FJ40 Brake question?

[tahoe40/45]

I have a 69 fj40 with disk brakes in front, I have a booster with a 1980,s master cylinder.Here is whats happening,brakes work fine when i first start driving.Pedal goes almost 3/4 the way down and stops fine,after a while the pedal will only go down almost 1/2 way down.At this point my brakes are rubbing.It wont even roll in neutral on a slight incline.It feels like some pressure is building up engaging the brakes.When I turn it off for a while it returns to normal. ?????? any ideas Thanks

 

[Storm]

I just got through with a simular problem. I shortened my brake rod (that pushes the piston inside the M/cylinder) all the way down, then I cut a 1/4" off the length at the back of the rod. I checked the dual pistons seals (the newer m/cyl has a front and back piston inline on one rod). My stop screw (small bolt between the front and rear outlets that keeps the piston from going back too far) was binding on the back of the front piston. I pushed the pistons in and set the screw all the way down. My brakes no longer seize up from building too much pressure. Hope that helps.

 

[Sharp38]

Generally the problem is caused by the piston in the MC being held away from it's resting place by the push rod. When it's away from the resting place, it blocks the bleed hole inside the MC that lets the fluid drain back into the fluid containers on top of the MC. When the fluid gets hot, it expands. Without being able to drain back, it puts the brakes on. Loosen up the four nuts holding the MC. Hold it in your hand and push on the brake (I go through the vent). You should be able to feel when the push rod starts to contact the MC piston. The push rod is adjustable. If you can't get enough in the adjustment, cut the rod off slightly. Be careful

Don www.wolfcreekrodworks.com

 

[tahoe40/45]

Thanks. I had the push rod out to far,shortened it up yesterday and no pressure build up. Thanks again Storm and Sharp38