The other day I noticed that my front brakes were pulsating a little. I didn't think much of it but then noticed a little brake fluid was seeping from around the gasket. I popped the lid of the master cylinder and the gasket the covers the entire top of the master cylinder was kind of pushed down into the cylinder and had fluid on top of it. I took the gasket out and wiped it down and reinstalled while visually checking that the fluid level was correct. The brake worked great for about 50 miles then started doing the same pulsating thing again. I took the master cylinder lid off again and it looked fine. No fluid on top and it had not been "sucked down" into the cylinder. I'm stumped on what the problem is with the pulsating and why the gasket had been sucked into the master cylinder the first time. The bike is a 2010 Road Glide Custom FLTRX and has 10,500 miles. I recently had the rear brakes replaced when I had the tire swapped but can't make a connection on what that would have to do with anything. Any help would be appreciated. Thanks

 

This pulsing you are having usually means a warped rotor in my experience.As far as the rubber bladder goes maybe it just wasn't installed right in the first place.Also the would be no connection between the front and rear brakes.
Where you low on fluid when you opened your master cylinder for the front brakes?

98 Road King Police

 

I don't think it's a warped rotor. When I removed and reinstalled the gasket the first time the pulsing was completely eliminated for about 50 miles. I'm wondering if maybe some air got in or something.

 

I agree that pulsation in the front brake lever usually means a warped rotor. Air in the lines is not going to cause pulsation in your lever, it is going to make the lever softer when you pull on it to operate the front brake.

 

Pulsing caused by warped rotors can be less obvious at lower temps, if the warp isn't too bad. Check the rotor thickness, as they get thin, they are more likely to warp, especially with hard braking.