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Non-Sport to Sport Suspension Conversion

Discussion in 'E39 (1997-2003)' started by catbert, Sep 2, 2010.

    catbert guest

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    I currently have a 2003 530i non-sport sedan with 50K miles. I would like to put the sport suspension under it ONLY to lower the appearance of the car. I've read about all kinds of aftermarket struts & springs and have no desire to begin experimenting with non-OEM suspension components.

    What would be required to properly change the suspension out to lower the car for the sport-package height? Is it just changing to the sport package struts/shocks/springs or is there more involved? The balance of the suspension (all control arms, etc) were replaced at 45K (I like that tight new car feel) so I don't want to replace anything that's newer if I don't have to.

    Thanks-

    Catbert
    Mine: 2003 530i
    Daily Driver: Toyota Avalon
    Mrs. Catbert: 2003 325xit
    • Member

    CSBM5

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    You'll need the sports suspension: front struts and rear shocks/struts, front anti-sway bar, rear anti-sway bar, and the front and rear bump stops. This would create the sports suspension package. However, if you just want to lower the car, you can do just the struts and springs. Note that it is likely cheaper to just get the Dinan Stage 1 suspension package that comes with Konis and springs only if all you want is to lower the car. You won't be disappointed with the Dinan springs/Konis imo.

    catbert guest

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    Thanks, Chuck. I have to admit I really, really like the non-sport ride (as opposed to handling) and I'm hoping to keep the car as close to that characteristic as possible, which is why I've been shy about considering aftermarket components. I didn't consider the front & rear sway bars and bump stops so thanks for bringing those up!
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    bcweir

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    You might need to think a bit about what you really want

    What you're proposing to do will almost certainly "firm up" the ride somewhat. Not sure if this is what you wanted to accomplish. Lowering springs and accompanying shocks do work together to lower a car, but by reducing the amount of travel of both the shocks and the springs, the ride will be firmer to varying degrees. How much so depends on how much the vehicle is lowered.

    Have you actually driven a car of the same model with the sport suspension before deciding to do this? Or ask a BMWCCA member who has the same model car with the sport suspension and/or lowered ride height?

    Ride comfort is a subjective matter. Multiple people can drive the same vehicle and come away with different perceptions of ride comfort.

    Not trying to rain on your parade here, but I wanted to point out a potential conflict with your goals with respect to lowering the car vs. maintaining the same level of ride comfort.

    Good luck regardless of what you decide.
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    CRKrieger

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    Brian's right here ... and we rarely agree on ANYTHING. :p

    Your goals are self-contradictory absent an aftermarket spring that retains the same rate as the OEM springs (and I know of none that do). I will second his suggestion that you drive someone else's car, equipped the way you're considering, to see if you like the ride quality. Once you've done that, if you still want to proceed, I would look for spring rates on all the springs available. Choose the one nearest stock for the ride nearest stock. There is a good chance it's the BMW sport suspension, but it might not be. Could be an Eibach set or even a Dinan set. I wouldn't hesitate for a nanosecond to use either of these reputable products.

    I would NOT worry so much about the antiroll bars in your situation. You're not looking for ultimate handling and the bigger (stiffer) antiroll bars will feel a little harsher when cornering as well as adding to the cost of this change.

    catbert guest

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    I understand. I've driven E39's with the sport suspension & I know there's a difference that will come with the change. I just want to minimize the impact as much as possible which is why I avoided the aftermarket components since everyone has opinions and they usually differ. Additionally, I know the results may vary with aftermarket components whereas the OEM sport height & handling are a known and generally agreed-upon quantity.

    Thanks for the insight on the antiroll bars. It's strictly the height that I'm after via OEM components. On the other hand, I don't want it cobbled up with something that 's not correctly done. If just the springs and shocks/struts, then I'm good with that. If it's also bump stops, I'll add them. If the antiroll sway bars are optional and may actually firm the handling, I'll pass on those. What I don't want is to modify the suspension in a manner that creates unanticipated wear, additional unusual maintenance issues, or makes the car take on unusual handling that diminishes the handling & ride normally associated with BMWs. I really like the car, & I just want to minimize the effects the suspension change may create. Too bad I can't suspend the laws of physics that are in play here!

    Thanks-

    Catbert
    Mine: 2003 530i
    Daily Driver: Toyota Avalon
    Mrs. Catbert: 2003 325xit
    • Member

    bcweir

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    I appreciate your attempt to clarify what you're trying to do...

    ...but ironically, I'm left even more confused than with your initial posting.

    Don't take this the wrong way, but you seem to be asking:

    "Well, I really want chocolate ice cream, except I don't really like the color brown. What I want is chocolate that tastes like vanilla, but only if it's beige and not really an off-white. I also want it to taste like dark chocolate, but not milk chocolate, and remember I don't want it to look brown...":confused:

    Keep in mind that ANY deviation from the original factory configuration THE WAY BMW BUILT YOUR AUTOMOBILE is going to change the way your car rides and handles. Not to further confuse things, but lowering your car is also going to lower the center of gravity. The car is going to handle differently.

    The wear and tear issue is going to be a factor not just from your suspension, but also how you drive, the toe in and toe out configuration of the tires, the type of rubber your tires are composed of (soft rubber compounds tend to wear faster than hard rubber), the treadwear rating of your tires, proper inflation of the tires, and even your driving habits (jackrabbit, heavy foot behavior will wear your tires and brakes faster than a more careful approach, but everybody's different -- your mileage will indeed vary).

    What would help the rest of us to help you the most is for you to decide what it is you want MOST out of the car. Do you just want a lowered look for your car, and if so, are you willing to give up an unknown degree of riding comfort to get it? Do you realize your car's handling will change once you start swapping in parts different from what BMW installed on the vehicle on the car's original assembly line?

    Decide on what you want the MOST, and be prepared to compromise on everything else to the appropriate extent needed to get the change you're looking for -- if any.

    catbert guest

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    Yep. The (very) tortured chocolate analogy is right on! No offense taken, but don't over-think it. (1) I want it lowered to the sport package height (2) using OEM components (3) with as little impact on the ride *as possible*. The ride will change and I've acknowledged that. I just want to know what it will take to do it right.

    Thanks-

    Catbert
    Mine: 2003 530i
    Daily Driver: Toyota Avalon
    Mrs. Catbert: 2003 325xit
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    bcweir

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    I think you may have misunderstood the ice cream analogy...

    ...I was establishing that your goals are self-contradicting.

    Much as I hate to do this to you, now that we have established that, please re-read Krieger's post above. I'm not sure you understood what he was saying about spring rates.

    superdave2002 guest

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    Lets see.......Desire: Lower car without sacrificeing ride quality. Hmmmm.
    If it's style, why not invest in a body kit instead of suspension parts?
    I've seen some very tastefully done kits that make the car appear lower than it really is.
    Just a thought.

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