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Last Post 19 Jun 2015 01:28 AM by  CM31
Ideal wheel rate to corner weight ratio
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dgoetz
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Posts:70


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21 Mar 2015 07:00 PM
    I am in the process of ordering custom shocks and springs for my Emod. I have already calculated my frt and rear motion ratio, wheel rates, corner and unsprung weights. From what i have read the ideal autocross wheel rate to corner weight ratio is some where between .8 and 1.2. In other words if i have a front average corner weight of 450lbs the ideal wheel rate to corner weight ratio would put the wheel rate between 360# to 540#. The rear average corner weight is 490# or ideal ratio between 392# to 588#. My question is does the sway bar or in my case lack of any effect the ideal ratio? My plans right now are to go with a front wheel rate of 450# or 1 to 1 and the rear 390# or a .8 ratio. The reason i am not using a 1 to 1 ratio on the rear is because i don't have a front sway bar and also there is more weight transferred to the frt under braking during turns. Am i on the money or where should I start?
    wrandleman
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    Posts:29


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    14 Apr 2015 04:41 PM
    I haven't heard of using a spring/corner weight ratio. The variable is bounce frequency which can vary widely due to geometry. If you're not a coil over just remove the shock and measure the bounce frequency directly. ~2.5, 2.75,3.0 Hz for street, DOT slick, Bias Slick is the high side.
    Dragonbill
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    Posts:3


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    15 May 2015 08:55 AM
    Yes there is an ideal corner wt to wheel rate ratio. Do not use a different ratio front to rear. If you need to do this to "balance" the car something else is quite wrong. While Frequency is a popular statistic, thee is no need to bring time base into the equation for a good spring setup. Time base is a shock function. If you would like help with this, check out www.smallfortuneracing.com
    CM31
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    Posts:1


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    19 Jun 2015 01:28 AM
    I agree that the front rate ratio and the rear should be the same, or very close. I have run from .65 all the way up to 1.4, and I have settled in on 1.05 front, .95 rear. It is a bit stiff, but the relative lack of body roll helps keep the tires more upright, and the transients are good. The lower rates, around .8 or less, gave a more forgiving car, but at the expense of being "mushy", and really didn't have enough spring to support the front under braking with rates .7 or so.
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