whats wrong with my brakes?

[randy]

Stick a vacuum gauge on it since that is quick and easy and report back

[Vegas69]

Agreed

[GregWeld]

I WOULD NOT remove the proportioning valve.... you most likely need that -- and at the very least -- need to understand WHY you don't have good brakes before doing something like that.


You do need to do as suggested and check the vacuum - at the take off port for the brake booster.... at the engine. Or if you have a small vacuum gauge hose - at one of the other ports.

If you don't know how to do this - or don't have a gauge - it's a very simple (therefore should be super inexpensive) to have a shop do it for you.

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After you do that -- check the brake pedal ratio....

Here's a link to show you what that is:


http://techtalk.mpbrakes.com/how-to-...ng-pedal-ratio


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Next --- open the master cylinder -- tell us if there is a larger volume between the two reservoirs.... the larger (if there is a difference) needs to serve the FRONT brakes -- and the smaller (if there is a difference) needs to go to the rear. You can simply follow the lines to find if they go to the front or to the back.



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Did you BED the brakes after the installation?? Do you know what this means??

[67_camaroRS]

ok thanks for the help. ill check the vacuum and other stuff this weekend. ill get back to yall.

[67_camaroRS]

I tested the vacuum with a tester and got about 9 inches of Hg Vac on idle. Got about 17 inches on 2000 rpm. the length of the pedal was 12 inches and to the master cylinder rod it was 4 inches which makes the ratio to 3:1 i believe.The master cylinders reservoirs were identical in length but the rear one is smaller from the inside. I did BED bleed the master cylinder when it was new. What is the next step? Vacuum Pump? or?

[GregWeld]

Good info.....


You really don't have enough vacuum for good power brakes.... Your idle vacuum is about HALF what you really need... and even at your 2000 rpm level you're only making 17"....

Pedal ratio is "okay" for power brakes -- but not when you have such low vacuum.

Also -- check that your booster is okay. With the car running -- apply the brakes --- hold em -- shut the car down --- your pedal should hold for about 30 seconds is the booster isn't leaking.

So Check that....


Then --- you've got a couple options....


Increase your pedal ratio to 4:1 or even 5:1 ---- if you can keep all things aligned properly....

Add an electric vacuum pump .....


Or junk that set up and run a good manual master cylinder and get your pedal ratio to 6 or 7:1 <this would be my choice>

Or go to a "hydraboost" boost system....

[craig510]

Post the piston sizes for you calipers and master cylinder. You will need the caliper piston area to determine ideal master cylinder size for a given pedal ratio.

[67_camaroRS]

Originally Posted by GregWeld

Good info.....


You really don't have enough vacuum for good power brakes.... Your idle vacuum is about HALF what you really need... and even at your 2000 rpm level you're only making 17"....

Pedal ratio is "okay" for power brakes -- but not when you have such low vacuum.

Also -- check that your booster is okay. With the car running -- apply the brakes --- hold em -- shut the car down --- your pedal should hold for about 30 seconds is the booster isn't leaking.

So Check that....


Then --- you've got a couple options....


Increase your pedal ratio to 4:1 or even 5:1 ---- if you can keep all things aligned properly....

Add an electric vacuum pump .....


Or junk that set up and run a good manual master cylinder and get your pedal ratio to 6 or 7:1 <this would be my choice>

Or go to a "hydraboost" boost system....

What option would give me the best results? Manuel Brakes or an Electic Vacuum Pump setup with power brakes.

For manual brakes, i will need a special MC?