I took apart my Nixon as it seemed to have no compression damping. I found that the control valve was missing an o-ring, rendering it useless. It was basically sitting open, allowing oil to pass throught the compression piston unimpeded. I decided to put a proper compression shim stack in my fork. The cartridge disassembled: Compression piston: Piston with shims: Piston installed on compression assembly: I figured I would speed up the high speed rebound while I was at it by removing one of the shims: With these modifications, I now have a speed sensitive fork, with adjustable slow speed damping with the top compression dial.
Shims effect mid speed, piston geometry effects highspeed and bleed effects low speed. Looking at your 2nd photo it looks like the piston could use some deburring. The majority of dampers on the market today wether automotive, motorcycle, race car etc are velocity sensitive dampers. Bypass shocks and electronic controlled shocks position sensitive dampers. Good work on figuring out the problem and getting it all dialed in!
Do you have the tool to vacuum back the IFP as this is super critical for that design to work. Also any lint, or debris in the shim stack is gonna be havoc on the performance of the damper. Only use medical grade rags as theae are near lint free.Just some heads up.
All the IFP is doing now is maybe keeping cavitation down. I don't really need it now that there is no pnuematic control valve. It's basically a TPC damper now. Thanks for the heads up on the lint, I cleaned everything pretty good before reassembly. I rode it today, works really well. Much less brake dive, and no sense of spiking. Time will tell.
