Chicagoland MG Club
Spridget Rear Axle
Rear End Noise
by Norm Kerr - Ann Arbor, MI
loud whine/howl at speed = ring and pinion are shot (gear tooth surface worn/damaged). Replace diff with a used one (typically, they last 150k miles with no maintenance, as long as they are never run dry, or been exposed to broken axle fragments).
worn U-Joint (confirm no play)
loose brake back plate (confirm bolts tight and holes not oval)
shaft worn at diff (max 0.010" spline wear). The axles seem to be softer than diff gear, so they wear first.
wire wheel spline wear (new splines are squared off on the top, worn splines are pointed). Clean off the grease from both the hub and the rim and then check the play without the nut. Maximum 1/8" play at tire. Replace wheels and hubs at the same time (one new one will quickly wear the other). They are NOT cheap (new hubs and wheels), so don't only do it half way. Think of how nice wire wheels look, while you are writing the check. Original hub spline outside diameter 2.450". Note, though, that a fair amount of spline wear can occur before this diameter decreases by much, hence the tire rotation test above, which directly measures the wear as a rotational free play.
==> photo before/after
worn splines encourage extremely tight wheel nut (pounding with a hammer to try and hold the wheel still by friction), which leads to spline bottoming out on the inner taper of the hub. So, spline marks on that taper are another indicator of worn splines.
Axle (half shaft) history ("or, so I've heard.." ):
Frogeye = 2A7085 (? material)
1098 era = ATA 501 (EN7 material)
1968 ~ = BTA 806 (disc wheel) / -807 (wire wheel), (EN17 material, with Identifying groove on the inboard end)
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