Sorting the front end

[greg the pole]

Fork oil height has the effect of adjusting the secondary "spring" in your forks. This spring is air. By raising the fork oil height you increase "spring". Inversely, you reduce "spring" with lower fork oil height, also referred to as air gap.

The air spring has an exponential effect. As the fork is compressed, subsequently compressing the air in the air gap, the effect will rise and then go exponentially vertical in comparison to fork compression. This is a valuable fine tuning tool when determining you point of best suspension action. The point where you want the whole spring, oil, damping rates, air gap to come in the play its best. It's effect is rarely played with by the lay person, just as actually turning the knobs and screws are on modern suspension but its effect, once the other base parameters are set can make for a wonderfully fine tuned suspension.

An example for a real world understanding;

A am running .95 linear springs. As I have improved my skill set in the dirt I have had to adjust for the optimum settings. With my skill set improving I am carrying more speed. Speed increases the force exerted against the fork. This is the classic E=mc squared. Twice the speed equal four times the force. As a result of this increased speed I am blowing through the fork stroke. As such, I need more spring to hold the fork in its middle third of travel better. This is simple to do by swapping my .95 for, say, a 1.00 spring. The problem here is that as the fork moves in to its stroke it is also affected by the air gap which exponentially adds more spring through air gap compression. To offset this I increase air gap (reduce fork oil height) and reduce the air "springs" influence on the overall ride quality. This reduces harshness at greater fork compression use.

I did not know that oil level does what you described ???
At any rate...Penske fork piston kit on order

 

[Firefight911]

I did not know that oil level does what you described ???
At any rate...Penske fork piston kit on order

The viscosity of the oil determines the interaction through the damping circuit in conjunction with either the holes or shim stacks, depending on the damping circuit type being used. The quantity of the oil determines the "spring" from the air gap. It does also provide lubrication from the spring rubbing in the internals, etc. but it takes a minimal amount of oil for that to be taken care of.

 

[greg the pole]

The viscosity of the oil determines the interaction through the damping circuit in conjunction with either the holes or shim stacks, depending on the damping circuit type being used. The quantity of the oil determines the "spring" from the air gap. It does also provide lubrication from the spring rubbing in the internals, etc. but it takes a minimal amount of oil for that to be taken care of.

Again good info thank you.
I'll get the penske fork piston kit installed, and try it out with 5w ams oil, and stock oil height. I'm guessing that will be a very good start.

 

[snakebitten]

Besides the know suspects:
-Ohlins..I know Snakebitten has them, but I don't want to know the price

Hey, they were cheaper than the paint job! ::001::

 

[greg the pole]

Hey, they were cheaper than the paint job! ::001::

oh man...I don't want to know. Nice paint job though

 

[Tony Down Under]

You will not get a linear feel, with one straight spring rate . You can get close with damping help, but I went a head and made up a second spring to replace the plastic spacer . I did not think i would get these forks to work but there not bad at all now .

Just wondering what the spring rate and length of the spring was to replace the spacer? Also, how much do you weigh, what type of riding do you do and what is the spring rate of your fork springs? I'm just curious.

Thanks,

Tony