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Krannie McKranface

How do I know what Eibach spring I have?

11 posts in this topic

I have (3) Eibach springs, one of which is clearly marked 0.01100, which is the 11 kg/mm.

The other two, the white printing on the spring is un-readable, and I can see no 'stampings' on the spring stating it's rating.

How do I figure out the spring rate on the unmarked ones??

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If you can't read the printing, then you need to actually measure it. Put some weight on it and see how much it moves. Some division and you have the rate.

There is a guy from Eibach here on TT. He helped me with an old spring that I'm about to install. Send him a PM. His user name is "Ryan at Eibach"

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If you can't read the printing, then you need to actually measure it. Put some weight on it and see how much it moves. Some division and you have the rate.

There is a guy from Eibach here on TT. He helped me with an old spring that I'm about to install. Send him a PM. His user name is "Ryan at Eibach"

Thanks CLEANORD

Hey, when are we going riding??????

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yeah cleo when we going riding???

one thing i have noticed is the diameter of the spring will tell a little too, i know it wont get you exact numbers like ryan will be able to but if there larger/smaller diamater than you 11kg youll know a little bit, might help him help you out. these springs all for the honda 600/650 bikes?

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yeah cleo when we going riding???

one thing i have noticed is the diameter of the spring will tell a little too, i know it wont get you exact numbers like ryan will be able to but if there larger/smaller diamater than you 11kg youll know a little bit, might help him help you out. these springs all for the honda 600/650 bikes?

650R :smirk:

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Get this figured out?

Here's a formula that might help:

RATE = 11.5 x Wire Diameter to the fourth power (D4) / by 8 x Number of Active Coils x Mean Diameter cubed.

(11.5 & 8 are constants, don't think they have anything to do with the following pic)

To figure rate for a progressive spring, use the same formula, but you have to split the # of active coils between the rate division. (ie - treat each section of a progressive rate spring as it's own seperate spring)

A pic for reference of coil spring terms:

8.jpg

from the handy -dandy article: http://dirtbike.off-road.com/dirtbike/article/articleDetail.jsp?id=332656

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excellent find!! i only asked if they were for a L cuz if hes interested in selling them maybe.

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That formula makes a lot of assumptions.

It may or may not give you an accurate number. In order to "calibrate" you will need to apply it to a known spring made from the same material. The fact that it scales with the wire diameter to the fourth power makes an accurate measurement very critical.

The constants will vary with different steel formulations. One mfgs steel might be a little stiffer than another's.

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That formula makes a lot of assumptions.

It may or may not give you an accurate number. In order to "calibrate" you will need to apply it to a known spring made from the same material. The fact that it scales with the wire diameter to the fourth power makes an accurate measurement very critical.

The constants will vary with different steel formulations. One mfgs steel might be a little stiffer than another's.

You have a point :thumbsup: - that formula assumes the constant "11" for the shear modulus of the "real" formula since most wouldn't have a clue regarding the materials elastic modulus, or Poisson ratio to calculate the actual shear value, & hence torsional modulus (for really those interested, seehttp://www.efunda.com/DesignStandards/springs/calc_comp_designer_eqn.cfm or http://www.ajdesigner.com/phpspringrate/spring_rate_equation_coil_diameter.php)

However, 11,250,000 is generally accepted value for the average torsional modulus for "spring steel" - although that number does vary between alloys. So... using "11" for the constant is a pretty good guess for the constant. It'll get you pretty close, but it's not exact.

It is used as the constant in just about every spring rate calculator (that doesn't cater to engineers), because most people don't care about the difference between 600 lbs/in & 608.2386 lbs/in

http://www.therangerstation.com/tech_library/coilspringrate.htm

http://www.pagedezigner.com/bluecoil/rate2.htm

http://www.pontiacracing.net/js_coil_spring_rate.htm

http://www.ac-parts.com/utilities/coilsprings.html

and so on, & so forth...

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