The MGB front hub assembly centres on the stub axle, king pin, and top trunnion, a design that remained consistent throughout production but requires careful attention to component compatibility when ordering replacements. Stub axle assemblies are available as reconditioned exchange units in two specifications.
The standard reamed assembly has king pin bushes fitted and reamed to size with vertical shimming already done, supplied complete with top trunnion on exchange. The uprated assembly replaces the standard thrust washers with needle roller bearings, giving lighter and smoother steering action, and is also available on an exchange basis. When returning old units, only the stub axle and top trunnion are required, none of the king pin hardware is reused. The king pin kit is supplied as a pair complete with stub axle bushes, O-rings, and thrust washers.
Front wheel bearing end float should be set between 0.002” and 0.004” using the shim selection available. Starting without shims, recommended two each of 0.003”), (0.005”), (0.010”), and one (0.030”) as a starting point. Wire wheel hub ordering, critical note: MGBs up to chassis GHN3-30850 (approximately 1962 to 1964) used 12 threads per inch (TPI) on the front hubs and wheel spinners. All later cars used 8 TPI.
These are not interchangeable and the wrong hub will not accept the spinner correctly. Always confirm which thread specification your car uses before ordering. 12 TPI hubs are listed as the MkI type; 8 TPI hubs are the later standard.