Brake Problem

[slr97]

Does anyone know if a 91-93 300ZX non-turbo brake booster/MC combo will fit on a 97 240SX? The problem I'm having is...after upgrading the brakes to 300ZX, the pedal has no pressure 'til the third pump....everytime. When the pressure is there, it brakes fine. Can anyone help.....please.....

[Nismo_Freak]

sounds like you have air in the system.... re-bleed the brakes

[slr97]

I've changed out the master cylinder and bleed it completely starting at the rear right and ending at the front left wheel. I've wasted about a gallon of brake fluid just to make sure it's air-free. But still......same result. Would changing the master cylinder to a 300ZX work any better?

[volthause]

If you've upgraded to calipers with larger pistons, your not moving enough fluid per stroke with the stock m/c.

Without getting too technical and too far into the laws of fluid dynamics, you can look at it like this: The piston in the master cylinder is designed to flow a certain amount of fluid over it's travel. You may consider it a constant. Force is applied to the piston, and the piston then moves the fluid through the system, and the fluid then acts upon the piston in the caliper, pushing the brake pad into the rotor which then turns rotational energy into heat and voila, the car stops.

When you increase the surface area of the piston that is being acted upon by the fluid, you need more fluid movement upon it to move it the same distance as you did before.

[ESPER]

so is this relevean to ALL z32 brake conversions?? in other words, when doing the conversion is this a normal problem i would have to deal with ?? thanks

[FrEaK]

I hope your bleeding the brakes with the engine running as well..

[i2ice4m3]

Freak, why is it necessary to have the engine running while bleeding brakes on the 240sx? is it absolutely necessary? I have a similar problem with my Z brake install- I bleed the system until no air bubbles come out, but i would get no pressure on the brake line. Please help! thanks

[yellow_jacket]

No, you do not need the car running while you bleed brakes. I can't even remember the amount of brake jobs I've done and had to bleed brakes and I have never had the car running. Not to mention all of the guys I have worked with and know and none of them do it with the car running(ASE Master Certified Techs).

[Doogz]

Yea, that would definately be the first time i have ever heard to leave the car running while bleeding the brakes. I see no point in it and have never done it myself either as yellow jacket already said.