FORK SPRING PRELOAD - OPEN CHAMBER CARTRIDGE
INTERNAL TOP-OUT SPRING
and WP 4CS

These instructions outline Fork Spring Installation on a WP 4CS Fork. The procedure is similar for any Open Chamber, Internal Top-out Spring, Cartridge Fork.

Check to see that your fork has an Internal Top-out Spring. Once the spring is out pull up on the damping rod. It should feel springy. If it feels solid these instructions do not apply. External Top-out Spring.


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 new fork spring. If there are preload adjusters back them out to minimum preload (all the way.)
 
Bottom the Outer Fork Tube fully.
 
Measure from the top of the Spring to the top of the Outer Fork Tube.
 
This is the Relaxed Length Reference.

7- On some models including WP 4CS the fork spring fits into a 7mm recess. This recess depth must be considered when calculating the preload.

Check to see if there are preload washers already in the recess.

 

8- Find out where the fork spring touches the cap. There are many styles; some with preload adjustment, some that require a special spacer.
 
On the WP 4CS fork caps in this example the spring fits into a 7mm deep recess. Check to see if your cap has a recess. This recess depth must be considered when calculating the preload.
 
The cap is NOT recessed on many models. The spring should always rest on a steel or plastic washer. It should NEVER rest on the aluminum fork cap. Be sure to take the thickness of these washers into consideration.

9- With the adjuster backed out all the way install the cap fully onto the rod.
 
Measure from the top of the Outer Fork Tube to the bottom edge of the Fork Cap. In this case add 7mm for the recess depth. This is the Set Length Reference.
 
The Relaxed Length Reference minus the Set Length Reference is the Preload.
 
Make sure there is positive preload. In other words the Relaxed Length Reference is greater than the Set Length Reference.
 
Adjust the preload by adding or subtracting preload washers in the recess on the cap. This should be 3-5mm on most dirt bikes. See your DVS Setup Sheet or the Product Search for recommendations.

10- Adjust the Preload by adding or subtracting preload washers. The washers must always be centered.
 
In this case preload washers can be installed into the recess in the cap to add preload.
 
On many Open-chamber forks washers are added at the bottom of the spring.
 
Preload should be 3-5mm on most dirt bikes. Street bikes can vary from 10mm to as much as 40mm of preload. See your DVS Setup Sheet or the Product Search for recommendations.

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!