On Mon, 7 Apr 2003 Lizirbydavis@cs.com wrote:
> I think that there would have to be a significant amount of axial load
> transmitted from the hub end of the half shaft to the trailing arm. I'm no
> engineer, but this means of locating the hub seems lousy. However, Triumph
> in their wisdom used it for 11 years without changing it.
Actually, Triumph used that hub design for a lot more than the TR6
production run. These hubs are used on Triumph 2000's, 2500's and Stags...
there may be others (like the Dolomite).
The design isn't lousy, it works just fine as long as you don't try to
kill the studs with 1/2" breaker bars and if you assemble it properly. To
their credit, Triumph produced a beautifully light semi-trailing arm
assembly. If you don't bleieve me, pick yourself up a replacement trailing
arm from an E30 or E36 BMW. Those are produced in steel and are probably 3
or more times the weight.
> I know that autocross/race types upgrade this part of the drivetrain.
> Is anyone aware of failures i.e.: the hub breaking away from the
> trailing arm studs?
I qualify as an autocross/race type.
The upgrade for the trailing arms is to drill out the soft metal and put
in helicoils or other threaded inserts so they won't "gall" from taking
the studs in/out. We then check them regularly during tear-downs (we don't
like to wait for parts to break... we want to know that they are bad
before they can contribute to our "untimely demise").
For those that "upgrade" the rear suspension or brakes, there are a couple
of other tricks. For example, a lot of us use Corvair stub axles with
custom hub bearing carriers (aka "the Group 44 setup"). The custom hub
bearing carriers are made from aluminium and have a really thick flange.
The stock studs are not adequate for this thicker flange, so we have to
use standard automotive studs adapted to the application. This means we
take a standard 2 inch stud (5/16-18 on one side and 5/16-24 on the other)
and hack it down to the size needed to get a nut on and still clear the
backside of the hub flange. SO, we drill out the trailing arm and install
5/16-18 helicoils and use the "normal" fine-thread attachment nuts.
Some folks go one step further and drill out to 3/8" and make custom
studs, but to do this job, you will then need to drill out the bearing
carrier flange for the 3/8" studs.
There is one other option, it is called a "step-stud". This would be 3/8"
course on one end and 5/16-18 (or 24) on the other end. The beauty of a
step-stud is that you get more stud into the meat of the trailing arm but
you don't have to modify the bearing carrier.
To go much beyond a 3/8" stud would be difficult. There's precious little
"meat" around the stud attacment points to accomodate anything bigger than
3/8".
Through bolting might be possible, but you would have to machine the
trailing arm to get a "flat" for the nut (or bolt-head, depending on how
you assemble the thing).
I have seen a TR250 hub carrier stud failure at an autocross (VTR '97 in
Ft. Worth, TX). Nobody was hurt, but there was about $4k of damage to the
car (frame, trailing arm, fender, paint and labor). You don't want this to
happen! But it does not have to happen. If your trailing arm is nasty and
not capable of taking a heli-coil, you can pick up a trailing arm for
cheap money (figure anywhere from $10 to $50) for another one...
> Joe Davis
regards,
rml
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