I recommended the change of axles on the TR-6 as that was the term we found
was the LIFE of the unit. We ( as factory guys) could not use other
componets and so lost a few to find that the life was a real tihing and to
pay atention to it. The late axles are of course ianduction hardened but
some of the early axles shafts in the TR-250 and early TR-6's were not and
they would be probably half the life of the induction hardened units.
Several people have found great solutions to the axle problems and if you
have a serious racer take their advice and MAKE THE CHANGE.
----- Original Message -----
From: Bob Lang <LANG@isis.mit.edu>
To: Barr, Scott <sbarr@mccarty-law.com>
Cc: <fot@autox.team.net>
Sent: Wednesday, February 16, 2000 6:35 AM
Subject: Re: The Hub of the Issue
> Hi,
>
> I'm not a metalurgist, and I've not been a racer for eons, so my offering
> is more along the lines of a "lint picking session"... but to answer
> the principle question: why do hubs break? I'd have to say "for a lot of
> reasons".
>
> Have the cornering forces increased? Well, in a word: yes. Think about it
> - have lap times changed since these cars used to race?? Yes. _If_ you
> can find a track that hasn't changed. But tire compounds are stickier,
> suspension settings generally tend to be quite a bit harder than they
> used to be - something's gotta give somewhere.
>
> But wait - there's more. Even when your car can slide, there are plenty
> of big forces on your little GT6 hubs... the metal will twist a little
> bit each time you stress it. Eventually, you can develop stress cracks at
> the surface, and if these pieces are stressed further - they will fail.
>
> There's also the bigger problem (at least from my perspective) of
> determining the lineage of your parts. Take for example that pesky hub
> that someone heated cherry red to take apart... I can't say with
> authority that such a process doesn't change the temper of the part, but
> my best guess is that it has to effect it somehow. If you're lucky, you
> get to see the cracks on the surface - if you're not lucky - well then
> you'll know how good the part is eventually.
>
> If you want to be sure of the integrity of the parts - get 'em x-rayed.
> At the very minimum crack test the parts that get stressed the most on
> some sort of regular basis. Your local welding supply store will have the
> stuff you need to check for surface cracks.
>
> But basically - things wear out. And when in doubt - replace.
>
> Now, a quote (from memory, so forgive me if I'm slightly off-base here)
> from the TR6 competition prep manual suggests replacing the TR6 rear hubs
> every _four races_. I'll bet this was suggested because that's how many
> races they would see before the all important bearing end-float would go
> into the "critical range" and likely fail if run any more, but Kas could
> probably provide some insight there. On TR6's, one of the failure modes
> is that one of the bearings will spin in place when the bearing end-float
> gets excessive, and this will score the axle stub and form a nice little
> place for cracks to start. And I further know that Spitfire axles are not
> made any more betterer (!) than big Triumphs - so I'll bet bearing
> end-float is real important and more important when they fail (the
> bearing spins, for example) you're wrecking the axles.
>
> The GT6 (and Spitfire) parts - being smaller and lighter, are probably
> just as prone to problems if things get "out of whack" regarding bearing
> end-float and torque spec and the like.
>
> Bottom line - if you don't want to ball your car up, you need to check
> this stuff on a very regular basis.
>
> And do as I say, not as I do. But I'm not a road racer, so a failure in my
> persuit would likely be less "life threatening" (well to me anyway,
> apologies in advance to any cone pickers should my car ever suffer an
> axle failure) than a road racer's might be. By way of example - if you
> doubt your car would be able to go full tilt through Road America's
> "kink", you're probably not doing enough preventive maintenance to get
> your confidence level where it should be.
>
> Hmmm. I'm overly wordy today. Sorry for rambling. X-ray your hubs, please.
>
> rml
> --------------------------------------------------------------------------
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