Topic: Front brake binding when turned

[Beav068]

Okay, I've got a (probably stupid) question for you folks.

On my '72 CB750, my front brake seems to "grab" when the bike is turned.  This is most noticeable when backing up, say to park.  If it is kept straight..no problem.  If the bars are turned one way or the other, it binds.

I've readjusted the brake and it is in spec.  I've done my share of auto repairs, but am new to motorcycle mechanics, so please feel free to treat me as a dummy and be as basic as you want.

Thanks for the help!

Tim

[.RJ]

Is the line getting pinched on the forks somewhere? 

[Beav068]

Hmm...I hadn't thought of that.  I'll check.

Is it possible that the "floating" caliper is somehow closing up when tilted?

Like I said, I'm not too familiar with bikes.

Tim

[750goes]

It sounds to me like your caliper pivot arm is not pivoting....
pull the caliper off and knock the pin out of the pivot bolt if you can and grease it, put it back together...simple...thers a small o ring in there as well..


 

[kirkn]

hmmm.... interesting problem.  My 78 750K8 does the same thing.

I'm in the process of overhauling the caliper, because it was sticking, too.  Separate issue.  But, I took the whole arm off, and as mentioned, greased the pin that holds the arm.

On the other hand, I'm not sure I understand how that would cause the problem.  I mean, turning the forks SHOULD turn the entire assembly an equal amount - forks, wheel, disk, caliper, arm, etc.  Why should turning the wheel cause the brake to bind?

On the OTHER other hand, someone mentioned to me that a worn wheel bearing can cause this, because turning the wheel can load/unload a bad bearing, and the slop could allow the disk to cock within the pads.

Hmmm....

Not sure either of those explanations ring true.  I'll let you know how mine reacts once I get it back together.  Plus, my own front wheel bearings were in very good condition.  No slop at all.

Actually, come to think of it, the front end of my bike IS back together, the bike is just waiting on the carb rebuild in progress.  But, maybe this evening I'll just push the bike out and around and see if the binding problem has been cured.

Hmmm.......

Kirk

[750essess]

Mine did this too, if everything is in good working order, its the fork flexing and binding up the caliper. I had a plastic front fender on it and dual disks, it was so bad you could hardly push it. Do you still have a front fender on it? The fender keeps it from twisting...some.

[Beav068]

I don't think it is flex in the front forks as:

1) I'm all stock with front fender and all; and,
2) It does it even if I raise the front, spin the wheel and turn the forks.  Not nearly enough stress to be causing fork flex.

I'm gonna try lubing the caliper pivot arm and see what happens.

On a side note, it didn't (noticeably) start doing this until I replaced my front left fork seal.  Maybe I put something back together wrong (not sure what, though).

Tim