Flange Alignment & Runout: Notes
- All flanges must be perpendicular in both vertical and horizontal planes to engine crankshaft. The only exception is "broken back" type driveline which has flanges that are not perpendicular in vertical plane (see illustration).
- With nonparallel or "broken back" type installation, working angles of universal joints of a given drive shaft are equal. (See illustration, Angle A = Angle B.) This is calculated as follows: Angle of output shaft centerline is subtracted from angle of drive shaft, which should equal angle of drive shaft subtracted from pinion shaft angle.
- Parallel type joints maintain a constant velocity between output shaft and pinion shaft. Vibration is minimized and component life maximized when universal joints are parallel.
- Using dial indicator, measure runout of transmission flange, center bearing flange, and pinion flange. If runout exceeds 0.005", replace flange. If dial indicator cannot be used, push a rod with a slip fit through flange bearing bore and see if it aligns with opposite bore; if it does not, replace flange.
- Rotate transmission flange until it is vertical, measuring from side. Check center bearing and pinion flanges; they cannot be more than 1° off vertical.NOTE: See Propeller Shaft Phasing in this article.
- Rotate transmission flange until it is vertical, measuring from side. Then measure angle from end and record. Check all other flanges for same angle. They must be within 1/2 ° of each other. Adjust as required.
- If difficulty is encountered when making above adjustments, horizontal alignment should be checked. As shown in illustration, even though vertical alignment is correct, horizontal alignment can be badly out of adjustment especially after major component replacement or serious accident.
- To make horizontal alignment checks, set up straightedges as shown in illustration. With transmission flange horizontal, clamp a straightedge to it so that straightedge is horizontal. Do the same with pinion flange. Using a straightedge that is 12" longer than rear wheel track, clamp it to frame side rails using large framing squares to align.
- Measure distance "X". If two dimensions are not within 1/16" of each other, transmission flange is misaligned horizontally. Measure distance "W". If two dimensions are not within 1/16" of each other, pinion flange is misaligned horizontally. Measure distance "Y", from edge of straightedge to center of axle shaft. If two dimensions are not within 1/8" of each other, axle housing is misaligned.