Rear Spring Shackles - Reversed Threads

[Richard Cope]

Received new spring shackles for my 39 Ply Business Coupe today from Andy Bernbaum.  Reproductions are not marked "L" and "R" like the nos.  One of the shackles has reverse threads on one end,  I believe the reverse threads attach to the spring eye on the passenger side, appreciate if someone could confirm.   Will also help me to disassemble the existing springs if confident about the location of the reversed threads.  

Thank you in advance for your help,

 

Regards,

Richard

[sser2]

It is the lower leg of the driver side shackle that has left hand thread. Left hand OEM shackle bushing has notches on its hex head to indicate this. Andy's new production bushing does not have these notches. When installing shackles, follow service manual procedure with 7/8 and 13/16 gauges.

[Richard Cope]

Great, Thanks for correcting my assumptions.  Seems like it would be easy to install incorrectly by flipping the threaded areas.  Any thoughts on the rational for having reversed threads on the drivers side

 

Thanks again!

Richard

[sser2]

When wheel hits a bump, shackle forces the bushing to turn. If rotation of this turning is in the direction of unscrewing the bushing out of the spring hole, the bushing could loosen up and come out of the spring hole after a series of bumps. With left hand thread, the action of shackle tightens the bushing. 

[Richard Cope]

Thanks sser2

Rich