Shackles: How long is TOO long?

So I'm at sort of a fork in the road with my rear suspension. Over the past 5 years I think my springs have hit their "final resting place" in terms of sag. I went from stock shackles, to stock shackles and relocators, to 1" lift shackles and relocators, to 2" lift shackles and relocators. All with the same lift springs. I could really use another 1/2"-1" of lift out back, but I'm starting to wonder how long of a shackle is too long? The ones I have now measure about 6.5" eye-to-eye, and they look pretty long. They're sitting at a perfect 45 degree angle when comparing the front spring bolt and rear bracket bolt location. I'm concerned a longer shackle with put a lot of stress not only on the frame, but the bushings as well. I already get way more creaking/rattling with the 2" lift shackles than I ever did with the stock ones.

Should I be looking for a new spring pack, and shorter shackle combo? Or put some slightly longer shackles and not worry about it? I realize a shorter shackle with ultimately take away some droop, but if it means thing will quiet down some, I'm willing to sacrifice. I also have the convenience of putting the shackles at their proper angle with the relocation brackets.

As far as noises go, all bushings are in good shape and all bolts are properly torqued. Springs were a take-off from a buddy's jeep years ago but I THINK they're RE's 3.5" pack.

I think it's time to bastard pack your leaf packs, or buy new ones.

DanMan2k06 said:

Over the past 5 years I think my springs have hit their "final resting place" in terms of sag.

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Like this?:anon:

Crap.. Big picture strikes again..

Did you make all of those changes to keep the same ride height or to lift more?

I think I read somewhere that the KOH car uses shackles that are about 7" eye to eye. But the leafs are deavers. I don't think a shackle that long is bad but that will depend on your leafs, wheeling terrain, wheeling style etc...

1990JEEPXJ said:

Did you make all of those changes to keep the same ride height or to lift more?

I think I read somewhere that the KOH car uses shackles that are about 7" eye to eye. But the leafs are deavers. I don't think a shackle that long is bad but that will depend on your leafs, wheeling terrain, wheeling style etc...

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I think they are closer to 10" or 12" now.

my new ones are 8" with a Johnny Joint at the frame end.

Dirtweazle... I lost it when I saw the pic lol.

1990JEEPXJ
Re: Shackles: How long is TOO long?
Did you make all of those changes to keep the same ride height or to lift more?

I think I read somewhere that the KOH car uses shackles that are about 7" eye to eye. But the leafs are deavers. I don't think a shackle that long is bad but that will depend on your leafs, wheeling terrain, wheeling style etc...

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It was for both more lift, and to keep things level. Going from the 1" to 2" shackle was purely to compensate for sag though. The springs still have a nice positive arch, so I'm not too worried about them taco'ing just yet.

Does the shackle length and angle affect spring rate at all?

Right now I have ironman4x4 adjustable shackles. They are about 8". They are starting to hangout abit low int the back now. We will see how they work out on the next few trips.

^ That's what I'm really starting to wonder as well? I mean I would assume it does in some way? Almost like preloading the springs. The physics of it is way over my head though, hopefully someone can chime in that could calculate the math.

I know that you are not running stock leaf packs, but an extended shackle ONLY, on a stock saggy leaf pack, puts more stress on the leaf pack. So, just using a longer shackle for height, etc. is a bandaid for what is going on meow. If you want to run a longer shackle, fine. But you need to do something about your leaf packs as well. SO, as I stated prior. Bastard pack what you currently have, or buy new.

GordoSmasho said:

Does the shackle length and angle affect spring rate at all?

Right now I have ironman4x4 adjustable shackles. They are about 8". They are starting to hangout abit low int the back now. We will see how they work out on the next few trips.

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Absolutely it does. Although the affects are dependent upon both length and angle. In other words an 8" shackle that is vertical at static ride height would behave very similar to a 5" vertical shackle. However, at 60degs the spring rates will be different due to the different roll centers.

I'm using dodge van leafs which are roughly 3" longer past the center pin than stock. Coupled with diy shackle relocators my shackle angle is exactly 45*. The rear end is plenty flexy and has a fairly gentle positive arch at ride height. It just sticks out the back a bit more than id like. I'm at roughly 4" of lift in the rear.

if the shackle is angle to the rear, not verticle there not too long.

^ Can not comprehend.


Bryson you were on to something there. That's exactly what I have been wondering. I'll have to get with one of my physics nerd friends.

Ok so I messed around with the suspension last night. I picked up a used YK pack and was planning on beefing up my springs with another full length leaf as a second leaf. I dropped the axle and took out the center pin of my current pack (presumed OME or RE's, definitely not stock), and they still have a TON of arch unloaded. WAY more than the YJ springs do at rest. This leads me to believe that they have sagged to the point where the pack is resting more and more on thick overload spring, which of course will stiffen everything up.

So my question is, what happens when you throw a flat leaf into an arched pack? I feel like it wouldn't do anything at all to help, perhaps even hurt my springs more.

I opted to put my spring pack back together as-is, and do a little more research. At this point I'm thinking about grabbing a set of the OME full length AAL's, maybe even 2 sets. For the time being it seems I have a VERY arched (at rest) pack, that is soft and flattens out substantially under load.

rockclimber said:

I think they are closer to 10" or 12" now.

my new ones are 8" with a Johnny Joint at the frame end.

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You also forgot the fact they are using WAY longer leafs and moved both spring mounts to accommodate said longer springs.

sidewaysstarion said:

You also forgot the fact they are using WAY longer leafs and moved both spring mounts to accommodate said longer springs.

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and this has what to do with the length of the shackle?

Longer leafs would need a longer shackle to be able to use all of the travel a longer leaf has to offer.

Regardless,

What will adding a flat leaf do to an arched pack?

DanMan2k06 said:

Regardless,

What will adding a flat leaf do to an arched pack?

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Add lift!!!!!