monoshock upgrades

[ted]

What is in the promax kit?

[motomaniac]

(eg: how do two 0.20mm shims behave compared to one 0.40mm shim? etc)
Nathan 2x .20 shimms are much softer/ less dampening than one .40. Why because its .40 but split in the middle.so less resistance.
Similarly with coil springs if you put 2x 5kg springs ened to end and a 10 kg spring of the same length and tested them the 2x 5's would be softer .There is a formula used to calculate this so that if you use dual springs , one soft one hard you can work out the overall rate.
A shimm is also a spring that bends under pressure and returns to its original form when the pressure is gone . ie oil pressure.Same physics pretty much.
Also if you are going to use a modern piston in a non linkage bike the shimm stack will be very different than a modern linkaged bike .

[Nathan S]

(eg: how do two 0.20mm shims behave compared to one 0.40mm shim? etc)
Nathan 2x .20 shimms are much softer/ less dampening than one .40. Why because its .40 but split in the middle.so less resistance.
Similarly with coil springs if you put 2x 5kg springs ened to end and a 10 kg spring of the same length and tested them the 2x 5's would be softer .There is a formula used to calculate this so that if you use dual springs , one soft one hard you can work out the overall rate.
A shimm is also a spring that bends under pressure and returns to its original form when the pressure is gone . ie oil pressure.Same physics pretty much.
Also if you are going to use a modern piston in a non linkage bike the shimm stack will be very different than a modern linkaged bike .

Cool, thanks. Seems obvious once you've pointed it out...

Although the relationship of shim stiffness to spring stiffness can't work exactly like you said, as the two 0.20mm shims are in parallel (you have to 'operate' both at once) rather than in series.

The formula for spring stiffness if the springs are stacked on each other is:
1/S1 + 1/S2 = 1/ST.
Where,
S1 is the stiffness of the first spring,
S2 is the stiffness of the second spring,
and ST is the total combined stiffness.

If there's two springs sitting next to each other (like a pair of fork legs), then its just:
S1 + S2 = ST

[motomaniac]

(eg: how do two 0.20mm shims behave compared to one 0.40mm shim? etc)
Nathan 2x .20 shimms are much softer/ less dampening than one .40. Why because its .40 but split in the middle.so less resistance.
Similarly with coil springs if you put 2x 5kg springs ened to end and a 10 kg spring of the same length and tested them the 2x 5's would be softer .There is a formula used to calculate this so that if you use dual springs , one soft one hard you can work out the overall rate.
A shimm is also a spring that bends under pressure and returns to its original form when the pressure is gone . ie oil pressure.Same physics pretty much.
Also if you are going to use a modern piston in a non linkage bike the shimm stack will be very different than a modern linkaged bike .

Cool, thanks. Seems obvious once you've pointed it out...

Although the relationship of shim stiffness to spring stiffness can't work exactly like you said, as the two 0.20mm shims are in parallel (you have to 'operate' both at once) rather than in serie

Yes you are quite right it wasn't an exact anology.The shimms are in parallel but you get the idea how 2x .20 shimms have less resistance than 1 x .4 shimm.

[oldyzman]

YSS may have one, they said that there were special prices coming up before xmas...
Brett

[madpugs]

hi guys, ive just gotten hold of a yz465 and its also been fitted with the 82 j shock, must have been the done thing at some stage. Am i better of keeping this shock or sourcing and putting a original shock back in the bike. i would probably prefer going with an original, but if the j shock is goin to be better for racing i will stick with it.  It also has 82 j forks on it so would be interested in your thoughts on these over stock 81 h forks.