Category Archives: R Bikes

Caliper Sliding Pins (Brake Maintenance)

Just a heads up.  I now have 54K miles on my motorcycle and the Rear Caliper Has locked up on me.  Why is this?  Sit down and grab a soda, coffee, tea, and I’ll tell you how.

The GS adventure uses what is called a floating caliper design (this is a common design on motorcycles).  The caliper is attached to a bracket and that bracket is attached to the rear axle.  When the rider hits the brakes only one side of the caliper has pistons which push the pads against the rotor. While this is happening the caliper then slides on the pins so the other side is taunt against the rotor.  This push pull action is what allows us to slow down or come to a stop at the light.

So what happens when something goes wrong?

I’m glad you asked.  In my case the pins that the rear caliper slides on have become so corroded that the caliper no longer slides.  When I hit the brakes the piston pushes against the rotor and the caliper doesn’t slide over for the extra surface area.  I have roughly half of the breaking force.  This was caused by water (from river crossings) and Road Salt from winter riding making its way onto the pins.  The elements were able to attack the pins because apparently I had a Teeny weeny hole in the rubber boot, which didn’t become apparent until I sprayed penetrant in there and noticed it was bubbling out in the middle of the boot.

So what is the fix?

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