Rear Pinion Angle -
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post #1 of 3 Old 06-13-2021, 08:22 AM Thread Starter
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Location: Two Harbors, MN
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Rear Pinion Angle

Maybe losing my mind here
Trying to set the rear pinion angle
Jeep is sitting on a modified Super Lift, SL coils and 2" spacer on top. SL lower control arms

I just bought a set of Core 4x4 rear upper control arms and from all my measuring and angle finding it seems i need shorter than stock uppers??? Is this at all correct?
I want my xfer case output to be parallel to the diff yoke correct?

Maybe i need a set of adjustable lower control arms?

Thanks, i hope i'm not completely stupid....

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post #2 of 3 Old 06-13-2021, 09:16 PM
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Are you having problems?

I don't have the SL and I have never been able to look over a rig closely with one, they use a body side drop bracket for the lower arms right? And they also use extensions on the upper mounts on the axle? So they are keeping the arms at the same angles in relation to each other but pushing the lower down in the front and the upper up in the back?

As a matter of K.I.S.S. The SL has been engineered to run a stock upper control arm and maintain "factory" geometry. So back to the first question posed... if it is causing vibration, then sure, time to start diving into this. But if its a matter of you trying to make it perfect if its not actually causing vibration, I would probably just roll with it.

Parallel at ride height would be best case scenario with our shorter uppers as it should minimize strain and vibration.

To go a bit further assuming maybe you are experiencing some issues... Considering the SL is designed to use the factory upper. I would expect any adjustment to be around the factory, + OR - a little. So yes, there would be a potential that they might need to be shorter to perfectly dial it in. Is the superlift lower arm longer than the factory arm?

One last consideration on my mind. I've seen too many (for my comfort) guys with upper control arm mounts ripped off who have the tier 3 and 4 core 4x4 control arms. MOSTLY tier 4 but I have seen someone do it with some tier 3 arms. With the thin sheet metal pocket I believe it just hammers the life out of the mount with minimal dampening through the more solid joint options. Just some food for thought.

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post #3 of 3 Old 06-23-2021, 05:49 PM
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So I had recently picked up Tier 4 arms, and was a bit concerned after hearing these comments. I reach out to Core 4x4, who said -

"To be honest, we have never even heard that before. The T4 arms are going to be the least likely to tear any mounts because they have the Johnny Joints on both ends of the arm, so there is no rotational pressure put onto the mounts. We have heard and seen T1 arms rip off mounts when people try to use them as if they were T4 arms, but not the other way around."
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