Front brake woes

[Ivan]

When I drive to work, it is dark, and cool. When I get off work, it is sunny and 100º. Possibly 40º of temperature change.

Lately, my front brakes have been dragging on lunch break or when I start the trip home. First time it happened, I checked the "spooge hole" to make sure it was clear of obstruction, and bled the brake. All worked fine, until the next hot day. Same thing happened again. So I took the MC cover off and looked into cleaning the hole again, and noticed the brakes released when I loosened the cover screws.

My guess is that the temperature swing is causing the air and fluid to expand in the reservoir and putting pressure on the brakes as the day heats up. Of course dragging brakes create more heat and aggravate the situation.

Most cars have a hole in the cover above the rubber membrane that allows air expansion. My XS cover does not. Is there supposed to be one, or is it supposed to be solid, and there is something else I am missing? I am considering drilling a very small hole in the cover to vent air, and the rubber membrane will keep the fluid fresh and water free. Anyone see any issues with this?

[Ken Talbot]

This spare cover has a groove that provides the venting you're talking about (right side of the photo, between the screw holes). Have a look at the inside of your cap to see if yours has one. It may be spooged up.

Under your cap, do you have a stamped steel plate that sits on top of the rubber gasket? The groove should provide venting across the top of the steel plate to the top of the rubber membrane.

[03mach1]

Also, make sure you don't overfill the m/c, it has to have room to expand.

I had a problem with my "Spooge" hole, it wasn't drilled all the way thru!! Tough to see, but it was started, but never made it thru into the plunger section. Had to completely removed the m/c and plunger to fix.

I had the same problem, sticky brakes and very hard brake lever, especially when it got hot outside.

[Ivan]

Yes, I have the steel plate. Will look into the groove. I didn't notice it, so it may be gooped up. Excellent post, thanks.

As for the pressure release hole not being drilled, I reckon mine is. I got squirted in the eye when I pumped the lever with the cover off. Also had a fine wire that I shoved through it to clean it, so I am pretty sure it is working.