I imagine that you are familiar with taper rollers on the front of typical rear wheel drive cars such as early Escorts, Cortinas, Triumph Herald/Spitfire/Vitesse and many many more, where they are in fact adjustable, and are done up more or less finger tight,before inserting the split pin.
That is not practicable in a front wheel drive installation, where the hub flange must be clamped very tightly to the CV, to transmit drive torque without fretting of the splines. So, the bearings are carefully made, with an individual spacer per pair of bearings, so that when the outers are fully seated in the hub, and the inners clamped very tightly against their specific spacer, correct running clearance is obtained. The high torque figure (and it is to the next split pin hole, so may be quite a bit higher) is very necessary.
In theory, Mini rear wheel bearings could have been made to be adjustable, but in fact they are not, and rely on bearing manufacture, with or without a spacer, to get the correct clearance. If they are not done up tight, the inners spin on the shaft, which soon becomes scrap, along with the bearings.
You will see that the major potential problem is the tolerance of the rib in the front hub or rear hub flange which the bearing outers seat against, It is probably not made to the same degree of accuracy as can be achieved by the bearing manufacturers.
I recommend ensuring that all bearing seats are very, very clean, and that the outers are firmly drifted into place. Then tighten up cautiously, spinning the hub all the time. If it starts to go stiff before reaching the correct torque, stop and find out why.
