| Re: Leafs vs Coils: How to relate spring rate? |
Subject: Re: Leafs vs Coils: How to relate spring rate? by ghoffman on 2008/11/9 22:58:40 Tom is correct, the motion ratios (shock travel/wheel travel) need to be equated. The leaf spring forces are reacted on the lower a-arm in the middle of the web(s) and the coil overs have both the ratio of lever ration and the angle of the coil-overs as well. This is not necessarily linear, and in the case of the C5 and C6 the rear motion ratios for a coil overs are not only not linear/constant but have a falling rate that makes a linear spring a bad idea. The rear shock is at a severe angle and that angle gets less with bump travel. This means that a linear spring that is appropriate at ride height is too soft at full bump and vice-versa. That is why we use a dual rate setup on our Hardbar/Penske coil over package and also use a very significant bump "rubber" (really a polyurethane foam) that makes it a triple rate to compensate for this non-linear motion ratio. |
