I'm in the process of rebuilding my stock '84 forks and installing the Race Tech emulators while I'm in there. I found that my fork springs are not the stock units and are installed with no spacers. The current set up delivers about 15mm of initial preload with the forks assembled and the preload adjusters at the minimum preload setting.
Form what I've read here 15mm seems to be just about right. However, when I install the emulators they'll add another 12mm of preload for a total of 27mm. I don't know a lot about suspension, but I imagine that this will be too much. What problems can this cause? I imagine that the forks might be too stiff, for one. I weigh about 150, if that makes any difference.
Since there are no spacers to cut down and I don't really want to buy new springs, I think the only way get the preload right will be to mill 12mm from the bottom of the fork cap/preload adjuster. Looking at the assembly, it looks to be doable.
Does anyone know of a better way to work this? Or should I just put it together as is with the 27mm preload?
The springs are most likely Progressive springs. If so the winding will be tighter at one end than the other.
If this is the case simply reassemble the forks with the emulators. The progressive springs, both progressive and later model FJ are initially very soft and gaining the extra 12mm will be an improvement in and of itself.
If by chance they are straight rate springs you are on your own, but its worth the trouble to assemble the forks and check sag. You should see appx 50mm of sag (many terms, I prefer ride sag) with you on the bike, and 18mm with the suspension supporting the bike alone (Free Sag)
The free sag number is the key. If the spring is too stiff you will have a number greater than 18mm, if there is too much preload you will see less than 18mm.
Ride sag can vary based on preference But I recommend a range between 38mm (very agressive riding) to 50mm (Sport tour). On bikes like the FL that have very little adjustment I try to get ride sag in an acceptable range with the free sag as close to 12% of overall travel as possible.
Great. Thanks for the info. My springs are progressive-wound, so I guess I'll slap them back together and check the sag measurements.