Basic Do-it-Yourself Jeep JK Wrangler Front End Alignment

WJCO said:
It is hard to measure on those. If you're happy with the handling, don't tweak it anymore. I think you should be closer to 6 (84 on gauge), but if it ain't broke, don't fix it.
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I'm confident I got it on the flat spot so that's an accurate measurement but now I'm really curious. I can't find anywhere that it states what the difference is from stock and if/or the settings should differ from stock. They should be the same, no?
 
Ddays said:
I'm confident I got it on the flat spot so that's an accurate measurement but now I'm really curious. I can't find anywhere that it states what the difference is from stock and if/or the settings should differ from stock. They should be the same, no?
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They aren't the same. Stock axle spec is 4.2+ degrees. To achieve more caster while still maintaining a good pinion angle, Dynatrac adds caster to the axle by rotating the 'C' when they weld them on. So you should have around 6+ caster and a near perfect pinion angle.

IMG_20170223_204224_729.jpg
 
WJCO said:
They aren't the same. Stock axle spec is 4.2+ degrees. To achieve more caster while still maintaining a good pinion angle, Dynatrac adds caster to the axle by rotating the 'C' when they weld them on. So you should have around 6+ caster and a near perfect pinion angle.

View attachment 245603
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thats what i was looking for...
 
Love these write ups ty Eddie. Was wondering about setting rear pinion and axle, front to back as well.
 
deezus said:
Love these write ups ty Eddie. Was wondering about setting rear pinion and axle, front to back as well.
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For the rear, you only need to set your pinion IF you're running an aftermarket u-joint style double cardan drive shaft. IF you do, you will need a set of adjustable rear upper control arms so that you can set your pinion to be in line with the drive shaft. A 21mm socket, 21mm wrench, torque wrench, floor jack and an angle finder is pretty much all you need.

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wayoflife said:
For the rear, you only need to set your pinion IF you're running an aftermarket u-joint style double cardan drive shaft. IF you do, you will need a set of adjustable rear upper control arms so that you can set your pinion to be in line with the drive shaft. A 21mm socket, 21mm wrench, torque wrench, floor jack and an angle finder is pretty much all you need.

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Thanks, I'm running an Adams 1310 but I do t think it's double cardigan.

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Eddie, I think my driver side axle is off, more forward than the passengers side. I'm having trouble finding a place to measure on the jeep to figure it out. I did measure from rear of front axle to sheetmetal under front fender and it was about 1/2 inch off. I am only concerned because upper bump doesn't hit lower bump flush on that side and it looks off to the eye. I also see, pics below, that caster is off by almost 1 degree. But thanks to your directions ill fix that too. I was told that measuring the lower arms isn't always accurate because from the factory, mounts can be off, not sure if that's true.
For some reason, can't post the pic.
 
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deezus said:
Eddie, I think my driver side axle is off, more forward than the passengers side. I'm having trouble finding a place to measure on the jeep to figure it out. I did measure from rear of front axle to sheetmetal under front fender and it was about 1/2 inch off. I am only concerned because upper bump doesn't hit lower bump flush on that side and it looks off to the eye. I also see, pics below, that caster is off by almost 1 degree. But thanks to your directions ill fix that too. I was told that measuring the lower arms isn't always accurate because from the factory, mounts can be off, not sure if that's true.
For some reason, can't post the pic.
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LOL! I wouldn't concern yourself with whether or not your factory mounts are off. Just make sure your control arms are the same length eye to eye.

deezus said:
View attachment 249506

This is what measurement I have at the axle. What is my caster?
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Now that's a nifty angle finder! If I'm looking at it right, you have +5.3° of caster. About 1° too much. So long as you're running a factory shaft or a gear ratio no more than 4.88, you should be okay so long as your drive shaft is balanced really well.
 
wayoflife said:
For the rear, you only need to set your pinion IF you're running an aftermarket u-joint style double cardan drive shaft. IF you do, you will need a set of adjustable rear upper control arms so that you can set your pinion to be in line with the drive shaft. A 21mm socket, 21mm wrench, torque wrench, floor jack and an angle finder is pretty much all you need.

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How long can I run with aftermarket shaft before adjusting the rear pinion? I have 1350s Adams shafts for about 6 months now with stock control arms. I don't drive the jeep much tough, and didn't take it off-road since new shafts yet.
I am planning to upgrade CA's this May, I am going straight to long arm. Will I be ok till then?
 
wayoflife said:
LOL! I wouldn't concern yourself with whether or not your factory mounts are off. Just make sure your control arms are the same length eye to eye.



Now that's a nifty angle finder! If I'm looking at it right, you have +5.3° of caster. About 1° too much. So long as you're running a factory shaft or a gear ratio no more than 4.88, you should be okay so long as your drive shaft is balanced really well.
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Ok, I'm running an aftermarket ds, and a 3.5" lift and 5.13 gears. So what would my optimal pinion be at? 88 right?
And that angle finder is about 30$ in the "jungle'. And more pinion is better? Ty

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deezus said:
Ok, I'm running an aftermarket ds, and a 3.5" lift and 5.13 gears. So what would my optimal pinion be at? 88 right?
And that angle finder is about 30$ in the "jungle'. And more pinion is better? Ty
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88 at the face would give you 4° of caster. That is stock and what you want to help mitigate drive shaft vibrations.

deezus said:
Here's my rear pinion on the axle. And of course my digital meter. [emoji2]
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Again, rear pinion angle only matters IF you are running an after market u-joint style double cardan drive shaft. If that is the case, you want to make sure it's in line with your drive shaft.

Now, I need to get me one of those cool angle finders :crazyeyes:
 
wayoflife said:
88 at the face would give you 4° of caster. That is stock and what you want to help mitigate drive shaft vibrations.



Again, rear pinion angle only matters IF you are running an after market u-joint style double cardan drive shaft. If that is the case, you want to make sure it's in line with your drive shaft.

Now, I need to get me one of those cool angle finders :crazyeyes:
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Ty Eddie gonna do it today. I am running a aftermarket ds front and back.
Yes you should get one, I got it because is small and magnetic. I also cant read any if my other I n es, this has big numbers, lol.

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WJCO said:
They aren't the same. Stock axle spec is 4.2+ degrees. To achieve more caster while still maintaining a good pinion angle, Dynatrac adds caster to the axle by rotating the 'C' when they weld them on. So you should have around 6+ caster and a near perfect pinion angle.

View attachment 245603
Click to expand...

So I finally got to adjusting mine according to this Dynatrac diagram and taking it for a test ride. It made the higher speed handling noticeably better. I have mine set at 6* now. Surprising what 3* change will do.
75mph & over was ambitious. Now its single hand on the steering wheel good. I hit 85 no problem. For guys running the PR44 with the unlimited geometry, it would probably be worth the $10 to get a cheap angle finder at HF or the like & check yours. If the alignment shops are setting your specs to stock they may be off. Thanks WJCO for posting that diagram.

This is at 70+ mph

0311171041.jpg
 
Ddays said:
So I finally got to adjusting mine according to this Dynatrac diagram and taking it for a test ride. It made the higher speed handling noticeably better. I have mine set at 6* now. Surprising what 3* change will do.
75mph & over was ambitious. Now its single hand on the steering wheel good. I hit 85 no problem. For guys running the PR44 with the unlimited geometry, it would probably be worth the $10 to get a cheap angle finder at HF or the like & check yours. If the alignment shops are setting your specs to stock they may be off. Thanks WJCO for posting that diagram.

This is at 70+ mph
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Awesome! When it comes to caster, every degree matters. Glad to hear you got your front end dialed in [emoji1303]


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wayoflife said:
Awesome! When it comes to caster, every degree matters. Glad to hear you got your front end dialed in [emoji1303]


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Actually its kind of embarassing that I lived with it the way it was. :grayno: I should have thought to do this a long long time ago.
This is such an easy check that everyone should verify where theirs is set at. And I'd be willing to bet that other guys with the PR44 U's have theirs set wrong like mine was. The alignment shops aren't going to go online to see where these should be set at. They're gonna set it to stock and it'll be wrong.

Thanks again Eddie for these articles - they're invaluable!
 
Ddays said:
Actually its kind of embarassing that I lived with it the way it was. :grayno: I should have thought to do this a long long time ago.
This is such an easy check that everyone should verify where theirs is set at. And I'd be willing to bet that other guys with the PR44 U's have theirs set wrong like mine was. The alignment shops aren't going to go online to see where these should be set at. They're gonna set it to stock and it'll be wrong.

Thanks again Eddie for these articles - they're invaluable!
Click to expand...

Glad to hear my write-ups have been helpful to you [emoji41]


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