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Axle Wrap


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So, thoughts on what people have done to control axle wrap on the rear axles??? I've investigated the options, but would prefer to hear what people have done and their results.

Truck description:

- S2A 88"

- Coiler Salisbury rear with 4.1s.

- Pinion pointing at t. case with double cardon prop

- Spring over with stock springs. Springs moved back ~3" from stock.

- 305 SBC, NP435, Series t. case, 80:1 in 1st low.....

- 35" tyres.

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Well.... If anyone cares, we built a ladder bar.

Narrow coiler radius arm. Chassis end cut off and welded to a large Rubicon Express joint. Regular series spring shackle to a the end of another radius arm, cut off and welded to the cross member. Still need to be welded up and braced to the diff center. Stopped the axle wrap. No effect on spring travel.

100_2180.jpg

Unloaded

Testingreardriveproblem2.jpg

Under load on gravel without the ladder bar.

Testingreardriveproblem3.jpg

Loaded with the ladder bar. Only movement is from compression of the radius arm bushings.

Testingreardriveproblem4.jpg

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Missed this thread entirely - if you are interested in what others have done a search for "wrap" on this forum should throw up most of the threads.

That's quite some angles you've got going on there, I'd be interested in a few more pics of the geometry of your setup. I note you're running SOA and fairly flat springs which helps reduce the binding due to the change in shape of the spring, as well as running the bar toward the fixed end of the spring.

I run a very similar thing on the back end of my 109 and it seems to work nicely, the front end is more of an issue.

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They are standard 88" springs. He was going to go with 109 SW springs to help, but it is too much lift and would need to get them de-arched. Anyway, this ladder bar was a 5 hour project and works great. I suspect he will put one on the front as well. He says it has completely transformed the way it drives. No windup at all , not hop. It just hooks up solidly.

I can guarantee when used off road the wrap was much worse. He was binding the prop and breaking the transfer case output shaft.

Here is a side view

100_2181.jpg

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That video is a brilliant demonstration of the problem, painful to watch!

I should've clarified my comments, I'm currently pondering a re-design of my front anti-wrap as I believe it's binding. The rear, which is basically the same as you've got there, works nicely due to the factors mentioned - rear springs are longer/flatter, and the bar can be mounted forward-facing to follow the fixed end of the spring rather than the movement of the shackled end. The front has more stuff in the way and more curved springs which makes things harder.

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You could do a shackle reversal. Does it matter that much if the ladder bar is on the shackle side?? What exactly do you have on the front ATM?

Shackle reversal doesn't seem to solve anything, some cars have the shackles at the front and owners reverse them to be the LR way as a modification, so go figure!

At the moment my setup is as described here.

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Nice work but you are definitely gonna have to strengthen the mount on your chassis. The power in the wrap is immense! SOA Does make wrap alot worse, and what is shown in the first clip confirms this. But there is lots to be learned from the yanks regarding leaf suspension as they have tonnes of experience with this stuff. Often including silly power and silly tyres combined with the weight of a small ferry! I Love your design it's simple and effective and with some more bracing I'm sure it'll work a treat for a long time.

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But there is lots to be learned from the yanks regarding leaf suspension as they have tonnes of experience with this stuff.

The problem is, for every good bit of tech on Pirate or elsewhere, there are 100 idiots who think they understand it. Most of their rigs are quite different - SOA, long flat springs, shackles at opposite ends, etc.

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Well FF, thats how it is with every bit of tech on the web isn't it? :)

The major problem with leafsprings are ofcourse their unpredictability regarding movement. Suppose the best leafspring suspension with absolutely zero axlewrap, would be a three linked axle with leafs featuring shackles at both ends. But this would rule out the whole idea of a leafspring.

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Leaf springs aren't unpredictable, they're a really very clever and efficient way to do things as they act as suspension and axle location all in one. The hard thing is trying to control the axle with a rigid link when you have a leaf spring locating it, which is in effect a variable link.

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The more I've delved into the geometry trying to work out my front anti-wrap, the more I've found that the leaf spring is doing quite a lot in one - compare all the stuff you have on a coiler to hold the axles in place as well as the springs themselves.

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Anywho....back on topic...the owner is interested in doing the front end as well. I suspect it will be next month as there are trips the next couple of weekends. I will report back on the how the rear behaves after getting it off road and whenever we do the front, I'll get those pictures and results up as well.

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