Spacer is used on ball bearings, but none is required on taper roller bearings.If your spacer is removed, the rotor will move inboard and the caliper will no longer be in the right place. Is one axle longer than the other? I assume that the spacer is inboard of the inner bearing?
not sure what's fitted in this application but the first bit above is not true. Check out mini cooper s: it has two taper bearings, one either side of a spacer ring and torqued up to 150lbs ft and that's tight. But this is a front wheel drive application.
