Shackle Question...

So I did the full leaf spring rear lift
Also, coil front...

The rear looked a touch off so I ordered 1/2" - 1" shackle leveling kit.
...basically a set of shacles that were slightly longer with the bolt hole for the 1/2" and 1"...

They just showed and the hole that should be for the 1/2" are just under 2"s longer shackles than the stock bolt...
...and the 1" hole is like another inch beyond that.

Does anyone know the increase in shackle length to lift?
I only want to raise the back like a 1/2" to better match the front.

I have always been under the understanding that the added length of the shackle has to be twice as much as the desired lift.

1" lift = 2" longer

They are easy enough to swap, try one set of holes and if it's not enough go to the next. (this thought process does not apply to all things, lol)

I just hit the sweet spot on the pinion angle. Perfect parallel and the drive angle is like 9*

I believe adding a 1/2" shackle lift, will rotate 1* change in pinion... clockwise as you face the driver side (US)
I have a 2.5* shim from a previous lift and
currently have a 1" (+ 3 washers to add a 1/4") = 1 1/2* - 2* counter clockwise.

Thus, adding the 1/2" mark and removing the 1" TCase drop, would put me off by roughly 2.5* ... which is the shim angle.

So, yes, it takes 15 / 20 minutes and 2 cold beers to swap the shackles.
But it takes 1 -2 hours and a couple more beers to add the shims and measure the angles.
... and increase the drive line angle to 11* or 12*

= not this weekend. Maybe next

been lazzzzzy and haven't gotten around to the shackles yet :indifferent0020:

Optimistic about this weekend for the shackles and the exhaust.
.... and a couple other upgrades

So I finally got around to installing the shackle lift... although it was sold as a 1/2" and 1", the lower lift was more like 1 1/4"
I measured the pinion change and it's about 1/2 * per inch. So, the 1 1/4" bolt added just over 1/2* change.

But that's within acceptable.

** I was hesitant as I had to drive it for my daily driver for the last 2 weeks.
***** just angst on my part as they only required an extra washer to add to the spacing on the T Case drop.

All is well