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XJ axle swap/build

Been a while since I’ve posted. Between getting the coof and traveling with the family I haven’t had much time to work on the Jeep. But I was able to get the 3rd track bar bracket in and it is parallel at ride height and the length is very close between track bar and drag link now. Have the front axle almost done. Need to install steering box brace and shock mounts, weld tie rod, then trim fenders more. Finally have it sitting on its own weight.
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Measure 5 times weld once haha. in all seriosity it'll be a lot more convenient to have another pair of hand help align the axle/set the pinion angle. What's the plan for drivelines?
 
Measure 5x is a good idea for sure. I’ve been thinking about using a laser level or a pointer to set pinion angle. I have a couple friends who are more than willing to help so that’s nice.

I haven’t really planned to much in regards to drive shafts. I was hoping the original ones might fit but I think the rear will need to be shortened and the front will need to be lengthened. If that’s the case I might try to lengthen/shorten then myself and sleeve them at the same time to make them beefy and keep them straight. Did you do new custom length drive shafts?


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To set the angle I used a piece of pvc pipe cut to within an inch (imagine it’s the driveshaft) between the two yoke nuts. Use an angle finder on the pinion yoke and match the angle with the pvc pipe. This was the fastest way for me to dial in a rough angle then I tighten down the spring perches and carefully adjusted until I could repeatedly and reliably get the same measurement. I’ve gone +70mph without a hint of driveline vibes.

South Bay Driveline. Have had nothing but positive things to say for them and their work.


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That’s a good idea, I have some PVC lying around from my mock up links. For squaring your axle to the body, what landmarks did you measure from?

Thanks, I’ll check them out.


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For the d60 I just finished, and the d44 that it replaced, I just used the axle flanges at the end of the tubes to measure to the spring pads, after I figured out the center-to-center for the spring pads first.

Also, some people recommend to have the yoke slightly down, 1 or 2 degrees, from a straight line for the driveline angle. Once it's under power, while driving, it makes up that difference from the torque required to keep the rig moving while driving.
 
For the d60 I just finished, and the d44 that it replaced, I just used the axle flanges at the end of the tubes to measure to the spring pads, after I figured out the center-to-center for the spring pads first.

Also, some people recommend to have the yoke slightly down, 1 or 2 degrees, from a straight line for the driveline angle. Once it's under power, while driving, it makes up that difference from the torque required to keep the rig moving while driving.


Thank you for the input, Rob. I’m doing ruff stuff u-bolt eliminators, so my plan is to bolt the bracket to the leaf springs, then lower it onto the axle which will be on Jack stands and I’m hoping that way will make it easy to square and to set pinion angle.

Did you set your pinion angle 1-2 deg down on both your axles? How did it treat you if so?


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That’s a good idea, I have some PVC lying around from my mock up links. For squaring your axle to the body, what landmarks did you measure from?

Thanks, I’ll check them out.


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hang the leaf springs and measure from outside face of the leaf pack to the inside face of the axle flange. You can measure from a bunch of things but leaf to flange seems to be one of the most reliable places to reference on each side. I did not account for the 1-2 degree compensation Rob mentioned. For what its worth, I haven't encountered leaf wrap symptoms. If I did, I'd look into an anti wrap bar before cutting off the U bolt eliminators and re-doing them.
 
hang the leaf springs and measure from outside face of the leaf pack to the inside face of the axle flange. You can measure from a bunch of things but leaf to flange seems to be one of the most reliable places to reference on each side. I did not account for the 1-2 degree compensation Rob mentioned. For what its worth, I haven't encountered leaf wrap symptoms. If I did, I'd look into an anti wrap bar before cutting off the U bolt eliminators and re-doing them.


Got it, thanks Nate. That makes a lot of sense. I’ve read in other threads about angling pinion 1-2 degrees, but I’ve heard from both sides that their set ups work without issue. I think it may be preference? Idk.


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Maybe. May be spring stiffness, gear ratio/final drive ratios. I'd have to think on it and draw force vectors or something.
 
The notion of angling the pinion down 1-2 deg relative to the drive shaft is to compensate for axle wrap. For sure there is no reason to make the pinion shaft parallel to the drive shaft. Only question is how much to angle it down. Adams recommends 1-2 deg.
 
Maybe. May be spring stiffness, gear ratio/final drive ratios. I'd have to think on it and draw force vectors or something.


Aww man, take it easy with those force vectors haha. I enjoyed that part of physics, but I don’t use them too often anymore. I think spring stiffness if probably it, but I’m sure hear ratios have something to do with it as well.


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The notion of angling the pinion down 1-2 deg relative to the drive shaft is to compensate for axle wrap. For sure there is no reason to make the pinion shaft parallel to the drive shaft. Only question is how much to angle it down. Adams recommends 1-2 deg.


I got ya. Sounds like that’s if you’re running leaf springs without a torsion bar, which is what I am doing, but I’d rather add a torsion bar to fix the axle wrap then change my pinion angle. The point of your pinion being parallel to the drive shaft is to limit vibration I believe.


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I got ya. Sounds like that’s if you’re running leaf springs without a torsion bar, which is what I am doing, but I’d rather add a torsion bar to fix the axle wrap then change my pinion angle. The point of your pinion being parallel to the drive shaft is to limit vibration I believe.


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Actually, the angle needs to be slightly off parallel to drive the needle bearings in the u-joint to circulate. 1-2 deg (or maybe 1-1.5 deg) off parallel should be the target whether or not you plan to limit axle wrap with torsion bars.
 
I did my Sterling 1.25 using the ruff stuff +2 perches. Angle the pinion down 2 degrees. Part of the reason is so the u joints get lubricated while they rotate. If they’re absolutely perfectly at zero they’ll burn up, but this won’t ever happen on our Jeeps. The pinion just moves up more than you’d think. At first I did mine without the full weight on the vehicle. Do yours with the new tires on all four corners. That’s what you’re going to be driving with so that’s what you should set it up with. I took as many measurements as I could before assuming the axle was centered.
 
For those of you who have done wider axles, what length did you go with brake lines? I have 22” now and I don’t think it’s enough. Iron rock has 27” front and 22” rear as a combo, ruff stuff has 30” fronts but no rear. Any advice would be awesome, thanks!


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