Fork oil weight

[olebiker]

Originally posted by chopwatchagot
actually it does make some difference, just not much. I don't know what the progressive instructions tell you to do but the difference would be in the amount of unsprung weight moving up and down with the wheel. If the springs are wound progressively then there is more mass in the end that has the tighter coils. The center of balance of the spring is not in the center of the spring lenghtwise. If the tighter coils are at the bottom of the tube then more mass is moving up and down with the wheel than if the other (lighter) end were down. It's just like progressively wound valve springs. The more massive end (tighter coils) needs to sit still (against the head) while the lighter end does the bouncing up and down.

That makes absolute sense I likely never would have thought of it.

[petejw]

I agree with Skids,
makes no difference in how they perform,

ive got the sheet from progressive, they state the same thing.

Suspension isnt a part of unsprung weight,
the wheels, tires, rotors make up the unsprung weight.
i think even the swingarm would be included in this.
the lighter the unsprung weight, the smoother/ more comfortable the ride.

progressive springs advise the oil b measured with out the springs, and the forks compressed, 5.5 inches from the top
and if u have a special, a spacer is required, with the springs in place and forks extended the spacer should protrude about half/full inch this would depend on the weight of the rider to determine preload.

my 2cents worth :-)

[skids]

You can't take your caculations to 10 digits when the spring "constant" is given with none! OK, I have no idea how many significant figures the spring constant is given as, but I'll bet a dollar to a doughnut that its variability makes the unsprung weight negligiable.

Originally posted by chopwatchagot
actually it does make some difference, just not much.

[pggg]

From the progressive suspension installation pdf

'Install your new fork springs into the forks. Mechanically, it
makes no difference which way the springs are installed. Some
manuals will state; install the spring with the close wound end towards
the bottom. This is done because sometimes there will be
less spring noise. The springs will perform exactly the same regardless
of which direction they are placed.'