SOA anti-axle wrap theory - JeepForum.com
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post #1 of 26 Old 06-23-2019, 09:38 PM Thread Starter
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SOA anti-axle wrap theory

I'll start off by saying I don't have a YJ(yet), although I'm planning on getting one in the next 6 months, finances permitting.

One thing I'd like to do is an SOA lift, so that I can preserve flex, while gaining height. Thinking of going to a 2" lift spring, although that might be hard to calculate if I go through with the following idea.

From what I understand, one of the disadvantages of doing an SOA, is the need for traction bars, or another method of preventing axle wrap. This is due to the narrow spring width on a YJ, as the suspension was designed as SUA.

I'm thinking of locating suitable springs from a truck that was factory SOA, which would be wider and would eliminate the need for additional parts to prevent axle wrap. I'd also be looking for an offset center bolt at the same time, so as to do an axle stretch(i.e. XJ springs, but wider). I'd be pulling leaves as needed to soften the ride.

Obviously, to do this, I'd have to modify/change the spring mounts to accept a wider spring, or else narrow the ends of the springs to work with the factory mounts. I'm leaning towards the former, so I'm not introducing any potential weak points into the springs/messing with the heat treatment.


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post #2 of 26 Old 06-23-2019, 10:48 PM
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Trucks can get away with going SOA because they have stiff springs that don't flex much, and they mount the shocks to counter the wrap a bit. Trucks also don't spend lots of time in a high-torque axle-twisting situation. Jeeps do.

Width of the spring has nothing to do with it. The spring plate on your axle is your fulcrum, and the spring is the resistance against twist. If you grab a spring pack of truck springs, great. You won't get flex, it'll ride horribly, but hey, you won't get axle wrap. If you remove springs from that pack, you're removing the twist resistance. It'll ride nicer, flex more, but it will also twist more.

You're not going to get rid of axle wrap and have lots of flex without an anti-wrap bar.

Also, a 2" lift on top of going SOA is going to be about 7" of lift. That's a dangerous amount of lift on a YJ.
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post #3 of 26 Old 06-24-2019, 05:15 AM
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Agreed with above. Only spring stiffness and spring shape can counter axle wrap without an anti-wrap/traction bar and trust me... you want the softest springs you can get away with. Lift springs are both stiffer and arched which helps prevent axle wrap. I built my anti-wrap bar out of tractor links and some random 3/16" steel I had laying around. Cost maybe $75-$100 and it was probably the easiest part of going SOA. There are some guys on here that run 2" lift springs in an SOA scenario. I'm not sure how they get away with it though because I was desparately trying to get my flat spring SOA to yield than 6.5" of lift and ended up buying and welding on all new leaf spring mounts just to get it down to only 5.5" of lift.

Don't forget you're going to have to fix your steering with a hi-steer arm or some kind of hi-steer setup like from a WJ. You also need to deal with driveshafts, get an SYE for the transfer case, longer brake lines, get rid of the D35, and you might as well put on all new shock mounts for frame and axle assuming you actually want your suspension to have some decent travel. If you start stretching more than a couple inches in either direction, you're going to have to do A LOT of work.

All of that said, my SOA has been great offroad but it's still back breaking on the road so I'm going to be building a 4 link setup in the rear really soon.


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post #4 of 26 Old 06-24-2019, 06:41 AM
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I am spring under and lifted about 5.75 inches and I am trying to get it down. Yesterday I was in an emergency situation that caused all 4 33's to lock up(You can do this on stock D30 and 8.8 brakes with single diaphram booster) I slid into the median and a small bump almost caused me to roll. I was in a similar situation on another jeep years ago with only 4 inches of list and the chain of events was much less dramatic. It was also on 33's. Just a little bit of lift height can make all the difference.

Not trying to scare you just giving you some food for thought

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. It started with a $200 axle, and a few thousand dollars later I was done :)
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diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

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post #5 of 26 Old 06-24-2019, 01:05 PM
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Yet one of the very popular swaps on Toyota pre-Tacoma and Tacoma trucks is 1/2 ton Chevy 52" and 63" springs. They flex like mad
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post #6 of 26 Old 06-24-2019, 02:17 PM
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Quote:
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Yet one of the very popular swaps on Toyota pre-Tacoma and Tacoma trucks is 1/2 ton Chevy 52" and 63" springs. They flex like mad
Length plays a big part in that flex. Chevy also runs inverted shackles which changes the loading on the shackle as well.


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post #7 of 26 Old 06-24-2019, 05:06 PM Thread Starter
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Quote:
Originally Posted by Awesome View Post
Trucks can get away with going SOA because they have stiff springs that don't flex much, and they mount the shocks to counter the wrap a bit. Trucks also don't spend lots of time in a high-torque axle-twisting situation. Jeeps do.

Width of the spring has nothing to do with it. The spring plate on your axle is your fulcrum, and the spring is the resistance against twist. If you grab a spring pack of truck springs, great. You won't get flex, it'll ride horribly, but hey, you won't get axle wrap. If you remove springs from that pack, you're removing the twist resistance. It'll ride nicer, flex more, but it will also twist more.

You're not going to get rid of axle wrap and have lots of flex without an anti-wrap bar.

Also, a 2" lift on top of going SOA is going to be about 7" of lift. That's a dangerous amount of lift on a YJ.
6" is what I'm going for, as the rigs I'm trying to keep up with are all running about that. One YJ is a SOA with 2" springs, another YJ has 6" springs. Also have a WJ in the club on a custom 4-link with 8-10" of lift on 40's. This isn't going to be a daily driver by any means, My daily is my WJ, and the YJ will be a street legal toy. I also live in the middle of no-where so next to no highway time, unless I road trip it to an event.

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Agreed with above. Only spring stiffness and spring shape can counter axle wrap without an anti-wrap/traction bar and trust me... you want the softest springs you can get away with. Lift springs are both stiffer and arched which helps prevent axle wrap. I built my anti-wrap bar out of tractor links and some random 3/16" steel I had laying around. Cost maybe $75-$100 and it was probably the easiest part of going SOA. There are some guys on here that run 2" lift springs in an SOA scenario. I'm not sure how they get away with it though because I was desparately trying to get my flat spring SOA to yield than 6.5" of lift and ended up buying and welding on all new leaf spring mounts just to get it down to only 5.5" of lift.

Don't forget you're going to have to fix your steering with a hi-steer arm or some kind of hi-steer setup like from a WJ. You also need to deal with driveshafts, get an SYE for the transfer case, longer brake lines, get rid of the D35, and you might as well put on all new shock mounts for frame and axle assuming you actually want your suspension to have some decent travel. If you start stretching more than a couple inches in either direction, you're going to have to do A LOT of work.

All of that said, my SOA has been great offroad but it's still back breaking on the road so I'm going to be building a 4 link setup in the rear really soon.
The plan for this is for it to be a street legal toy. I've already got the WJ steering parts, as long as I don't need the steering box(my daily is a WJ and I have a parts rig). Sounds like I'll be using an anti-wrap bar. I'll probably use your ideas using the tractor link, or custom make something from scratch(I'm planning on making a lot of the parts for this thing)

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Originally Posted by Siva283 View Post
I am spring under and lifted about 5.75 inches and I am trying to get it down. Yesterday I was in an emergency situation that caused all 4 33's to lock up(You can do this on stock D30 and 8.8 brakes with single diaphram booster) I slid into the median and a small bump almost caused me to roll. I was in a similar situation on another jeep years ago with only 4 inches of list and the chain of events was much less dramatic. It was also on 33's. Just a little bit of lift height can make all the difference.

Not trying to scare you just giving you some food for thought
I'm not planning on high speed or highway driving. I live in the middle of no where and the nearest divided highway is probably 20 miles away, and that's only a few mile stretch.
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Yet one of the very popular swaps on Toyota pre-Tacoma and Tacoma trucks is 1/2 ton Chevy 52" and 63" springs. They flex like mad
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Originally Posted by Waternut View Post
Length plays a big part in that flex. Chevy also runs inverted shackles which changes the loading on the shackle as well.
So If I were to go to longer springs, I wouldn't need anti-wrap bars? Not sure I'd want to as I'd have to lengthen the frame to accommodate, but food for thought wise. Or would I be better modifying the spring perches, similar to the Rocky Road SOA kit, where I lengthen the spring perch on the axle, so that it has a wider footprint on the axle?

My intention for not wanting anti-wrap bars is that it's less parts to break and also less parts under the Jeep to get hung up. If you look up Fourth Coast Jeeps on Facebook(Youtube channel in the works, but nothing there yet), you can see the type of environment/ trails I'm planning on running this thing in.

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post #8 of 26 Old 06-24-2019, 06:08 PM
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Ive been drinking so take it for whats its worth BUT i am SOA, I was SOA before the LS swap and had a 4cyl. Even with the 4cyl the springs would wrap under heavy acceleration and a 4cyl can barely accelerate. What i am getting at is that you need a anti-wrap bar no matter what you do if you are SOA, PERIOD no exceptions. RuffStuff has a nice affordable kit that is easy to put together. Do not sacrifice ride quality and articulation as Mr. Awesome pointed out just because you dont want to get a 200$ kit ladder bar, i think you will still have wrap no matter what springs you use.
As far as the 2" lift springs go.. What size tire are you running? i have 1.5" RE lift springs SOA and its really TALL. I rode SOA on stock sagged out springs for a long time on 37s and had plenty of room. Dont know why i went to 1.5" lift springs instead of replacement stock height springs, i was probably drinking when i did that too. I wouldnt get 2" lift springs with SOA unless you are running atleast 40s.

This was my ladder bar on sagged out stock springs on 37s
https://www.ruffstuffspecialties.com/catalog/AWKIT.html this is the kit i used, its beefy


See how tall 1.5" springs are SOA on 37s? id reconsider the 2" lift springs just saying

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post #9 of 26 Old 06-24-2019, 06:09 PM
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My anti-wrap bar sits as close to the driveshaft as I can get it and at about the same angle...maybe 6 inches or so to the side. I'd rather break the anti-wrap bar over the driveshaft any day. That said, without an anti-wrap bar and even having the anti-wrap perches, your springs will be short lived and they're also more expensive than a bent $20 tractor link.

You could run longer leafs by pushing the center leaf spring mounts more towards the middle. I have and still kinda am considering that for my front leafs to get some extra droop. However, I think you're considering the longer leafs for the wrong reason. Do it for suspension flex and travel....not for anti-wrap purposes.
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post #10 of 26 Old 06-24-2019, 07:28 PM
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Quote:
Originally Posted by CSP View Post
Yet one of the very popular swaps on Toyota pre-Tacoma and Tacoma trucks is 1/2 ton Chevy 52" and 63" springs. They flex like mad
They flex because they are longer and have leafs removed.

Those Toyotas put out a fraction of the torque Jeeps do (taking gearing into account), and yet those guys are still running anti-wrap bars. You're still going to twist your springs and eat your u-joints without an anti-wrap bar if you have flexible springs.

EDIT: Actually, you're right; some of those Toyota guys aren't running anti-wrap bars. They have much longer driveshafts than we do and the axle torquing doesn't affect their u-joint angles as badly. They're still going to break more springs than they would if they had an anti-wrap bar.
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post #11 of 26 Old 06-25-2019, 11:35 AM
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Quote:
Yet one of the very popular swaps on Toyota pre-Tacoma and Tacoma trucks is 1/2 ton Chevy 52" and 63" springs. They flex like mad
I've done a version of this swap for a turbocharged Yota. Chevy uses a long, thick bottom leaf that acts as a "helper" when load is high. When you remove leaves from the spring pack the remaining leaves settle closer to the helper leaf so the amount of twist available is reduced. The helper will also work to reduce spring wrap under high torque. This type of design allows more axle drop when the wheel is in suspension but resists compression. It's good when the wheel is falling into a hole but not as good if the wheel is climbing over a rock.


Quote:
So If I were to go to longer springs, I wouldn't need anti-wrap bars?
No. You will still need a method to control torque. Thick springs can be better because at any point on the spring there is more resistance to bending or twisting. Thick springs can still ride well if they are made longer which is why thick, long springs are on many of today's vehicles.

Just out of curiosity, why would you not want to install an anti-wrap torque bar?
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post #12 of 26 Old 06-25-2019, 04:04 PM Thread Starter
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Quote:
Originally Posted by Bong_Holyeo View Post
Ive been drinking so take it for whats its worth BUT i am SOA, I was SOA before the LS swap and had a 4cyl. Even with the 4cyl the springs would wrap under heavy acceleration and a 4cyl can barely accelerate. What i am getting at is that you need a anti-wrap bar no matter what you do if you are SOA, PERIOD no exceptions. RuffStuff has a nice affordable kit that is easy to put together. Do not sacrifice ride quality and articulation as Mr. Awesome pointed out just because you dont want to get a 200$ kit ladder bar, i think you will still have wrap no matter what springs you use.
As far as the 2" lift springs go.. What size tire are you running? i have 1.5" RE lift springs SOA and its really TALL. I rode SOA on stock sagged out springs for a long time on 37s and had plenty of room. Dont know why i went to 1.5" lift springs instead of replacement stock height springs, i was probably drinking when i did that too. I wouldnt get 2" lift springs with SOA unless you are running atleast 40s.

This was my ladder bar on sagged out stock springs on 37s
https://www.ruffstuffspecialties.com/catalog/AWKIT.html this is the kit i used, its beefy


See how tall 1.5" springs are SOA on 37s? id reconsider the 2" lift springs just saying

Max tire size will be 33" on stock axles, so I don't break shafts all the time. Possibly 35" if I'm feeling its safe. May eventually go to one tons so wanting to get ready early. Lift height is primarily to get the Jeep out of the water. Some of the trails we run can almost swallow a 40" tire.


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I've done a version of this swap for a turbocharged Yota. Chevy uses a long, thick bottom leaf that acts as a "helper" when load is high. It will also work to reduce spring wrap under high torque. This type of design allows more axle drop when the wheel is in suspension but resists compression. It's good when the wheel is falling into a hole but not as good if the wheel is climbing over a rock.


No. You will still need a method to control torque. Thick springs can be better because at any point on the spring there is more resistance to bending or twisting. Thick springs can still ride well if they are made longer which is why thick, long springs are on many of today's vehicles.

Just out of curiosity, why would you not want to install an anti-wrap torque bar?

When you remove leaves from the spring pack the remaining leaves settle closer to the helper leaf so the amount of twist available is reduced.

Main reason is for simplicity and less parts to break.

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post #13 of 26 Old 06-25-2019, 05:16 PM Thread Starter
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A few video's of the Jeep's I'm building this thing to keep up with. The WJ's on 40's.





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post #14 of 26 Old 06-25-2019, 07:20 PM
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Main reason is for simplicity and less parts to break.
Oh, then it's simple. Put an anti-wrap bar on and you won't break springs or u-joints as often.

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post #15 of 26 Old 06-25-2019, 10:32 PM
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Originally Posted by Ravenbar View Post
Max tire size will be 33" on stock axles, so I don't break shafts all the time. Possibly 35" if I'm feeling its safe. May eventually go to one tons so wanting to get ready early. Lift height is primarily to get the Jeep out of the water. Some of the trails we run can almost swallow a 40" tire.

Main reason is for simplicity and less parts to break.

Not to be offensive but trying to tell it like I see it. I feel your expectations for the jeep and the level of effort you're willing to put in are not lining up. A rear axle swap is cake walk compared to doing a SOA lift and all the other aspects that need to be taken into consideration to do it correctly.

Simplicity is a 4-5" SUA suspension. A good SUA suspension set up well can be very comparable to a SOA lift and take a whole lot less effort. I've wheeled with guys on 40+ tires but even on 35's, beadlocks, and lockers I'm not going to hold a candle to what they can do. When I was on 33's and only a front locker, I was testing the limits of my jeep regularly but I was taking the easier lines and would hang back and help out whatever way I could when those guys start getting rowdy.

When you're ready to at least ditch the D35, then consider more custom suspension setups. Until then, be the guy who quietly surprises people with what they can do with a limited budget and setup.
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