picked up a 94 4Runner for my son's first vehicle, it has been a labor of love, and we are ALMOST done. It was 2wd, converted it to 4wd with locking hubs and new gears, etc. the brakes flat out suck though. but not all the time, and before i drop 300 bucks on a new booster i wanted to throw this out there and see if the general consensus was a bad booster.

Everything is factory toyota stuff. When i am driving and push the brakes, sometimes the front end locks up completely, sometimes everything acts normal, and sometimes i have to pull the E-Brake to get it stopped. I have new pads all around, bled everything, adjusted the rears and ensured nothing is disconnected.

The check valve is functioning in the booster, but it does run pretty rough for no real reason, maybe a leak inside the booster?

any ideas?

 

Most likely too late to ask, but did the brake fluid you flushed look odd? any film or ring in the brake master reservoir?

You could try unplugging the vacuum hose to the booster and plugging the hose to the engine. If it still locks up with the booster removed from the system than something else is the culprit. Yes, the pedal will be harder to depress, but if the braking performs consistently with the booster disconnected than you probably found your cause.