C2 braking efficiency

[Randy S.]

I replaced all my calipers, pads, fluid (dot 4), rubber hoses and new master cylinder (standard) on my 66 last spring. I've never been happy with the stopping distances. The caliper vendor said it could be air in my fluid ( I have hard pedal)or I could need new rotors. I'll bleed them again but why would new rotors help?
I did not turn the rotors last spring.

[Craig S.]

Re: C2 braking efficiency

I would not suspect the rotors personally, the only rotors I have EVER replaced are those somebody else botched up before I bought a car. They can be lightly deglazed if necessary, so the new pads seat easer and faster, but I would suspect air first...Craig

[Mike Cobine]

Re: C2 braking efficiency

DON'T turn your rotors unless they are grooved severely. Even then, have someone turn them who can turn them on the hub. You do not want to separate them from the hubs.

You probably have a problem of rust. Rust is a great lubricant in brakes. Take some medium grit sandpaper (120 or so) and use a block to wipe the rotor clean on both sides if they are rusted. You are NOT trying to grind them back to bare metal but merely clean the loose rust off the surface. Do not "sand" on the rotors, hold the block with constant pressure and turn the rotor.

Take the disc pads out and clean them with sand paper. Most likely they have rust embedded now.

With a clean fresh surface on the rotors and the pads, you should see an improvement.

[Duke W.]

Re: C2 braking efficiency

What are the actual issues - excess pedal effort, lockup ????

The spec for the C2 system without a vacuum booster is 120 pounds of pedal effort for a 1g stop. Of course, unless you have racing tires they will lock up before 1g.

In typical street and highway light to moderate normal braking the drum brake system probably takes less effort.

Pad material has a big impact on pedal effort. Typical street pads usually have a Cf in the range of .25 to .35, and pedal effort varies linearly with pad coefficient. Racing pads may have higher coefficients, but usually only at elevated pad temperatures.

What kind of pads did you install?

Duke

[Randy S.]

Re: C2 braking efficiency

The specific issues are excessive pedal effort and long distances to stop, I don't think I can lock up the brakes but I haven't tried.

I suspect I probably have air in the line although the pedal seems hard.

The pads were "standard" pads furnished by the caliper vendor nothing fancy just street pads for my driver.

[Duke W.]

Re: C2 braking efficiency

I doubt if you have air in your lines. If you did the pedal would be spongy.
Find out the make and model number of the pads from your caliper vendor.

It sounds like you may have pads with too high a coefficient, but fairly high pedal effort is part of the base disk brake design.

Stomp on them as hard as you can at low speed and see if you can lock them up.

Duke

[frank mccracken]

Re: C2 braking efficiency

I have the same thoughts about my car. It needs a pretty high pedal pressure. I can lock the wheels up but not easily. The existance of non power disc brakes is not high on the agenda of most auto parts suppliers, consequently their standard brake pads are, I'm sure, not geared for us. Most likely your auto parts store can get in contact with their brake parts manfacturers representative to get his educated recomendation.

[Roy B.]

Re: C2 braking efficiency

I added the power booster original in my 67 using cheep soft pads and now they will put you through the window.