ZRX forks pre-load adjustment

[Al]

Hopefully this sneaks under the radar because they are routinely fitted hereabouts and they are on a Gpz 1100B.
I have zero knowledge of modern forks, the J is the newest bike ive owned
The ZXR (edit; should say ZRX) forks have approx. 10mm or so, blue pre-load adjusters on top. There are about five / six annular rings machined on them about 2mm apart.
Question; from fully up to fully down, how much could you expect this to raise the front end up. In my ignorance i will say i have the view that pre-load adjusters only serve to make the forks longer but i could see that at some point along that scale it may also compress the springs causing them to be effectively stiffer. I dont know what the pitch of the thread is that is attached to the adjusters but cant think that adjusting between two rings let alone a total of perhaps 10mm will be felt or detectable or serve any useful purpose.
Does anyone know how much uplift, (extension) full adjustment would give and whether in fact they do make the front end more harsh the further you go.
I know the rake and trail i need and have searched the ZRX forums and cant find this particular adjustment described in any detail, except to mention what works for different people.

AL

[warren3200gt]

Doesn't raise anything. Just preloads the forks so that they don't dive until the preset load is exceeded in my experience.
I put about an inch of pre load in my 650's and 900 & 1000.
I do like a stiffer front end and hate the fork dive of soft forks when braking.

[Robw]

Al, I have them fitted to my lawson and Warren is correct, they don't do anything to the length, just adds preload to the forks.
Rob

[Al]

Many thanks gents.
AL

[zed1015]

Those preload adjusters don't alter the uncompressed length of the forks BUT they do reduce sag by preloading and consequently stiffening the springs so do affect the ride height of the suspension.
They also do make a noticable difference to the front end firmness and resistance to dive.

[Al]

Thanks Rob, i think there may be two different versions of ZRX forks internally but still trying to get my head around adding pre-load and it not changing the ride height. If you compress the spring it must get shorter and if you add length to it they must get longer!!
There are some 'pre-load spacers' in some models which are 55.5mm i believe. Maybe there is something to be acheived by altering those perhaps. I really need to have a play with them and see what the actual; fully extended, static and rider sag are and go from there.
Front end is sitting very low and the rake is down at around 24 degrees so some uplift needed i think.
AL

[KWACKERZ1]

Al,
I have some Zrx forks sitting around I could check the length with the adjusters in and out if you want.

Not sure which zrx model they are from though.

[Al]

Thanks Phil could be interesting but may not show up what's what on uncompressed forks.
I'll PM you.
AL