Front brake sticking

[Borsom]

My front brakes on my 78 650 seem to be sticking, I took the caliper off and depressed the piston which worked for about a week now the front tire has almost completely locked up again. I am new to bikes does anyone have a suggestion for a an easy fix or is a rebuild or new master cylinder in order
Thanks

 

[retiredgentleman]

My front brakes on my 78 650 seem to be sticking, I took the caliper off and depressed the piston which worked for about a week now the front tire has almost completely locked up again. I am new to bikes does anyone have a suggestion for a an easy fix or is a rebuild or new master cylinder in order
Thanks

There is no "easy" fix when restoring motorcycles that have sat around for over 30 years. Take the caliper/piston apart and clean the parts until they are surgically clean. Pay special attention to the grooves where the rubber sealing rings sit. Buy new rubber sealing rings, as they make the piston retract. The slider bolts must be free and lubricated as well. Replace with new brake fluid.

There are 2 small holes in the bottom of the M/C reservoir. Make sure they are both clear of dirt/debris.

Did I mention, parts must be surgically clean.

 

[Borsom]

I took apart the caliper and cleaned the piston and the bore to a mirror finish and works great now but not sure what a slider bolt is

 

[Fleksta]

I took apart the caliper and cleaned the piston and the bore to a mirror finish and works great now but not sure what a slider bolt is

The bolts (or slide pins) that the moving half of the caliper rides on when pushed/pulled by the piston; they need to be clean and greased.

 

[Brian902]

The bolts (or slide pins) that the moving half of the caliper rides on when pushed/pulled by the piston; they need to be clean and greased.

I agree. Just removed the rubbers and bolts on all three of mine, I have dual front discs and one rear, and lubricated both rubber and bushing. They were all stuck and not moving as easily due mostly to the dry fit between the tight rubber sleeve and the sleeve it slides on. Big difference with a little white grease applied.
.

 

[gggGary]

There is one sliding pin on the late caliper 77-84, and none on an early caliper 72-76.
Did you replace the brake line? The side pin is easy to R&R I mostly find they are fine even after 30 years here in the midwest.

View attachment 54585

Part 6, 7, 8 in this image

A caliper rebuild how to here.

 

[Borsom]

I did not replace the brakes hoses yet I am not sure how old they, I suppose I will buy a mc rebuild kit and hoses to make sure i won't go over the handlebars anytime soon

 

[retiredgentleman]

I did not replace the brakes hoses yet I am not sure how old they, I suppose I will buy a mc rebuild kit and hoses to make sure i won't go over the handlebars anytime soon

Wash the dirt off the brake hose and you will see the manufactured date is printed on the hose. It almost certainly says 77 or 78, which means its 37 years old.
For safety's sake..................buy new brake lines.

 

[XSLeo]

In gggGary's pic the rubber part, #6 goes in the caliper. Part #7 is what the rubber part slides on. #8 Is a bolt is what holds part #7 in place. You lube between #7 and #6.
On the hoses there is a plastic ring that has the manufactured date on it. Rubber brake lines like tires should not be used if over 6 years old.
Leo