What is the static anti-squat percentage in this 4-link setup?

The Geometry Summary shows a static anti-squat of 68%, and the travel anti-squat at 0.00 travel is also 68%.

What are the link coordinates used in this calculation?

Upper links: frame end at x 30.00, y 12.00, z 33.00 in; axle end at x 0.00, y 2.00, z 31.00 in. Lower links: frame end at x 39.00, y 10.00, z 26.00 in; axle end at x 3.00, y 25.00, z 21.00 in.

Where is the instant center located?

The instant center is at 144 in on the X-axis and 41 in on the Z-axis.

What vehicle specifications were entered into the calculator?

Wheelbase 112.0 in, tire diameter 42.00 in, tire rolling radius 19.75 in, vehicle CG height 43.00 in, vehicle mass 6,000 lb, front unsprung mass 800 lb, and rear unsprung mass 700 lb.

What is the roll axis angle and what does it indicate?

The roll axis angle is -1 degree, which the spreadsheet notes as roll understeer; the travel roll axis reads -1.05°.

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4 Bar Linkage Calculator V3.0 - Short Link Static Suspension Geometry

Suspension 4-bar linkage geometry diagram with plotted links, roll axis, and wheel circles

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4-bar linkage suspension geometry diagram plotting upper and lower links, anti-squat lines, roll axis, and wheels.

AI caption June 2011 · Photo 147 of 846

This document is a screenshot of a spreadsheet-based suspension design tool titled "4 Bar Linkage Calculator V3.0." It models the geometry of a 4-link (four-bar) rear suspension for a vehicle with a 112.0 in wheelbase, 42.00 in tire diameter, 19.75 in tire rolling radius, 43.00 in vehicle CG height, 6,000 lb vehicle mass, 800 lb front unsprung mass, and 700 lb rear unsprung mass. Input coordinates (x, y, z in inches) are given for the frame and axle ends of the upper links (frame 30.00/12.00/33.00; axle 0.00/2.00/31.00) and lower links (frame 39.00/10.00/26.00; axle 3.00/25.00/21.00). The calculated geometry summary shows 68% static anti-squat, a 30 in roll center height, a -1 degree roll axis angle (roll understeer), and an instant center at 144 in (X-axis) and 41 in (Z-axis). Travel results at 0.00 travel show 68% anti-squat, 30.49 travel roll center, -1.05° travel roll axis, and 0.00° pinion change. A side-view plot displays the link geometry with tires, anti-squat lines, roll axis, roll center, and instant center, plus an inset "Travel" chart. A reader can learn the specific 4-link geometry values being modeled, likely for a Scout suspension build.

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Frequently asked questions

What is the static anti-squat percentage in this 4-link setup?: The Geometry Summary shows a static anti-squat of 68%, and the travel anti-squat at 0.00 travel is also 68%.
What are the link coordinates used in this calculation?: Upper links: frame end at x 30.00, y 12.00, z 33.00 in; axle end at x 0.00, y 2.00, z 31.00 in. Lower links: frame end at x 39.00, y 10.00, z 26.00 in; axle end at x 3.00, y 25.00, z 21.00 in.
Where is the instant center located?: The instant center is at 144 in on the X-axis and 41 in on the Z-axis.
What vehicle specifications were entered into the calculator?: Wheelbase 112.0 in, tire diameter 42.00 in, tire rolling radius 19.75 in, vehicle CG height 43.00 in, vehicle mass 6,000 lb, front unsprung mass 800 lb, and rear unsprung mass 700 lb.
What is the roll axis angle and what does it indicate?: The roll axis angle is -1 degree, which the spreadsheet notes as roll understeer; the travel roll axis reads -1.05°.