New lower control arms are 1/4 inch longer

Natethegreat202

Natethegreat202

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Hey guys, apologies if this is a stupid question. Ordered some new lower control arms. They just came in and when measured they are .25 in longer than what is currently on my TJ. I’m running a 4 in lift and the new control arms are fixed. Website stated they were for 4 in lifted TJ but couldn’t find measurements anywhere so took a leap of faith. The Jeep drives great now, straight line no vibrations or death wobble from 0-75mph. Would hate to screw that up although I feel this shouldn’t make a difference. Would just hate to put them on only to have to remove them again. Upper control arms are all stock and freshly replaced.

Current lower arms are 16 in from eye to eye

New ones are 16.25 in from eye to eye

Thanks!
 
rouxbicon said:
Won't it roll the pinions down, possibly inducing driveline vibes?
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Not if they're all longer by the same amount. Think parallelogram where lengthening both sides the same amount keeps the angles on the side the same.

Edit: Nevermind I just caught onto the fact that you're only installing lower control arms.
 
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Jerry Bransford said:
Not if they're all longer by the same amount. Think parallelogram where lengthening both sides the same amount keeps the angles on the side the same.
Click to expand...

He indicated he is only replacing the lowers, with new ones that are 1/4" longer than what is on there now. The uppers are staying the same. Seems to me that is going to roll the pinions down. I don't have the experience to know if that extra 1/4" will be enough to induce driveline vibes or not, but since he says he is happy with the way it drives now, I question changing only the lower control arm lengths.
 
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Jerry Bransford said:
Not if they're all longer by the same amount. Think parallelogram where lengthening both sides the same amount keeps the angles on the side the same.

Edit: Nevermind I just caught onto the fact that you're only installing lower control arms.
Click to expand...

Yeah uppers are all still stock. So are you guys thinking this could effect the driveline and lead to some possible vibrations or wobble?
 
Increasing the length of the lower control arms ONLY, will cause the pinion to roll forward, thus decreasing your pinion angle. This can induce driveline vibes. If the arms are intended for a 4 inch lift, they most likely sell a pair of uppers that are slightly longer as well, to compensate for this.

Was there any reason specifically why you were changing your lower control arms? Are the bushings toast or something?
 
Natethegreat202 said:
Gotcha, so thinking I'm good to install the new slightly longer lower control arms?
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Install the arms and see. You can measure caster with an angle finder on the flat spot next to the lower ball joint. You want as much caster as you can possibly get before you start getting vibrations. You likely wont experience vibrations.

You should pull the coils out and cycle your suspension to see how everything lines up at full bump.
 
Sensei said:
Increasing the length of the lower control arms ONLY, will cause the pinion to roll forward, thus decreasing your pinion angle. This can induce driveline vibes. If the arms are intended for a 4 inch lift, they most likely sell a pair of uppers that are slightly longer as well, to compensate for this.

Was there any reason specifically why you were changing your lower control arms? Are the bushings toast or something?
Click to expand...

Gotcha. Yeah I was hoping they would be the same length. So I have a 4 in lift but A 2 in or so transfer case/tranny drop so my skid is pretty low. I believe that’s what has contributed to never having wobble issues. Yeah the lower arms are veryyy old. Bushings are alright considering age but the metal and bolts are rusted on the them. I’m pretty much tearing up the entire Jeep so figured I would swap them while it’s taken apart. But noticing the size difference has stopped me from here. Thinking I’ll maybe just return the arms and wait for correct size or adjustable. Also found this? Upper control arms have been stock since I’ve had the Jeep and this diagram says I should be good with stock uppers until 4 1/2in of lift? But does the T case drop compensate at all? I’m also on 33s if that matter. Thanks y’all!! Sorry this has been a bit of a headache haha
 
Sensei said:
Increasing the length of the lower control arms ONLY, will cause the pinion to roll forward, thus decreasing your pinion angle. This can induce driveline vibes. If the arms are intended for a 4 inch lift, they most likely sell a pair of uppers that are slightly longer as well, to compensate for this.

Was there any reason specifically why you were changing your lower control arms? Are the bushings toast or something?
Click to expand...

4309D29D-BE44-4D1E-8471-8075FE763CB7.png
 
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Honestly, you'd probably be able to run them without any driveline issues given the small difference and you having a 2 inch t case drop. Especially if you currently don't have any hints of vibes or shaking. I didn't start having vibes on my tj w/ 3 inch lift 1 inch t-case drop till I swapped my rear axle for a Ford 8.8. Then I started getting vibes thus needed a SYE and new driveshaft.

It's only two arms, so if you swap them in and immediately start experiencing driveline vibes while pressing the accelerator, you can swap them back out without too much hassle.

If you have issues getting the bolt holes to line up when installing the arms, jack the jeep from the frame, then use ratchet straps wrapped around the axle and attached to the frame to crank the axle into place while its suspended in the air.
 
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Sensei said:
Honestly, you'd probably be able to run them without any driveline issues given the small difference and you having a 2 inch t case drop. Especially if you currently don't have any hints of vibes or shaking. I didn't start having vibes on my tj w/ 3 inch lift 1 inch t-case drop till I swapped my rear axle for a Ford 8.8. Then I started getting vibes thus needed a SYE and new driveshaft.

It's only two arms, so if you swap them in and immediately start experiencing driveline vibes while pressing the accelerator, you can swap them back out without too much hassle.

If you have issues getting the bolt holes to line up when installing the arms, jack the jeep from the frame, then use ratchet straps wrapped around the axle and attached to the frame to crank the axle into place while its suspended in the air.
Click to expand...

I gotcha, yeah that is what I figured but wanted to post to be safe. Thanks so much for your time!
 
Natethegreat202 said:
Hey guys, apologies if this is a stupid question. Ordered some new lower control arms. They just came in and when measured they are .25 in longer than what is currently on my TJ. I’m running a 4 in lift and the new control arms are fixed. Website stated they were for 4 in lifted TJ but couldn’t find measurements anywhere so took a leap of faith. The Jeep drives great now, straight line no vibrations or death wobble from 0-75mph. Would hate to screw that up although I feel this shouldn’t make a difference. Would just hate to put them on only to have to remove them again. Upper control arms are all stock and freshly replaced.

Current lower arms are 16 in from eye to eye

New ones are 16.25 in from eye to eye

Thanks!
Click to expand...

Front or rear?
 
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