Topic: Front brake caliper miss-aligned

[fredmalito4]

We are having a problem with the front brake on a 1978 750k. It appears that the caliper is not parallel to the rotor. I am assuming that this is the cause of our spongy brake lever and poor front braking ability that we've been fighting. The front master and caliper have been rebuilt using OEM parts. The bracket moves freely. Pads are new. We've tried gravity, pressure, and reverse pressure bleeding to rectify the issue. Adjusting the caliper spacing does not appear to make any difference.

I have uploaded a video and picture that I hope will show the issue. When pulling the lever, the caliper applies enough pressure to move the entire wheel assembly into the correct position by loading the left bearing. It also flexes it's bracket as well.

I cannot see that there is anything installed incorrectly. The bearing feel tight. I can only surmise that something is missing from the bracket or it is bent. Any other ideas are welcome. Thanks!


Fred

[Coredozer19]

Check the fitment of the non piston side brake pad. And there is an adjustment screw on the wheel side of the caliper arm. Screw it out to get it to move right or toward the driver side.

[fredmalito4]

Adjusting the screw doesn't rectify the issue, but I will double check to make sure the inner pad is installed flush. I'm reasonably sure it is, however. Thanks!

[Coredozer19]

Come to think of it. If you just put new pads in. They come with a new plastic ring for spacing. Make sure you didn’t double them up. And we are talking about the pad on the wheel side.

[Coredozer19]

Make sure you didn’t put the pads in on the wrong sides. It kinda looks from the picture that you did. The inside pad should have a hole for a small retainer type cotterpin.

[ekpent]

 Spongy feeling lever is another issue. Bleeding all the air out will hopefully help that issue. None of my earlier year 750's have that much thread showing on the adjuster screw for the caliper. There is a procedure for setting those up with a feeler gauge in the manual I believe. Make sure you don't have any tiny leaks at the crush washer fittings and hopefully your master rebuild is working like it should with no pitted bore,parts in wrong etc.

[scottly]

Is the fender brace mounted between the fork lower and the mounting bracket? The bracket should be against the fork, and the brace should be on top of the bracket.

[fredmalito4]

The pads are installed correctly, as the cotter pin is through the pad. There is only one spacer, and it’s on the wheel side. No leaks. Possibly the master may be an issue, as the shop used a poor medium for this metal when blasting it and it may have damaged the bore. I honed it as well as I could, so hopefully it’s OK.

HOWEVER; I seem to recall that the fender is between the fork and bracket. I will double check that when I get home.

[pjlogue]

The caliper isn't supposed to be perfectly parallel to the rotor.  Mine isn't and never was even from the factory.  (your's looks like excessive amount of non-parallel.)  The fender brace should not be between the fork lower and the brake bracket.  The brake pucks float a little to compensate for the non-parallel position.  There should be a domed disc that sits in the piston pocket and the back of the backing puck should be slightly domed. 

-P.

[754]

The bore has little to do with the function of the brake, it only has to steady it slightly as it moves in and out.
 The groove being clean however is crucial, as the seal will tighten up if it's not clean.

[fredmalito4]

I don’t have anything between the caliper piston and the pad IIRC.

NOTE, 754, I was talking about the master, not caliper.

[754]

Ah I see, old rubber lines can have poor feel, braided line will be much firmer..

[fredmalito4]

Scottly, looks like you nailed it.  Somewhere along the line prior to me getting the bike, someone install the fender between the Fork and the caliper bracket. I will try to find time Tuesday to rectify this, and see if that cures the problem. Thank you!

[scottly]

Your case is not the first time the brace has been installed incorrectly.