09:24 AM
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OP, how’s the pedal feel with the engine off and no vacuum on the booster? With the engine running and vacuum sucking on the booster, does it feel different?

Post a link to the brake kit you purchased.

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post #10 of 13 (permalink) Old 04-30-2019, 09:37 AM
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I had manual brakes on my 66 with 4 piston disc up front for 20+ years- never had a problem stopping.
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post #11 of 13 (permalink) Old 04-30-2019, 11:18 AM
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Deja Vu all over again.
Pull the booster and heave it as far as you can.....install manual master and be done.

Seriously, brakes are not simple all the time and not as simple as everyone seems to want them to be.
I did an SSBC rear disc conversion fairly recently that had me mystified for a couple of minutes
and took a couple of different bleeding techniques to rectify. I have 40 years of design, re-design,
(for when the SSBC stuff just isn't right) install and troubleshooting experience.
The OP should call up CSRP and get some tech assistance.
I would tend to want to believe this is a bleeding issue maybe.

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post #12 of 13 (permalink) Old 04-30-2019, 02:28 PM
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I'm assuming your SSBC rear calipers have the lever-driven parking brake system? That means you need to adjust your rear caliper pistons. Typically, you can keep applying the parking brake over and over to do this but many times, especially from a new install, you need to rotate the caliper piston CCW with a disc brake caliper adjusting tool as far as possible while still being able to slide the pads over the rotor then finish off with the parking brake.

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post #13 of 13 (permalink) Old 05-02-2019, 05:57 PM
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On their rear kit I got the pistons close by rotating them and then putting the calipers in place.
SSDB's official instruction on the procedure-

Parking Brake Adjustment
a) The caliper pistons adjust hydraulically by pumping the pedal. When a hard pedal is
achieved, there should be a clearance between the pads and rotor of 1/32” to 1/16”.
NOTE: IF THE PISTONS BECOME EXTENDED TOO FAR, THE INNER BRAKE
PAD CAN BE REMOVED AND THE PISTON CAN BE SCREWED BACK INTO
THE CALIPER USING NEEDLE NOSE PLIERS OR A CALIPER ADJUSTING
TOOL AVAILABLE AT MOST PARTS STORES.

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