Reply to "Torque spec for stub axel"

Several things contribute to outer rear stub-axle nut loosening and/or wheel wobbling. One is having an undersized axle- common on OEM axles '71-76 and rarely with aftermarket axles. Regardless, the ball bearings should both be interference press-fits on the axle- the bearing spec is +0.0006" to +0.0100". If the axle wears and causes a visible track on a stub-axlethat you can catch a fingernail on (usually 0.001 or more), that wheel will wobble.

Second is too little torque on the axle spanner nut. 300 ft-lbs is too little for big sticky tires; 400 or more is better. Do not worry about stripping the threads- that size nut strips in mild steel at around 1200 ft-lbs. Incidently, the spanner nuts are supposed to be one-use-only, but we all reuse them.

Third, the internal spacer between the bearings is also mild steel and if slight wobbling occurs, the spacer will be indented on its ends, which shortens it. This obviously slacks off the nut tension which then causes even more wobbling in a vicious-circle scenario.

And finally, pressing the axle & bearings together or apart will often distort the thin steel outer bearing retainer into a shallow cone, which allows the outer bearing to move in it's machined recess. If this happens or the internal spacer is shortened too much, the splined halfshaft adapter may bottom on the axle splines, so even though you have really torqued down on the nut, the whole stack of components are NOT held tight in the carrier. The steel retainer can be pounded flat to fix this part.

It is also (likely) affected by the use of 2X or larger, wider tires of far stickier compounds than in 1970 on giant wheels, and then cornering hard & often.

The main fix is a properly sized outer rear stub-axle, proper assembly of all the parts and checking the fit periodically. Yes- tapered rollers can replace Dallara's OEM ball bearings, in at least two basic designs that both need precision machining- but they really aren't needed with good parts and attention to detail. I added one tapered roller (my own design) to the right rear of our street Pantera, with a properly sized axle and ball bearings on the left as a long term test. Both have been in there some 18 years with no trouble for either and no particular advantage to either. Stock ball bearings run cooler with less rolling friction (all known real-race cars use ball bearings for this reason) while rollers have a higher load rating and because they are not press-fitted, can be disassembled with far less effort, if necessary.