Shackle flip geometry?

[Hal9000]

So I'm in the midst of a mad thrash to finish my rear axle swap before the weather gets too unruly around here (All I have to work on is a basketball court... No fun in winter!). And one of the things I have left to complete is to flip my rear spring hangers for the shackle flip I'm doing.

My question is, do you re-mount the shackle hanger at the same location on the frame, move it forward, or move it back? Is there some formula to figure out how much you need to move the hanger to get the shackle at an acceptable angle?

Thanks.

 

[Hal9000]

No ideas huh? I'm sure there's somebody out there with more skill and experience than I have... I'd sure love to get some guidance before I decide to go my own way and learn from my inevitable mistakes.

 

[jamie]

im with you. i need to know these things

 

[Silverhorse]

I have seen people do it usually on Chevys. Not sure why it's not more popular here? I have 5" springs so If I did it i would have to much lift. good luck. I do know after having Toyotas for many years, that the shackle will lean slightly forward at the top at rest and when the axle is down on one side (flexed out) the shackle will be strght up and down. Maybe an expert will chime in.
Somebody help a brother out!!!!

 

[hstock68]

hey guys im with you wanting to know the same thing. i just posted a thread with some detailed questions. mabey we can get a response tomorrow haha

happy trails,
houston

 

[matt2500]

move it back... so when your springs are at ride height the shackle is at about 5-10 degrees leaning tward the back of the truck

 

[Hal9000]

Thanks Matt...

Next question, and yes I know this will depend on the springs somewhat, but without the hanger (or axle for that matter) in place there's no way I can check it at ride height. Is there any way to judge where it will sit with the springs totally sagged out?

 

[broncnaz]

With out the hanger or shackle in place I'd say your shooting in the dark for ride hieght. You really need to tack at least one up and put the weight on it to know for sure.

 

[sstlaure]

You just want to make sure the shackle can't flip over at full extension. I tacked my mounts in initially and cycled the suspension to double check it.

Taking all of the leaves out except for the main leaf helps in cycling the suspension as well. (I put a block of wood in to make up for the lost thickness of removing the leaves.)

 

[bronko69er]

I some some pics in my build thread of my (at the time) shackle flip.

 

[Hal9000]

Yup, I've got a link to your build thread saved somewhere. But I guess I failed to mention that I'm also swapping to longer springs at the same time to push the rear axle back a few inches, so I can't just put my hangers in the same location as yours. I guess I'll just tack them up at the same distance as the donor vehicle and mock everything up before I mount them solid.

Just out of curiousity, has anybody measured the total front/rear swing of the shackle as it articulates?

 

[Nobody]

The way I did it on my Bronco II, is I temp mounted the hangers and springs with axle attached then forced the axle to full droop. then adjusted the rear hanger so the shackle was about vertical at full droop. This gives you a little "extra" movement to prevent the shackle from inverting. Then when loaded, your shackle angle is set perfect as to not limit travel.

If I don't go coils in the rear I'm probably going to reuse my fullsize bronco springs on my EB. They worked beatifully. Worlds better than these 11 leaf springs I have now.

 

[Hal9000]

Good idea, thanks for the tip.

 

[Hal9000]

move it back... so when your springs are at ride height the shackle is at about 5-10 degrees leaning tward the back of the truck

Wait a minute? I think this is wrong isnt it? At ride height, I want the shackle to be pointed slightly rearward at the spring end right? That way it won't pull too far forward and "flip up"... If I move the mount back, that will make the shackle point forward at the spring end...

I'm tacking things together in a few minutes. Just want to make sure I'm thinking about this the right way.

 

[Silverhorse]

Wait a minute? I think this is wrong isnt it? At ride height, I want the shackle to be pointed slightly rearward at the spring end right? That way it won't pull too far forward and "flip up"... If I move the mount back, that will make the shackle point forward at the spring end...

I'm tacking things together in a few minutes. Just want to make sure I'm thinking about this the right way.

Correct, The shackle should lean forward at the top.

 

[Hal9000]

We'll see how close my first shot was tomorrow when I get the axle under the bronco and flex it out. I moved the shackle hangers forward 1.5" from the factory eye to eye distance for the springs I'm using...

With out the hanger or shackle in place I'd say your shooting in the dark for ride hieght. You really need to tack at least one up and put the weight on it to know for sure.

I'm shooting in the dark for ride height in more ways than one! Shackle flip, longer shackles, longer leaf springs (my eye to eye is current set at 51" for 54" springs vs 52.5" on the un-flipped donor vehicle... we'll see) wheelbase stretch, and all homegrown to boot. I'm just concerned about getting the shackle hangers in the right location for the moment. Once that's done I'll get the height adjusted by having a new leaf pack made or having these arched. I skipped mentioning all the other "unrelated" factors for this thread because I didn't want to confuse anybody.

 

[Silverhorse]

Posts some pics! ;D

 

[Hal9000]

Camera's broke and truck is ugly (so are most of my upside down welds), but I'll see what I can do the next time I work on it..

Didn't get much done today on account of missing a few critical parts that I thought I had... Namely the right length bolts for the shackles and also the correct spring plates. I've ordered some 3 way offset spring plates. Hopefully they'll get here quick, Between the spring plates and the leaf springs that I'm using, I can now change the orientation to get anything from a 1" to 5" stretch in 1" increments (Can we say "selectable wheelbase"?). I'll probably set it for either 2" or 3" at first depending on how close to the rear subframe The pumpkin gets.

 

[68 Broncoholic]

Are you getting the adjustable wheel base from the leaf spring perch that is welded to the axle? I run those but I've only seen 1" back or forwards, not 5".

It would be a good time to stretch the rear axle back but I'm curious what you are using for the 5" back...

 

[zeeman1]

Not sure if this will help, but this is what mine looks like sitting flat.