EMULATOR TUNING GUIDE

by Matt Wiley (with a little help from Paul Thede)

 

Vintage & Damping Rod Style Forks

  • Most Riders prefer the Blue #40 Gold Valve Spring set to 2-4 turns of preload > best working range is 2-5 turns; if less or more Emulator Valve Plate preload is needed, move to the softer 26 lb Silver Spring OR up to the 64 lb Yellow Spring with 3 turns as the starting setting. Total tuning range is 1-7 turns for any given spring, 1.5-5 turns optimum range. Gold Valve Kits are supplied with optional valve springs as needed.
  • 15wt Fork Oil is typical. Set to 130 - 160mm Oil Level (Fork Spring out, chrome tube at the bottom of the stroke, measuring from the top of the oil to the top of the fork tube). Oil Level Tuning Range is 100-180mm in general.
  • For Street the most common initial Fork Spring Preload is 15 - 25mm with RT Hi-Performance Fork Springs. The Tuning Range for Street is 5-35mm. The Range for Dirt is 5 – 15mm.
     
  • To adjust the Gold Valve Emulator you must remove it from the fork.  When you remove the fork springs, use a twisting motion to avoid oil drips.  To remove the Emulator, use a parts grabber or telescoping magnet.  Adjust the Emulator Valve Spring Preload a half turn at a time.  More Valve Spring Preload will make the forks stiffer. 
     
  • Before installation, be sure the jam nut on the Emulator is snug using a socket.  Adjust Fork Spring Preload with spacer length or washers. Adjust Fork Oil Level with Fork Springs OUT, Gold Valve Emulator IN, Forks bottomed out (chrome tube at bottom of stoke)

TUNING VARIABLES

VARIABLE

OPTIONAL

PRIMARY EFFECT

Valve Spring Preload *

0 - 7 Turns

Overall firmness, controlling a mushy feel and the speed the front end dives under braking. 2 - 4 Turns initial setting is standard. 1 - 5 turns usable range

Valve Spring Rate***

#26 Silver
#40 Blue
#64 Yellow

Overall firmness and the ride on square shaped bumps. Note that most 33-36mm vintage forks work better with the 40lb/in spring at 2-4 turns

Emulator Valve Plate Bleed Holes

1 – 4 Bleeds

Initial fork movement low speed damping & plushness before valve plate opens; small bumps, chatter, etc.

Oil Viscosity**

5wt - 30wt

Use oil viscosity to set rebound, this affects traction and stability. Heavier oil equals slower rebound, lighter oil equals quicker rebound.

Oil Level

100-180mm

Sets Final Firmness in the last 1/3 of Fork Travel

Fork Spring Rate

.38 – 1.0kg

Holds up weight of Bike/Rider, Sets Ride height, Sag, Fork Travel, Overall Front End Firmness

Fork Spring Preload

5-35mm

Fine Tunes Ride Height, Sag, Fork Travel, Firmness of Fork

* Measured from zero preload (no tension) on the Valve Spring.  To find zero preload back off on the adjuster bolt until the spring is loose then tighten it until the spring just touches.
** Use oil viscosity to set the amount of rebound damping, then adjust the compression with the Emulator settings.  The Emulator does not affect rebound, however oil viscosity does. 
*** The primary compression adjustment is the amount of Emulator Valve Spring Preload.  Increasing Valve Spring Preload makes the fork stiffer.  The effect of all the variables will overlap providing extreme tuning flexibility.


Tuning Details

  • The Gold Valve Emulator controls Compression Damping as the fork hits the bump. More or less Gold Valve Emulator spring tension (preload) makes compression Stiffer or Softer. Changing to different rate Emulator Valving Springs will Increase or Decrease overall stiffness by changing the slope of the damping curve (it will also effect the fork speed at which the valve plate opens). A Half Turn of Emulator Spring Preload is noticeable, a full turn is significant. Tune in half turn increments until you find the best setting. 
  • Another tuning variable for low-speed compression damping is the number of bleed holes in the Emulator Valve Plate (under the colored valving spring). Emulator Plates may have either 1 or 2 pre-drilled holes in the valve plate. Adding additional holes (up to 4, same size as originals) will add plushness to low speed fork response (small bumps, slow fork movement). This is a good way to address fork chatter issues you may encounter on the race track or harshness over small ripples and such on the street or trail. These holes control oil flow that is too low to open the spring loaded valve plate. NOTE: Bleed holes have little effect on high-speed damping (large bumps, fast fork movement).
  • Oil Viscosity controls Rebound Damping; how quickly the fork extends after the bump. Thicker oil slows fork movement down, thinner oil speeds it up (5/10/15/20/30wt etc). Please note that Suspension Oils are not constant in viscosity between brands! Choose a brand and stay with it to ensure consistent results when making changes! NOTE: Oil viscosity should be used for tuning rebound damping. For compression damping, adjust the Gold Valve Emulator Valve Spring Preload, Valve Spring Stiffness or number of Bleed Holes.
  • Main Fork Spring Preload controls Ride Height. 15-25mm is the useable range for Street. For Dirt  3-15mm is typical. Move down/up in spring rate if you fall out of this range. NOTE: Tune in 2 - 3mm increments using washers supplied with the spring kit (or adjust spring preload spacer length when needed).
  • Oil Level controls bottoming along with fork stiffness in the last 30% of fork travel. Tune in 10mm increments.  Measure the oil level with the Fork Spring out, Gold Valve in, chrome tube at bottom of stroke, top of fork tube down to the top of the oil. NOTE: Tuning fork oil level will only affect the feel in the last 30% of fork travel. Use this variable to address bottoming issues or if not using most, or full, fork travel.

There is no ‘right or wrong’ setup, rather what works best for a given rider for their particular riding style. We encourage experimenting with settings to find your personal ‘sweet spot.’ Always take notes and record your changes. It is easy to go back to the original settings. Keep in mind

‘The best youve ridden is the best you know!’

For more details on how Emulators work.

racetech.com