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inboard ratios help

inboard ratios help

inboard ratios help

(OP)
hi im building new race car and gonna try and put in board suspension on the front. my question is why use ratios like 2:1 and not just 1:1. secondly if i normally use a 250 spring and using a 2:1 ratio do i divide the spring by 2 which would make it a 125 spring?

RE: inboard ratios help

You may use 1:1 ratio, or any suitable ratio for a good istallation. A 1:1 ratio makes the coilover travel a longer distance than  if you use an Mr of 0,5 as the coilover travel only 1/2 the distance which put higer demand for the shock to control the wheel movement regarding play etc. But it allowes for a tighter installation.

However, the spring required is Mr^2, and the reason is that it concern the change in N per mm, and not the lever ratio only.

Regards
Goran Malmberg

RE: inboard ratios help

(OP)
ok if i choose a 2:1 ratio, the wheel comes up an 1 inch while the shock goes down 2 inch?? how do i work out wot spring i would need? sorry but im new to this.i normally use a 250 spring but thats on outboard suspension. ive ordered chassis Design - Principles and Analysis by Milliken and Milliken is this book anygood?

RE: inboard ratios help

To maintain the same rate at the wheel "wheel rate", if you go from a MR of 1 to a MR of 2 you will need to divide the original spring rate by 4 to get the same wheel rate.
ie the wheel rate is the spring rate/MR^2

So a 250lb spring @1:1 means you need a 62.5lb spring @2:1

RE: inboard ratios help

EDIT*
Sorry,

just had the formula around the wrong way for the convention you used for motion ratio. In that case wheel rate=spring rate x MR^2.

Spring rate still needs to be 1/4 of original.

RE: inboard ratios help

(OP)
tell me if im being think but under stand to divide by 4, but say i used 1:6 or that i dont really understand the calcuation.

wheel rate=spring rate x MR^2.
                    250*2.1 ?????????

RE: inboard ratios help

I think an old Greek guy called Archimedes might argue strongly for 1:2 mechanical advantage = 2:1 change in load and 1:2 change in distance. It is a simple lever for crying out loud.

Regards

Regards

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RE: inboard ratios help

Probably off-topic, but possibly relevant - about a year ago Hot Rod Magazine had a paragraph in one of their issues about this site.


Norm

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