How To Determine Steering Spline Size

Steering Shaft Sizes

To determine the spline size of a component (rack and pinion, steering column, and steering box), measure the outside diameter and count the number of splines.

If there is a flat spot on the shaft and some of the splines are missing, count halfway around where there are splines and double that number — you’ll need to know how many teeth are in a theoretical full circle.

Steering Shaft Splines

Common Steering Box and Rack Sizes

Use this steering box/steering rack size chart to select the proper rack and pinion or steering box spline size for your system.

If the chart does not list your application, just measure the diameter of the shaft and count the total number of individual splines. If there is a flat, count half of the splines and then double that number.

GMPower BoxModel 800 (77-Prior)13/16″-360.81336
GMRackCorvette (84-Present)17mm DD0.670.57
GMRackFiero17mm DD0.670.57
GMManual BoxCorvette (69-82)3/4″-300.7530
GMManual BoxModel 122 (65-85)3/4″-300.7530
GMManual BoxModel 525 (86-Present)3/4″-300.7530
GMPower BoxModel 605 (78-84)3/4″-300.7530
GMPower BoxModel 800 (77-Present)3/4″-300.7530
ChryslerBoxManual Box3/4″-360.7536
FordBoxManual & Power3/4″-360.7536
FordPower RackMustang II & Pinto – Power3/4″-360.7536
GMManual BoxCorvette (63-68)3/4″-360.7536
GMManual Box3/4″-360.7536
MiscellaneousVW Rabbit – Diesel3/4″-360.7536
MiscellaneousJaguar & MGB3/4″-480.7548
GMManual BoxVega5/8″-360.62536
GMManual BoxCorvair5/8″-360.62536
ChryslerBoxPower Box5/8″-36C0.62536
ChryslerRackOmni Manual Rack9/16″-260.56326
FordManual RackMustang II & Pinto – Manual9/16″-260.56326
ChryslerRackOmni Power Rack9/16″-360.56336

Common Steering Column Sizes

Use this steering column size chart to select the proper steering column shaft size for your system.

If the chart does not list your vehicle application, then measure your column’s output shaft. If it is a DD shaft (two rounds and two flats), then measure the rounds – it will either be a 1″ DD or 3/4″ DD. If there are splines, then measure the diameter of the shaft and count the individual splines.

Ford ColumnSmall Spline3/4″-360.7536
Ford ColumnSmall DD3/4″ DD0.75DD
Ford ColumnLarge DD1″ DD1DD
GM ColumnSmall Spline3/4″-360.7536
GM ColumnLarge Spline1″-48148
GM ColumnSmall DD3/4″ DD0.75DD
GM ColumnLarge DD1″ DD1DD