How to Replace a Harley FLHT's Fork Seals

Updated April 17, 2017

Harley-Davidson motorcycle fork seals on touring models such as an FLHT serve the important purpose of maintaining the suspension of the front end. Motorcycle seals hold the fork oil inside the fork tubes and keep the oil from leaking out. Proper installation is important to ensure leak-free forks. You must use care when removing the fork tube and inner parts to ensure that you are able to properly install the new fork seals.

Raise the motorcycle onto a motorcycle lift or jack to remove the front wheel and fender. Remove the windshield, fairing cap and fairing.

Loosen the pinch bolt just below the fork stop with a standard wrench, along with the fork cap bolt on top of the fork tube. Slide the fork stop up and off the fork tube. Remove the fork tube from the lower fork bracket. This will loosen the fork tube from the Harley.

Remove the fork tube plug from the threaded end of the damper rod inside the fork tube, using a wrench. Remove and discard the O-ring on the fork tube plug. Drain the fork oil from the tube by turning it upside down and allowing the oil to drain into a drain pan.

Clamp a fork spring compression tool into a vice. Pull on the fork slider to compress the fork assembly and place the end of the assembly with a hole over the post at the bottom end of the compression tool. Place the spring compressor around the top of the locknut on the spring of the fork assembly. Adjust the tool until all three retaining pins slide inside the holes in the spring compressor. Turn the length adjuster screw that's inside the fork tube clockwise by hand to compress the spring. Remove the locknut from the end of the damper rod, using a wrench. Turn the length adjuster screw counterclockwise to release the tension on the fork spring.

Remove the fork tube from the fork slider. Remove the fork oil seal, slider spacer and slider bushing off the fork tube. Discard the used oil seal and bushing.

Coat a new bushing for the fork leg with new fork oil. Spread the bushing apart at the split line to allow room to slide it onto the fork tube.

Install the damper cartridge into the fork tube by hand, pressing until the end of the cartridge drops through the bottom of the fork tube. Install the lower stop onto the damper cartridge.

Install the fork tube into the fork tube slider. Take care not to scratch the fork tube to ensure that no fork oil leaks. Install the fork slider bushing by coating it with new fork oil and inserting it down into the fork tube. Press the slider spacer into the tube until it touches the slider bushing.

Install a new fork seal -- lettered side up -- over the fork tube inside the slider. Using the fork seal installer like a slide hammer, drive the seal into the fork tube until the seal is seated. To seat the seal, you must press the seal into the tube with the fork seal installer until it stops. Add Type E fork oil.

Repeat for the other fork leg.

Things You'll Need

  • Motorcycle lift or jack
  • Standard wrench set
  • Drain pan
  • Fork spring compression tool
  • Vice
  • Fork seal installer
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About the Author

Christina Teter is a business professional who began her freelance writing career in 2010. Her work has appeared on Leavr and other online publications. Teter has a Bachelor of Science in accounting from Truman State University.