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Thread: Why high spring rates?

  1. #1
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    Default Why high spring rates?

    I have a 96' Honda Civic Hatchback that I'm trying to get lower to the earth and I have a curious question.
    Why is it advised to get higher spring rates when lowering a car, how should I go about finding what the correct spring rate is, is it mainly a try and fail method? And yes I understand that the strut needs to be valved accordingly for optimum handling.
    If anyone could chime in with some knowledge or a well thought out article I would appreciate it.

  2. #2
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    because the stiffer it is the less likely it is to move around. and when the car is really lowered, you dont want the thing to move around because that means itll scrub etc

  3. #3

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    are you looking to get coilovers?

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    Good post. I will add bookmark on your post and wanted to say that I have really enjoyed reading your forum posts.

    light meters
    Last edited by Chuck Brown; 01-31-2012 at 01:52 AM.

  5. #5
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    Quote Originally Posted by trism View Post
    because the stiffer it is the less likely it is to move around. and when the car is really lowered, you dont want the thing to move around because that means itll scrub etc
    I understand that it makes the car move less but at what point does the suspension not move enough.

    Quote Originally Posted by bmac9269 View Post
    are you looking to get coilovers?
    Yes I'm looking at getting Function & Form Type 2's, I'm trying to figure out if I should be fine with the 12kg (F) and 8kg (R) or if I should look more into Fortune Auto and get custom higher rates. I'm just not positive on how to decide.
    Do not that I'm planning on going as low as possible, which is why I'm looking into this.

  6. #6
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    Quote Originally Posted by ilotek View Post
    I understand that it makes the car move less but at what point does the suspension not move enough.



    Yes I'm looking at getting Function & Form Type 2's, I'm trying to figure out if I should be fine with the 12kg (F) and 8kg (R) or if I should look more into Fortune Auto and get custom higher rates. I'm just not positive on how to decide.
    Do not that I'm planning on going as low as possible, which is why I'm looking into this.
    this is a very good question, i can shed some light on the subject

    think of spring rates as the value at which it takes to compress a spring. so if your rates are 500 lbs it would take 500 lbs to compress your spring. convert that to Kilograms for metric.

    We use high spring rates so that if our customer has his wheel lip or frame a few mm from hitting the fender or asphalt we can utilize the stiff spring so the spring will not compress like a soft spring causing the car to lower itself under a load or just inertia.

    You must be careful while using crazy rates because if the damper isnt valved properly, you wont get the proper amount of dampening so its essentially like dropping a bowling ball on a 1000lbs spring with no dampening...the bowling ball will shoot back up with great force and then slam back on the spring and repeat till the laws of physics stops it. so you valve the coilover to dampen at a certain rate to help the spring not compress so violently. the next step is rebound, that controls the part of how much the car will rise up after a compression. once you limit how high the car will rebound after a compression where the coil and spring shoot back up, you have a complete coilover system.

    as far as determining what rate for your application it is somewhat trial and error unless you can provide some insane measurements that require special tools to measure. i go off experience with other cars and their rates and wheel specs. hasn't failed me yet.
    you are correct though, it was a huge learning process but after you get in to it its second nature.

    At fortune we hand valve all our custom coilovers which you will not find on a coilover at least 4 to 5 k or more. We're talking Moton, JRZ ,Penske etc etc. most companies have you choose from like 3 sets of valving values they have.

    Thats alot to take in and understand so id be happy to clarify anything, i love talking about this

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  7. #7

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    i have F&F type 1s on my 98 civic and get compliments all the time on how smooth it rides. i would highly recommend them as well. and jesus summed up spring rates pretty well for ya

  8. #8

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    Quote Originally Posted by Jesus Christ View Post
    this is a very good question, i can shed some light on the subject

    think of spring rates as the value at which it takes to compress a spring. so if your rates are 500 lbs it would take 500 lbs to compress your spring. convert that to Kilograms for metric.

    We use high spring rates so that if our customer has his wheel lip or frame a few mm from hitting the fender or asphalt we can utilize the stiff spring so the spring will not compress like a soft spring causing the car to lower itself under a load or just inertia.

    You must be careful while using crazy rates because if the damper isnt valved properly, you wont get the proper amount of dampening so its essentially like dropping a bowling ball on a 1000lbs spring with no dampening...the bowling ball will shoot back up with great force and then slam back on the spring and repeat till the laws of physics stops it. so you valve the coilover to dampen at a certain rate to help the spring not compress so violently. the next step is rebound, that controls the part of how much the car will rise up after a compression. once you limit how high the car will rebound after a compression where the coil and spring shoot back up, you have a complete coilover system.

    as far as determining what rate for your application it is somewhat trial and error unless you can provide some insane measurements that require special tools to measure. i go off experience with other cars and their rates and wheel specs. hasn't failed me yet.
    you are correct though, it was a huge learning process but after you get in to it its second nature.

    At fortune we hand valve all our custom coilovers which you will not find on a coilover at least 4 to 5 k or more. We're talking Moton, JRZ ,Penske etc etc. most companies have you choose from like 3 sets of valving values they have.

    Thats alot to take in and understand so id be happy to clarify anything, i love talking about this
    Just to clarify, spring rate is the amount of weight required to compress the spring by 1 inch. Obviously you know that Jaze, but just so the op doesn't think it only takes 450lbs to compress the entire spring lol

    For your car you'd be fine with a 12k/8k set up. You'll have no problems if you're not gonna go crazy low. If you do want to go super low evetually bump the rates up by around 100 lbs(1 - 2k). It's not a heavy car. With that said, I would still recommend a set of Fortune Auto.

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    Quote Originally Posted by Ollie View Post
    Just to clarify, spring rate is the amount of weight required to compress the spring by 1 inch. Obviously you know that Jaze, but just so the op doesn't think it only takes 450lbs to compress the entire spring lol

    For your car you'd be fine with a 12k/8k set up. You'll have no problems if you're not gonna go crazy low. If you do want to go super low evetually bump the rates up by around 100 lbs(1 - 2k). It's not a heavy car. With that said, I would still recommend a set of Fortune Auto.
    you are 100% right, i forgot to mention that

    also, it is measured by how many kilograms to compress the spring 1MM for metric.

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  10. #10
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    Quote Originally Posted by Ollie View Post
    Just to clarify, spring rate is the amount of weight required to compress the spring by 1 inch. Obviously you know that Jaze, but just so the op doesn't think it only takes 450lbs to compress the entire spring lol

    For your car you'd be fine with a 12k/8k set up. You'll have no problems if you're not gonna go crazy low. If you do want to go super low evetually bump the rates up by around 100 lbs(1 - 2k). It's not a heavy car. With that said, I would still recommend a set of Fortune Auto.
    Thanks for the extra input. I plan on going crazy low and already contacted Jaze about a set of 13kg (f) and 11kg (r) from Fortune.

  11. #11

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    sorry for digging out this thread, but i wanted to know what's determening for high spring rates, is it only how low you want to go, or it depends what's the weight of the car?

  12. #12

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    basically when you have less then a inch of ground clearance you dont even want the car to move that inch.
    doing it for the internet and the scene kids.

  13. #13
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    As far a stance is concerned: If you can drive around without hitting the ground or your wheels/tires, your spring rates are fine. The only reason you would need stiffer is if you want to go lower or poke more. The stiffer the spring, the less the suspension moves.

    As far as handling is concerned: Spring rates are much more important. Generally, you want the front/rear wheel rate difference to be roughly the same as the weight distribution of the car. an extremely basic example is if the car has a 60/40 F/R weight distribution, you would want the wheel rate of the springs to be 600lb's front/400lb's rear. That is the basic rule, different suspension designs can change things however.

    Wheel rate is different then spring rate, the amount different depends on the suspension design. For instance, a MacPherson strut has close to a 100% wheel rate because the spring is located almost directly over the hub. A trailing arm suspension has the spring located around halfway between the hub and the pivot point, making the wheel rate around half the spring rate.

    For handling, you generally want the softest spring you can get while still controlling body roll, squat and dive, so that the suspension has the travel to stay in contact with the road. Too stiff a spring makes the suspension harder and makes the car bounce over little imperfections and lose contact.


    That's not to say getting stiffer springs for your coilovers will make the car handle bad, just that it won't be optimum. You can still have a stiffly spring car handle great.


    The heavier the car the stiffer you want the springs as well. Spring rate is measured in the amount of weight it takes to compress the spring a certain amount. A 500lb spring on all 4 corners of a 2000lb car will compress 1", whereas a 500lb spring on all 4 corners of a 4000lb car will compress 2" (assuming both cars have 100% wheel rates). This applies not only to droop, but also bump absorption. 2000lb's is much easier for a 500lb spring to control then 4000lb's. You would need 1000lb springs to make the 4000lb car react the same. If the 4000lb car had trailing arm suspension where only 50% of the springs power was getting to the wheels, you would need 2000lb springs to make it act the same.

    Suspension is quite complicated, but that's a good start at least for those who care. It's simple if you don't care about ride or handling; if the car hits too much, go stiffer.

  14. #14

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    thanks a lot for the dissertation, really appreciate it...

    just one more thing, you said that if it doesn't rub or wheels hit the fender it gotta be good enough... well i'm good with that, but even when my suspension moves no more than 1cm, the ride is still somehow bouncy, which means that i must go stiffer if i'm not wrong...

  15. #15

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    Well since this is a thread for spring rates Ill just ask this here.
    I'm driving an e46 sedan on rokkor tuning coils and I'm ordering shorter springs soon, I want to know what would be a good size spring / rate combo for these coils so I can go more low in the rear?

  16. #16
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    Quote Originally Posted by projektzwo View Post
    thanks a lot for the dissertation, really appreciate it...

    just one more thing, you said that if it doesn't rub or wheels hit the fender it gotta be good enough... well i'm good with that, but even when my suspension moves no more than 1cm, the ride is still somehow bouncy, which means that i must go stiffer if i'm not wrong...
    Bouncy means the shocks aren't matched to the springs. Either they're too soft to handle the amount of force the spring has, they're too low causing the valving inside to be outside of its range, or they're bottomed out and you're hitting the bottom of the shocks/bumpstops.

    Getting stiffer springs will only change the speed and travel of the bounce.
    Quote Originally Posted by e46cruiser View Post
    Well since this is a thread for spring rates Ill just ask this here.
    I'm driving an e46 sedan on rokkor tuning coils and I'm ordering shorter springs soon, I want to know what would be a good size spring / rate combo for these coils so I can go more low in the rear?
    Use the info I posted above to figure out what you want. Realize that you have shitty coilovers and the shocks likely won't be up to a stiffer spring rate.

  17. #17

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    Quote Originally Posted by Byron View Post
    Use the info I posted above to figure out what you want. Realize that you have shitty coilovers and the shocks likely won't be up to a stiffer spring rate.
    yup ive realized that along time ago lol
    but my girl is getting me a early present i decided on smaller springs since i dont want to spend any of my money ive been saving up for bags, which you should see on sometime early next year

  18. #18

    Default Help with spring rates

    Okay so I just got my wheels in & I was wondering what would be a good spring rate to run on my 2002 Acura rsx im going extremely low & was trying to get really stiff spring rates.

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