Which way up for fork springs?

[Glyn Pickering]

Managed to source some new ptrogressives here in NZ. Just wondered if the tighter coils should go at the top or bottom of the fork leg.
The instructions in the box say it doesn't matter. Are there any recommendations either way?  Also do I need to pre load new springs with spacers? I weigh about 85 kg with all my kit on and have a small fairing on the front.

Regards

Glyn  

[Blake]

Im pretty sure tighter coiled end goes up from remembering pictures from progressive springs.  id say go that way.. i would naturally think thats the way to go...(pretty sure tighter wound springs are the lesser rate).

as for preload id say try them out as they are first.  if you like it, then throw in a little spacer.. its up to personal preference.


Blake

[Extent]

I would put tighter at the top, but it shouldn't matter, the spring will compress the same either orientation.  If you don't preload the spring chances are you'll sit too low in the suspention travel.

Tighter wound coils make up the lower rate, as they're the first coils to bind, effectively removing them from the spring.  The less coils you have the higher the springrate becomes.

Preload is not just personal preference, it is a setting critical to the steering characteristics of the bike and the performance of the suspention, don't just leave it to chance.  You generally want your static sag to sit at about 1/3 of your total suspention travel.  I would start with the stock spacers in as a baseline and take measurements from there.  If you need to change the preload on the front you can use PVC pipe that fits in the fork cut to the length you need.

Here is a good article on setting your sag
http://www.sportrider.com/tech/146_9508_tech/

[h2olawyer]

Glyn -

Progressive says to remove the stock spacer.  See the link below, then check the application note (note #9).

http://progressivesuspension.com/appview.asp?AppsNumber=457

Their notes seem to be fairly inclusive.  Some require stock spacers, some come with spacers and others might require spacer modification.

May all your bumps be smoothed!

H2O

[Extent]

That they do, in that case I would start w/ their recomendations for the baseline and go from there.  thx H2O

[Glyn Pickering]

Thanks guys, as usual great info. This has got to be the best bike site around. Now why did Yamaha ever stop making these bikes!
Only they will know (or maybe not).

Ride safe.

Glyn

[jasonm.]

The progressives do NOT need a spacer unless you are 250#. The tighter coils go at the top. The wider coils are actually the softer end of the spring. At least that's what it says in my books.

[Extent]

A spring's rate, in pounds per inch, is inversely proportional to the number of coils in action; the fewer the coils, the stiffer the rate. If this seems backward to you, recall that you can more easily bend a six-foot piece of 1/4-inch steel rod than you can a six-inch piece.

The spring is all made out of the same metal of course, since all the coils compress the same amount the tightly wound coils are the first to bind, since they have less distance to move.  As a progressive spring starts to bind the part that is actually springing gets shorter, and the rate increases.  A dual rate spring switches over to the second rate when all of the lower rate coils bind (which happens at the same time since they're all wound to the same distance.