Lower Control Arm Time (driveline vibes)

Just picked up the Jeep from ORE this afternoon after having them install 5.13s and a J.E. Reel 1350 front drive shaft with new yokes. Starting at about 50, I am getting a faint, high frequency, oscillating vibration/hum. It is worst at about 55 and slowly fades as speed increases but does not completely disappear.

Before gears and driveshaft, everything was smooth. I am running factory arms with AEV drop brackets. Caster was measured last at 4.8.

Thinking a set of EVO front lower control arms are in order to dial the caster down/pinion up a bit.

I should add that the plan is for these to be semi-temporary. Planning something like long arms with either bolt ons or DTD in the coming year or so.

Couple of quick questions:

1) Rough starting measurement for the EVO arms?

2) Rough caster pinion angles to start with? Maybe 4°/2°?

3) Thoughts on retaining the brackets? With plenty of highway driving, I'm tempted to keep the brackets for geometry correction and run them until the get bent up on the rocks.

Thanks guys!
-ERAU

Sell it......

I don't really have any experience with gears, so I'll go the arms/brackets. I would think the new arms would be well worth the money. Not hugely expensive and im sure easy to resell. I have front lowers and rear uppers adj, easy to dial in. There's really no starting pt on the length, it's so custom to each jeep.

ERAUGrad04 said:

1) Rough starting measurement for the EVO arms?

Click to expand...

23" eye to eye but, you will most likely need less depending on how much lift you actually have.

2) Rough caster pinion angles to start with? Maybe 4°/2°?

Click to expand...

You definitely want +4°. Anything less and your Jeep will be flighty.

3) Thoughts on retaining the brackets? With plenty of highway driving, I'm tempted to keep the brackets for geometry correction and run them until the get bent up on the rocks.

Click to expand...

:cheesy: You seriously have to ask? Get rid of those stupid brackets. I can almost guarantee that you won't even notice the difference. :yup:

I'll second not noticing a difference without the geo brackets. I've had mine on and off a few times & can't tell a difference. Other than I hit them sometimes when they're on. My lift is only 2.5 though FWIW.

wayoflife said:

23" eye to eye but, you will most likely need less depending on how much lift you actually have.

Click to expand...

Thanks for a good starting point!

wayoflife said:

You definitely want +4°. Anything less and your Jeep will be flighty.

Click to expand...

I'm going to try to come down from the 4.8 to the factory 4.2 first. Going to try to keep the caster as high as possible without any driveline vibes.

wayoflife said:

:cheesy: You seriously have to ask? Get rid of those stupid brackets. I can almost guarantee that you won't even notice the difference. :yup:

Click to expand...

I deserved that comment! EVO arms are ordered and hopefully will be here Friday. Brackets will be the first thing to go!

Thanks Eddie for the help! :thumb:

As a general update to this thread, I pulled the front driveshaft off tonight when I got back to the Bay Area from ORE. Went back out for a drive and the vibes are gone all the way to 75mph. So unless the brand new J.E. Reel shaft is out of balance (which I highly doubt), it's pretty much confirmed that I need just a hair less caster.

wayoflife said:

23" eye to eye but, you will most likely need less depending on how much lift you actually have.



You definitely want +4°. Anything less and your Jeep will be flighty.



:cheesy: You seriously have to ask? Get rid of those stupid brackets. I can almost guarantee that you won't even notice the difference. :yup:

Click to expand...

Thanks Eddie for all the suggestions!

Arms are in and brackets are out!


I have to admit, I was a little skeptical about pulling the brackets, but I am really glad I listened. I can tell NO difference between having the brackets and not. And that even includes a little less caster too!

Thanks again and next time first round is on me!