Raising oil level 2011 forks?
- Thread starter fire1998
- Start date
swazi_matt
Active member
I don't know the internal diameter (id) of your shocks but can tell you how to work it out
Vol=pi x id x h
So in cc that would be 3.14 x id (in cm) x 2cm
Vol=pi x id x h
So in cc that would be 3.14 x id (in cm) x 2cm
wasp4banger
New member
Sorry to correct you Matt, but the above would give the area of the internal curved surface, pi x d gives the perimeter I'm afraid. (unfortunately for me, I'm a far better mathematician than rider!)
about 100cc per leg I reckon. The volume should be pi x id x id x h / 4, remember area is (pi x id^2) /4 or pi x ir^2.
Hope this helps.
thumperrider1
New member
I would just add 20cc at a time in each leg with a syringe via the bleed screw until it feels good and isn't bottoming out.
swazi_matt
Active member
Sorry to correct you Matt, but the above would give the area of the internal curved surface, pi x d gives the perimeter I'm afraid. (unfortunately for me, I'm a far better mathematician than rider!)
about 100cc per leg I reckon. The volume should be pi x id x id x h / 4, remember area is (pi x id^2) /4 or pi x ir^2.
Hope this helps.
You are 100% correct. I was going to sleep when I did it and this morning it struck me! Was hoping I could sneak back in and change it without anyone knowing lol
As for deducting spring and push rod, isn't the oil height measured with all of this removed? So all you need to do is to do the calc, get a cc syringe and add through the bleed hole
noobi
New member
I think its done with no spring, but everything else present. I just do it by volume. If you knew what the oil height and the volume of oil you put in was you could work out what the ratio of volume/height is.
swazi_matt
Active member
i am guessing that the lower fork tube is 4.5cm diameter, so internal diameter would be about 4.1cm (assuming wall thickness of 2mm)
then the ratio would be:
13.2 * h = vol (cc)
then the ratio would be:
13.2 * h = vol (cc)
GMP
Active member
You want to relate a change within normal oil levels to volume (fork compresssed, spring removed). This normal level of the oil spans a length of the the spring guide over its "X" cross sectional shape, note this next time you service the fork. So, you need to calculate the equivalent level change in mm/cc. First you need to calculate the the cross sectional area in sq. cm. of what we are talking about. Total area of upper tube, subtract area of lower tube WALL cross section only(not entire area), subtract cross section of spring guide (hard to calculate do to shape and without measurement). Now, this area is simply your level change factor in mm/cc. Multiply this factor by the desired oil level change to get the amount of oil to add or subtract.
Next time the fork is apart for an oil change, start with the level within the range, add a precise amount of oil, measure again. Cover as much of the normal range as possible with the oil addition for best accuracy. Calculate mm/cc for future reference.
Remember, this is only valid for an equivalent change in oil level that spans the internals of the fork with the same cross sectional area. For minor adjustments like you want to do its fine.
Next time the fork is apart for an oil change, start with the level within the range, add a precise amount of oil, measure again. Cover as much of the normal range as possible with the oil addition for best accuracy. Calculate mm/cc for future reference.
Remember, this is only valid for an equivalent change in oil level that spans the internals of the fork with the same cross sectional area. For minor adjustments like you want to do its fine.
I'm sure most suspension tuners have been there and done that. The common sense approach would be to check the oil level during service and then raise or lower it and measure the fluid you added or subtracted. If you're not sure what oil level you want leave it low and then if you want to raise it say 10mm you can add the appropriate amount through the bleed hole.
I set the oil height on my 50mm Zokes at 130mm thinking I would add fluid to tune it like I want but as it turned out with the 10w Bel-Ray oil and 130mm level it was perfect so I didn't change anything. Les at LTR did tell me the exact amount to add to raise it 10mm at a time but I have since forgot.
You could add 10cc at a time until you're happy but I think you egg head math whizzes are making this a lot harder than it needs to be.
I set the oil height on my 50mm Zokes at 130mm thinking I would add fluid to tune it like I want but as it turned out with the 10w Bel-Ray oil and 130mm level it was perfect so I didn't change anything. Les at LTR did tell me the exact amount to add to raise it 10mm at a time but I have since forgot.
You could add 10cc at a time until you're happy but I think you egg head math whizzes are making this a lot harder than it needs to be.
To make things easier I have used those clear plastic measuring cups that come on top of the medicine bottles like Nyquil, or Robitussen.
They are marked usually in mL , which is equal to a cc. 5 10 15 20 25 30ml.... I used a medical syringe to force the oil through the bleed hole. If I drain any, I drain it out of the bleed hole into the same meauring cup after I take the forks off.
I experimented by taking out 20mL/cc, then replacing it by 10. I am pretty happy with the Sachs 48's. I moto in the sand as well and need a stiff front end.
They are marked usually in mL , which is equal to a cc. 5 10 15 20 25 30ml.... I used a medical syringe to force the oil through the bleed hole. If I drain any, I drain it out of the bleed hole into the same meauring cup after I take the forks off.
I experimented by taking out 20mL/cc, then replacing it by 10. I am pretty happy with the Sachs 48's. I moto in the sand as well and need a stiff front end.
Egg head math whizzes? If that went over your head the reply I was thinking of definitely would have.
Ha Ha, actually there is not much math that does go over my head. Your's and my answer are actually very similar. I was trying to point out that since the bottom line is to get the forks working like you want without taking them apart and since it's unlikely that you can figure the cross sectional diameter of the dampening rod or figure the internal diameter of the fork tube without disassembly an measuring you can put all the numbers you want to this and not get there.
Faced with this you can;
A. Take them apart and measure
B. Ask a suspension who has already figured how many CCs will change the level Xmm
C. Add oil 10cc at a time until it rides like you want.
I would choose B. if you're sure what level you want or C. if your tuning for the best ride.
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