Upgrading Harley’s 39mm Front End, Pt 3

Even More Forking Around

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. Insert a screwdriver in the indented area of your fork dust cap cover. Tap the screwdriver a few times with your rubber mallet, and the cap will pop off the fork tube.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. You can see that under the dust cap is a rubber dust seal. You can use a small flat-blade screwdriver and pry in between the rubber boot and the fork leg and the dust seal will pop off easier than the dust cap did.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. Next, using the same flat-blade screwdriver that was used to take off the dust seal, pry the retaining clip from the inside of the fork legs beveled edge.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. Grab the fork tube with one hand and the fork leg in the other, and slide the two pieces apart.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. Remove the dampeners from the fork lowers and clean off any residual fork fluid that may be still lingering on the damper tube. Place the damper tube in a vise and drill the lower damper holes to 5/16-inch.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. After you have completed drilling all four damper holes, it’s a good idea to use a deburring tool or a file to get rid of any unwanted metal and any sharp edges.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. Again, pictured is the drilling of the stock damper rod to allow a heavier weight fork oil to pass through with ease when the forks are working under a load.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. This is what your damper rod should look like after the holds are bored to the appropriate size and cleaned up with our deburring tool.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. Pictured here is our Race Tech gold emulator kit for 39mm H-D forks as well as set of Speed Merchant preload adjusters to help us dial in the fork responsiveness. We will be also using Bel-Ray 15-weight fork oil as per the Race Tech Gold Emulator instructions.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. To start we begin by setting the gold emulator valve adjustment to 2.5 turns out to start. This is a good place to set your adjustment to start, but you may have to come back and take the forks apart and readjust the valve to get the reaction from your particular front end.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. Place the damper rod through the lower fork spring.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. Drop the damper rod and spring into the fork tube as per the HD service manual states.

Words and Photos: Jeff Leighton

Upgrading Harley’s 39mm Front End

Upgrading Harley’s 39mm Front End, Pt 3

  1. Insert the Race Tech gold Emulator valve into the fork tube. It should sit on top of the damper rod.

Words and Photos: Jeff Leighton

Harley-Davidson's 39mm front suspension is adequate for cruising but it's not optimized. It can stand to be stiffer. Fortunately, the aftermarket knows this and offers a ton of ways to pull every ounce of performance you can get out of the forks. As you may have figured out from parts one and two of this story, building a better 39mm front end is a pretty big job. That's because this isn't just a spring upgrade. From the Chassis Design Company trees to the Race Tech emulators and spring kit, we're pulling every bit of performance we can out of the front end. In the end, though, it's worth all the hard work. We're even changing the weight of the fork oil. Thanks to JIMS USA, we also have the specialty tools to take some of the pain out of the job. Here’s how we're doing it.

Sources:

Bel-Ray

Chassis Design Co.

JIMS USA

Race Tech

The Speed Merchant