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      11-11-2018, 08:08 PM   #6
ashiohsiao
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Drives: 2012 F20 118i
Join Date: Oct 2018
Location: Taiwan

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Flat Ride

"Flat Ride", in essence, refers to the rear springs having faster frequency than the front springs.

Basically, if the front springs frequency is faster than the rear's or the same, you get this:
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Without flat ride, the rear-end is unable to catch up with the front-end movement, whether in dealing bumps or potholes, or in cornering:
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With the rear springs having faster frequency, you get this:
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And now the car feels stable and smooth:
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Luckily, most BMWs have flat ride with stock suspensions, but if you have the chance to compare with a car that doesn't have flat ride, you will be surprised how big of a difference it is.

Shaikh has quite a few videos that talk about flat ride in depth, if you are interested:
https://www.youtube.com/watch?v=ZR0W0XyxN_Q
https://www.youtube.com/watch?v=Zpax2pMDGdw&t=2s

For my F20, I actually tried to contact BMW to get the exact frequency for my springs, but for some reasons, BMW did not have the data... so I used the bounce test to get a rough idea of the front and rear overall frequency:
https://www.youtube.com/watch?v=F-n60O2PmUg

Last edited by ashiohsiao; 11-12-2018 at 01:26 AM..