racetech forks springs Z1000 - interesting advice from race tech

[Harveyz]

Hi

Not being a great fan of progressive springs - I went in search of linear spring for the big old beast Z1000ST. I found them at racetech - did the old calculation and ordered 0.9 kg springs. They duly arrive. - now the strange part - the orginals are 586mm long the race tech ones are 340mm long. contacted race tech - does this mean I have to have a 246mm space - that seems huge. The advice from their tech experts was:

Z1000St has way to much preload - so I need to use a 139mm spacer. Giving total fork and spring length to 479mm ( 340+139). This being 107mm shorter (586- 479) than the originals. Hence this will drop the fork stantion 107mm into the fork legs.

Has anybody tried it - my thought - while reducing ground clearance - it should by standing the ST on its nose a bit quicken the steering.

[warren3200gt]

4 inches is a hell of a front end drop.

[Al]

4 Inches does sound excessive. Standard spring are probably around 0.6 kg/mm or so and the very very short Race Tech ones are likely 50% stronger at 0.9 kg/mm. I would expect the bike on standard springs to sag by three inches or so if you took it off the main stand, and an inch at most with the Race Tech linear springs. They come supplied with plastic tube which you cut to length so just cut it long and creep up on the best settings.
If you go too short, a trip to the plumbers merchants will see you right. Alternatively you could include some Emulators (they add about and inch) and get full control of the front end.

viewtopic.php?f=4&t=27150

AL

[Harveyz]

[quote="Al"]4 Inches does sound excessive. Standard spring are probably around 0.6 kg/mm or so and the very very short Race Tech ones are likely 50% stronger at 0.9 kg/mm. I would expect the bike on standard springs to sag by three inches or so if you took it off the main stand, and an inch at most with the Race Tech linear springs. They come supplied with plastic tube which you cut to length so just cut it long and creep up on the best settings.
If you go too short, a trip to the plumbers merchants will see you right. Alternatively you could include some Emulators (they add about and inch) and get full control of the front end.

viewtopic.php?f=4&t=27150

I think you're on the right track. Chap at Racetech said the ST had way to much preload and this set up should set static sag to around 30mm. once I solve the fork bush issue I'll reassemble and check it out ( half way there with fork bush. - found NOK have a guide bush 40mmx12mmx2mm which fit - at a price £40.) Fitting 0.9kg springs in my mini twin made a massive difference under braking- hopefully the big old beast will stop diving like the titanic every time I hit the brakes hard once the race tech's are up and running.