Spring rate Question?

[trailrider894]

okay so in the ebay listing... it said this " HERES A CUSTOM AXIS SHOCK EIBACH REAR SPRING RATED AT 300 LBS AND 9 INCHES LONG IN GOOD SHAPE. " I want to know how to gauge whether a 300lb spring would be right for a certain rider with a certain weight, riding style, etc... Any help here??

[XC_Raptor700R]

The shock would need set up for you and your riding niche no matter what, for it to perform correctly. You can't just buy it and bolt it on unless they set it up for you. Well you could but you wouldn't be getting your money's worth. You will also want to set your ride height once it's bolted in.

[trailrider894]

Originally posted by XC_Raptor700R
The shock would need set up for you and your riding niche no matter what, for it to perform correctly. You can't just buy it and bolt it on unless they set it up for you. Well you could but you wouldn't be getting your money's worth. You will also want to set your ride height once it's bolted in.

Trust me, i am fully aware of why this shouldn't be done. I am just asking the question to gain knowledge. This is NOT something i plan on doing to my quad. I am just trying to figure this out because it puzzles me.

[chronicsmoke]

yah I saw that on ebay too, he had a couple of different springs for sale.. I'd like some more info too :bandit:

[trailrider894]

Originally posted by chronicsmoke
yah I saw that on ebay too, he had a couple of different springs for sale.. I'd like some more info too :bandit:

I think i am gonna call Race Tech and find out.

[number52]

depending if the linkage you're running requires a single or dual rate spring setup is the first thing to look at. Let's just assume your linkage is made for a single rate spring since that's what you're looking at.

To tell what spring rate is needed for your weight all you need to do is to measure your sag with a know spring rate with barely any preload on it. You want to shoot for a sag measurement around 4.5" If your measurement is less than that then you need a lighter spring and vise versa.

[trailrider894]

Originally posted by number52
depending if the linkage you're running requires a single or dual rate spring setup is the first thing to look at. Let's just assume your linkage is made for a single rate spring since that's what you're looking at.

To tell what spring rate is needed for your weight all you need to do is to measure your sag with a know spring rate with barely any preload on it. You want to shoot for a sag measurement around 4.5" If your measurement is less than that then you need a lighter spring and vise versa.

I am not saying that you are wrong, but i've never heard of a linkage that wasn't specifically designed for an aftermarket shock that required a dual rate setup. Can you clue me in?

Your method makes sense, but i am still not figuring out how to convert this guys 300lb statement into.

[dustin_j]

Listen to number52, he knows what he's talking about :D Multiple springs are used to provide progression. A linkage can do the same thing; that's why the GT Thunder linkage only uses a single spring (on purpose). Some linkages don't have very much progression and require dual rate.

Your stock rear spring is 325 lb/in. Looks like the ad you are referring to said 300lb spring. Springs are rated by force required to compress a specific distance; usually pounds to compress one inch. Thus, if you set your race sag to 4.5" and you had to put too much preload on, then you need a stiffer spring. Conversely, if you took all the preload off your spring and still didnt' get 4.5" of race sag, you need a lighter spring.

[trailrider894]

Originally posted by dustin_j
Listen to number52, he knows what he's talking about :D Multiple springs are used to provide progression. A linkage can do the same thing; that's why the GT Thunder linkage only uses a single spring (on purpose). Some linkages don't have very much progression and require dual rate.

Your stock rear spring is 325 lb/in. Looks like the ad you are referring to said 300lb spring. Springs are rated by force required to compress a specific distance; usually pounds to compress one inch. Thus, if you set your race sag to 4.5" and you had to put too much preload on, then you need a stiffer spring. Conversely, if you took all the preload off your spring and still didnt' get 4.5" of race sag, you need a lighter spring. ]

Thanks for clearing that up!! I understood the race sag part from when i first started dong suspension work on my quad, but this add confused me.