Offset Spring Pin (1 Viewer)

ratchet

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I am putting hybrid spring packs in my FJ40. I am using a Jeep Cherokee main leaf, a half ton chevy main leaf (with the eyes cut off; to help with the weight) and then 4 stock cruiser leafs.

The center pin on the XJ main leaf is offset. The eye to eye measurement is approximately 52" and the short side is approximately 23". I had stock FJ40 springs reversed and don't want to move my axle rearward so I redrilled the XJ main leaf to match the short side of the FJ40 springs.

My question is will it be a problem to have the center pin so offset on the spring pack? With the way I drilled it the short side is approximately 19 1/2" (I was shooting for the same as stock FJ40 but screwed it up).

Did I neutralize the benefit of longer springs by doing this?

The difference between my custom spring and stock XJ is only 3 1/2" inches so I don't think it will be a problem but am not sure.

Here are a couple of pics. In the pictures the full weight of the vehicle is supported by jack stands not the floor jacks. I also am not done welding and boxing the spring hangers. Also the full weight of the vehicle is not on the springs and the shackle angle will be set to approximately 55*.

Richard
DSCF0010 small.jpg
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Eskimo

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Seems to me that's gonna create some interesting behavior / caster/pinion angle changes as it cycles...
 
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Seems to me that's gonna create some interesting behavior / caster/pinion angle changes as it cycles...

Agreed. I thought it was important to keep the axle mounting location on the spring mostly parallel to the ground (at ride height at least). Having the axle offset on the spring shouldn't be that big a deal (it just might be a tad stiffer), I think it's common to find factory vehicles with axles offset on the leaf spring but I've always seen them with mounting points that took into consideration that mounting angle. If you recess the mounting point of those shackles you could improve that angle. I'm sure we have some suspension guru's on the board and it would be great to hear from them too.
 

ratchet

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Agreed. I thought it was important to keep the axle mounting location on the spring mostly parallel to the ground (at ride height at least). Having the axle offset on the spring shouldn't be that big a deal (it just might be a tad stiffer), I think it's common to find factory vehicles with axles offset on the leaf spring but I've always seen them with mounting points that took into consideration that mounting angle. If you recess the mounting point of those shackles you could improve that angle. I'm sure we have some suspension guru's on the board and it would be great to hear from them too.

I should have mentioned in the original post that the pinion angle was set pointing directly at the tcase output (about 12* up) and the axle was cut and turned for about 5* caster. This was with the stock reversed FJ40 springs. When I put these new springs in it changed the pinion to about 9* and the caster to about 8*. I will be using 3* shims to correct this for now because I don't have time to do the cut and turn again.

I thought about recessing the upper shackle mount but the exhaust and motor are in the way and I didn't want to remove them just for this. Also since I am using FJ60 axles (which I also should have mentioned) it would have made the outboard more complicated. Since the pinion angle was set where I want it (or close to it) I don't think the non-horizontal axle mounting point is an issue. **EDIT**I don't know for sure though. At ride height the perch (axle mounting point on the spring) is approximately 10* off horizontal. Is that excessive? With my stock FJ40 reversed springs it was appoximately 5*. I'm not saying that was the correct way to have it but I ran it that way for a couple of years with no problems and it drove great. **EDIT** Thanks for your opinion.

Eskimo- you are probably right, however, it is only 3 1/2 inches further offset than on a stock XJ spring so how much difference can it make? Also with the pinion pointing at the tcase I don't think it will be enough to bind it but I don't know....I guess I will just have to try it and see. Thank you also for your input.
 
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Did I neutralize the benefit of longer springs by doing this?



Richard


If I'm understanding you correctly, you have two spring pins, one that was stock, and one at the location you really wanted. Is that right?

If thats true- the spring won't flex between the two bolts, there is no way for it to change length if its bolted fast at two places.

If you would take out the stock spring pin, that would probably work, but you're asking the leaves to flex in a different place than they were designed to, which might make for some interesting behavior. (I don't know if its bad or not).
 
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That thing is gonna nose dive like crazy when you hit the brakes. I'd re-evaluate before you go too much further. I think your leaf packs are fine though. You'll probably rub on the fronts of the fenders depending on your tire size. It's hard to tell what you've got going on at the shackle end in the frame but It would help to raise the rear end of that spring up into the frame a bit . As complicated as it might be , Now would be better than later . Just a thought.
 

ratchet

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If I'm understanding you correctly, you have two spring pins, one that was stock, and one at the location you really wanted. Is that right?

If thats true- the spring won't flex between the two bolts, there is no way for it to change length if its bolted fast at two places.

If you would take out the stock spring pin, that would probably work, but you're asking the leaves to flex in a different place than they were designed to, which might make for some interesting behavior. (I don't know if its bad or not).

No I don't have two spring pins. I drilled a hole for a new one and removed the old one.

Too tall - so becuase the axle mounting location is on the up slope of the spring it will nose dive worse than normal when I hit the brakes? Or is it some other reason? If the perch location was made horizontal to the ground would that change it? This is an effect I hadn't thought of.
 
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Kavik

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Try mocking up with just the main spring in place. Lower the front end (w/ the jack) until the spring goes flat (full compression). Then you will know what shackle angle you will have at full compression.

I would move your rear shackle hanger forward as far as possible to get the shackles to lay down, but not too close to crowd the main spring at full flat or contact the frame.

I used a 2x4 to keep the main flat during mock up...
DSCF6045.JPG
 
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you tend to get nosedive when you reverse the shackles and angle the spring up at the front -down at the back. This allows the vehicle's weight to compress the leaf spring under braking. In straight-on scenarios it's not a big deal but when you are turning and have to brake it can cause unpredictable handling characteristics which can be dangerous.
 
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The other option is to move the front hanger down to get the spring more level, but that kind of defeats the purpose of doing a SR, so you won't have fanges hanging down possible getting hung up on stuff. But, if you tires are big enough it might not matter since your tire would hit whatever obstacle first and not the mounts. I too will be running offset hybrid leaves in front but don't have the outboarding issues you have since I'm doing it on a fj60 with fj60 axles. Happy fabbing. :)
 

ratchet

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Update:
I ended up moving the front spring hanger to the end of my bumper. This allowed me to keep the location of the spring pin closer to stock while still keeping the axle where I wanted it. I thought it would flatten out the perch angle but they are still at about 10*.

The vehicle is back together and drives fine. It does nose dive when I brake but it doesn't seem any worse than my previous set up which was reversed stock 40 spring with the shackle reversal. I have done some test cornering and braking and it doesn't feel out of control, however, I'm sure it would be different in a panic situation.

Overall, I am pretty happy with the new setup. It flexes better than it used to which is what I was hoping for. The only problems are that it is too tall and I have to limit the compression to keep the springs from going to a negative arch. I will definitely be lowering it in the future and may shorten the bump stops and see how quickly the springs wear out.

Thanks to all who responded.
 
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