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      08-24-2011, 04:12 PM   #1
AUChris9
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335i sport springs on 328i Non Sport

Anyone else installed this configuration on your car? If so was it any lower for you? I know sport springs in general are lower but due to the fact that the 335 is heavier I'm thinking that it doesn't actually lower a 328i non sport at all.
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      08-31-2011, 07:01 PM   #2
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Quote:
Originally Posted by AUChris9 View Post
Anyone else installed this configuration on your car? If so was it any lower for you? I know sport springs in general are lower but due to the fact that the 335 is heavier I'm thinking that it doesn't actually lower a 328i non sport at all.

I'd actually like to know as well. anyone?
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      09-01-2011, 01:24 AM   #3
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A bit high

Let's try to calculate the difference at the front, where it's easiest. Orb says 335i ZSP front spring rate is 145 lbs/inch. Difference in weight between cars is 243 pounds. Divide by 4, is 61 pounds per corner less. That's almost half an inch higher. I ignore motion ratio because it's so close to 1, but it works against you too, making your 328 a teensy bit higher still.

If the ride height on the 335i you're borrowing from was 14.5 inches at the front, then that's nearly 15 inches, which is going to look high, maybe same height as non-sport.

Hope this helps you get an idea.
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      09-01-2011, 07:24 AM   #4
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Lucky U. That was impressive. You are exactly right. 335i sport springs on a 328i are equal or higher than non-sport 328i springs and my car is proof. If I were to put 335i Eibach sport springs on a 328i do you think the same .5 difference would apply? If so that would put my exactly where I want to be which is .9 lower in the front and .5 in the back.
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      09-01-2011, 11:24 PM   #5
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Are you thinking of the Pro-Kit, or the Sportline? The Pro-Kit has a rating almost the same as the ZSP springs (according to the Spring Rates sticky thread), but Pro-Kit springs are highly progressive, which means the rate changes with position and defeats my impressive math-fu.*

The sportline I don't know the rate (they're also highly progressive) but if I had to guess, I think they will be significantly stiffer (higher spring rate) and therefore will be more than 0.5 inch higher on your 328i than they would on a 335i. But it will be, like 0.6 or 0.7 inch higher, not more than that.

*I made a slight error including unsprung weight in the calc, but it makes almost no difference.
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      09-02-2011, 08:50 AM   #6
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Are the sportlines stiffer? Don't assume. On the LS1 fbody for some strange reason, they are lower but also have lower springrates. So there's one case

Maybe they got them right on the e90?
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      09-02-2011, 09:23 AM   #7
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I just talked to Eibach. They say the spring rates are:

Eibach Pro-kit
Front: 148 lb/in
Rear: 457 lb/in

Since they are progressive I don't know if that is an average or initial. Interestingly enough they use the identical front spring in the 328 and 335 sedan package which lowers 1.2 for 328 and 1.4 for 335. The rear spring rates are identical but the 335 spring package comes with a slightly longer rear spring to compensate for the weight and the result is the same rear lowering of 1 inch from stock non sport height.
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