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The stock rubber steering rack bushings on the left are not only soft but also have deep grooves in them to allow more flex. The probably can allow up to half an inch of moment when flexed by big sticky tires. The Turn In Concepts parts on the right are machined from sold delrin plastic and have virtually no give at all.
When viewed from the side you can see how the Whiteline bushing will raise the front pivot up to reduce the percentage of front suspension anti dive.
Howard presses the Whiteline bushings and ball joints in place making sure everything is properly lubricated with the supplied grease.
The lower control arm is reinstalled.
Here you can see how the Whiteline bushing is offset towards the inside of the chassis. This kicks the lower control arm forward for an increase in caster.
Here you can see how the bushing moves the forward pivot upwards, decreasing anti dive, raising the roll center and improving the camber curve.
2 comments
Mike,
Appreciate all your suspension articles on motoiq.
If I understand correctly the stock alignment spec is:
Camber: 0, Caster: 5°54′, Steering Axis Inclination: 15°31′ , Toe: 0mm
and the modified is:
Camber: 3.5 deg neg, Caster: 8°, Steering Axis Inclination: 11° , Toe: 3mm toe out
The camber, castor and toe all seem pretty conventional (and good) mods for getting good turn in, good mid corner front end grip and a car that is responsive to the wheel without getting to spookiness and instability. I am intrigued, and have to admit my ability to think about the geometry without a model is at its limit.
Is the effort of reducing the steering axis inclination about minimising scrub radius? Or is it something more.
In short, could you explain a little more what your aims and ideas are around “We prefer to run minimal scrub and lead the caster with king pin angle by a few degrees.”?
Tuning JDM and British cars I never found an extra degree of castor I didn’t like, but can admit to never being up for exploring KPI. Though with an adjustable strut top and camber pins on a mcpherson strut its very very doable.
Thanks!
David
Actually reducing KPI increases scrub but it also makes for more wheel tilt in the wrong direction that is countered by the caster.