Topic: Brain Transplant: Front Brake Pucks Grinding Rotor

[YoungBlood]

Young and dumb back again. I managed to replace the front fork studs, but it seems one problem is leading to another. While waiting for the studs to come in the mail, I also replaced my throttle lines. However, the ones I ordered were "short", and I did not think twice about this until I received them. Trying to deal with less lineage, I had to run them on the driver's right, and above the ignition coils. Although to get them to have enough slack when turning the handles right to left I had to move my throttle handle and the master brake cyclinder/front broke handle inward. This caused the front brake top line to get a bit more curved than it used to be.
Now, with all this said, the problem I faced today was trying to get the wheel and rotor to slide into the brake housing. I could not! There was not enough clearance between the brake pucks. This is where I became young and stupid... instead of taking the brake apart and compressing the piston like I should, I cheated. I loosened the bolts holding the back and front puck together to gain extra clearance. I also tried some other things that must not be spoken (they involved a flat head). Then after gaining about a mm or two I squeezed the rotor and wheel in and tighten back the caliper housing bolts. Next, I tightened the front wheel to specs with the gap in the rear. But now the wheel is too tight... I once again was stupid and thought maybe I can get away with riding it around the block a little and this will loosen up the heavy heavy drag. Nope! Rotor got so hot it burned the rotor guard.... I could use some help here.
First: How do I gain extra clearance so that I can fit my rotor properly in-between the caliper.
Two: Could it be that extra bend in the front brake line from moving the handle bars inward has caused this restriction in caliper clearance?
Three: Why is it that when I drove around the block, the front brake would not engage by pulling the front brake handle? Even though it would automatically come to a quick stop as though I was pulling the front brake. I understand that the pucks are tight against the rotor, but why? Did I accidentally squeeze the brake lever when doing the throttle cable change?

Thank you for any suggestions and thoughts. And I know I need to start slowing down, but the week of no riding to make some repairs is driving me crazy.

Sincerely,

Trevor

[Kevnz]

It sounds like the kink in the brake line is retaining fluid pressure and keeping the brake on. Try cracking open the line at the brake switch union and see if your brake frees up. Just a bit, and be prepared for a bit of fluid leakage. With luck you won't need to bleed the brakes, but you can do it just by slowly pulling the lever and watching the tiny bubbles come up through the master cylinder. The piston should normally retract a fraction when there is no line pressure to give clearance. If, when you do this, the brake is still binding, there must be some issue within the caliper.

[754]

Is your fluid too high  ? When you pushed the pads in, the fluid needs somwhere to go..

[Don R]

 Stop and read the manual at the top of the forum page. Section 4 has brakes. I usually print the section that I need, the page numbers may not match. Check print preview.
 Slow down and try to do it right, not like I do it.

[markmyodb]

It could be the set up of the pad clearance is off. the way you loosened the bolts (and other nameless things) did not address realigning the pads to the rotor. the wheel will float left right enough to cause the stationary pad to be mechanically engaged.

As Don said, review the manual its on the website if you don't have one. 

[pjlogue]

Did you put new brake pads on?  If yes then you may need to remove any paint on the sides of the pads so the pads have clearance and will fit inside the caliper housing properly without any drag or force needed to push them in or take them out.  They should be  loose inside the caliper.  Your best bet is to tear down the caliper and clean everything properly and reassemble.  (same with the MC and caliper mounting bracket)  Any debris in the O ring groove in the caliper will cause the piston to bind preventing full retraction.  i.e. your brake will bind after applying the brake.  Caliper mounting bracket pivot can become corroded and prevent the caliper from floating {self centering over the rotor)

If the brake lines are old you can get a problem where the lining of the brake line becomes detached from the line and act as a one way valve and prevent the unloading of the system.  Same thing can happen if the very small port inside the MC is blocked (deteriorated brake line can block this or even gelled up old brake fluid)

Brakes are not something you want to guess at or say "good enough" with.  They tend to fail at the worst time.  Take the time to do a complete and proper job.  The reward will be solving the problem and having a reliable brake system and possible saving you a lot of grief from a bad accident.

-P.

[Rookster]

The quickest fix is to remove the back of the caliper. This should allow you to swing the piston side of the caliper off the disk. Then remove the master cylinder cap. Use a tube or turkey baster to remove some fluid from the master cylinder. Now push the brake piston in by putting pressure on the pad. You should be able to do this with just hand pressure. If you can’t push the piston in by hand then you have a problem with either the lines or master cylinder.

When the original brake hoses fail they often allow brake fluid to be pushed through them but don’t allow the fluid to flow back. This locks on the brake. The only fix for this is to replace the brake hose. 

Scott

[754]

The best way to retract pads with caliper assembled .. 2 tire irons..

[Boxy]

I had the same problem and it ended up being the nylon washer that sits on the back of the brake pad on the piston side. It slipped out of its groove and fell between the pad and piston. I ended up using a small amount of high temp silicone to hold it in place until final assembly.

[YoungBlood]

That ended up being the problem! Funny, but a headache. I was able to solve my problem by removing the pucks and pressing the caliper further back with a c-clamp and some cardboard. I also went ahead and adjusted the break, all is going well again. Thank you everyone for your opinions and advice.
The brakes are quite squeeky, but I am confident the culprit is the fact there is no grease on those pucks. The person I purchased my bike from never greased them, and I didn't have any lying around when I got the shoes far enough back for the rotor to slide in properly.
New questions: 1. why 20W-50 and not the Honda recommended 10W-40.
2. Is there an alignment procedure for my front forks after reinstalling new seals and reinstalling the forks back onto the frame?
3. What rpm do you all idle at? I know manuals will say ~1000, but it seems my bike runs better at 1200-1400.
4. I want to tune the bike, where should I start? I am a novice... contact breakers and gapping? timing? cam chain? intake/exhaust valves on rocker arms
PS: I have a 1975 Honda Cb750f I'll post a pic) and I bought a carb rebuild kit and carb synchronizer. I have read around and heard that I should play with the carbs LAST.
Thanks,
Trevor

[Don R]

 The 10/40 spec was intended to be a minimum for cold weather riding in the original manual. The translation from japanese to english in the manual lost a little detail.  That's the way I heard it anyway.