Must have read 200 shackle questions...no answer

Hope everyone has a good 4th of July.
Maybe someone out there can help. I got a cj5 that the PO lifted 4 inches using Skyjacker springs. He also installed some taller home made looking shackles, put some castor shims under the rear spring perch to help with the rear driveshaft angle,( I think he robbed them from the front??) and dropped the trans/transfer case using spacers. All in all, a pretty decent lift. However, I wanted to get rid of those longer shackles to help with the wandering steering. I bought some stock length shackles and put them on but noticed something odd. In the front of the vehicle, the shackles are vertical...great! But in the back, the shackle slants to the front of the vehicle approximately 30 or so degrees if viewed from the side. Is this normal? I assume the rears had to be vertical also. I should mention that I never loosened the u-bolts retaning the springs to the axle...just took off the old shakles and installed the new. Would this cause the shackle not to "re-center"? I was wondering if the axle had to "seat" itself on the springs.
Would the shims be causing the shackle angle? Would it be wise to leave the longer rear shackles in place? (I honestly cant remember if they were vertical before replacement or not...I think not or I would have noticed it) Will this shackle angle cause any problems? I dont really know which way the shackle should travel when the spring flexes....to the front or the rear (from the vertical position). If the shackle deflects rearward when the spring flexes...then I am in good shape. But if it deflects to the front..disaster?

Thanks from Mike in KC

Semper Fi

 

Shackles are supposed to flex with the bottoms going toward the outside of the vehicle. In the front, the bottoms will kick out to the front, in the rear,the bottoms to the rear. From the sounds of things, you're ok. I am worrying more about the front shackles. Have you driven the JEEP yet? If not, take it around the block and let them seat... then look at them. HTH

 

I'm not sure which way to read your question, but if this picture works, you want the shackles to look like the near one, not the far one-

 

Ideally you'd want the shackles to be at center or slightly past center when the Jeep is sitting unloaded, but what you describe should be ok. The rears trail the axle, so their tendency will be to pivot backwards as they should.

You don't have much control over this, since there's only one place on the spring where the axle can be located (with or without shims) and the length of the spring is fixed. The only way you could change it is to use springs that are longer or have less arch, or softer springs, or change the weight of the Jeep.

 

:iagree: Drive it around a little bit to see if they settle in right.

 

...or relocate the shackle mounts.

Verticle shackles on a Jeep usually lead to inverted shackles on the trail in my experience.



Ideally, the spirngs should be a little longer...

 

Thanks for the reply. You said the front should be more cause for concern? Meaning the shackles should't be plumb? I thought that meant full weight of the heep was resting squarely on the springs. Yes , I drove it around quite a bit yesterday. Didnt settle any. These springs appear to be very new...still clean, stickers still on em' maybe in time they will flatten a bit.
So there is no "wiggle room" at all to move the axle for and aft on the spring perch? I thought the centering hole was a bit oversized than the pin allowing a slight movement. That's why I asked if it waas relevant to unloosen the U-bolts while doing a shackle change to allow the axle to rotate,shift, and/or move a bit. I never did.

 

This appears to be a common problem with the Skyjacker 4" lift. I resolved the rear shackle angle by moving the spring pivot mount slightly forward. Properly setup, the rear shackles sould be slightly angled toward the rear. The problem appears when you go offroad and the shackle pops forward after you have flexed the springs. It sticks there, up against the bottom of the frame(see pic above). You might be able to duplicate this by jacking up the rear until the wheels are hanging and then lowering the Jeep back onto the tires. Shackle length is not really an arbitrary decision with a 4" lift. Hopefully I can explain this without it being too confusing. Measure your spring from eye to eye. Lets just say it's 30"(it's not, I'm just picking numbers). Then measure along the length of the spring and you get 36". Now measure from center to center, your spring mounts on the frame. To make it easy we'll say that they measure 30" just like your eye to eye measurement on the spring. So, to let your spring flex to it's maximum length, your shackle must be 6". Otherwise the shackle will bottom out up against the frame toward the rear, and the spring will still be trying to grow, but can't. I had this exact problem with my Skyjacker lift. With lifts less than 4" it is not nearly so critical. It is really created by the huge arch in a 4" spring. I actually moved my rear pivot mount about 1/4" forward to get the proper shackle angle and my shackles are 4 5/8" long center to center. I hope this isn't too confusing.

 

Sorry for being so wordy above, but when you get these springs dialed in you'll find it's the best riding suspension you can have in a ECJ, on and offroad, except for maybe a flat spring (no arch) springover.

 

Yes, it sits slightly higher in the rear. Not too terribly obnoxious though. So ok, safe on the fronts.
Would the longer shackles originally on there cause it to sit even higher? (I could put the rears back on) When I put on the new stock length ones, I didnt notice any drop, although I'm sure there had to gave been...

Mike in KC

Semper Fi