Isn't it cheaper and faster to add a SLIGHTLY longer shackle or would that mess with the angle of the shackle.
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This was done ALL the time back in the '60's. I remember seeing many a car with very long (6inch or more) shackles with the car lower than what it was when the springs were weak, and before the shackles were extended. This was especially true on late 50's Fords.
It puts more stress on spring already giving out.
As I said above, re-arching is, to me, the best way to go. Extending the shackles is on the other end of the spectrum.
