Brake questions

I have a few brake questions.

My brakes seem to be loosing pressure slowly after bleeding and usage. all the lines look good and the fluid stays full, but i loose pedal pressure. it is a new master cyl. what could be causing this? also only one of my drums get warm with use? could i have bad wheel cyls? would that cause that? how much do wheel cyls run?

Thanks
Tommy

 

Brakes may need adjusted. There is a cam on the backing plate in 9" brakes that adjusts the shoes. Did you have the same problem of loosing pressure before you replaced the master cylinder? If so it could be bad wheel cylinders. Pull a drum to see if there is any wet looking areas. Also just because it is a "new" master cyl. doesn't mean it is a "good" master cyl.

 

I didn't know they could be adjusted...i will have a look at that. the master cyl looked Identical to the one i removed because it was bad. Wheel cyls are next for me. thanks for the heads up on the adjustments...

Tommy

 

Most master cylinders require bleeding before you hook up the brake lines. More of a priming than a bleeding. But essentially the same thing. Did you do that? If you didn't, dig out the directions that came with the MC, it should tell you how.

 

A buddy of mine(the previous owner) did it so i don't know if he did or not... are those directions on the net?

TOmmy

 

Take a look here:
http://www.misterfixit.com/brakbld1.htm

I just bought a couple of 15/16" wheel cylinders - $9 ea.
While you're at it, pick up a set of speed bleeders - it'll save time and frustration.

 

Don't be suprised if the "new" master cylinder is the culprit. These things sit on the shelf for long periods of time at the parts store, the whole time the rubber lip seals deteriorating. Working as a mechanic, I see about a 40% failure rate on new master cylinders. Don't be afraid to ship it back and ask for a new one. But definately check those wheel cylinders, they don't sound like your current problem but crucial never the less.

 

I am taking it over after christmas to my father-in-laws shop and i think it is time to go through all the brake system. New wheel cyls, pads, etc...I would rather be safe than sorry, especially since i have already had them go out on the trail...scariest riding experience i have ever had.

Tommy