Clay
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| posted on 28/5/05 at 05:20 AM |
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Adjustable Suspension Geometry
Ive been considering methods of incorporating adjustability into my suspension design on the custom chassis ive been working on and am wondering if
anyone can shed some light on the methods i've though of, and tell me if they are good ideas, or shouldnt be tried.
My Goal is to have adjustable, caster, control arm angle front to back for anti-dive.
As most of you know, you can tune out anti-dive in the front by angling the control arms. If you look at a side view of the chassis with control arms
drawn, if you tilted the control arms so that lines extended on their planes intersected at the center of gravity, you would have 100% anti-dive at
the front, and if you did this at the rear, you would have 100% anti-squat.
Now, this is going to be difficult trying to describe without pictures but ill do my best. this example is assuming you are using spherical rod ends
to link the control arms to the chassis. If you tilted the rod ends horizonal, you could put larger or smaller spacers on top or underneath the
sperical joint at the front and rear joint of one control arm. Using different sized spacers at the front and bottom would make one end higher than
the other, This would tilt the control arm right? And the spherical joints would still be perfectly horizontal. Would this still be effective way of
introducing anti-dive technology? or would the spherical joints have to be tilted with the control arm to get the proper arc travel?
My next adjustment goal is caster, in this example you are using spherical joints to attach the control arm to the chassis. The sperical joints are
oriented vertically in this example, with spacers in front of and behind the joint. Using larger spacers in front of both sides of the top control
arm, and bigger spacers behind both sides of the bottom control arm would place the bottom control arm further forward than the top control arm tuning
in some degree of caster right? So could you just use different spacer sizes to adjust the angle of caster you want?
if there is an easier way to go about doing these, please let me know, im just trying to cover my ass so i dont have to be stuck with my original
suspension geometry design forever if it turns out to be less than perfect.
Clay Marsh
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Matthew_1
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| posted on 28/5/05 at 10:10 AM |
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I may not quite have understood your post. But am I right in thinking that you're effectively going to have the bolts holding the wishbones on
vertical rather than horizontal? This will allow adjustable anti-dive but will be difficult to engineer as when you adjust the anti-dive you'll
have to move the mounting bolts closer or further apart - imagine you give 45deg incline then the bolts will be much closer than at 0deg incline.
My chassis uses custom, adjustable suspension geometry, you can alter camber, castor but not anti-dive/squat. For anti-dive I fixed it at 35% with an
inclination of about 1.75deg, to get 100% anti-dive requires a lot more inclination which affects the whole suspension considerably. The same is true
of the rear though I only use about 25% anti-squat - but on the back you'll get a whole load more complications in that you'll need to
design a suspension setup with control-rods for adjusting toe-in/out - similar to the front really with the steering rack, but effectively fixed
steering. You certainly can't use the stock design of MK or Tiger since inclining those designs produces a "twist" in the upright.
I can adjust castor by moving the top wishbones forwards and backwards along their mounting bolts which allows me to alter the angle between 3 and 7
deg.
I did try putting some pics in my archive but the thing keeps telling me I've got unsupported MIME types or something so they won't go in.
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britishtrident
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| posted on 28/5/05 at 10:38 AM |
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The benefits of anti-dive are so small and the pit falls so big it isn't worth the effort of making it adjustable -- even less benefit in a
car with firm suspension. If you want just put in a very tinyl %.
The pit falls with anti-squat are less so you can use a little bit more but again making it adjustable isn't worth the effort.
For adjustable caster you can use spacers just put rose joints on the wishbone pivots.
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Clay
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| posted on 29/5/05 at 06:08 AM |
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So i guess i will forget about the adjustable anti-dive configuration. If i understand how to setup anti-dive you would need to know where the center
of gravity for your chassis is. How would you locate the cg?
Should i just forget about anti-dive all together in the front? and just use stiffer springs/ anti-roll bars?
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tadltd
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| posted on 29/5/05 at 08:36 PM |
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Have a look here for info on how to set-up your chassis, and on how to measure C
of G position.
Best Regards,
Steve.
www.turnerautosport.com
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