Hi,
You mentioned that the Kimberly book suggests replacing the rear stub axles
at 60k miles. The Official service manual (Bentley reprint) does not
mention the rear axle as a service item, at least as far as I can find at
this time.
However two items are worth mentioning.
1. The TR6 Competition Preparation Manual suggests swapping out the axles
every four races.
2. Stub axle failure is not that uncommon, although the reasons for the
failure need to be described.
Now, to address your initial point: should you swap your axles at 60k
miles? A short answer would be: If the freeplay is within spec - I wouldn't
bother. If you had 100k miles on them and they're still within spec
(doubtful, but possible) then I'd consider pulling the hub assemblies and
having them rebuilt.
Keep in mind that the outer axle assembly is designed as a replacement
unit. In days of yore, you would drive (or tow) your TRiumph to the local
Triumph dealer and they would basically swap in a hub assembly. Presumably
they would then rebuild them for later installation on other client cars.
On the other hand, if your axles are "sloppy", then I wouldn't hesitate to
get some rebuilt units to swap in. I would not suggest that you try to
rebuild them yourself unless you are a fairly competent mechanic _and_ you
have the right tools... but this discussion goes on with this list
incessently, so I won't try to labor the point.
As for failures of the axle stub itself, there are a couple of ways they
can fail. In one case, the process of separating the wheel flange from the
axle stub can cause stress cracks on the very end of the axle. I have seen
this. The cracks can (over time) propagate and a worst-case scenario might
involve the complete failure of the stub axle. But this is relatively rare
in the realm of "normal street driving". The other, probably more common
failure mode occurs when the bearings' free play gets excessive. This
allows the inner bearing race on the inner bearing to spin in place - the
spinning cuts grooves into the axle itself. Now, the axle stub is probably
forged and the hardness of the metal is only "so deep", I don't know the
actual number. However, if the grooves caused by a spun bearing are deep
enough, you will wear into softer metal and under stress, the axle will
fail. This latter case is also pretty rare given regular street usage. But
I'll point out that grooves cut into the stub axle would necessitate
replacement of the axle itself... as far as I can tell, the stub axles are
available from the "big two", but I have not bought any so I bear no direct
experience
So, is the part highly stressed? Well, yes and no. Should the part be
replaced at 60k miles. Well, yes and no. If the end-float is excessive,
should the axle be replaced or rebuilt? ABSOLUTELY.
I hope this helps you make your decision.
regards,
rml
TR6's
=====================================================================
Bob Lang | TR 6 Guy | Editor: New England Triumphs
Phone: | 617-253-7438 (days)| 781-438-2568 (eves)
Occupation: | ComputerZ | TR fixer-Upper
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