What's really involved in SOA? -
Now remember SOA is going to give you at least 5-6" of lift, which means 35"+ tires. The stock rear axle isn't going to live on 35"s, so at a minimum it should be replaced. The Dana30 with some upgrades can usually sort of handle a 35" tire. In my opinion there isn't much point on going SOA on a Dana35, because you will be replacing it when it breaks, which means doing things over again.
So your're still gung-ho on the SOA idea, and have a new rear axle. Cool. Got a SYE installed yet? You're going to need that. Install the SYE before you start the axles, as you need it in place to set the pinion angle. Personally I would remove any transfer case drop you may have too if its not necessary.
Ok so now you have a new rear axle, and an SYE, check, SOA is on its way. Cool. Time to remove the stock axles, and any shims that maybe on your leaf springs. If you are going to run an aftermarket shackle you should already have that installed. Set the perches on the axles, and set the axles under the Jeep. Go ahead and put the u-bolts on and take them down snug, do not tighten them. Once the axles are under there, place jack stands under the axles, so the weight of the Jeep is on the axles and springs. Now the rear is pretty straight forward, set the pinion angle and tack the perches in place. Do not fully weld the perches yet, just tack them. Now time to the front, except its a little more complex. On the front it's often a compromise between caster angle and pinion angle (Alignment Terms explained in the FAQ). You need at least a couple degrees, preferably 3-4 degrees of caster. If your caster approaches 0 or even worse yet goes negative the Jeep will tend to wander and generally be hard to control. On most axles you can sacrifice enough pinion angle to keep some positive caster angle and everything will be great. However there are some axles that the axle "C"s must be cut off and rotated, and re-welded to achieve acceptable caster angle and pinion angle. In my opinion if you have an axle that the knuckles must be rotated, its a job for an axle shop that can place the axle in a jig to ensure everything is square. If the caster angle is different on each side, the Jeep will pull to the side with less positive caster, hence let the pros do it. Once you have the pinion angle set, and you've double checked the caster, go ahead and tack the front spring perches in place. Double and triple check your pinion angle measurements. Once you're sure the perches are in the right place, go ahead and jack the Jeep up again and place jackstands under the frame, no weight should be on the axles while welding the perches. Go ahead and remove the axles if you wish, the welds must be good, so you want to be as comfortable as possible.
So you welded the perches on, the Jeep is sitting on its new SOA axles and it looks good, except its still not driveable. Crap. The rear axle is much more prone to spring wrap, so an anti-wrap bar is a must. (FAQ: AntiWrap Bars) Without an anti-wrap bar, you will break leaf springs, driveshafts, pinion yokes, etc. The only anti-wrap bar that really works is the tried and true ladder bar style setup, so don't even think about trying any of the single link setup ideas floating around out there (cough BamBar cough Tractor links cough). Now the problem is that the wrap bar has to go on the passenger side of the Jeep. (Wrap bars further explained here) If you put the wrap bar on the driverside you will run into torque steer issues, and quickly sag right rear springs. Hope you don't have a fancy muffler on there, cause its time to cut it off, (I was able to rotate my muffler vertically and still keep it on the passenger side, see the link above about wrap bars.) as its in the way of the anti-wrap bar (Again remember do not weld to the axle with weight on it).
So the rear axles in, you have your anti-wrap bar on the passenger side, and measured/ordered a CV driveshaft. Cool. Time to work on the front some. First big issue is the steering. There are two things that you can never take shortcuts on, thats brakes and steering, this is a safety issue. Basically you need some sort of high-steer, z-links and the like are a huge mistake. On the stock front axle you'll need to consider something like a Teraflex knuckle, or WJ knuckle to make the steering work. I used a stock pitman arm with a Teraflex knuckle when I first did my SOA and had the stock front axle. Don't be surprised if you need new draglinks because the stock ones aren't the correct length. If you are using anything larger than a Dana30 in the front, you'll need/want a real high steer kit. So the steering isn't to bad to install, pretty much all bolt on stuff, but high-steer stuff isn't cheap, it will be one of the more exspensive pieces of conversion. Time to move onto another possible issue with the front. Check the clearance of the front driveshaft and transfercase skid, you may have to cut the skid plate some.
Ok so the Jeep is finally self supporting and has steering, we might be getting somewhere. Cool. Time to do something about the brakelines. SOA will give you some serious articulation, you need to make sure your brakelines are long enough. (FAQ: Stainless vs. Rubber Brake Hoses for more information)
Sweet so now the Jeep will drive, steer and stop, finally might be somewhere. You did weld shock tabs onto the new axles right? Got long enough shocks? Most people choose not to run a track bar or sway bar at this point, but if you do you'll need mounts for those as well.
Ok congradulations, your Jeep is now driveable, except, this project is now a run-a-away train, and just gaining momentum. Did you forget about gears? While not necessary to actually driving the Jeep (if you only replaced the rear axle make sure the gear ratios match front and rear before using 4WD!), you'll find that the Jeep will lack some serious power if you try and run 37"s with a stock 3.07 ratio. While your pricing gears, might as well price lockers. Oh and while your at it might as well price a new cage to help protect you, as your center of gravity is a bit higher than it once was.
Related Topics: | SOA: | SOA vs SUA - | AntiWrap Bars - | Choosing a lift for a CJ / YJ - | What is an SYE and do I need one? |
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