Rear Axle Taper - What It Does

[rotorwrench]

How well a tapered shaft joint holds depends entirely on the condition of the tapers. The shear key will allow the key to shear if the wheel bearing fails and decides to weld itself together and lock up a wheel. It's there as a safety to protect the shaft and act as a back up for a loose shaft. It will only act as a backup for a period of time if the taper joint comes loose. During the time its loose, it will not only fret the key but it will also fret the key ways and be subject to extreme working of the key when braking or hot footing the gas pedal. The design might as well have been a spline type set up if it needed no shear key. many of these old parts are now 90+ years old and were not babied during there service life. It's a wonder so many are still in service.

This is a good link about tapered shafts:
https://www.machinedesign.com/motors...w-away-the-key

[Joe K]

Originally Posted by Conaway2

After reading all the comments, I think I need to find another carrier/axle assembly that’s in better condition than the one I have. I recently replaced all the bearings and races in the rear axle assembly and adjusted bearing preloads and gear backlash - following the article by Tom Endy. However, the ring and pinion gears show a lot of wear, as do the axle tapers.

Um. If you "blued" the contact surface and can sustain contact between the pinion and ring gear, your issue with the drivers side drum is not there.

Generally "contact" is the proof of the pudding - and sign of proper mating/orientation. Without "gear grind" or noise your gears are probably fine.

You've ruled out pre-load and bearing issues. If you can get the preload in the pumpkin, then there is no relative movement between the carrier and the pumpkin.

I would look to the spider gears or their carrier. Or - your axle. There may have been relative wear between the axle and the inside of the carrier. Refreshing either the carrier or if wear appears uniform, "shimming" the axle within the carrier may be enough to tighten up relative motion between parts.

(I.e. you may notice an issue with the driver's side brake drum, but going the other way in a turn may present an equivalent issue with the passenger side.)

It is VERY possible the axle "shoulders"/carrier seat have worn. Normally there is not that much differential movement here - the axles only turn relative to the carrier in a turn. But 80 years is 80 years - and they do sell shims in various sizes just for this purpose.

Joe K .