disc brake problem

....not a crack. What happens is the inside of the rubber lines deteriorate with age and soften. They then act as a handy dandy checkvalve. The master cylinder will provide enough pressure to push fluid through the lines, however they will not be abl;e to force it back...hence the brakes will stick. An easy test for this is to sim ply crack the bleeder valve on the sticky wheel and retry your spin test....if some fluid comes out and the wheel spins freely you have likely found your culprit.

Gareth

I don't remember if disc brakes have any adjustments like the star wheels on drum brakes, if so check that.

Hoses usually fail by swelling up and restricting the flow of brake fluid. It's fairly easy to force fluid past the hose with your foot on the pedal, but more difficult for it to return. Acts sort of like a check valve. Whenever someone complains about dragging brakes with no obvious cause I always suggest new lines.

good luck

nate

Ant wrote:

Hi

While lifting the front of my 72 SB I realized that the front wheels do not turn very easily, I actually have to put some force to turn the front wheels, and the left one more than the right one. I guess the disc brakes are braking a bit too much, bleeding the brake circuit will help? any ideas?

thanks Ant

Oh.....not a clue. The car is quite new, so Im still discovering the lemon inside. But I would assume that a crack or a problem in the rubber lines would mean less braking, instead of more braking, right?

Ant

Gary Tateosian wrote:

What Gareth is gettin at, is that your rubber brake lines may be so old thet they have started to deteriorate on the inside. It's a very well known problem, the ruber inside starts to lose shape and begins to swell. It swells so bad that the passage inside gets blocked completely. When you push teh brake pedal, the pressure will force brake fluid through, and your brakes seem to work. But when you take you foot off the pedal, the liquid won't have enough pressure to bleed it all back into the master cylinder, but instead the pressure trapped behind the clogged brake line will keep the brake pads pressed against the rotor.

Easy way to find out if this is what's happening: hit teh brake pedal hard once, then get out of the car and open the bleeder valve of teh suspect brake caliper. If brake fluid squirts out in a rush and the wheel suddenly starts to rotate freely, then this is just what happened. Swollen rubber brake line.

Of course it's also possible that the brake pedal is adjusted wrong.. it would effect both front wheels though. The pedal has to have a tiny amount of free travel before the pedal rod touches the piston inside teh brake master cylinder. You need to know what to look for when checking this. Brake pedal should be VERY loose to move in the upright position, it's a very slight movement but enough to say it's not yet pushing anything, just flopping around a bit. This tiny movement is barely visible to the eye, but needs to be there. If the pushrod (at teh base of teh brake pedal) is adjusted to zero free play, then there's a risk that the fluid return passages in the master cylinder aren't opened for the fluid to flow back properly. (Master cylinder piston not retracting all the way back when you lift your foot off the pedal)