RazMan
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| posted on 7/7/07 at 03:23 PM |
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Bump Steer
Can anyone point me in the direction of an explanation or tutorial about dialling out bump steer? I have heard that it can make a dramatic difference
to handling and I just want to experiment a little to see the effects.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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nitram38
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| posted on 7/7/07 at 03:39 PM |
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If you draw a line between your top and bottom inboard wishbone mounts, your steering rack knuckles/swivel joints should also run along this centre
line when the rack is centred.
Basically this will ensure that the steering track control arms move through the same arc as your wishbones when they move up and down (straight line
only).
If they move outside this arc, then effectively the rack will be shortened or lengthened and toe the wheels out or in as the bones move up and
down.
This will give you bump steering i.e as you go over bumps, your car will move from side to side.
So basically you either get a rack that fits between these centre lines or raise or lower the rack until they coinside.
On both my homebuilt cars I have had a rack built by titan motorsport that is in line with my top wishbones and the swivel joints fit centre to centre
on my inboard wishbone pivot points.
My track rods then follow the same arc as the top wishbone, hence no bumpsteer.
Not locost, but it does look good!
[Edited on 7/7/2007 by nitram38]
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Uphill Racer
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| posted on 8/7/07 at 10:07 PM |
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The rack inline, and swivel joints centered with top wishbone inboard joint will only remove bump steer if the steering arm ball joint is centered
with the outboard wishbone/ upright joint.
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MikeRJ
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| posted on 8/7/07 at 11:14 PM |
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quote:
Originally posted by nitram38
If you draw a line between your top and bottom inboard wishbone mounts, your steering rack knuckles/swivel joints should also run along this centre
line when the rack is centred.
This is not true for all cases, it depends very much on the wishbone lengths and geomtery of the upright.
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nitram38
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| posted on 9/7/07 at 03:12 AM |
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My top wishbone connection to the upright and the steering connection to the upright are both parrallel and at the same height as each other.
As my wheels move up and down in the straight ahead postion, they follow exactly the same arc.
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