Fork Spring Preload 
OPEN CHAMBER CARTRIDGE
INTERNAL TOP-OUT SPRING
 & WP 4CS

These instructions outline Fork Spring Installation on a WP Four Chamber Fork. The procedure is similar for any Open Chamber, Internal Top-out Spring, Cartridge Fork.


Yes, that's Master Suspension Technician Alan "AJ" Peck's arm again.

Note: Click on the images to enlarge.

 1-  Back out the adjuster on the fork cap all the way.
 
This step is really for reassembly so the needles are not damaged in the process.

2- Loosen the fork cap with a pin spanner (shown).
 
For the WP 4CS fork we have a really cool Fork Cap/Comp Assembly Tool (TFCW PS3648) available.

3- Use the pin spanner or fork cap wrench and a 19mm wrench to remove the cap from the damping rod.

4- Remove the cap.

5- Remove the spring from the fork tube. 

SET THE FORK SPRING PRELOAD
 
6- Install the fork spring on the rod.

7- Measure the Relaxed Length Reference. The Relaxed Length is measured between the top of the Spring and the top of the Outer Fork Tube (with the fork tube fully bottomed).

 

8- On this 4CS fork caps the fork spring fits into a 7mm recess. Double check your cap recess depth.
 
This recess depth must be considered when calculating the preload.
 
On many models this is not necessary as the cap is not recessed.

9- With the adjuster backed out all the way install the cap fully onto the rod.

10- Measure from the top of the Outer Fork Tube to the bottom edge of the Fork Cap. Add 7mm for the recess depth. This is the Set Length Reference.
 
If the Set Length is less than the Relaxed Length there is postitve preload.
 
The difference between the Relaxed Length and the Set Length is the Preload.
 
Adjust by adding or subtracting preload washers placed at the bottom of the spring. See the DVS - this is usually 3-5mm on most dirt bikes.

11-Tighten the jam nut to the fork cap on the damping rod.

12- Tighten the fork cap.

13- Set the adjusters to the recommended settings.
 
Put on the cool Race Tech fork stickers and have fun!