Steering geometry?

[gmsclassics]

I've changed the radius arm bushes on the front suspension and this has upset the caster angles - now running about 0.3-0.5. Camber is set at about -2.2 each side with a lot of shims. Toe 1-1.5mm.<br>
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What caster does anyone else run on a car primarily set up for the racetrack? Presumeable I will have to shorten the radius arms to get back to a standard 2.25. Any idea how much I should take off?<br>
<br>
Geoff

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[scotsprint]

First of all, these comments are from the grapevine of Sprint racers and modifiers rather than from personal experience. Sprints always have suffered from instability under heavy braking. Most folk put this down to the narrow rear track but the real cause is the 2 deg camber angle. Heavy braking forces the tyre contact patch rearwards by compressing the flexible bushes and this reduces the camber angle to zero or worse thereby removing the self centring effect that the camber angle should give. The stearing in effect goes "over centre", and any deviation from the straight ahead position produces a positive feedback loop, i.e. the steering pulls off centre causing wandering and instability.<br>
Most track cars have caster angles of 4 to 6 deg.and this sort of caster angle makes the Sprint much more cstable under braking. The downside is that the steering will be heavier. From the existing caster angle use a pocket calculator and some simple geometry to work out how much the tie bar should be shortened by. The caster is altered by repositioning the holes at the wheel end by the required amount. You must buff off the old reinforcing washers with an angle grinder, weld up the holes, redrill then weld on new strengthening washers. Once it is back together get the angles checked again. An alternative would be to make up some sort of adjustable threaded end for the front of the tie bar so that adjustments could be made in situ.

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[alex]

my girlfriend bought a sprint with all roll cage,spax,hi lift cam, webbers, elec ignition, polybushed, etc etc because 'its fun to drive'..so I drive every now and then and have noticed the squirming mentioned...always wondered why?..<br>
every days a school day..

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