FORK SPRING PRELOAD
EXTERNAL TOP-OUT SPRING
DAMPING ROD or CARTRIDGE

Recommended Preload is available in Product Search or on your DVS Setup Sheet if you are using Gold Valves.

FIRST STEP - Identify your Top-Out Spring Type (displayed in Product Search)
     External Top-Out Spring - These instructions - continue
     Internal Top-Out Spring - Click Here

Dirt bike preload ranges from 4-6mm. Fork preload is NOT a tuning variable. Too much preload will make the ride harsh particularly on acceleration bumps.

Street bike preload ranges from 5 to as much as 35mm. Preload can be used to affect ride height and chassis geometry. It can also temporarily be used for increased loads however this is best done with spring rate.

Preload can have a huge effect on the feel of the fork so make sure you look it up on the Product Search or DVS Setup Sheet.
 

Click to Enlarge

Damping Rod with External Top-Out Spring

External Top-Out Cartridge
1 - These instructions cover all EXTERNAL TOP-OUT SPRING FORKS
 

"External top-out" means external to the damping rod or cartridge tube

This includes:

     All Damping Rod Forks

     Some right side up Cartridge Forks

 
 
 
2 - TOOLS AND SUPPLIES
  • Tape measure (metric)
  • Tubing cutter for spring preload spacer
  • Preload Spacer material
  • Steel Spring Washers
METHOD 1

DAMPING ROD

EXTERNAL TOP-OUT CARTRIDGE
3 - Setting the fork spring preload is done by making the correct length preload spacers.

1. If your forks have Preload Adjusters set them to minimum.
 
2A. If you have a damping rod fork with an Emulator. Install the Emulator Adapter first if required. Drop the Emulator down the tube. It sits on top of the damping rod (or Adapter) with the Emulator Valve Spring facing up and is held in place with the main fork spring. Visually check to make sure the Emulator is sitting squarely on top of the damping rod or the Adapter.
 
2B. If you have a cartridge fork with an external top-out spring the cartridge rod does not need to be attached to the cap for this process.
 
3. Extend the fork tube all the way.
 
4. Insert the fork springs into the fork tube. (On top of the Emulator if used.)
 
5. Install a steel or plastic fork spring washer or special collar.
 
6. Install the fork spring spacer tube. Any length that goes above the top of the fork tube is ok for now.
 
7. Install another steel or plastic fork spring washer or special collar.
 
8. Set the fork cap on the washer.
 
 
9. Measure from the top of the fork tube to the sealing lip on the fork cap. This is a direct measurement of fork spring preload.
 

Direct Measurement of Preload
(THIS ONE HAS WAAAAY TOO MUCH, we will need to cut the spacer)
 

10. Adjust the spring spacer tube length to achieve the proper preload.
 
In this example using the image above:
 
For 15mm preload you would shorten the spacer by 31mm.
 
46 - 15 = 31mm shorter
 
NOTE: You must have steel washers on both ends of the spacer. The spacer must not rest directly on the spring or the cap.
 
 
 
NOTE: RT Springs are often a different length than stock. This is how they are designed. You will have to make your own custom spacers.
METHOD 2

4 - Be sure to check if the thread on the cap hits the thread in the fork tube before touching the washer. This would give a false reading. If this occurs add some spacing washers until it clears.

 

Measure from the spring washer to the top of the fork tube.

It is a little hard to see but in this case it is 11mm.

 5 -  Measure the Fork Cap Height

In this case 18mm. (The fork cap is upside down)

 

Calculate the Preload

(Fork Cap Height) - (Spring Washer to Top of Tube) = Preload

18 - 11 = 7mm Preload

Adjust the Spacer Length or add washers to get the recommended Preload.

 
NOTE: RT Springs are often a different length than stock. This is how they are designed. You will have to make your own custom spacers.