Hello Richard,
The bearings originally used in your differential for the Output Shafts were Double Row, Angular Contact, Ball Bearings. The centre race was split and when assembled and with no load applied to the centre race, the outer ends of the centre race sat slightly proud of the ends of the outer race and there was a slight gap between the inner ends of the inner race. The gap between the inner ends of the inner race provided a predetermined, correct pre-load for the bearing. When the bearing was put in place and the nut securing the bearing in place tightened, the two halves of the inner race were drawn together until inner ends of the inner race came into intimate contact. This action put the bearing in pre-load. The correct, original bearing is shown in the following picture:
Unfortunately, this bearing hasn’t been available for many years. The bearing that is used in its place is a Double Row, Angular Contact, Ball Bearing, but the inner race is not split and therefore, there is no facility to pre-load the bearing and it is manufactured and assembled with no pre-load.
This alternative bearing has the same OD and ID as the original, but is 2mm narrower, 27mm as opposed to 29mm of the original. Accordingly, the After Market suppliers of parts for the diff, supply the bearing with two, 2mm thick spacers, one for the outer and one for the inner race, to make up for the 2mm narrower bearing dimension . These spacers should be placed on the outer side of the bearing. If these they are left out, you will end up with 2mm of Output Shaft End Float. Further, there should be shims between the inner face of the end plate, which doubles as the mounting plate for the brake caliper and the mating faces of the differential housing. Leaving these shims out will also result in end float of the Output Shaft.
I get quite a lot of my work, reworking repairs carried out by some describing themselves as experts. One of the largest Jag Parts suppliers in Australia and repairers of differentials, in a discussion relating to the setting of the Pinion Shaft pre-load, when asked how he actually measured the pre-load, stated " I check that with a Dial Indicator". Well, I hadn’t had a good day, and when I suggested that he was unique in the world, being able to measure less than no movement (my definition of pre-load to the lay person) with a Dial Indicator and that he was an idiot, he hung the phone up; go figure!
Regards,
Bill