How to rear shackle flip 72 j4000?

[brentwood]

I ordered a pair of 4in front lift springs from alcan. And would like to do a shackle flip in rear.
How do you do a rear shackle flip on a 72 j4000?
Any special parts needed?

[Kaiserjeeps]

I would do it with a correct set of springs. Or spring and lift block combo. The shackle flip is not a good idea for two reasons. One is with enough articulation the shackle can flip back up to it's factory position and next thing you know is one side of your truck will be squatting needing to be set back to how you had it. Second is it will raise your pinion completely taking your U-joints out of phase. By 8 plus degrees actually. That will make a terrible vibration. I just went through all this with the 70 wagoneer in my build thread. I have not updated my posts to reflect my incorrect assembly of hanging the rear shackle under the pin. I was 8.3 degrees out. I fixed it and now I am inside 1 degree out.
Hell creek is the only company that makes a lift for the J trucks if I remember correctly. They are expensive but you get it right the first time. Maybe BJ's sells a lift kit too. I am not sure.
Anyway, my 1.5 cents worth.

[brentwood]

Better to leave the lift blocks that came on truck than rear shackle flip?

[Cecil14]

Lift kits come with lift blocks instead of shackle flips for a reason. Often times a shackle flip isn't possible at all, but in the cases where it is, it's not the stablest option. OEMs don't tend to run that way either, for that reason.


If you can avoid the flip, that would be the safer bet.

[brentwood]

Understood, thanks.
I'll leave the blocks while I save up for rear springs.

[44BZ]

My 68 J2000 has the rear shackles flipped down. I've had no issues with vibrations, binding, or flipping back at all. Been that way since I bought it, 9 years ago. I don't see the problem.