Shackle rumours; I need proof. - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 12-27-2001, 11:48 PM Thread Starter
 
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Shackle rumours; I need proof.

Ok, In this shackle business, there is rumours going around that a 1-inch shackle is actually only 1/2 inch of lift. I presume we are talking about a shackle that is 1 inch longer then stock. In order for this shackle to make only 1/2 inch of lift difference, it would have to be at a 45 degree angle. but, it, is not in most cases. My shackles are about 5 to 10 degrees off of being completely vertical. which means that if I install a 1 inch longer shackle, then I am actually getting about 4/5 inch of lift, not 1/2 inch, which is actually a big difference in the scheme of things. Tell me where I am wrong. I need educating. But that is how I see it.
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=-Ben


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post #2 of (permalink) Old 12-28-2001, 12:00 AM
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Re: Shackle rumours; I need proof.

Thats how I see it. If your 1" longer shackle was vertical, it would give you 1" more lift, 45deg. angle would give .5" lift, etc.

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post #3 of (permalink) Old 12-28-2001, 12:23 AM
 
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Re: Shackle rumours; I need proof.

howdy,
using my advanced knowledge of geometry I would predict that you would have to lift both ends of the leaf spring 1 inch to raise the axle 1 inch. Remember the axle is in the middle point of the length on the leaf. it is a triangle thing. It help to visualize the leaf spring as a straight line.

but, shackles are only used on one end of the leaf. so shackles that are an inch longer will only raise the axle half that distance.



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post #4 of (permalink) Old 12-28-2001, 12:40 AM Thread Starter
 
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Re: Shackle rumours; I need proof.

So, now it is the complete opposite of what I said,
Now that we have BOTH ends of the spring to worry about, UNLESS the shackle is vertical, will you even get 1 inch of lift, but since most are angled somewhat, you are going to get even LESS lift??

Tough stuff...


=-Ben
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89 FSJ - 6-inch Rustys on the way!
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post #5 of (permalink) Old 12-28-2001, 01:48 AM
 
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Re: Shackle rumours; I need proof.

yup...

I would think that the loss due to the shackle angle would be small comparatively. but you are on the right track. if the shackles had 45 deg. angle you would lose 29.3% of the lift [sin(45)=.707] . you lose 50% of what is left after that, due to only raising one end of the leaf.

but remember (in a static situation) that the length of the leaf should remain mostly constant and would rotate in an arc away from the shackles perch. the end effect is that, the longer ( within reason) the shackle is, the less angle the shackle will have. Not to mention that as you get close to vertical the loss in height compared to angle is real low. Remember the derivative of sin(90) is zero.


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post #6 of (permalink) Old 12-28-2001, 01:50 AM
 
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Re: Shackle rumours; I need proof.

Thats why you need to lift both ends of the spring ,,,,,like this to get the right lift[img]/wwwthreads_images/icons/smile.gif[/img]

NO, NO, NO, DON'T. This guy should be shoot, if he did'nt aready kill himself in this thing.

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post #7 of (permalink) Old 12-28-2001, 02:20 AM
 
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Re: Shackle rumours; I need proof.

now that is what I call a shackle lift.... who makes it?

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post #8 of (permalink) Old 12-28-2001, 03:15 AM
 
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Re: Shackle rumours; I need proof.

That is some really sweet work Wayne. Did you do that fabrication? You usually paint it all pretty before its done. Hehehe

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post #9 of (permalink) Old 12-28-2001, 03:44 AM
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Re: Shackle rumours; I need proof.

Wayne, I dont see anything wrong with it......HAHAHAHA....what the hell were they thinking....Wait, I know...that whole thing started out as a "Hey Y'all, Watch This!"

-Remy

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post #10 of (permalink) Old 12-28-2001, 06:49 AM
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Re: Shackle rumours; I need proof.

uh.. thats what my jeep looks like... [img]/wwwthreads_images/icons/laugh.gif[/img]... i bet that guy is from NC... hehehehehe

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