DirtRider . Net MX, SX, Arena Cross, Off-Road Community

This is the text version of DirtRider.Net
Click Here for the Full Version

Pages: 1

percentage
(Click here to view the original thread with full colors/images)

Posted by: overbore---------------------

If you could say how much oil flows thru each
part of the overall suspension like on the forks midvalve,
base,ect.
What would it be?
And is there anywhere that explains how the linkage
effects the suspension compared to one without a
linkage.
Thanks overbore.

Posted by: marcusgunby---------------------

I think(dont quote me) 75% mid 25% base valve, and a linkage amplifies shock movement 3 times at the end of travel.

Posted by: overbore---------------------

Thanks marcus.
I talked to a guy at race tech awhile back that said that the base valve was 80 percent and
the midvalve about 20 percent which I thought was wrong.And thanks for the response on the
linkage question.I know that it changes the damping curve somehow but still dont see it looking
at it.I know that I always have more questions than answers,but if the linkage magnifies 3 times
then does that mean that it progresses a whole lot at the end of the travel?
one more quesiton if someone would be so kind to answer also,
If a person didnt have the right springs for the bike he needed,which is more important
free sag or race sag?
I will try and just watch and listen again for awhile if someone will answer these questions.
Thanks overbore

Posted by: marcusgunby---------------------

On a rt setup he maybe correct with no mid valve, on the linkage rt used to have some curves upon the net a while back-they do get alot steeper on the last third of the travel.

On sag i think rider sag as it sets the fork angle but i hear on ktms its free sag-never really understood other than ktms are stupid LOL.

Posted by: Rider 007---------------------

Quote:

Originally Posted by overbore

And is there anywhere that explains how the linkage
effects the suspension compared to one without a
linkage.
Thanks overbore.

The whole purpose of the linkage is to vary the ratio of the axle to shock piston speed. The speed of the shock piston relative to the axle speed (as it swings through its arc) gets progressively faster, which increases the hydraulic resistance.
You would need to study kinematics to delve into this subject.

Honda's Pro-Link is short for "Progressive Linkage".

Posted by: overbore---------------------

Thanks gentlemen for the answers.
overbore.

Posted by: Air Chunk---------------------

The amount of oil that goes through the base valve is the amount of oil displaced by the damper shaft. Most forks have a 12mm shaft. So it would be shaft diameter times the length of stroke equals oil displaced through the base valve.

Mid valve is like this . Lets say it is a 25 mm piston mid valve in a 25mm bore of tube, connected by the 12mm shaft . it is the tube vol minus the vol . displaced by the shaft equals what goes through the mid valve.

12mm shaft over a 300mm stroke equals a very small volume goes through the base valve(displaced volume)

25mm minus 12mm shaft vol. over a 300mm stroke equals a much larger volume that goes through the midvalve.(swept volume)
Hope this helps ---Pete

Posted by: overbore---------------------

Thanks pete.That explains it all.Its a wonder anyone trying to get a good grasp on
something ever figures it out with hearing different things.I knew I could count on this
place.
overbore.

Posted by: Air Chunk---------------------

Posted by: kevin5758---------------------

If you calculate Pete's information, you will get about 35cc of oil passing through the base valve, and about 92cc passing through the midvavle. This would put you at 37%-63%. (base vs. mid respectively) Then you have to consider how each component works.

In simple terms, the leverage ratio is the wheel travel / shaft travel. If the wheel travel was 300mm, and the shaft travel was 125mm, the overall lev ratio would be 2.4.

A leverage ratio chart will display the wheel vs shaft travel at that point in the travel. (as below)

A sample leverage ratio might look like this.

travel - lev ratio - shaft travel
0mm - - - 3.0
25 - - - - - 2.9
50 - - - - - 3.8
75 - - - - - 2.7
100 - - - - 2.6 - - - - - 9mm
125 - - - - 2.5
150 - - - - 2.4
175 - - - - 2.3
200 - - - - 2.2 - - - - - 11mm
225 - - - - 2.1
250 - - - - 2.0
275 - - - - 1.9
300 - - - - 1.8 - - - - - -13mm

Making some general comparions, for the first part of the travel, the shaft moves less in relation to the wheel, making for a supposedly plush ride, and for the last part of the travel, the shaft moves more, increasing damping force for better bottoming resistance.

In the above example, for the wheel to move from 75-100mm, the shaft moves 9mm. For the wheel to move from 175-200mm, the shaft moves 11mm. And for the wheel to move from 275-300mm, the shaft moves 13mm.

The faster the piston moves, the more oil it has to displace thru the shim stack, resulting in stiffer damping. So, the goal is to get a plush ride with good bottoming resistance. Add a two stage shim stack to the mix, and you have an even more progressive damping curve. (progressive in the sense it starts softer and progressively gets stiffer)

Posted by: marcusgunby---------------------

I plotted a graph of the 03 kx 125 as a few people were not happy with the feel of the new setup, unfortunatly i didnt have time to take off the bump rubber, so i couldnt plot the last few inches and this is where it really stiffens, upto the bump rubber it was reasonably linear.

Posted by: overbore---------------------

I hadnt went back and read my post from last week and wow,thanks for the explanation
of the leverage ratio.I still didnt quite understand it,but didnt want to ask again,but now
it makes sense.
Thanks again all for the help.
Still learning everyday.
overbore

Text Version Home

This is the text version of DirtRider.Net Click Here for the Full Version

percentage

This is the text version of DirtRider.Net
Click Here for the Full Version