Hmmmm. Now, and I have no idea whether axles were a problem in the 50's
and 60's (Kas can you help here?), apply contemporary tire compounds, tread
designs and such to these axles and then rerun the discussion of tires, and
other modifications to suspension bits that allow higher lateral g-loading
(read cornering force) to these old race cars. Some of the clubs that are
persnickety about profile, tread width and compound are not totally
unreasonable. Or are they?
----- Original Message -----
From: Jack W. Drews <vinttr4@geneseo.net>
To: <fot@autox.team.net>
Sent: Tuesday, August 01, 2000 8:20 AM
Subject: TR axle breakage - my theory
> Delete now if you're sick and tired of all this axle talk. Otherwise,
> especially if you're a technophobe, read on.
>
> Every hub / axle assembly that I've taken apart has exhibited a puzzling
> thing. The surface appearance of the axle on the inboard third of the
> mating surface has been different than the outer 2/3 or so. I never
> understood why this was. Furthermore, with the new axles and hubs, this
> same effect was noted and was disturbing to some folks. To others, like
> me, since I did not have an explanation, and since the old parts looked
> like this too, I dismissed it.
>
> Switch gears with me for a moment. To have a fatigue failure, you have
> to repeatedly bend or stress a part. These failures down inside the hub
> are all fatigue failures. How can the axle be bending down inside the
> hub?
>
> If you look at a cross section of the HUB / axle assembly, you will note
> that the flange where the wheel bolts on is at the same position on the
> OD as the end of the axle keyway occurs on the ID. I think that this
> flange makes the hub such a large diameter at this point, that from the
> flange outward the axle and hub act as one part, as intended.
>
> Inboard of the flange, at the seal diameter, the hub is a relatively
> small diameter. I think that under heavy cornering loads, when this
> whole thing tries to bend, the hub ID opens up slightly (kind of
> bell-mouthing) and allows bending inboard of the wheel flange. This
> bending starts at the end of the keyway, explaining the different
> surface appearance of the axle. It's actually rubbing from here on
> inboard. Unfortunately, the area where it starts to bend is right at the
> end of the keyway, with its sharp edges, so a fatigue failure starts.
>
> Therefore the problem is not a metallurgy problem, but rather a parts
> design problem that is exceedingly difficult to overcome. Wonder what
> the SCCA would think of all that?
>
> Anyway, that's mah story an ah'm stikkin to it.
>
> --
>
> TR6 -- 29 and still running
> TR4 -- 39 but no longer racing
> uncle jack -- temporarily sidelined
>
>
>
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