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Re: Stripped Stud in Trailing Arm

To: lizirbydavis@cs.com
Subject: Re: Stripped Stud in Trailing Arm
From: "Robert M. Lang" <lang@isis.mit.edu>
Date: Mon, 7 Apr 2003 12:04:31 -0400 (EDT)
On Mon, 7 Apr 2003 lizirbydavis@cs.com wrote:

> In the process of installing my new hubs and half-shafts, I was unable
> to tighten the studs to the proper torque.  I may have stripped them.  
> They may have been already stripped. Who knows.  Unfortunately I had
> already rebushed and reinstalled the trailing arms.  Two questions:  
> 1.  So what? An "expert" just told me that he has never taken off a
> hub without finding at least one stud stripped out.  Is this the cause
> of the wheel falling off incidents I've heard about.  My "expert" told
> me not to worry about it.  2.  Is it possible to helicoil the trailing
> arm in situ?  I'm not inclined to take these trailing arms
> off...again.

You can drill and tap for heli-coil with the trailing arm in place. You do
need to drill the hole square to the trailing arm though.

I did all 12 holes on the race car a couple of years ago with the trailing
arms in-situ. To make drilling the holes easier, I made up a jib to bolt
to the trailing arm that was drilled out for the 21/64" drill and a "peg"
that was correct ID for the 5/16" drilled hole (so I could center the
jig). So, I would center the jig with the pin, lock it down on an adjacent
stud pull the pin and drill, remove the jig and tap the hole and then
install the helicoil.

All this was necessary because I am just about incapable of drilling a
hole square to a surface. I attribute this lack of ability to my vision. I
have a pretty sever astigmatism in both eyes, so things look square to me
one way, but when I move my head they look totatlly different.

I'm not as bad as architect Frank Gehry, but then again, I don't design
"artsy" buildings. See:

http://www.frank-gehry.com/pics-2/pages/a17_jpg.htm

for an example of what I'm talking about.

If you need pictures or better description of the "jigs" that I used to
drill the trailing arms, ask away. I have to say that I am "digital camera
impaired", so any pictures will take some time to produce. But I did find
the jigs to be invaluable in getting my trailing arm studs in good order.

I agree with your friend, most trailing arms that I come across have at
least one messed up stud. And it's not just because of heavy-handed
mechanics, screwing steel into aluminium has many "issues". One such issue
is screwing the studs in too tight in the first place... I actually put
the studs in finger tight with loctite blue (242), wait over night and
then install the regular elastic stop nuts to spec (10 - 13 ft/lbs.) This
seems to reduce the number of stud hole failures considerably.

> Joe Davis

later,
rml
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