 Jim McCall McShop
"4th Year" Platinum Supporting Member
Posts: 653
Loc: Billings Mt/ Lake Havasu ...
Reg: 02-18-10
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06-10-12 10:22 AM - Post#2235430
In response to NWSooner
Camber and toe-in are the two factors that control tire wear. Radial tires have considerably more grip on the road so less toe-in is needed as too much will cause tire wear, because of the additional grip they have over biased-ply tires such as the original. For radials toe-in should be no more than 1/16th of an inch. Camber should be +3/4 on left and +1/2 on right as this will allow the car not to pull to the right from the crown of the road. Now for the caster, which is the measurement of the angle of the spindle. If the top and bottom ball joint are directly above and below each other, then that would be 0 caster. Bearing in mind there 360 degrees to a revolution, when you lean the spindle forward at the top, then you are in - caster and when you lean it back you are in + caster. Remembering my reference to a top standing vertical as it spins until it slows down and falls over. Your front wheel and tires have that same force. The more you go negative with the caster the more that force has control of the steering, and the more you go positive, or to the back with the top of the spindle the less that force affects the steering. So my answer for the caster is a minimum of + 4 if not more for the caster. Caster does not affect tire wear as camber and toe-in but controls drivability of the vehicle. Higher caster causes the steering to return to the straight position when you release the steering wheel after turning, and at higher speeds causes the car to track straight down the road when you release the steering wheel. In the 50's, 60's and 70's power steering was an option and the more you increase caster the harder it is to turn the steering wheel at slow speeds, and because of this Chevrolet recommended about +1 caster so there would not be complaints of hard steering.The last factor in all of this called king pin inclination. The upper ball joint is slightly more in to the middle of the car than the lower ball joint. If you were to draw a line from the upper ball joint through the lower to the pavement and draw another line vertically from center of the wheel, the two lines should intersect at or before ground level. As you reverse a wheel or extent its center line outward from the hub you will cause the point of intersection of the two lines to be below ground line causing excessive pressure on all of suspension, and again make the car drive poorly and your steering parts to fail prematurely. All of my cars are set at 4-6 degrees of + caster and all drive GREAT.
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