Brake problem, help.

[Second Shadow]

I have a 93' 240sx se(four wheel disk), manual trans, without ABS. Recently my brake light was mess up and stayed on all the time. it was just the plug in the brake pedel that touches the switch so I plugged it with a bolt and now it works fine. However now, after about 10 to 15 minutes of driving, the brakes slowly start to engage on their own, and about 3 minutes after that they are lock so hard the car won't move. The pedel has a little slop at first but as soon as the brakes start to lock, it gets hard as a rock. if I pull the vacuum line off the booster they unlock and work but the booster doen't and the pedel is still as hard as a rock and it takes A LOT of force on the pedel to get them to work at all. I've already changed out the booster and master cylinder, and bled the system quite extensively. I don't think it's the calipers because once the locking starts they all do it at the same time but work fine before that. One other thing, that other switch next to the brake light switch(ASCD Cancel) I also pluged that hole with a bolt. I don't know what it does but it seems clear that it's suposed to be pluged so the switch works when you're not pushing the brake. Any thoughts?

[180fan]

you need to grease up the caliper pins. You'll see some accordian shaped cylinders made of rubber where the caliper bolts into the bracket. Under that rubber accordian boot, you should find at least some grease there. pull the pin out and grease well.

[Second Shadow]

Is there a specific type of grease you would recomend(like with or without moly b)?Also I forgot to mention this just in case it is relevent; after I pull the vacuum line and the brakes unlock, if I reattach the vacuum line to the booster the brakes will work fine again for another couple of minutes (except the pedel is still too soft) and then lock again w/the hard pedel. Also, they won't seem to lock up unless the car is actually moving; you can't get them to lock just pumping them in the driveway with the engine running.

[180fan]

Hmm could be your booster or that one way valve goofin up. The one way valve you'll see inline with the vac line poppin up from the booster. Make sure air flows in only one direction.

The booster could be locking up, if it takes some time to cool down and let up, that's usually the pins. I'd still grease the pins anyway but the booster may be shot.

[Second Shadow]

I'm going to grease them tomarrow, but since the check valve was right on top of the engine I went ahead and checked it, and it seems to be working fine. I've already replaced the booster and the master cylinder though, and it didn't change anything at all. this all started when I plugged the two holes in the pedal with bolts. Although the car stopped just fine the pedal seemed soft and, then the lock-up problem happend. I just removed the pin that connects the pedal to the booster to see if the bolts were messing up the pedal adjuestment (allowed the booster to release as far as it could without the pedal stoping it) but it didn't change anything.

[Second Shadow]

Okay, I fixed it. Turns out the bolts I installed on the pedal were the problem. I didn't adjust the pedal enough after I installed them, so my brakes were always engaged just a little bit. I think it was some kind of pressure build up in the booster combined with the valves cylinder. It's still a little hard to understand how it made it do that, but the important thing is the problem is fixed. Thanks for your help.