Bad Brake Booster???

[gibgoaz8]

The brake booster on my 1978 FJ40 works sometimes and sometimes it does not. In other words, sometimes it feels like I have power brakes and then again it feels like they are completely manual and I have to push the brake pedal real hard to slow my cruiser down. Short of removing, replacing, rebuilding, etc.., is there anything that I can try to do to make it work better. I am getting good vacuum to the booster from my intake manifold. Any advice would be appreciated.

 

[Racer65]

The brake booster on my 1978 FJ40 works sometimes and sometimes it does not. In other words, sometimes it feels like I have power brakes and then again it feels like they are completely manual and I have to push the brake pedal real hard to slow my cruiser down. Short of removing, replacing, rebuilding, etc.., is there anything that I can try to do to make it work better. I am getting good vacuum to the booster from my intake manifold. Any advice would be appreciated.

I would start by checking the pedal height to see if it's within spec.
Did you happen to replace the master cylinder recently? If so, and you installed an aftermarket MC, it is possible the booster rod on the MC side needs to be adjusted to work with the new MC.
Is the plastic check valve working? Take it out of the booster and blow air through it. Air should only pass one way.
Is there a constant hissing noise when brake is applied? If so, you need to replace the booster. A new one is not available. The only remanufactured unit out there is CENTRIC Part # 16088103...and there aren't many of those around, and results vary...

 

[65swb45]

Pull out the fitting in the intake manifold that the booster draws vacuum from. Chances are you have some carbon buildup, which could interfere with prompt vacuum recharge in the booster.

Best

Mark A

www.marksoffroad.net