2008 Polaris Sportsman 500 EFI/X2/Touring/500 H.O. Service Manual, Page 317Get this manual
BRAKES 9Measure the inside diameter of the rear caliperThe caliper body is 2-step pistonThe rear step is measured as well as the outside step
Assembly
1Install new O-rings in the slide bolt bushing holesBe sure O-ring and seal grooves are thoroughly cleaned of all residue, or piston may bind in boreApply brake fluid to piston seals and install carefully with twisting motion to ease assembly until fully seated
.94in(23.88) mm) 1.5 in(38.1 mm)
= In mmRear Caliper Piston Bore I.DInner Bore Service Limit: .94" (23.88 mm) Outer Bore Service Limit: 1.5" (38.1 mm) 10Inspect caliper piston bore for scratches, severe corrosion, or galling and replace if necessary2Carefully assemble caliper body, making sure O-rings are properly positioned in grooveTighten the caliper anvil bolts and then torque the anvil bolts evenly to specification