Topic: '72 CB500: How to put my brakes back on?

[roach374]

So I pulled my forks off to do a rebuild, and figured while I'm at it, I'll flush the brake system and replace the pads in the front.

I picked up a couple of EBC pads, but I'm having trouble putting the whole thing back together again. Basically I've got the forks on just fine, and the wheel, but the calipers seemed to be clamped all the way shut, so I loosened the two bolts holding the two halves of the caliper together, positioned them in the right ballpark on the fork, and on either side of the rotor, and started tightening the bolts. My thinking here was that the piston was out slightly, and putting some pressure on it would push it back in. The problem is that with the bolts fully tightened, the brakes are fully engaged, and the front wheel won't spin (this is without the brake line even installed, so no fluid in the system).

I *know* that "Caliper B" pad (the one without the piston. Not sure what that's called) is correctly installed, the retaining pin is in place, etc. I *think* that "Caliper A" pad (with the piston) is also correctly in place, but don't know how to check that to be sure.

I've completely removed the bleeder valve and brake line, so hopefully any pressure behind the cylinder is relieved, but I can't actually get the piston out to (e.g.) check the seal or anything. I know the brakes were working more-or-less fine before I messed with them.

The manual says "After replacing the pads, adjust the clearance between the brake disc and pad to 0.15mm (0.006in.) with the caliper adjusting bolt." But this is the bolt with the spring on it, that just moves the whole caliper assembly left or right. It doesn't increase or decrease the space between the pads, so it doesn't really help. (Plus I don't have any tools that can measure 0.15mm. Maybe a piece of paper would work?)

Can anyone recommend a good tutorial or video for re-mounting and aligning the front brake caliper after changing the pads? Bonus points if it includes torque values for the various nuts & bolts!

[Stev-o]

Sounds like your piston is stuck in the caliper.  I would remove the caliper and clean till it's spotless [especailly the groove] replace the seal and reassemble.  Should be a basic rebuild service.
Good time to give it a coat of caliper paint too, if needed.

[Scott S]

 The EBC pads are known to have some thick paint on the outside edges. Sand off the paint and make sure the pad moves freely in the caliper.

 Also, review the method for centering the caliper over the rotor.

[roach374]

Also, review the method for centering the caliper over the rotor.

Thanks! Where would I go to "Review the method"? I don't see anything on this in the manual (or at least not where it talks about how to disassemble the caliper).

[Scott S]

 You need to get the front wheel off the ground enough to spin it back and forth. Use the center stand and have a helper push down on the rear seat, or use a jack under the bike.

 Loosen the lock nut on the adjuster screw, on the outside of the caliper holder.

 Stick a long, flat blade screw driver between the spokes and turn the large head on the adjuster screw until the wheel drags as you rotate it back and forth. I like to actually lock it up.

 Once you feel it drag, loosen off just enough that it spins freely.

 While holding the screw in that position, tighten the lock nut.

 Also, did you clean and lube the pivot pin on the caliper holder? Does the arm actually move freely?

[Deltarider]

Also, did you clean and lube the pivot pin on the caliper holder? Does the arm actually move freely?

I suggest just to check first. My pivot pin still moves freely after 44 years!

[Bobarama]

I had the sticking problem as well. Sanded the edges of the pads and added a thin coat of disc brake line to cure it. My piston and seal were new.