Scratch Builder
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| posted on 10/11/05 at 11:00 AM |
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Coilover Angle
Greetings from warm, beautiful and humid Queensland.
Coilover angles other than vertical have an impact on spring rates and travel and linear
movement of the shock absorber working components.
From practical
experience/experiences, at what variation to the vertical, do discernable changes
take place, for a road going clubbie? I have read a few excellent texts on the subject, with some clear analysis and
graphs, however most are biased towards 'track cars'. Any comments
related to more mundane applications, would be appreciated.
Regards
+100 Nissan Skyline liveaxle locost ,with Toyota 4AGE 20Valve Silvertop and T50 Gearbox.
J
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NS Dev
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| posted on 10/11/05 at 12:31 PM |
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difficult question to answer.
You really need to just apply simple maths and work out the effective spring rate and how it changes. Obviously this is fairly pointless unless you
can change the shocker length as you will be relying on them as droop and bump stops, so the length of the shocker must be changed if the angle is
changed to keep the balljoints within their articulation limits.
Other than that, a vertical shock mounted on the wheel centreline (impossible obviously in this application!) will apply its's full spring rate
directly. Any inclination will then reduce effective rate and any move inboard of the outer shocker end will do the same.
Best just to calculate from the angles, displacements and rates to work out equivalent wheel rates, it's not hard to do approximately.
[Edited on 10/11/05 by NS Dev]
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trikerneil
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| posted on 10/11/05 at 01:03 PM |
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I've got my shockers at about 45 degrees more for the look than any efficiency. I worked out the spring rate for vertical shocks then took the
sine of the inclined angle (sin 45 = 0.7071) and assumed the springs would only be effectively 0.7 times as strong. I upped the spring rate
accordingly and added a bit for luck (50 lbs I think). It seems to work for me.
There's a pic in my archive (justfinished_2)
The bottom bracket twisted due to the change of angle so you'll need to take that into account.
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kb58
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| posted on 10/11/05 at 02:40 PM |
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quote:
Originally posted by Scratch Builder
... at what variation to the vertical, do discernable changes take place...
The only way to answer that is to know how sensitive you are! Seriously, it's very much a personal judgement issue, and how the car will be
driven. Buiding a show car? You'll never notice, Building a race car... then it all comes down to you personally, just what can you detect in
how the car is acting.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Dale
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| posted on 12/11/05 at 02:51 AM |
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Pretty sure it works out to be
spring rate at the wheel / (distance from bush to shockmount/distance from shockmount to balljoint)^2 * (cos of the delta from 90deg of the shock)^2
= spring rate.
Worked and measured to within a few pounds on mine.
Dale
Thanks
Dale
my 14 and11 year old boys 22
and 19 now want to drive but have to be 25 before insurance will allow. Finally on the road
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