Brake system question...

[Dana_Drury]

Hi Guys,

Quick question. I had just rebuilt all my calipers, replaced the soft brake lines, two front hard brake lines that had snapped as well as putting in a new master cylinder.

The brake pedal still needs quite a way to depress before it starts braking. The brake system has been bled thoroughly, including the master cylinder, could this simply be a case of the system needs time to bed in?

Is there a way to adjust the connector to the master cylinder. The pedal returns to its proper height. And pumping the brakes doesn't really make that much of a difference. (Unlike when you are bleeding them and getting air out of the system they go spongy after a while).

Any suggestions, or do I simply need to be careful till the system beds in?

Thanks.

[Chuck Moreland]

What is likely is that the pistons have not adjusted to the proper position in the caliper seals yet. When you release the brake they are being pulled too far back. So the next brake application requires a long piston travel, and long pedal travel to match.

You have a couple options.

1) Wait. In a few hundred miles they will settle in.

2) Drive the car on a non-busy street and repeatedly press and release the brakes. This may accelerate the seating.

3) Remove the pads one at a time and press the pedal to push the pistons out. Put a thin peice of wood in where the pad goes to prevent the piston from popping out. Now that you have the piston extended, push it back just enough so you can barely slide the pad back in. You may have to tap the pad slightly, it should be a tight fit. Do this to all pads. When you are done you should not be able to see daylight between any pad and the rotor.

[Early_S_Man]

Dana,

I have said many times on this board that rebuilt brakes should be usable and 100% functional at the end of your driveway ... and that the BS you hear about taking it easy for 150-500 miles can get you killed if you believe it!

The excessive pedal travel is due to an excessive gap between pads and caliper pistons! Take the pads out and pump the pedal SLOWLY a couple of times, then put the pads back in ... if there is zero clearance and force is required to get the pads back in ... othrwise, pump some more until the caliper pistons are out until the zero clearance is achieved!

The following threads discuss the same problem in detail:

Brake Bleeding

Brakes

Please note that the type'A' calipers used since 1976 don't have the self-adjusting anti-knockback feature I discussed in the above threads! Early Ate type 'L,' 'M,' and 'S' calipers DO HAVE the anti-knockback mechanism!