j2eDX
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| posted on 18/3/07 at 09:25 AM |
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Help Designing Suspension
I'm in the process of designing a 3 wheeler and believe that the hardest part would be the suspension. I want it to handle well and my life
depends on it. My plan is to use unequal non parallel A arm. The problem is I have no experience building a car from scratch so I like to hear your
experiences. Or websites,books references I can look at. I hope this would help myself and others to come.
1. Front suspension is unequal nonparallel a-arm. What other possibilities?
*What donor parts to use? Sierra MKII is a Ford Escort, what year? Autozone has suspension parts for cheap. Are the hubs, joints,axels, steering arm,
steering column, etc. interchangable.
* What length, width of tube should I use? ball joint or rosejoint?sizes of U-brackets
,boss,polybrushes. Be great if someone could provide a detailed drawing.
*Dimensions of A-arms,
*Up and down travel
*Are r1 shocks/springs adequate for f1 style purshrod suspension. Would the angle of the shock/spring have any adverse effects maybe on the up &
down travel or ride height.
*Caster angle? I read that the caster should have a positive angle so the car would self-center.
*How to implement anti-roll bar into the suspension.
*Other possible answers that would help in the designing process.
[Edited on 18/3/07 by j2eDX]
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JB
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| posted on 18/3/07 at 01:58 PM |
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Suspension Design
Unfortunately it is very difficult to give a detailed answer on suspension design in a reply like this.
My advice would be to buy and study some books (or borrow from the libaray).
Books by Allan Staniforth and Carroll Smith are the ones I learnt most from.
Normally 3 wheeler and handle well do not apear together!
The way I designed my suspension is as follows: Decide on a roll centre height, lower wishbones as long as possible and level. Top wishbone angle is
determined by the RC height, length is altered until RC movement is minimal.
Castor angle in the region 4 to 7 degree, more critical to get it the same each side.
1 1/8" dia lower wishbone, 1" upper. 1/2" sphericals on the lower and 7/16" on the upper. But my car weighs 1000kg
ARB needs positioning so as much wheel movement as possible is translated into bat movement.
If you use the motor bike shocks ensure the leverages are correct. I personally would not use bike shocks on a car. I like big shocks with lots of
shock movement.
Mount everything in double shear.
Have a look at www.beardmorebros.co.uk
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kb58
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| posted on 18/3/07 at 04:37 PM |
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I completely agree, and I also recommend suspension books by Staniforth and Smith. You need to take it slow and do lots of reading first.
There's no deadline, and no rush, so read and learn everything until you become comfortable. As far as a recommended reading list, here's
mine:
http://www.kimini.com/Reference/index.html
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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Bob C
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| posted on 18/3/07 at 04:46 PM |
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Pure gold above: - it's your design so become an expert & do it yourself!!! Also checkout micke freidrikson on here, presently converting
his 3 wheeler to a 4......
All the suspension references concentrate on 4 wheelers,
Bob
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Doug68
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| posted on 19/3/07 at 12:20 AM |
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I'm spent some time looking at 3 wheelers, the dynamics of these vehicles are quite different to 4 wheel vehicles.
Do some scouring of the web and you will eventually find the information you require.
Here's a link to something useful to start with.
Things that I remember from my research are the end with 2 wheels always want to slide first and the closer the C of G is to the end with 2 wheels the
greater the resistance to rolling over will be.
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stig mills
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| posted on 20/3/07 at 03:47 PM |
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I would suggest that as you appear to be starting from scratch that it would be more important to consider the engine location first as in a 3 wheeler
it's location has significant implications upon handling. A bad example would be a Reliant Robin with it's engine hovering around the
single front wheel. I would place the serious mass as low as possible between two wheels , be it front or rear.
Either way when you come to the suspension you would need to look seriously at the roll centres and introduce substantial camber gain to compensate
for inevitable high levels of body roll. Try knocking up a model from 3x25 and experiment.
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