1930-31 (maybe earlier, too??) MYSTERY

[West Peterson]

I asked this question on Tom ????'s restoration page, but I thought I would ask it hear as well, on a dedicated post.

 

While working on our Speedster a few weeks ago, I was reminded of a mysterious thing about Packards of that era. I've often wondered the purpose of the extra pin on the rear of the rear spring shackle. This is a photo of Tom's spring. The extra pin seems to serve no purpose, and is a smaller pin than the one that actually holds the spring.

Can anyone shed any light on the reason for this extra pin?

 

[West Peterson]

This from AACA Forum member Allen Strong:

think of the rear spring bracket as a ladder, and the two rungs on the ladder, support the side rails and give it strength at the top and the bottom. The spring pin is really designed to, carry the weight of the spring and not necessarily support the strength of the shackle bracket . There is an incredible amount of sideways thrust placed on the shackle bracket during turns and bumps. The additional pin at the bottom at strength to this ladder.
 

[DavidMc]

To put it another way, having three pins keeps the shackle straps parallel against cornering forces.  See sketch

[Tom M]

West thanks for posting this query. I was not aware of the purpose also. Now I have a better understanding how it works and the reasoning/purpose of this mysterious/extra bolt.

 

Allen and Dave thanks for explanation. I now have a better understanding of the purpose of this said mysterious/extra bolt.