On Fri, 10 Jun 2005, Navarrette, Vance wrote:
> Shannon:
All.
> 5/16-24 (so called UNF or fine thread) is correct for stock.
Yep.
> However, if you go with 5/16-18 you can use an off the shelf
> "manifold stud" which is
> coarse thread (UNC) on one end, fine thread on the other. By putting the
> coarse end into the
> trailing arm, you will have a stud that is much less prone to pulling
> out, since the coarse
> threads are much stronger in aluminum.
I agree.
> The Triumph engineers made a bad call on this design, using fine
> threads in the aluminum
> trailing arm. HOWEVER, I have not heard of anyone experiencing a failure
> from studs pulling
> out of the trailing arm. I *HAVE* heard of broken axles however, and
> they are hardened steel!
> So perhaps the concerns over UNF threads in the trailing arms are
> overwrought.
I actually have seem the studs pull out, but it's pretty rare. In fact I
have a rather spectacular video of a certain Yellow TR250 loosing the
driver's side hub and outer axle assembly in a hard cornering manuever at
the autocross at the '97 VTR National in Ft. Worth.
You want the studs to be secure in the trailing arm. The fine thread vs.
course thread argument is inconsequential compared to the "safe vs unsafe"
argument.
One point of information regarding the installation of the heli-coils and
studs - make sure you get the studs perfectly square to the trailing arm.
If you don't get 'em square, it's a real PITA to get the bearing carrier
to seat on the trailing arm. This is experience speaking here, experience
and a severe inability to drill holes perpendicular to any surface. I
wound up making a "jig" to guide the drill in nice and square... no more
problems installing those babies!
> Vance
regards,
rml
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