shackle reverse

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Dec 18, 2005
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Okay. im getting some time to work on my fj40 again. Doing soa and sr. going to use stock springs and flipping them. right now all i have is the frame and spring hanging. Going to put the shackle mount in the middle of the frame. (not really middle)
My Q is. how long of shackles do you guys use? how much deg you leave on it? i heard alot of 45. Heard you have to put the front mount 1 1/2 pass the frame. But im not sure. mostly be use 1ton 60 cut down

Eric
Thanks
 
aaaaaa002.jpg
 
I dont know sh.. from shinola but I intend to use the same mount locations, just reverse with the 2-1/2" ccot shackles in back.
 
The shackle angle depends on several factors. You'll have to research it, but mine is at 45deg. Not sure what you're asking on the 1 1/2 thing, are you flipping your front springs with the SR to keep your military wrap on the correct side? I moved my mounts foward and reversed springs but my tire ended up almost in the center of the fender downslope which was ok with me. And for the thru the frame with the shackle, generally around a 5" shackle is adequate so you don't raise your rig too much.
 
... Doing soa and sr. going to use stock springs and flipping them...

stock spring with soa? So longers psrings are NOT needed when doing SOA?
 
my other rig has stock springs that are like flat. and have awsome flex. if i stay leaf springs all the way arould in this rig ill run 55 in the rear beacuse they are longer and im going to move my rear mount and everything
 
To answer your question quickly, it should be about 5 inches, maybe a little longer. Once you have weight on the suspension check the angle, if the shackle is too verticle, grind your shackle hanger tack, and move it foward, re-check. Shouldn't be very hard; just remember to tack, check, then weld, don't just weld it out right away.
 
stock spring with soa? So longers psrings are NOT needed when doing SOA?

stock springs are just fine if not perferred
 
It isn't hard to calculate the limits of the spring flex so you don't run into problems with the spring hitting the frame or inverting and not getting the maximum articulation from your spring.

The curved lenght of the top leaf (from eye to eye) is the maximum lenght of the spring when it is flat. Further compression or unloading of the spring is going to shorten the eye to eye distance. Using this maximum measurement, you can measure from the front hanger back to where the spring end of the shackle would be and then you can see where the frame mount end of the shackle would need to be with the shackle at 45 degrees. More than 45 degrees and you could end up with the spring hitting the frame and/or shortening bushing life.

You can also measure the eye to eye distance at full droop by loading the spring with the weight of the axle and wheel. Based on that measurement, you can tell if the shackle lenght and angle will allow the spring to fully droop. If not, you can increase the length of the shackle.

Measuring is always better than guessing.
 
okay. i took one spring pack all the way apart. and only have the main one. so if i could put a wood and strap it down to make it flat! The shackle at this point have to be at 45 degress?
 
Here we go

Spring is flat

fronts001.jpg


Flat spring at 45

fronts002.jpg


!
fronts003.jpg


1 1/2 from buttom of frame to center hole

fronts004.jpg



about 57 D main spring (no load)

fronts005.jpg


fronts006.jpg


I readed somewhere that the mount has to be 1 1/2 pass the frame.

tech links

fronts007.jpg



fronts008.jpg


Thanks for any tips

Eric
I think in the
 
I guess a standard shackle-forward setup is out?

edit: guess I should have read the thread-title ;p
 
Last edited:
I guess a standard shackle-forward setup is out?

edit: guess I should have read the thread-title ;p

kinda to late to stay that way lol. I just dont like how my other rig hits everyone rock on the shackles. so thats why i went this way on my new project
 
Is that 45 degrees with respect to the ground or the flat spring or what? Is the frame parallel to the ground? The shackle angle looks steep, but for a flat spring, it can't get any longer. You don't want the spring eye hitting the frame. Maybe move the frame mount for the shackle back a half inch.

How about the droop? Put about 250 lbs on the spring and see how much it sags and see if you have enough shackle swing to accommodate full droop.
 

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