This Mustang Parts Installation Guide Works For
Installation Time: (approx) 4 Hours
Note: Check your pinion angle before you start, so that you know which way to adjust the new arms. But beware that if the upper and lower control arm bushings are worn out, the axle may shift when the car is driven, making your measurements less accurate.
WARNING: DO NOT INSTALL THE CONTROL ARM WITH A LENGTH (center to center of the bolt holes) LONGER THAN 9.63 inches for P/N 555-4100 (with bushing end) or 9.45 inches for P/N 555-4101 (with rod end). ALWAYS CHECK TO MAKE SURE THERE IS AT LEAST 11/16" OF THREAD ENGAGED ON BOTH SIDES OF THE ADJUSTER. SHORTENING THE CONTROL ARMS MORE THAN 1/2" FROM STOCK CAN CREATE NOISE, VIBRATION AND HANDLING PROBLEMS. FAILURE TO HEED THESE WARNINGS MAY LEAD TO SERIOUS INJURY.
Pinion angle is the difference between the centerline of the driveshaft and the centerline of the pinion shaft of the differential. To measure it you must be able to work under the car with the suspension fully loaded and the car level. A drive on lift works best for this.
Use an angle measuring gauge (adjustable protractor) to measure the difference between the pinion flange and the drive shaft directly. These gauges are available for under $10 from a hardware store. Place the edge of the gauge vertically against the front of the pinion flange, beside the driveshaft. Extend the measuring arm forward parallel to the bottom of the driveshaft. Extend a straight edge under the driveshaft to the measuring arm of the angle gauge. Hold the straight edge flat against the bottom of the driveshaft and adjust the measuring arm to read the angle. Depending on the gauge you use, you may have to subtract 90° from your reading to get the correct number. Your final measurement should be between 0 and 5. Examine the diagram at the bottom to determine if the pinion angle is nose up or nose down.