Stiffer spring and oil level

[James]

Originally posted by clw
James--Was I curt? Didn't mean to be! Sorry if I offended you.

Nope, I'm cool...just making sure I didn't come across wrong to you :thumb: I had also reached the point where I had nothing more to contribute and figured I'd sit back and see where it went and/or hunt for the proper formula/scientific explanation.

I'm with ya Glitch....almost like the wider fork should be stiffer because you have to compress more air. Could we relate this to aerodynamics or even ballistics where a sharp pointed bullet will meet less air resistance than a flat nosed bullet? I know this might be grasping at straws but it's better than working.

I'm all tapped out for ideas. I'm gonna keep watching though as it looks like Marcus has taken the lead on testing the hypothesis. :worship:

 

[DEANSFASTWAY]

Actually I just look at it this way if you add oil by same volume in different size forks you are raising the comp ratio by a greater amount in the smaller fork . So the way I perceive it it that 10cc in a 43 fork wold equal out to like around 15cc in a larger fork to add the same compression ratio raising benefit. Ill try to think up a way to show the math ,something like volume over displacement+ratio, given the correct data we may actually be able to convert that over intototal air pressure acheived but I might need some carbonation?fruitification in thre meanwhile .Maybe tomorrow in the shop Ill test it out for real and see what difference it takes to go 10mms in38/41 43/46/48s and Ill give you a cc measurement .Or add 10 mms to fork and get a height measurement . It would be nice and actually I really shopuld know this by practice and for trackside tuning. And to write it and make a table . It would be good for me to establish a rule for each indiviual fork type . Anybody who already has done this feel free to chime in . But doesnt it seem real simple when youi think about adding 10ccs to a 43 fork as opposed to 10ccs to a 48 fork ? dont you think the smaller sized fork tube would have a greatewr oil level which would then translate into a higher compression ratio. All of the oil is ganging up on the air and compressing it . Air is compressible Oil is non compressible .PEACEFROMTHEEAST

 

[marcusgunby]

LOL do you know how much i wished i never mentioned 48mm vs 43m forks.:)

Its all about trying to fit something into a space occupied by air-i feel in my thinking i know the answer but cannot put it down in writing to make me convinced its correct.

I think Mace is good on this type of stuff-come on mace make us look silly if we arnt doing a good job alread :uh:

group hug anybody?

 

[James]

Originally posted by James
Now if we start both tubes 50% full, the 43 would have 218ccs and the 48 would have 272ccs. Add 200 ccs to each, the 43 becomes 96% full and the 48 becomes 87% full. I think the 43 would be noticeably stiffer than the 48 in this case.

Dean, I think I was agreeing with your assumption about adding "oil by same volume to different sized forks" here.

I think where Marcus and I and all got tangled is where we are trying to determine if 25% (or any percent) of two different sized forks was air...would the smaller or larger have a stronger airspring - considering that both contain 75% oil and 25% air (or some other ratio).

I think we need a chalk board, some beverages, and a group hug :think:

 

[clw]

Syringes eh! I've got some 1ml (for the dog) and some 12ml (for the garage), empirical data forthcoming.
Marcus, How did you compensate for all the stiction?

 

[marcusgunby]

Just mafe sure they were smooth-couldnt really do any thing else-i was wondering it its a fair comparison as the forks may have the same size damper rod and the syringes have different size pistons.

 

[Papakeith]

.02 from me ;) Here's how I see the scenario. Probably all bamboozled in my thought process, but here it is anyway.
the smaller cylider may have a sharper rise in pressure, but it will take less force to get it there. In the case of the 125 piston vs the 500 the 500 may only have a 8-1 ratio but it takes more force to compress the volume of air in the larger cylinder.
If we look at the air spring in the 43mm fork; at the same oil level with the same amount of compression. the larger (48) fork leg must have the greater airspring.

 

[DEANSFASTWAY]

Yup , I agree on all terms . Guess what though : its good we brought that up because Ive been wanting to dop the cc/oil level change table anyway . I could also record air pressure when compressed (thats what its all about anyway)Unless someone else already has .If so please represent . Oh and by the way I like my CORONAs cold with lime and it helps to have some good lookin mommas to gawk at if you know what I mean ,But I always end up spending all my money and waking up with a swelling head . CHEERS