Losing feel in front brake

[MNKeith]

Confused.

I have an '08 EC250 with a front brake that has a mind of it's own. When cold, I have normal lever feel. After a brief amount of riding, the lever travel shortens dramatically and is quite stiff. The front brake still operates but I lose leverage with the shortened pull and the feel just isn't very good. It doesn't seem to return to what I deem normal until the bike has been put away for the day.

This problem has been the same through:

Various brands and flushes of fluid.
Varying amounts of fluid in the master (from bottom of sight glass to top)
Multiple brake pads
And now on a brand new front brake line (replaced due to wear)

Now I'm on to either the caliper or the master? Or something I'm not thinking of. Any experience or thoughts on this?

[memphis2857]

Take the caliper apart and rebuild/clean it. It's probably all cruddy and when it gets hot the tolerances in moving parts gets tighter and it gets sticky.....maybe?


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[Rick]

Try putting a zip tie on the lever and throttle grip, pull it tight with a good amount of pressure. If there is a bubble it will work it's way back to the master cylinder... I'd try this first....could be an air issue.

[twowheels]

Originally Posted by Rick

Try putting a zip tie on the lever and throttle grip, pull it tight with a good amount of pressure. If there is a bubble it will work it's way back to the master cylinder... I'd try this first....could be an air issue.

I would have thought the same if it got spongy when riding, but not the other way around. Rebuilding the slave and master seem like good routes to follow.

[MNKeith]

I'm very confident it's not an air issue.

I'll dig into the caliper first and see what I find. Gotta take that off this week for some unrelated maintenance anyways.

[gasgasman]

Check the slide pins on the caliper. They may be binding when hot.

[MNKeith]

A year and a half later and I was at the same point.

Brake always worked, just lacked feel and I'm not a AA rider so priority level lost out to drinks on the patio most of the time.

I bled different ways. I replaced lines. I rebuilt the MC. I cleaned the MC. I swapped the MC.

Sometimes I'd get slight improvement, but then back to rock hard.

Never had irregular wear on the pads and didn't see how the caliper could cause this.

Welp. Swapped calipers yesterday. BIG difference. Normal lever travel and progressive front braking. I have yet to get in to the old caliper and see if the seals or pistons are wonky, but whatever is going on, that was the culprit.