Brakes Feel Spongey after overhaul

[Spetz]

I just got:
-Zimmerman front rotors (left rear ones standard)
-Textar pads all around
-New brake lines front and rear
-Brake bleed

However, the brake pedal travel is quite long. The first inch or 2 of travel does nothing, and then they grip. They grip fine but towards the bottom of the travel.

The mechanic said this will become normal after a few days of driving.
Is this true? Does it take a while for new brakes to work well?

[Yak]

My experience is that brake feel improves after changing lines and a proper bleed.

There is a process with seating new pads to mate up with the rotors and "cook" a little of the bonding agent out of the pads, but that may mean slightly reduced braking effectiveness and not a spongey feel.

The mechanic is not entirely out to lunch, but a spongy feel and long travel is probably an improper bleed.

Link to TireRack article on seating pads: http://www.tirerack.com/brakes/tech/techpage.jsp?techid=85

[1stbenznc]

My first thought would be sure any air is out of the system. Did the reservoir ever go too low? If no air, the pads may need to be mated to the rotors by following the bedding procedure.

With fresh fluid and new lines they should feel more firm.

How did you bleed the brakes- friend pumping and wrench or a vacuum bleeder?

[1stbenznc]

That's funny Yak! No one responds all day and we have the same response within a minute of each other!

[ps2cho]

Almost certain you have air in the lines. Rebleed the system.

Your mechanic is a little off...or at least for these MB brake systems. New discs and pads will grip fine. It won't be GREAT for a good 50-100mi, but it will still stop hard enough to kick on the ABS. Pedal travel shouldn't be that long

[sptt]

My pedal engages immediately and is getting a little better afetr new front pads and rotors. Maybe there's something to this...please let us know by updating

[Ferdman]

Spetz, the master cylinder has a rear chamber that needs to be full of brake fluid when bleeding the system. Discuss that fact with your mechanic because it sounds like there is air trapped in the brake lines, probably the lines to the rear calipers.

[Spetz]

I didn't personally bleed the brakes so I am unsure how it was done.
To be honest it does not feel too much different than before the rotor/pad change, except that there is more bite, but the same pedal travel.

It still brakes strong, and I can get ABS to kick in, but when I drove brand new cars, they have brakes which are so responsive you have to feather them, and this is what I expected from the 124 after the overhaul.
I will go back to him and ask him to redo it. Is there a different procedure to bleeding these brakes or is it the standard procedure?

[rocky raccoon]

The only foolproof way of brake bleeding is by using a pressure bleeder.

The "two-man" method presupposes that both chambers are filled, the reservoir is never permitted to get low and the inside man never lets up on the brake pedal. Also for best results the brake pedal should not be fully depressed thus putting the master cylinder piston seal into potentially roughened territory.

The vacuum bleed method offers the potential of air being sucked into the system around the threads when the bleed screw is loosened.

A pressure bleeder will automatically keep the master cylinder full and air out. It also allows an easy one-man job with the ability to observe the state of the fluid while doing a complete flush. Pressure bleeders are reasonable in cost ($50 to $70).

BTW, I agree that you have air in your system. The only other explanation for a spongey pedal is too soft brake lines that expand when pressure is applied. Not likely is new lines were installed.

[ps2cho]

I bought the motive power bleeder for this job and it works great. I paid $60 for it and it makes the job so easy.