Jaguar engineers put their pants on in much the same way as the rest of us. Thinking, manufacturing methods, accuracy change. Preload of diff pinion bearing, measure by the amount of torque required to rotate the pinion shaft, was specified by Jaguar for early cars at approximately 9lbin torque. For later cars with the same differential, it was specified at around 26lbin torque. The specified End Float of the Rear Hub Bearings, in the life of E Type production, went from a nominal End Float of 0.004" (0.002 to 0.006) down to 0.002" (0.001 to 0.003"). Things change; evolution.Pre-loading the hub bearings is directly contrary to Jaguar's specification and is bound to increase the heat produced in the bearing . I don't wish to be rude but what is this fascination for knowing better than the manufacturers ? It crops up time and again in this forum
The fit of front wheel bearings on the stub axle is far from optimum in engineering terms. Every Jaguar stub axle I've examined that has fair mileage, show a distinct wear margin from 4 to 8 o'clock. This wear margin is due to the inner race of the bearing rotating on the stub axle; hardly the design criteria for a tapper roller bearing operation. The bearings would function much better if the inner race was an interference fit with the shaft, or there was a spacer place between the inner races of the inner and outer bearings. The reason for the running fit of the bearing inner race with the shaft is for expedience of assembly and disassembly; no engineering principles involved.
End Float setting of the rear hub bearings is not wrong, but it is not the best setup. Bearing manufacturers will tell you this. I count as a friend a past (retired) chief engineer of Timken Bearings; I had dinner with him and his wife this very night. He and I have discussed this matter at length and he is unequivocal in that Taper Roller Bearings work better in light preload.
Regards,
Bill
