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Cornering Optimizing your suspension system.

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Old 01-16-2013, 01:59 AM
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bobesser bobesser is offline
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Default Koni FSDs and JCW springs installed

So I am prepping for the coming autocross season and decided to build to SCCA D-Stock rules (even though I mostly autocross with the BMW club).

I had to decide what suspension to go with. Specifically, I decided to use the Factory (dealer installed) JCW suspension. But, with D-Stock, I can replace one sway bar and the shocks. So, I ordered JCW springs and the front JCW sway bar. The front bar, by the way, is a Hotchkiss H-sport Comp bar.


When ordering springs, you have to work directly with a MINI parts person (or someone who knows) because there are four different part numbers depending on if you have a manual or automatic transmission and if you have a sunroof or not.

Anyway, changing the front sway bar was a BEAR (6 hours work by two guys with a lift)! I would strongly recommend against it unless you *really* hate body roll and you have to because of the rules you are working towards (for example SCCA D-Stock). The rear bar was pretty easy (only 3 hours solo).

The big question was what shocks/dampers to use. At the extreme high end was Truechoice Double Adjustable Koni Sport shocks. At the low end was factory JCW shocks. In my price range, it was going to be either Koni Sport (single adjustable) or Koni Frequency Selective Dampers (FSD).

I did a lot of reading and research and found that Per Schroder of Grass Roots Motorsports ran them on a Gen 1 MINI with great success. Basically the low frequency behavior is similar to the lower settings on the Koni Sports and the high frequency behavior takes the edge off track irregularities - thus keeping the wheels on the ground for better traction. Also, Tire Rack did a comparison using E46 BMWs with sport springs, and either stock shocks, Koni Sports (softest settings), or Koni FSDs. The FSDs rode best and returned the best autocross times.

So, Koni FSDs it was. I know I could have probably squeezed a bit more performance out of the Koni Sports with a lot of testing and tuning, but, I don't have the time to be a research driver. Also, the car is a daily driver and the soft behavior of the FSDs on road bumps was appealing.

So, Four hours of wrenching later I have my suspension fully installed.

I haven't really driven it aggressively, so, I can't comment on performance driving really. I have done donuts in a wet parking lot and it seems fairly responsive and balanced. What is hugely impressive is how it handles road irregularities. For comparison, the previous suspension was the base Cooper S suspension. The car is smoother in all circumstances - I won't say it erases the bumps and such, but, it really, really smooths it out compared to the factory system.

I will report back in March after the first autocross of the season.

Bob
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'09 (factory) JCW Hardtop. Mods: JCW springs and front sway bar, Koni FSDs, Hotchkiss Comp Sport rear sway bar.
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Old 01-20-2013, 05:38 PM
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Konstantinos Konstantinos is offline
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I'm looking at doing the same thing you've done. Please post more as you use your FSDs day to day. I've been looking at putting on either the sports or the FSDs but haven't found a conclusive answer yet.

What made you go with JCW springs instead of something like TSW springs?
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