:confused:

Does any one else see a question???

What happened?
:confused:

He prolly got disconnected while writing the post... I wonder if its a bug in the forum code? :D

Nice! Gotta love this 19.2K dial-up in this hotel!

OK, This Pig has a set of Add-a-Leafs and god aweful 90* extended shackles plus a fine set of Bias Ply tires.

Read: aweful, aweful ride!

OK, my plans are to add some cushy 33 x 9.50 Radials and some shorter shackles.

My question is, how can I ge these shackles at a 45-60* angle? All I can think of is cutting the hangers and rewelding them back to gain some angle.

I really don't want to do this. What about a set of 55 rear springs on the front? 60 rears on the front...will either of these options work to keep the tire centered, yet provide a longer spring and better shackle angle?

If I use stock shackles, I think my angle will be better, but they will be at the wrong angle. I know that is not optimal, but is it bad for what I am going to use this truck for?

I am looking for options. I won't SOA this truck even though the ride is AMAZING on a SOA truck. This baby needs to be stock.

Short of modifing the shackle hanger I cannot think of another way of getting your angle better. The front 55 springs have a true center pin. So if you run the rears in the front you will have a 1.75" longer wheelbase.
I am not sure about the 60 springs though.

Just get a set of stock shackles and remove that dam add a leaf. See how well it does from there....

Again sweet pig!!!
:fj:

seems like most of the problem is the add-a-leaves, remove them and see what happens, should let the spring flatten therefore lengthen,your not planning on hardcore wheelin so dont worry about the "optimal" shackle angle, as long as theyre not pointing towards the axle at rest.

Nolan, I have a suggestion that might solve your problems. Try talking to alcan springs and have them make you a set of springs to your specs. They will make any spring that you want. Longer, shorter, pin in the center or offset. Just contact them and give them the skinny and they will custom build you a set an length that you want. Alcans are what I run on my 40 and I love them. They have a web site alcanspring.com
Great company and they are just a hour away from Moab, so if you can wait you can pick them up when you are out in may. Give them a shout, might solve your problems.
:usa: :fj:

Alittle off topic....sorry

RHINO, have you gotten my PM's?

Originally posted by RHINO
seems like most of the problem is the add-a-leaves, remove them and see what happens, should let the spring flatten therefore lengthen,your not planning on hardcore wheelin so dont worry about the "optimal" shackle angle, as long as theyre not pointing towards the axle at rest.

That is what I was thinking...will I be able to run the "tall/skinnies" 33 x 9.50's without the mild lift? I really doubt it, but it is worth a try!

Jeff...I have owned Alcan before and I am their biggest fan. I agree that would be the best choice, but I don't have a grand to drop right now on this Pig.

In fact, before I found this Pig, I was going to get 1" lift Alcans with Orbit Eyes in them for my FJ-40.

Not now!!

what if you talk to a spring shop
4 new maine leafs, with the centre pins keeping the axles in the factory location, but with say 3 inch longer main leafs, you only need to buy just the 4 main leafs, and it shouldnt run you more than $200 for the lot, i dont think... (thats what we'd pay for a new main $50 each)

or arent bnronco springs a fair bit longer and i talked to a guy a while back, who said they were $25 each at junkyards, and quoted how much longer than FJ springs they were, maybe they'd do the trick

good luck

Speaking of optimal shackle angle...

A while back I was helping a buddy relocate his shackle hanger to achieve a "better angle", so we got the bright idea of determining which angle was best. We clamped the shackle hanger to the frame at 90, 60 and 45 (it is hard to keep clamped at more than 45 degrees) and then we measured the spring rate at three different weights (1, 2 or 3 - 200 pound adults). The bottom line was there was no measurable difference in spring rate at 90, 60 or 45 degrees.
It just seems more obvious that the spring should compress more easily at 60 or 45 degrees, but we couldn't detect a difference.

Someone 'splain it to me why a 45 degree shackle rides better if the spring doesn't compress more easily.

I'm kornfused, cause I'm a Pin Head.

Originally posted by Pin Head
Speaking of optimal shackle angle...

A while back I was helping a buddy relocate his shackle hanger to achieve a "better angle", so we got the bright idea of determining which angle was best. We clamped the shackle hanger to the frame at 90, 60 and 45 (it is hard to keep clamped at more than 45 degrees) and then we measured the spring rate at three different weights (1, 2 or 3 - 200 pound adults). The bottom line was there was no measurable difference in spring rate at 90, 60 or 45 degrees.
It just seems more obvious that the spring should compress more easily at 60 or 45 degrees, but we couldn't detect a difference.

Someone 'splain it to me why a 45 degree shackle rides better if the spring doesn't compress more easily.

I'm kornfused, cause I'm a Pin Head.


Spring rates do not change by the orientation of the shackle. However, the closer the shackle is to vertical the more "energy" is transferred directly to the frame. Kinda like the difference between trying to get a direct hit on a stuck bolt vs, having to hit it at an angle. Vector Physics, yuck...
So, when a shackle is at a 45* angle less energy is "directly" transferred to the frame....

Did I just confust the issue or help???

Also, Nolen started this thread. How the heck did my name get on it suddenly???




And Nolen, I was able to fit 36x12.50's under my cruiser with just a shackle lift. (sort of, not much room) I firmly believe that a shackle lift (reposition the hangers) will give you all that you need to fit the 33x9.50's The super skinnys help out a lot.

Originally posted by Jason M
So, when a shackle is at a 45* angle less energy is "directly" transferred to the frame....


The same amount of force is transferred to the frame. The real difference is the direction of the force. When the shackle is vertical the force acting on the frame is vertical and you feel it more. When the shackle is at an angle some of the force is in the direction of the frame (horizontal). At 45*you get about 70% (sin45*) of the force acting in the vertical direction that you would have if the shackle were at 90*.

Originally posted by Cruiser Ken


The same amount of force is transferred to the frame. The real difference is the direction of the force. When the shackle is vertical the force acting on the frame is vertical and you feel it more. When the shackle is at an angle some of the force is in the direction of the frame (horizontal). At 45*you get about 70% (sin45*) of the force acting in the vertical direction that you would have if the shackle were at 90*.

That sounds reasonable, but it seems to me that there are only two things here, the spring and the rest of the car and any force that is not absorbed and stored in the compression of the spring is going to be transfered to the rest of the car. (Who discovered that conservation of energy thing, Isaac Newton?) The spring compression was not measurably affected by the shackle angle, so the same amount of energy is going to the frame (Bump!).

I'm still kornfused... :rasta: :question:

pin head; in lamens terms, the shackle moves easier because of the added angle so the force feels smoother.

nolen; the 33" skinnies will fit on the pig with bone stock springs, mine did with no rubbing except at full articulation, inside top of rear wheelwells, so with even mild shackles they will be fine.

That is what I wanted to hear. I will take those &%$#@ huge shackles off and stick some 1 1/2" over stock shackles on and be done with it.

I ordered some 33 x 9.50 Wild Country's for it today.

I will probably take the Trailmaster shocks off and replace them with 9000's and then I will be done.

Anyone have a FJ-55 PTO?

Originally posted by RHINO
pin head; in lamens terms, the shackle moves easier because of the added angle so the force feels smoother.


I thought about that too, but it still don't make no sense to me. I can move that shackle with my pinky whether it is at 90 degrees or 45 degrees as long as the spring is disconnected. With the spring connected, that shackle isn't moving anywhere if the spring doesn't compress. In other words, it is the spring compression that determines whether the shackle moves. But yet, the spring doesn't compress any more at 45 degrees than 60 or 90. What's up with that?

I'm sorry that I stepped in the shiat bucket with this topic, but I'm just a po country boy that jus
don't understand.
:zzz:

Well, not so sure my previous arguement is valid. Once I started drawing up the forces acting on the spring. Therefore I punted and checked the web for any info on this subject. I came across this:

-----
Shackle angle determines the rate as well. A shackle with a 3 degree layback incorporates a stiffer installed rate than a shackle at 25 degrees layback. In addition, as the spring is put under load the shackle angle increases; therefore, the spring rate decreases under travel. To determine the effective angle of a shackle, pull a string from the center of the front eye to the center of the rear eye of the spring, and then a line from the rear eye through the shackle pivot point. Measure the angle derived from the two lines. You can decrease the spring rate by increasing the angle, or increase the rate by decreasing the angle. Also, excessive torque of the shackle bolts will increase the installed rate.
-----

This is from the following web page. There is more to read there as well. Scroll down the page to the shackle stuff and keep reading from there.

<a href="http://www.landrumspring.com/technical.html">Landrum Spring web page</a>

LOL pinhead, i dont know how to splain it, but if you think how the spring moves, (back and forth) and the axle (up and down). i dont think the shackle cares about the back and forth so much, its the up and down, the shackle on an angle will let the axle move up and down more with less force being made to straighten the spring, with the shackle at say a 45, it is going in more of an upward curve immediately. but when its near vertical it goes almost straight for a while before starting that upward curve. thats the best i can do. some things just dont make much sense, like why hair grows on a mans face but not a womens, even though she has hairy pits.

Also from the Landrum site:

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Leaf spring mounting angles are one of the most important factors in a leaf spring system. <B>In fact, it is more important to get the mounting angles correct than selecting the proper spring rate.</B> No matter what spring you put on the car it may not perform properly if the angles are misaligned. To counteract the effect of incorrect mounting angles, you may have to install erratic spring rates, shock rates, wheel off sets, unsuitable ride heights, and/or undesirable tire stagger, each of which will cause unpredictable handling characteristics.
-----

Originally posted by RHINO
some things just dont make much sense, like why hair grows on a mans face but not a womens, even though she has hairy pits.

Well now, that's a fact! :eek:

I don't know, but it was a Jeep; so maybe it was a Jeep thing.

This is a great thread! I really like the way that Pin head is "pushing back" to get to the bottom of this question and not just saying "whatever."

I feel that this is a valid argument on both sides, but speaking from experience, the shackles at 90* are a nightmare!

Whenever I eased off the angle on shackles, the ride got better.

Well, I will be able to tell first hand after I start on my new Pig!

This was bothering me, so I stayed at a Holiday Inn Express last night :zzz: and I thought about it hard.

Yes, shackle angle can affect the OVERALL suspension rate, but how much depends on several factors.
The overall suspension rate is the the sum of the intrinsic spring rate (which apparently doesn't change) PLUS the change is shackle vertical height due to the rotation of the shackle.

How much the shackle height changes depends on:
The arc of the spring,
The length of the shackle,
and the angle of the shackle!

The greater the arc of the spring, the greater the lenght of the shackle and the closer the shackle angle is to 45 degrees the more the shackle height changes in response to spring compression.

For a high spring arc, the effect of shackle angle will equal or exceed the intrinsic spring rate effect, but for a flat spring where the shackle height actually increases as the spring compresses (and droops) and the eye to eye distance shortens, the ride would actually be better at 90 degrees than at 45.

Whatever :D

Originally posted by Pin Head
For a high spring arc, the effect of shackle angle will equal or exceed the intrinsic spring rate effect, but for a flat spring where the shackle height actually increases as the spring compresses (and droops) and the eye to eye distance shortens, the ride would actually be better at 90 degrees than at 45.

Whatever :D

I agree with Pin Head on this one. If you did infact have flat springs (IE : no arch at all) or negitively arched springs the ride would be better with a 90* shackle than a 45* shackle. When the spring compresses with a flat spring the distance eye to eye actualy shortens so it would be better with a virtical shackle because when the spring compressed the shackle end of the spring wouldnt have to move down(in relation to the frame).

With a spring that has any arch at all this argument has no merit. With an arched spring i think the ride would be better with a 45* shackle for the above mentioned reasons.