What is the point of shackle reversal kits?


Nov 7, 2017
Luray VA ( Lou-Ray)
Just like it sounds, the u bolts are reversed from stock orientation so they point upwards. Prevents the inevitable rock carnage to stock bolts, another option is a u bolt skit plate to protect them
Highly recommend this. After a few days of smashing my stock u bolts up on rocks at Rausch Creek I did this and it was money well spent. The 4 plus kit actually has machined slots in the plates to give you a even better angle and protects the U bolts as well. I did not add the u bolt skids but mine performs better on the rocks with this mod.


Jan 6, 2012
With lifted spring under axle setups the springs usually have a decent arch to them. In order for the springs to move through they're arch and cycle freely you need long shackles otherwise the wheel travel will be limited. The short shackles do increase tightness in the leaf spring suspension overall though which is kind of good with the fj40s very small leaf spring bushing diameter. If you put long shackles on a shackle forward setup you will smash them into everything on the rocks. Technically in my opinion, each new set of leaf springs you get should have its own specific shackle setup. The shackle mount on the frame should be moved so the shackle is at the correct angle at ride height, and the proper length to allow the leaf to move through its arch freely. On my cruiser I tried to get the shackle angle at ride height and length right for my alcan springs, which you can do for any aftermarket springs. The springs really seem to move through they're arch decently.

Shackle forward also affects cornering differently. As you corner one side of the suspension compresses and the axle walks slightly and should create either slight under steer or oversteer depending on the setup. The flatter the leaf spring at ride height the less this happens ie stock leafs. So lots of pros and cons. The majority of people i think just build a fj40 to get ice cream down the street, so as long as it gets them to dairy queen they are happy. In that scenario none of this really matters.


Supporting Vendor
Supporting Vendor
Dec 5, 2004
Miami, Arizona
with no intent to cut into @lcwizard's (4Plus.com) market on 40 shackle reversals, but honestly, you can a buy a whole lot more useful stuff from him for the money - U-bolt flip kits would be my first suggestion, beefy bumpers, anti-inversion shackles . . .
It's OK Claudia, I passed on the drawings to manafre years ago. I haven't built them except for in house use in many years. I don't
like selling them without some control over the rest of the build. In the hands of the wrong person or spring manufacturer you can
do as much damage as help. The market has shifted to stock restos so they don't have the place in builds that they used to.
There was a time when all 40s were seen more on a trail than a cover for classic vehicle magazines

Users who are viewing this thread

Top Bottom