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Coil Bind - Eibach Shock Spring

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After replacing the shock spring on my 02 XR4 with an 8.5 Eibach, I love the ride... but need to dial in a bit more preload. The problem is, I'm already at the minimum installed length for the spring based on the manual. i.e. 205mm which translates into about 12mm of preload and I'm concerned about getting coil bind on the spring. Based on my previous adjustments, I figure if I dial in another full turn, or roughly 1.5 more millimeters of preload... I should be just about right on static and race sag. Plus it will sharpen up the turning a bit.

So here is my question... Eibach says I shouldn't run more than 15mm of preload in the information that came with the spring. That would equate to an installed spring length of 202mm.... which means I could easily bump up the preload without a problem. When I asked them why the service manual states a minimum installed length of 205mm... they just gave me a vague answer like... "Honda is just being conservative". I don't really understand that response. The spec for installed spring length for coil bind should be an exact spec... how could Honda be "conservative" on that number? Unless Honda assumes that you are compressing the bumper rubber 100% or something unrealistic like that.

Anyone know how Honda gets that coil bind spec for the stock spring... and if it translates to an aftermarket spring like an 8.5 Eibach? I'll post this in the suspension forum as well... but thought you guys might know more about the XR4 specifically.

Thanks!

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The two springs are different; coil bind will not necessarily occur at the same compressed length. Eibach should have just said that.

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Measure the diameter of the spring wire. Multiply that spring wire diameter by the number of turns in the spring. With the spring removed from the shock measure the stroke of the shock, remember that the shock stroke will be greater than can be measured by hand due to bottoming cushion compression. Now take Honda’s minimum spring length and see if the sum of the diameter of the wire and number of turns equation will fit into the minimum spring length subtracted from the shock stroke. I can tell you from experience that an Eibach spring will bottom if loaded beyond Honda’s minimum spring length number. Spring bottoming is no good! Buy a stiffer spring.

After replacing the shock spring on my 02 XR4 with an 8.5 Eibach, I love the ride... but need to dial in a bit more preload. The problem is, I'm already at the minimum installed length for the spring based on the manual. i.e. 205mm which translates into about 12mm of preload and I'm concerned about getting coil bind on the spring. Based on my previous adjustments, I figure if I dial in another full turn, or roughly 1.5 more millimeters of preload... I should be just about right on static and race sag. Plus it will sharpen up the turning a bit.

So here is my question... Eibach says I shouldn't run more than 15mm of preload in the information that came with the spring. That would equate to an installed spring length of 202mm.... which means I could easily bump up the preload without a problem. When I asked them why the service manual states a minimum installed length of 205mm... they just gave me a vague answer like... "Honda is just being conservative". I don't really understand that response. The spec for installed spring length for coil bind should be an exact spec... how could Honda be "conservative" on that number? Unless Honda assumes that you are compressing the bumper rubber 100% or something unrealistic like that.

Anyone know how Honda gets that coil bind spec for the stock spring... and if it translates to an aftermarket spring like an 8.5 Eibach? I'll post this in the suspension forum as well... but thought you guys might know more about the XR4 specifically.

Thanks!

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I weigh 150 - 155... and I chose the 8.5 based on other rider feedback. I think the rate is right, as I am approaching static and race sag numbers that should be about perfect if I can add another couple of millimeters of preload. Plus the bike feels really good now. The more I think about it... I will just contact Eibach again. they should be able to give me the exact spec before coil bind without me having to go to all the trouble of recreating it on my own.

The help and suggestions are appreciated.

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