Subject: [Fot] New Vertical Links

From: "Robert M. Lang" <[email-masked]>
Date: Thu, 7 Nov 2013 20:44:17 -0500 (EST)

Hi,

On a whim, I purchased a couple of brand-new vertical links for my race 
car. The parts look pretty good and the dimensions all see okay. I noticed 
one oddity, though. The ACME thread that goes into the trunnion on both 
links is about one turn too short... It looks like they started to cut 
(roll or otherwise form the threads but the tooling lifted off (or 
something)). The undercut on both sides is almost exactly the same, e.g. 
the last full turn isn't usable.

Hence, the trunnion does not thread on all the way.

All this is a long winded way of asking: is it okay to try to hand cut the 
remaining thread or is this something a crafty auto machinist can handle. 
I have no idea how to make these parts work as-is because with one-less 
turn into the trunnion, the geometry changes...sort of a lot (the 
vertical link is like 1/4" longer or so).

Any guidance is appreciated.

regards,
rml
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Bob Lang              Triumph TR6!!            |  This space for rent
Former NER Solo Chair                          |
Voice:617-253-7438                             |  Cell: 339-927-4489
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From: Bill Babcock <[email-masked]>
Date: Thu, 7 Nov 2013 16:08:23 -1000

As I recall, you dont have to fix that, though all my measurements are TR3.
Yes, its wrong, yes, it makes the link a little longer, no, it doesnt affect
geometry significantly, in fact, it turns out to be slightly better (on TR3s
anyway). It pushes the roll center out a little further, which isnt all that
big a deal, but it also gets the angle of the upper and lower arms a little
closer to the steering link angle, which mitigates bump steer. I dont have my
notes with me, but I did a roll/bump of the longer link on the software I use,
and as I recall it was pretty neutral in effect.

On Nov 7, 2013, at 3:44 PM, Robert M. Lang <[email-masked]> wrote:

> Hi,
>
> On a whim, I purchased a couple of brand-new vertical links for my race car.
The parts look pretty good and the dimensions all see okay. I noticed one
oddity, though. The ACME thread that goes into the trunnion on both links is
about one turn too short... It looks like they started to cut (roll or
otherwise form the threads but the tooling lifted off (or something)). The
undercut on both sides is almost exactly the same, e.g. the last full turn
isn't usable.
> All this is a long winded way of asking: is it okay to try to hand cut the
remaining thread or is this something a crafty auto machinist can handle. I
have no idea how to make these parts work as-is because with one-less turn
into the trunnion, the geometry changes...sort of a lot (the vertical link is
like 1/4" longer or so).
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