Triumph Repair: rear drive noise, wheel bearings, spider gears

Question
Advice about the new clutch was great. Its gradually wearing down and disengaging. Now the car is moving there is a knocking noise at the rear as it is being driven. We have narrowed it down to the rear offside wheel area. Up on blocks with the engine running, wheels turning, there is no noise. Nothing is visibly loose, the drive shaft does not seem to be hitting anything, bolts to the U/J are clear of hitting anything. The knock is related to the turning of the wheel and occurs twice per wheel revolution. I know noises are notoriously difficult but this one has us baffled.
Roger

Answer
Hi Roger,
If you are sure it is two times the wheel rotation then you can rule out a ring and pinion in the differential and Spider gears are not rotating at all when going straight. Look at either wheel bearings, axle "U" joint or something fouling on the inside of the brake drum. Drive the car in a large and small circles in both directions to note the noise and straight. Find a smooth road and make "S" turns as you drive to note any changes and apply a little hand brake as you drive to note any changes. Switch wheels on the rear just as another possible. Check the large axle nut.

That will be a difficult one to locate since it will not do it on a lift.

Howard