Ridemonkey.com - View Single Post - Tuning blackbox speedstack in boxxer wc/team

Udi · 10-19-2006, 07:20 AM

Here it is.

A: rod for stack. floodgate/LSC rod (male) goes through this
B: spring for return valve on rebound
C: shim for return valve on rebound
D: piston, turned so that top faces compression shims
E to H: compression shims
I: endcap

Shims F,G,H are identical, E is twice as thick as one of those.

Low speed oil flow can bypass the shims through the stack to some extent, as fatty pointed out. Any faster than that given speed, and the ports will start spiking and then the shims will bend (they are quite firm though - so the shims do seem specific to HS).

To further affirm that, oil can even flow through the piston and around shim E (smaller diameter) and out to the sides without bending the larger shims. So I imagine it takes a pretty fast hit to actually bend them (explains the high speed spiking issues).

I think my first point of attack is just going to be to leave the whole stack out. I'm impressed the damper is constructed to allow this.

For anyone else interested:
Dissasembly simply involves taking the MC cartridge out of the fork, removing the small button head screw that holds the LSC assembly in (2mm allen key), and pulling the LSC assembly out. Finally, hold the compression knob and use 1/2" socket to undo the blue hex nut until it comes off. Shimstack drops out attached to it.

As an update (10/07), if you are removing the stack, make sure the blue hex/core part goes back in - as this affects the floodgate setting (acts as a spacer, if you know how the floodgate works it'll make sense). So basically - unscrew stack from damper, remove all parts (B through to I), and then screw part A back in as it did originally.

I hope that seals the deal, happy tuning.

10-19-2006, 07:20 AM	#83
Udi Turbo Monkey Join Date: Mar 2005 Location: Australia Posts: 1,822 Rep Power: 3	Here it is. A: rod for stack. floodgate/LSC rod (male) goes through this B: spring for return valve on rebound C: shim for return valve on rebound D: piston, turned so that top faces compression shims E to H: compression shims I: endcap Shims F,G,H are identical, E is twice as thick as one of those. Low speed oil flow can bypass the shims through the stack to some extent, as fatty pointed out. Any faster than that given speed, and the ports will start spiking and then the shims will bend (they are quite firm though - so the shims do seem specific to HS). To further affirm that, oil can even flow through the piston and around shim E (smaller diameter) and out to the sides without bending the larger shims. So I imagine it takes a pretty fast hit to actually bend them (explains the high speed spiking issues). I think my first point of attack is just going to be to leave the whole stack out. I'm impressed the damper is constructed to allow this. For anyone else interested: Dissasembly simply involves taking the MC cartridge out of the fork, removing the small button head screw that holds the LSC assembly in (2mm allen key), and pulling the LSC assembly out. Finally, hold the compression knob and use 1/2" socket to undo the blue hex nut until it comes off. Shimstack drops out attached to it. As an update (10/07), if you are removing the stack, make sure the blue hex/core part goes back in - as this affects the floodgate setting (acts as a spacer, if you know how the floodgate works it'll make sense). So basically - unscrew stack from damper, remove all parts (B through to I), and then screw part A back in as it did originally. I hope that seals the deal, happy tuning. Attached Thumbnails Last edited by Udi; 10-03-2007 at 09:52 PM.