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Help with alignment after ProRock 44 install

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Old 02-05-2018, 02:14 PM
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Default Help with alignment after ProRock 44 install

Hoping to get some advice/help with my alignment/steering issues I've been having since swapping out my Dana 30 and 35's for a Dynatrac ProRock 44 and 37's. Prior to the swap my Jeep handled pretty well considering it was on a 3.5" lift and 35's. Drove straight and had no wandering issues but did feel a little floaty.

Prior to the axle swap here's what I had in regards to lift, steering, etc.:
  • Rock Krawler 3.5" Flex Lift, which includes Front and Rear Lower Adjustable Control arms, Adjustable Front Track Bar and Rear Track Bar Bracket.
  • Yeti XD Tie Rod and Drag Link (bottom mount)
  • Currie AntiRock Sway Bar (Front only)
  • Bilstein 5100 shocks
  • OEM Stabilzer
  • BF Goodrich KM2 35ís
With this set up the steering and handling was pretty good, not the best Iíve been in but totally manageable on the freeway at 70-75 mph.

In December I did a front axle swap and moved up to 37ís. I have been having issues with the handling since then. Iíve had it aligned twice since the axle swap from two different Jeep/4x4 shops and still canít get the damn thing to feel half way decent. I have a hard pull to the left, the Jeep feels like it is swerving back and forth at 60mph and up, like I have to keep fighting with the steering wheel. Much more floaty feel than it had before.

Hereís whatís been added since I did the axle swap:
  • Dynatrac ProRock 44 Unlimted Front Axle
  • Adams Driveshaft 1350 Solid Front Drive Shaft
  • Nitto Trail Grappler 37ís
  • Rubicon Express Front Upper Adjustable Control Arms (just added these 2 days ago to try and help with the high caster I had 8.1 degrees front left wheel and 8.5 degrees front right wheel).
Here is the most recent alignment print out I have. Front Left Caster is 3.8 degrees and front right is 4.5 degrees. The thing thatís got me scratching my head is that this feels pretty damn close to how it felt after the first alignment that had me at 8.1 degrees caster on the left front and 8.5 degrees on the right (I wasnít given a print out for that and was told it was 6.5 degrees and could get better with adjustable upper control arms).




Any advice or suggestions of how I can tighten the steering up (preferably with my current parts) would be greatly appreciated.
Thanks -
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Old 02-05-2018, 02:19 PM
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Here are my control arm pics for reference:

Front Lower:


Front Upper:


Front Drive shaft:
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Old 02-05-2018, 02:39 PM
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Your front tires appear to be toed out. You can set them with a tape measure, target about 1/16" toe in. 1/8" is often recommended but on mine is too much. Your caster is not far off. With larger tires 4.0 - 4.5 degrees is just about right. Be mindful of your front driveshaft angle, 1 - 2 degrees on the front shaft should be in the pocket.
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Old 02-05-2018, 04:11 PM
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Originally Posted by SoK66 View Post
Your front tires appear to be toed out. You can set them with a tape measure, target about 1/16" toe in. 1/8" is often recommended but on mine is too much. Your caster is not far off. With larger tires 4.0 - 4.5 degrees is just about right. Be mindful of your front driveshaft angle, 1 - 2 degrees on the front shaft should be in the pocket.
Cool, I was definitely planning on getting my toe in vs out. Was surprised to see that the "4x4/ Jeep" shop that did the alignment set it up that way. Hopefully that will help some.
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Old 02-05-2018, 05:47 PM
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What was the caster before the new axle went on?

The PR44-U is caster corrected. The spec listed in the faq is ' 6-8 degrees caster (and 2-4 degrees at the pinion)'. If I read your post right, you tried 8.1*/8.5*, and have now dropped to 3.8*/4.5* ?

I have been running this axle since 2010. At the install, my jeep left the shop with caster a bit over 10*. Major driveline vibes. Went right back and it was lowered to 8*. No vibes, drove fine. But just as a personal opinion, caster was higher than I liked having it, so I dropped to 7*. I have never had the caster down around 4*, so can't comment on whether that could be causing some of the flightiness you are feeling.

Are those Toe numbers correct? One side started out-of-spec and ended in-spec, the other side started in-spec, and they purposely took it out-of-spec? As sok66 mentioned, take another look at that.
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Old 02-06-2018, 09:55 AM
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Originally Posted by nthinuf View Post
What was the caster before the new axle went on?

The PR44-U is caster corrected. The spec listed in the faq is ' 6-8 degrees caster (and 2-4 degrees at the pinion)'. If I read your post right, you tried 8.1*/8.5*, and have now dropped to 3.8*/4.5* ?

I have been running this axle since 2010. At the install, my jeep left the shop with caster a bit over 10*. Major driveline vibes. Went right back and it was lowered to 8*. No vibes, drove fine. But just as a personal opinion, caster was higher than I liked having it, so I dropped to 7*. I have never had the caster down around 4*, so can't comment on whether that could be causing some of the flightiness you are feeling.

Are those Toe numbers correct? One side started out-of-spec and ended in-spec, the other side started in-spec, and they purposely took it out-of-spec? As sok66 mentioned, take another look at that.
Not sure what the caster was at prior to the swap. It drove reasonably well so I never had it measured.

The 8.1, 8.5 is what the shop that did the axle swap had it at. They told me it was at 6.5... not sure why the difference but after driving it for a month I decided to take it to another shop to have them check it out. Thatís when I found out my caster was actually that high and not 6.5. We added upper control arms to get it down to the 3.8, 4.5. It was flighty at 8.1/8.5 and is flighty at 3.8/4.5. The shop that did the latest alignment had it at 6.4, 7.3 and weíre getting drive line vibes. Thatís when we added upper adjustable control arms to get it down to the 3.8, 4.5 itís at now.

Iím adjusting the toe to 1/16Ē toe in today and will see if that makes any difference. Driving to King of the Hammers tomorrow and depending on how it drives will make caster adjustments when I get back. Just need to figure out where to adjust it to.


Last edited by ragnarok_jku; 02-06-2018 at 09:58 AM.
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Old 02-07-2018, 06:17 AM
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Originally Posted by nthinuf View Post
What was the caster before the new axle went on?

The PR44-U is caster corrected. The spec listed in the faq is ' 6-8 degrees caster (and 2-4 degrees at the pinion)'. If I read your post right, you tried 8.1*/8.5*, and have now dropped to 3.8*/4.5* ?

I have been running this axle since 2010. At the install, my jeep left the shop with caster a bit over 10*. Major driveline vibes. Went right back and it was lowered to 8*. No vibes, drove fine. But just as a personal opinion, caster was higher than I liked having it, so I dropped to 7*. I have never had the caster down around 4*, so can't comment on whether that could be causing some of the flightiness you are feeling.

Are those Toe numbers correct? One side started out-of-spec and ended in-spec, the other side started in-spec, and they purposely took it out-of-spec? As sok66 mentioned, take another look at that.
Most of the aftermarket housings are angle corrected at 10 degrees total offset (difference between caster & pinion angles), vs stock whihc is 6 degrees. On a Pro Rock Unlimited, Tera R44, Currie Rock Joc, etc., the pinion angle will be the difference between caster angle subtracted from 10. So, if yoy have 6 degrees caster, the pinion nose will be angled up at 4 degrees. Adding the third factor, that should bring the angle on the driveshaft to within 1-2 degrees of the pinion angle. The taller the lift the more angle you need on the pinion to get the driveshaft angle in the pocket and eliminate vibrations. This is critical because the transfer case will eventually grenade if the vibrations are left uncorrected. Currie once had a tech sheet on this and recommended no more than about 4.5 degrees caster if you're running large tires, with a good tech explanation. You might check their site and see if it's still posted.
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Old 02-07-2018, 01:58 PM
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Yeah, I was just posting my experience and what was listed in the PR faq, thinking too much into angles gives me a headache.
PR44u - They are configured for a nominal 7 degrees caster and 3 degrees pinion angle. The axle can be adjusted using the control arms between 6-8 degrees caster and 2-4 degrees at the pinion.


Didn't find the Currie document you mentioned, but did find this.
RJ44 - Optimized for 4” lift kit with 5 degrees of pinion angle to reduce driveshaft angle and 5 degrees of caster for improved steering
And just a thought, could that tech sheet have been for a non-corrected housing with a taller lift? In that case, I would certainly agree with the 4.5* max recommendation.

Last edited by nthinuf; 02-07-2018 at 02:03 PM.
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Old 02-07-2018, 04:54 PM
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The bigger tires will also cause you to have a little pull just because there is more rubber on the road.

What track bar are you running? I had a flighty feel to mine and it was the track bar.

Did not see if you did a high steer or not. If not I would recommend getting your draglink and track bar as parallel as you can.


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Old 02-11-2018, 07:30 PM
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Originally Posted by Canvas View Post
The bigger tires will also cause you to have a little pull just because there is more rubber on the road.

What track bar are you running? I had a flighty feel to mine and it was the track bar.

Did not see if you did a high steer or not. If not I would recommend getting your draglink and track bar as parallel as you can.


R/
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Currently Iím running Rock Krawlerís adjustable track bar. What track bar were you running when you had the flighty feel? Was it stock or aftermarket?

Donít have high steer. Iíve got Steersmarts bottom mount Drag Link. That had crossed my mind to try out the Steersmarts top mount Drag Link if I canít get my current set up dialed in. My track bar and draglink are prettty parallel, which is why I havenít made the switch just yet.
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