Checking the half shafts
Half shafts, otherwise known as axle shafts, are fitted in rear-wheel-drive cars only. They give relatively little trouble during normal motoring, although they are highly stressed components.
The inner end of the shaft is supported and driven by the differential , and the outer end is supported in bearings between shaft and axle housing .
These bearings have either built-in or separate oil seals . The bearings can be ball bearings , taper roller bearings (both with inner races), or straight roller bearings which use the axle shaft as the inner race.
When a half shaft fails, the rear wheels cannot be driven.
The main symptoms of a worn half shaft are a knock or clunk when accelerating or decelerating. The cause is wear and excessive play between the shaft and differential splines .
However, the same symptoms can be caused if the crown wheel and pinion gears in the differential are not meshing correctly, the drive-pinion flange splines are worn, or the drive-flange bolts are loose.
If you are not sure of the noise source, consult a garage. Special tools are needed to check wear, called between two parts such as the teeth of gears. data-term-id="1310">backlash
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