FJ40 Shackles

[Rotor]

Hi
Ive got a 81 BJ40 with 2" over springs on the front and stock springs on the rear but with shackles that measure 5 1/4" [135mm]centre to centre, as the rear end looks like its sagging a bit I was thinking of fabricating some more shackles at around 7" [175mm] centre to centre, can anyone forsee any drive shaft or other problems in doing this.
Thanks In Advance
John

 

[CruisinGA]

You may need to purchase shims to point the pinion down after going with longer shackles. Shims available at napa.

get a magnetic angle finder, check pinion angle before and after new shackles, and compensate with spring shims.

 

[Hodag]

Longer not necessarily better

I've had 8" long shackles on my 40 from the PO. Two words, suck and balls. Shackles that tall seemed to relocate the rear axle forward and left the shackle nearly verticle. This in turn leads to absolute crap for articulation, and I suppose that if they were long enough, they could even invert. This would also suck.
I know that long shackles are cheap to make, and that can be appealing. But I would suggest taller springs or a spring-over. Youll be happier in the long run, and safer too. Hodag

 

[Romer]

Why not put lifted springs on the back. Not sure why you would want to run a 2 inch lift on the front, but only longer shackles on the rear?

My cruiser had extended shackles with stock springs and was level before I installed the lift. So I used 1 inch extended shackles on the rear when I installed the 4 inch springs.

Like people, as they get older, the rear tends to sag!

 

[DocB]

Look for some used lift springs instead. Shackles of that length will put more stress/leverage on your springs and flatten them even faster. Ideally, you don't want the shackles straight up an down either, rather angled slightly or up to 45 degrees so they will articulate when compressed, not just move up and down.