Rear shackle angle

kcustom73

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So I know this has probably been discussed a thousand times before, but my situation is a little different.

Seeing that I'm stretching my 40, I decided to get OME HD springs for my truck. Now the rear bumper was completly rotted so I fabricated my own and got new rear leaf spring gussets from Cruiser Solution. I have since modified the gussets to remove the flat plate (have to make my own for my custom application).

Now before I weld all of this up, I can adjust the gusset to whatever position I want to get the proper shackle angle.

If I'm not mistaken, the shackle should point towards the rear of the 40. I'm thinking I should install it with the shackle straight up and down and has the truck settles a bit it should push it towards the rear. Any experience/opinions on this would be greatly appreciated as I want to get this setup this evening.

Pic of where I'm at now with the setup

shackle.jpg
 
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Put the wheels on and the truck on the ground. I just put on 4 h*ll creek on my rear and it looks worse then that, once I put the wheels on and put it on the ground it looked more like your, and once I jacked the front up to level the vehicle the rear shackles went to straight up and down. I figure based on reseach here that is normal, and once I get it on the road with some weight in the back I can get it to settle down a little more and get a normal angle. So mine changed from much worse looking to your to better then our once on the ground and front lifted to make a little more level.
dscf5049.jpg
 
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If I were you I'd try to swap out those springs for fj55 rear springs. They will be longer and since you're already having to weld your hangers, you can set the shackle angle however you want.

I really like my ridiculous shackle angle and the ride I get from it, but I'm not sure it's applicable with lift springs with that much arc. They are fj62 stock rear springs, SOA.

attachment.php
 
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You can't just make the shackle angle anything you want. It has to accomodate the full range of the spring lenght at full compression and droop. Your springs have a lot of arch, and if you make the shackle angle an arbitrary 45 degrees, the end of the spring will hit the frame when the spring compresses. Measure the length of the spring along the curve to determine the maximum eye to eye lenght and then use this to set the hanger location so that the spring will not contact the frame. A longer shackle may help you get a larger range of motion.
 
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X2 on what Pin Head said.

You can also use his suggested way of measuring the maximum eye to eye length to decide what your minimum shackle length should be if you're contemplating a different spring and not wanting to move the frame eye. As Pin Head said, the minimum shackle lenght should allow the spring to fully flatten before the shackle hits the frame.

Don
 
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As long a shackle as reasonable with as gentle an angle that will allow full flattening of the spring will give you the softest ride and greatest articulation/suspension travel.

It will however put more stress on the springs (tending to flatten the main leaf more quickly).

I have run an angle like fast Eddy shows on a couple of rigs and loved it. With the weight I carry on the trails I have gone back to a little bit steeper angle in the rear and a lot steeper in the front (the really gentle angles I was running up front contributed to less than steller road manners).

Edit: As to your specific question... Personally I would want it off of vertical even with the springs at their brand new arch. But those are pretty short shackles... If you want to get the most out of your suspension, I'd suggest slightly longer ones.

Mark...
 

kcustom73

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Fast eddy, the springs I have are brand new OME HD and don't really want to swap them out.

Pin-head and handcannon, I like your reasoning and will do some measuring tonight to figure out what the flatten spring looks like.

Mark, I'm going to DD this 40, so are you sawing that a steeper angle gives you better road manners?

Taking everything into consideration, I think I will start with a fairly vertical and work from there. I'll probably angle towards the rear a little and if needed can get longer shackle later if needed.
 
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No, what I was saying that using very long shackles at a very gentle angle on the front end created problems because of the additional side to side shift that it allowed at the front end of the front springs.

If you are working with standard length springs and nominally "normal" length shackles, this is not an issue.


Mark...
 
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Measure the length of the spring along the curve to determine the maximum eye to eye lenght and then use this to set the hanger location so that the spring will not contact the frame. A longer shackle may help you get a larger range of motion.

You can't just measure the spring along it's length either. The length of the shocks or those little shackles are going to be the limit of how much flex you get out of the springs.

He's going to have to guess a good spot, tack the hangers in place, install the shocks and flex it out to see what happens.

I'll bet those springs are 8" different between the eye-to-eye measurement and along the curve. I don't think that measurement is that useful with that much arch.

If you're not going to use longer shackles, you will, for sure, want to run a steep shackle angle, maybe even pointing a bit towards the front to get any amount of flex.

It doesn't really apply to your case, but my springs go completely flat just before the shackles contact the frame, then I still have some travel left (12" shocks), so the springs can go inverted some and pull the shackles back down. The shackle reversed front is set up similarly.
 
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kcustom73

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Fast eddy, I don't mind running longer shackels if needed. The springs I have are the OME heavy because of the 27" stretch and I'm going to be towing a trailer on occasion. This going to be my DD and mostly an expedition rig so an extreme amount of flex is not necessary. I am however running a lot of weight on the back (custom bumper 33" spare, rear fuel tank) and this should help flatten the spring a bit. . Like you said I might start with a pretty vertical shackle and see where it get me. Time to put the wheels on the axle and go from there.
 
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Time to put the wheels on the axle and go from there.

Yea. Tack the perches in, pointing about 10 degrees forward, then put all the weight on it you're going to need. Then you'll have an idea about how it's going to sit. You can move the perches, maybe swap some longer shackles and make bump stops later.
 

Josie'sLandCruiser

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Hi All:

Chances are those rear leaf springs are way over-kill for your needs! You should remove 2 of the main leafs at a minimum. This will allow the suspension to settle-down and help with the rear shackle angle as well.


Good luck!

Alan



So I know this has probably been discussed a thousand times before, but my situation is a little different.

Seeing that I'm stretching my 40, I decided to get OME HD springs for my truck. Now the rear bumper was completly rotted so I fabricated my own and got new rear leaf spring gussets from Cruiser Solution. I have since modified the gussets to remove the flat plate (have to make my own for my custom application).

Now before I weld all of this up, I can adjust the gusset to whatever position I want to get the proper shackle angle.

If I'm not mistaken, the shackle should point towards the rear of the 40. I'm thinking I should install it with the shackle straight up and down and has the truck settles a bit it should push it towards the rear. Any experience/opinions on this would be greatly appreciated as I want to get this setup this evening.

Pic of where I'm at now with the setup

shackle.jpg
 

kcustom73

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update

So the mounting plates are done, the tires are on and all the weight is on the wheels. I've put somewhere arond 500lbs in the back of the 40 and this is what I end up with.

dscf6667-1.jpg


dscf6670-1.jpg


dscf6671-1.jpg


I adjusted the shakles with about 10deg to the rear and now I'm just going to let it sit for a bit ( a week or so) to let the spring settle and then tack everything in place. Now I'm just debating if I flip the springs or not.
 
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Where is the spring end of the shackle going to be when the spring is compressed flat? If looks like it will hit the hanger with a couple more inches of extension.
 

kcustom73

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Pin_head, do the spring ever completly flatten out? The OME heavies that I have seem pretty stiff.

I know right now it is not in its stock location (the FSM calls for 1070mm and I'm at 1010mm IIRC from the center of the fix end of the spring to the center od the shackle hangar). If I put it to the stock location the shackle will point towards the front of the truck (if I understand things correctly, that's a no-no). I wonder what s stock 40 and heavy OME springs looks like?
 
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Pin_head, do the spring ever completly flatten out?

Yes, at least mine did. If you don't wheel it more than over the speed bumps, then it may not be a problem.

Stock springs are nearly flat. Their eye to eye distance shortens as they compress and droop. You can easily get away with a 45 degree shackle angle with flat springs. The shackle lenght and angle on high arch springs is more complicated, since you need to make sure that it does not hit the frame on compression and at the same time it does not limit droop or invert. To do this, start with the maximum and minimum eye to eye length and then mock up their positions with a shackle and the hanger.

The shackle angle has very little to do with ride quality, so that should be the last of your concerns.
 

Cruiserdrew

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Too me, that shackle just looks physically too short for the amount of arch in the spring, so when the spring flattens and elongates, you run out of swing in the shackle.

Get someone using those springs and the associated OME shackle intended for that spring, to tell you how long the shackle is.

The shackle you have on there I think is the one intended for the front.

I agree with Pin Head that the angle per se isn't that important. Pointing just slightly off vertical to the rear at rest will be close to right.
 

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