Spongy brake pedal??? - Team Camaro Tech
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post #1 of 20 (permalink) Old Apr 21st, 08, 05:58 AM Thread Starter
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Spongy brake pedal???

The brakes on my 67 Camaro are seeming to get softer and softer every time I drive it. These are aftermarket 4 wheel manual disc brakes from:

http://www.ecihotrodbrakes.com/early...nversions.html

The longer I drive it with out braking it seems the softer they get. They are fine once I pump the brakes a few times then they stiffen up. They are nice brakes and seem to stop better when I first got the car. I don't see any visable leaks and the master cylinder is full.

Should I think about bleeding the brakes or upgrading to a better master cylinder. I am not sure what master is on the car now but it a stock GM from a truck I think.

Thanks, Erik

67 Camaro Pro Street, 540 Bill Mitchell Merlin big block, Merlin Aluminum heads, Holley 870, hydraulic camshaft, 2" Hooker Super Comp headers, Mallory and Crane ignition system, TH400, 2600 stahl, Ford 9" w/ 4:10 gears and posi.
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post #2 of 20 (permalink) Old Apr 21st, 08, 07:00 AM
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Re: Spongy brake pedal???

Try this. Jack your car up all four wheels. Have someone push on brake pedal slowly. Turn wheels by hand until they stop. See if your front or back wheels stop and you can still turn the others. What i am trying to do is see if most of your pressure is going to front or rear brakes. And if there is a difference then bleed the weaker end until air is visabilie from bleeders. I had to run throught a almost a complete bowl of fluid to fix problem. I would say there is air somewhere in your system and would not stop bleeding until i see it visualy. I have a large bowl on my master too. At let car set for a monent before starting this to let brakes settle. Do not pump up to get solid pedal before doing this.
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post #3 of 20 (permalink) Old Apr 21st, 08, 09:25 AM Thread Starter
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Re: Spongy brake pedal???

When you bleed the brakes do you take the cover off the master cylinder during the process or leave it on?

Erik

67 Camaro Pro Street, 540 Bill Mitchell Merlin big block, Merlin Aluminum heads, Holley 870, hydraulic camshaft, 2" Hooker Super Comp headers, Mallory and Crane ignition system, TH400, 2600 stahl, Ford 9" w/ 4:10 gears and posi.
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post #4 of 20 (permalink) Old Apr 21st, 08, 10:24 AM
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Re: Spongy brake pedal???

Quote:
Originally Posted by Erik Beckett View Post
When you bleed the brakes do you take the cover off the master cylinder during the process or leave it on?

Erik
Leave the cover on, otherwise there's a good chance fluid will go flying all over your paint! This sounds like you simply have air in the system somewhere. Check for leaks while you're messing with this - if it's leaking, one of the MC reservoirs will be low (or empty) on fluid.

There's also a chance the MC could be bad. Hold moderate, steady pressure on the brake pedal. If it slowly goes to the floor, then the internal seals on the MC are probably shot................

Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970
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post #5 of 20 (permalink) Old Apr 21st, 08, 10:25 AM
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Re: Spongy brake pedal???

If you leave it off, brake fluid may spray out all over your engine compartment. You don’t have to lock it down, but leave the cover in place.

(After you pump up the brakes, the fluid will move back to the Master. Sometimes, it can shoot out like a jet. This happened to me while I bled the back brakes—the pressure built up in the front and then came shooting out. What a mess!)
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post #6 of 20 (permalink) Old Apr 21st, 08, 10:47 AM Thread Starter
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Re: Spongy brake pedal???

I called the company whose brake kit it is and he told me that the I need to set my emergency brake once or twice. That the brakes on the rear are like self adjusting brakes and they need adjusted.

I will do both: bleed and try the parking brake.

Thanks, Erik

67 Camaro Pro Street, 540 Bill Mitchell Merlin big block, Merlin Aluminum heads, Holley 870, hydraulic camshaft, 2" Hooker Super Comp headers, Mallory and Crane ignition system, TH400, 2600 stahl, Ford 9" w/ 4:10 gears and posi.
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post #7 of 20 (permalink) Old Apr 21st, 08, 11:28 AM
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Re: Spongy brake pedal???

I thought you had rear disc brakes. I thought the parking brake cable had it's own set of pads. And bleeding don't effect these
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post #8 of 20 (permalink) Old Apr 21st, 08, 05:07 PM Thread Starter
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Re: Spongy brake pedal???

I do have rear disc brakes. I am an idiot when it comes to brakes, I am just doing what the guy told me. I applied the brake a few times but i wont be able to drive the car for a few days. I am not sure why the ebrake cable would help a spongy brake pedal.

Erik

67 Camaro Pro Street, 540 Bill Mitchell Merlin big block, Merlin Aluminum heads, Holley 870, hydraulic camshaft, 2" Hooker Super Comp headers, Mallory and Crane ignition system, TH400, 2600 stahl, Ford 9" w/ 4:10 gears and posi.
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post #9 of 20 (permalink) Old Apr 21st, 08, 08:01 PM
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Re: Spongy brake pedal???

The ebrake applies the disk mechanically somehow, no extra pads. and the adjustment is important. If you don't use the ebrake once ina while, after a while the rear brakes won't work at all.

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post #10 of 20 (permalink) Old Apr 21st, 08, 10:01 PM
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Re: Spongy brake pedal???

Hey Erik,
Don't take this wrong, but take it to a professional.
You don't have enough experience for the problem you are having.
Brakes are dangerous when not properly installed or adjusted. You can also ruin a really nice restored car.
Or, if you have a friend that is a mechanic, he can help you also.

Your breaks either have a leak, air in the lines, or a bad master cylinder. Their is a procedure for bleeding brakes. The E=brake can effect it, but I don't think that is your problem here. If you have OLD lines, they can suck air in and you not know it. Follow the entire system and see if you see anything a little wet. You would be amazed at how little brake fluid leaks while sucking air. Look at all wheel cylinder and caliper seals

Good Luck!
Good luck!
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post #11 of 20 (permalink) Old Apr 22nd, 08, 05:10 PM Thread Starter
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Re: Spongy brake pedal???

I was under the car today and the rear brakes are FORD brakes from a Lincoln back in the day I guess. They must have came on the Ford 9". i did notice a little fluid on my drivers side rear rim today as well. These brakes do have emergency cables and they go right to the calipers themselves. There are bno extra pads or anything.

So the fronts are from the company i posted above and the rears are from Ford, soiunds like a mutt huh!

I did apply the ebrake a few times today but there was no difference. Not to mention by other issue I had today that I posted about in the engine forum. I will call my local race shop and see what he has to say.

Can anybody recommend rear disc brakes for the Early Big Ford ends?

Thanks, Erik

67 Camaro Pro Street, 540 Bill Mitchell Merlin big block, Merlin Aluminum heads, Holley 870, hydraulic camshaft, 2" Hooker Super Comp headers, Mallory and Crane ignition system, TH400, 2600 stahl, Ford 9" w/ 4:10 gears and posi.
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post #12 of 20 (permalink) Old Apr 22nd, 08, 06:12 PM
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Re: Spongy brake pedal???

I have no experience with floating-caliper disc brakes, but on '65-'82 Corvettes with fixed calipers, the symptom you describe (good bleed, hard pedal, followed by steadily-falling pedal while driving) is ALWAYS caused by excessive lateral runout in a rotor (over .005" TIR), which causes "air-pumping" through the piston seals. Unless your rear axle shafts are set up good and close for play or the axle flanges and rotors aren't dead-on for runout, that could be your problem.


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post #13 of 20 (permalink) Old Apr 23rd, 08, 02:11 PM
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Re: Spongy brake pedal???

Eric.
There is a bracket that the cable attaches to. Is that bracket loose, like when you move it towards the front of the car, it just flops around. You have to adjust the piston that the bracket attaches to. If they are adjusted right there will be a little forward movement and you can feel it push the piston. That is why the rear brakes dont work. Also when they are right you will see brake dust on your rims. Do you see this? I have the big lincoln rear disc in my prostreet car and it took me forever to figure out how to adjust them. Once I had them adjusted they work great. When you move the arm towards the front of the car it pushes the piston / brake shoe to the rotor and it is only about a 1/16 to 1/8" movement. It is not like the front calipers. Let me know if this is what you have and I can tell you how to adjust. They are a real pain to adjust. You might want to take it to a mechanic to adjust them. Just make sure they know how to adjust them.

Mike
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post #14 of 20 (permalink) Old Apr 23rd, 08, 02:24 PM Thread Starter
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Re: Spongy brake pedal???

That is exactly the setup I have on my car as well. I just talk to a guy and he told me to take the brake cable of and rachet each side a few times and that should fix it. If not then I am at a loss.

Erik

67 Camaro Pro Street, 540 Bill Mitchell Merlin big block, Merlin Aluminum heads, Holley 870, hydraulic camshaft, 2" Hooker Super Comp headers, Mallory and Crane ignition system, TH400, 2600 stahl, Ford 9" w/ 4:10 gears and posi.
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post #15 of 20 (permalink) Old Apr 23rd, 08, 05:02 PM
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Re: Spongy brake pedal???

No that will not fix it. It is really hard to explain. If you PM me your phone number and a good time to call, I will call you.

They sell a tool that is for adjusting the piston. It is square looking w/ prongs on the end of it and fits on a 3/8" extension. You insert it into the inside of the piston to adjust it. One of mine had the indention to adjust it and the other doesnt. You can adjust it without the tool also but is messy and a pain. I will try to find a picture of the tool and post it. You have to remove the caliper and shoe to adjust it.

Mike
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