Brake half soft and the rest is hard and sticking

[mac9k5]

Yo I have been having this problem for a while the car is a 280z and I just can not figure this out. The first half of the brake pedal is soft (like stepping on nothing) but the brakes actually work for the most part in the soft section, not very well mind you but they are there. And the rest of the pedal is just regular hard pedal like what you would expect but if i step on it hard enough to get to the hard part the pedal likes to stick. Also if i press on it fast it feels really sluggish and kinda hard, its weird. I have changed the master cylinder i have bled it countless times to no a vale and i replaced the front right caliper (it was leaking) and did not help, although now it does tend to the right when i brake. so any ideas as to why the pedal is so weird?

[Kenji]

Could be a few things,

 

1. Master cylinder, could be bad, the rubber seal inside the master cylinder could be bad. This is the problem for the pedal feel

2. the brakes still need to be bleed more, check all fittings,(loosen and tighten all of the points to insure that they won't seize and to make sure that they are tight and do not leak)

3. The pulling to one side is because the lines have air in one side, or that one side sticks, you did check pads for even wear right?

Edited February 27, 2010 by Kenji

[mac9k5]

Thanks man i will give more bleeding a try, but the master cylinder is new and the car has even ware, for now.

Edited February 27, 2010 by mac9k5

[bjhines]

SPELLING IS NOT OPTIONAL!!!! Do they still teach kids spelling and grammar these days? God damn... BOTH OF YOU!!!!

 

It sounds like you have air in your lines. If you describe your method for bleeding the brakes we might be able to help.

 

The pulling to one side is more likely to mean that you have a bad front caliper. The squishy pedal seems like air in the system. The pedal staying low means you have something SERIOUSLY wrong with the installation of your master cylinder.

Edited February 27, 2010 by bjhines

[mac9k5]

I very easily could of messed up the bench bleed of the master cylinder, would that do this funky, stuff if so i will check that out.

[bjhines]

Seriously, I know English is not everyone's first language, but you have got to do better if you want help from intelligent car guys. You have not posted an easily readable response YET... "Could OF" is ghetto vernacular. Punctuation is NOT OPTIONAL.

 

The piston in the MASTER CYLINDER must retract all the way back in order to expose the hole to the fluid reservoir. You cannot bleed the brakes if the master cylinder piston is not completely retracting. I have run into problems with new master cylinders buggering the bleed process. The piston and seals can get stuck partially retracted and fluid simply will not flow properly through the system. Vacuum bleeding can exacerbate the problem by pulling the piston forward in the MC and blocking the reservoir hole. You can try pushing air into the lines from the caliper end to "seat the piston back" in the MC. Fluid should flow easily once the piston retracts completely. Watch out though, pushing air into the lines from the caliper end can suddenly "free" the piston and blow brake fluid(from the reservoir)all over your car's paint job. Brake fluid is an effective paint remover.

Edited February 27, 2010 by bjhines

[mac9k5]

Thank you, I will give that a try sorry for the poor grammar.