9.1 KYB Suzuki Posi-Damp Fork


    37, 38, 41mm
    Suzuki RG500 Gamma, GS1150E 1984-86, GSX-R750 1986-87

Suzuki's PDF - Posi-Damp Fork is very similar to the standard KYB Anti-Dive Fork. Emulator installation disables the PDF. It does not matter if the external compression valve hardware is either removed or left intact. It will be disabled by the location of the compression feed holes.

The use of proper rate springs and Emulators eliminates the need for the PDF and improves the ride quality significantly.

The picture below is not from this fork (sorry-you might be able to help out on this). However it is very similar. There are 2 or 4 small diameter compression holes below the step near the bottom of the rod. 

Modification is largely the same as cup-top damping rods as outlined in the Standard Emulator Instructions. The difference is the additional compression holes MUST be located above the step in order to bypass the anti-dive unit. Otherwise the forks will be quite harsh.



Modify the Damping Rod - Add Compression Feed Holes

Starting at 6mm above the step, drill a total of:

  • Six 6mm (1/4") compression feed holes - for 17mm and smaller diameter rods

Add holes in 10mm increments with each set of 2 holes perpendicular to the last to maintain rod strength.

Deburr the holes inside and out.

Do not bother modifying the holes below the step.


Some models do not have the second soft top-out spring.


Wave Washers

The washers between the step on the rod and the bottom-out cone create a check valve that opens on rebound.

Pay attention to their order. There are two wave washers and one flat washer. The order should be "wave, flat, wave".



Follow the Standard Emulator Instructions

Install the assembly into the fork leg from the top.

  1. Install the Top-out Spring on the Damping Rod.
  2. Install the wave washers and bottoming cone.
  3. Install the Lower Fork Leg and tighten the bottom bolt.
  4. Setup the fork spring preload.
  5. Remove the spring and install the fork fluid.
  6. Install the fork spring. Re-check the preload to insure the Emulator is seating properly (not cocked).
  7. Install the fork cap.

This block-off plate requires a gasket.


Block-Off Plates - optional

The PDF is completely bypassed with the addition of the new compression feed holes.

You have 2 choices. You can:

  1. Leave the PDF intact.
  2. Install Block-off Plates. There may be companies that sell block-off plates. If you are fabricating a block-off plate you must make sure it seals.