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Quick and Easy Trailer Disk Brake Repair


Quick and Easy Trailer Disk Brake Repair
Items Needed:
• Wheel lug nut wrench
• Jack or car ramps
• Trailer supporting blocks
• Rags
• Open ended Wrench Set
• Adjustable Wrench
• Allen wrench set
• Air compresser with nozzle
• Flat head screw drivers (large and small)
• Grease pump
• Clear cup or bottle
• New caliper O-ring (1 for each wheel with brakes – manufacturer specific)
• New caliper dust seal (1 for each wheel with brakes – manufacturer specific)
• Clear hosing (roughly 12 inches long; inner diameter = brake bleed nipple size)
• Brake Fluid (2 bottles DOT 3)
• Silicon Grease
• Thread sealant
• Marine trailer bearing grease
• 1 lovely assistant (for a few minutes)

• Raise trailer with jack so wheel is off the ground.
• Support trailer with supporting blocks.
• Rotate tire with hand to listen for rubbing bearings or other noticeable problems.
• Remove wheel lugs with wheel lug nut wrench.
• Remove tire.
• Now is a good time to open the wheel bearing cap and inspect wheel bearing grease. Change/add new grease as needed. Close up bearing cap.
• Remove two bolts that hold the brake caliper in place.
• Remove brake fluid hydraulic hose from the caliper.
• Inspect brake rotor (discs). If grooves or pits are present, either have the rotors turned by a brake shop or replace.
• Drain old brake fluid into a bottle.
• Gently use compressed air to blow out caliper piston (just a tiny amount of air will punch it out).
• Remove old caliper dust seal.
• Remove old caliper o-ring.
• Inspect caliper cylinder and piston for any signs of damage. Replace as needed.
• Apply silicon grease to new caliper o-ring and dust seal.
• Install new o-ring in caliper cylinder
• Install new dust seal to caliper piston (lip should be facing in the direction that will hold brake fluid in)
• Rub a little brake fluid on piston to ease insertion.
• Press in piston with your hands. You may need to wiggle back and forth as you press.
• Install new brake pads onto caliper.
• Reattach brake fluid hose to caliper.
• Apply thread sealant to caliper bolts to keep corrosion/rust out
• Reattach caliper to trailer.
• Reinstall wheel. (Apply thread sealant to bolts to keep corrosion/rust out).
• Tighten lug nuts.
• Inspect master cylinder for rust (replace if damaged).
• Fill master cylinder reservoir with new brake fluid
• This is where you need your assistant. Have one person to add fluid to the master cylinder reservoir and pump master cylinder while the second person opens/closes the bleed screw on each brake caliper.
• Loosen brake caliper bleed screw. (If there are two, use the higher one. If both are at the same level, use the rear one.)
• Install a clear hose on to the bleed screw and put the other end of hose into a bottle/cup. If you make an upside down “U” with the hose it will help you minimum
• Pump the master cylinder to bleed brakes.
• Close bleed screw once no more air bubbles are seen out of bleed screw.
• Bleed other brake.
• Make sure master cylinder reservoir is full.
• Test completed work.

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