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Old 11-15-2010, 08:14 PM   #1
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Testing Spring Rates

Anyone know of a shop or a DIY method to test spring rates? I've got a set of coil overs with unknown springs and want to test out the rates.

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Old 11-16-2010, 01:08 AM   #2
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What you can do is get a really fat chick to sit on the coil and see how much it depresses. Fat chicks are easy to find, seeing as they all want lots of attention and sex.
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Old 11-16-2010, 07:50 PM   #3
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^ this man speaks the truth
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Old 11-16-2010, 08:15 PM   #4
Bullet Ride
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Yeah the fat chick method is pretty much the easiest way to do it. You'll might need two fat chicks though depending on the spring rates.

In all seriousness though if you're going to attempt to load up a spring I'd weld a steel tube vertically to a flat plate to hold the spring, go to the gym and load it up with some of the big free weight plates and measure the deflection

One trick way that might work would be to put a piece of threaded rod through the spring with a plate on the top and bottom of the spring and put a nut on either end of the threaded rod. Then crank the plates together enough to get a deflection measurement and use a torque wrench to measure the torque required to tighten the nuts that much. You can look up the coefficient of static friction for steel on steel (nut on the plate) and determine the Force exerted by the spring on the plate. It should be something like

spring force = 2*Torque / (bolt_size*coefficient_of_static_friction)
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Old 11-17-2010, 11:33 AM   #5
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Essentially you just need to find out how much weight it takes to compress the spring 1".

Get something with a known weight, then use something to measure the height of the spring like a string. When the spring compresses 1" then that is the weight per inch.

200lb/inch. etc.

You could put the spring in a shop press which has a gauge. I'd be careful and just collapse it one inch which is all you really need to do.

Performance one step at a time.
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