MGM Motorsports LLC
4 Link Calculator

4 Link Plotting Made Easy

Measure two holes at each bracket, predict the remaining pattern, calculate the instant center and anti-squat, then export every possible setup.

Vehicle & measurement inputs

inches

Vehicle reference

Hole patterns — enter the first two heights

Prediction assumes equal spacing. Enter the first two hole-center heights measured from the same level floor; choose whether the pattern continues upward or downward.

Display settings

Where to measure

side view
MEASURE FROM A LEVEL FLOOR TO THE CENTER OF EACH BOLT HOLE LEVEL FLOOR / GROUND REFERENCE AXLE BRACKET AXLE CENTERLINE D B B and D = axle-bracket bolt centers CHASSIS / FRONT BRACKET C A A and C = chassis-bracket bolt centers UPPER LINK: D TO C LOWER LINK: B TO A BDAC AXLE CL TO B/D CENTER LEVEL FLOOR — all heights measured vertically from here rear axle centerline LOWER LINK UPPER LINK ACBD A = floor to lower front bolt centerC = floor to upper front bolt centerB = floor to lower axle bolt centerD = floor to upper axle bolt center AXLE CENTERLINE ↔ FRONT BOLT-HOLE CENTER AXLE CL ↔ AXLE-BRACKET BOLT CENTER Measure every vertical height from the same level floor to the CENTER of the bolt hole.
A lower front / B lower axleC upper front / D upper axle
Combinations0
Highest anti-squat—
Longest forward IC—

All possible setups

#A lower frontB lower axleC upper frontD upper axleAnti-squat %IC lengthIC heightStatus

Anti-Squat, Instant Center & Tire Starting-Point Guide

tuning suggestions

Use this as a starting point—not a guaranteed setup. Horsepower, vehicle weight, track preparation, tire size/construction, shocks, and launch control all affect the result.

Anti-squatTypical hitIC length / heightPossible tire starting point
Below 80%Softer tire hit; chassis tends toward squatLonger and/or lower IC usually softens the applicationBias-ply slick can help absorb and work with a smoother hit; useful on marginal surfaces
80%–120%Balanced starting rangeMedium IC length and heightEither bias-ply slick or radial may work; choose from track prep, power, and suspension control
120%–150%Firm hit; rear separation becomes strongerShorter and/or higher IC usually applies force fasterDrag radial can benefit from a controlled firm hit on a prepared track; avoid crushing the tire
Above 150%Very aggressive hit; greater risk of spin, bounce, or unloadingShort/high IC is generally the most aggressive combinationUse only with careful shock and power management; confirm with the tire manufacturer or chassis tuner
Longer / lower IC = generally smoother, slower force application  •  Shorter / higher IC = generally quicker, harder tire hit

Always inspect the tire, verify clearances, use the tire maker’s recommended pressure range, and test changes gradually at the track.