INCLUDES: NPL Collar, NPL Spring, Go-Between and Sizing Collar (selected models).

TOOLS REQUIRED: Service Manual, Vise with Soft Jaws TMVJ 065 or equivalent, TSPA 01 Preload Adjusting Tool or Spanner Wrench, ¼” Flat Blade Screwdriver, TSSM 01 Sag Master or Calipers.

DIGITAL VALVING SEARCH (DVS) printout: See DVS for your custom spring setup. 

Support the rear of the ATV securely. Remove rear shock per the procedure in your service manual. 

NOTE: your model may look different.

Click to enlarge.

Stock Spring Disassembly

D1 Clamp Shock into a vise with Soft Jaws

D2 Loosen Lock Ring.

D3 Remove all spring preload using a Spanner Tool or by loosening the Collar by hand.

D4 Clean and lube the threads.

Remove the Retaining Collar
D5 Use a small Screwdriver or similar tool. Gently pry the Bottom-out Bumper away from the end of the shaft.

D6 Using the Race Tech Spring Compressor (TSSC 01) pull the Spring away from the lower Shock Mount and remove the Spring Retainer(s).

D7 Remove the stock Spring.


Note: Some Base Kits contain a threaded NPL Collar (TRX450R, Banshee, 2001 Raptor 660). For these Kits the stock Preload Adjuster Collar should be removed at this time. The stock Preload Adjuster Lock Ring will be reused with the new threaded NPL Collar.

Shock Disassembly (Required for YFZ450, TRX250R, Banshee, Raptor 660/700 and LT500)

D8 On these selected models NPL Spring Base Kit installation requires complete shock disassembly. The NPL Spring Base Kit parts must be installed on the body before the Shock Shaft is installed. 

Caution: If you are unfamiliar with rebuilding the shock STOP!!  Seek a qualified suspension technician.

NPL Collar and Spring Assembly

A1 Install the NPL Collar (single flange) with the long end of the flange facing the bottom of the Shock.

A2 Install the NPL Spring over the NPL Collar.

A3 Install the Go-Between Collar. If your Collar has a step on the inside diameter the larger diameter must go towards the threaded portion of the Shock for proper clearance. For NPL Collars with no step on the inside diameter reference the model listed below for proper flange length installation.


> TRX400EX, Raptor 660 and TRX450R – long flange into the NPL Spring

> LTZ400, KFX400, DVX400, YFZ450 (04-05), Banshee and Warrior – short flange into the NPL Spring.

A4 Install the Main Spring (sold separately).  Refer to Race Tech’s Spring Search on racetech.com for Spring Series and rate selection.

A5 Some models have a Spring Sizing Collar included in the Kit. This Collar should be installed at this time.

A6 Install the original Lower Spring Retaining Collar using the Race Tech Spring Compressor.

NPL Gap Setup 

A7 Refer to the DVS Specs from racetech.com.

A8 Adjust the Preload Collar to set the Gap between the flanges of the NPL and Go-Between Collars.  Use a Caliper or Tape Measure.

A9 Gently tighten the Lock Ring against the Preload Collar being careful not to change the Gap. 


NPL Gap is the distance between the NPL Collar Flange and the Go-Between Collar Flange that extends into the NPL Spring.  

This distance determines the ride height of the ATV. A larger Gap equals a lower Ride Height; a smaller gap creates a higher Ride Height.