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Old 8 Apr 2016, 23:48 (Ref:3631327)   #1
sambeeb
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Join Date: Aug 2015
Australia
sydney
Posts: 15
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rear twist beam motion ratios

Hi,

In trying to work out my F:R wheel rates in my FWD er, I'm stuck on how to calculate the motion ratio of a twist beam rear end.
The things that I find difficult to get my head around are the fact that the left and right wheels are always coupled to a certain extent, and difficulty in figuring where to measure trailing arm pivots from.
Regarding the permanently partially coupled left and right wheels (through the twist beam) I'm guessing that I can never think in terms of one wheels motion ratio - one wheels is always dependant on the other yeah? I'm thinking I'd need to calculate the whole axle at once with the piggy back RARB disconnected, but then also reconnnceted at the soft, medium and hard settings to get the full picture. And I'd have to repeat all that again if I ever changed rear springs.

Regarding finding the pivot to measure from, you have the pivot mounted to the chassis, but the trailing arms of the axle don't actually pivot from there, they pivot from the common twist/torsion beam itself don't they? I'm sure there'd be some theoretical coupling point between the chassis pivot and the twist beam that should be a reference point but I just can't find any info.

any help greatly appreciated
sam
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