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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > Why not keep stock sport pkg struts when lowering car?



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      04-27-2013, 01:53 AM   #1
Shanghai_Texas
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Why not keep stock sport pkg struts when lowering car?

I know it prematurely wears out the struts but how long does that process take? 20k? 50k? 100?
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Last edited by Shanghai_Texas; 04-27-2013 at 02:03 AM.
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      04-27-2013, 07:18 AM   #2
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Well when I had my G35 coupe, I got up 115k (springs only) & all was still good. Now that I have a BMW I put springs only (H&R Sport Springs, E93) We'll see.
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      04-27-2013, 09:31 AM   #3
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The factory dampers lose most of their effectiveness by ~40k miles with the stock suspension.

The damper's purpose is to control the energy of the spring. By installing a stiffer, lower spring on an already under-powered factory damper, you'll:
A) degrade ride quality. The damper has less room to travel; it will blow through that reduced travel, rebound off the bumpstop and jostle you over all but small bumps because it is unable to build up enough force to control the energy in one movement. Harder & harsh.
B) wear out the damper faster. The damper has to work harder because the spring absorbs more energy than the damper is designed to handle.
C) be making a poor economic choice (explained below)

Regarding C), add up your costs for spring-only:
1. Cost of the springs
2. Installation & alignment
3. Cost of new dampers in about half the mileage your factory dampers would have left in them w/ stock suspension
4. Installation & alignment

When you could make this economic decision:
1. Cost of the springs and dampers appropriate for your spring choice (or a pre-assembled set of coilovers)
2. Installation & alignment

...and have the benefit of good handling & ride quality from the start (provided you buy good quality dampers like Koni Yellow).

P.S. I'm less than interested in rebuttal arguments like "I have lower springs on stock dampers in my BMW, and the car rides great". That's equivalent to saying you can't tell the difference between salisbury steak and filet mignon.
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      04-27-2013, 10:13 AM   #4
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^^ What he said!
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