Position of flex joint on fabbed control arms

I'm in the process of fabbing some adjustable upper and lower control arms using Johnny Joints. Question, does it matter whether the Johnny Joints are mounted on the axle side or the frame side? And should the upper and lower arm's joints be on the same side, i.e. both on the axle side or both on the frame side? I'm thinking it would be better to have all the flex joints on the axle side, but if one look at the RE adjustable SF arms as an example the SF joint on the lower arm mounts on the axle side whereas the SF joint on the upper arm is on the frame side. This might be because they don't have a flex joint solution on the axle end like Johnny Joints have.

As it is at the moment I have three options wrt my upper control arms. The first is to modify the upper control arm mounting on the axle to work in a similar fashion to the lower control arm mounting (I'm fabbing a new front axle so I have to make new mountings in any case) and thus just mount a normal Johnny Joint on the axle end like one would with the lower control arm. Second is to keep the axle end standard and fab the upper control arm with the Johnny Joint on the frame side (like the RE arms) and the third would the to cut off the threaded bolt on the Johnny Joint (I have the ones with the dom tubing with the threaded bolt welded to it) and replace the bushing on the axle end with the Johnny Joint. This will allow the flex joint on the axle end, but with OE mounting of the upper control arms.

Any suggestions?

I would put the bushing side on the axle side of the arm. The reasoning is because it allows any vibrations to be absorbed by the bushings before transfering through the control arm. If you flip the control arm, you are essentially increasing the unsprung weight of the front axle. More unsprung weight = more weight transfer to the chassis and a more uncomfortable ride.

Your ability to flex won't change either way it's mounted.

If you look at the RE install directions they state the opposite. Rubber on the frame side to increase flex with the LCA's. Although the UCA's have the joint at the body side since the bushing is in the axle. :dunno:

No, it doesn't matter. Put it where it's easiest to build.

If your serious about the flex and not the ride,put JJ's on both ends,your unibody will love you for it !!

Bryson said:

If you flip the control arm, you are essentially increasing the unsprung weight of the front axle. More unsprung weight = more weight transfer to the chassis and a more uncomfortable ride.

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wanna try again?
are you thinking the weight of the heim vs the weight of the bushing? because the unsprung weight is PRETTY MUCH the same, regardless of which end is where.
I know wikipedia isnt the best source for info, but you need to do some learnin
http://en.wikipedia.org/wiki/Unsprung_weight

also, more unsprung weight isnt allways a bad thing, it lowers you COG

RCP Phx said:

If your serious about the flex and not the ride,put JJ's on both ends,your unibody will love you for it !!

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NO kidding. I was riding with a buddy last night that JJ's on both ends. He bought the Jeep built. He had only had it about two hours and wanted me to look through it.

Full Traction long arm kit with JJ's on both ends of the LCA. HOLY CRAP. You felt every vibrationa and noise under that rig. I thought mine rode like a tractor. We were out there till after 11pm trying to figure out why that thing made so much noise and why the vibes were so bad when the front driveshaft was installed. Best we could figure it was the JJ's and the unibody amplifying the noise.

Look at the rubicon express super flex kits and how they do it. depends on want you want as far as ride comfort and noise levels.if i had a 4 link uca's would be flex joint frame side and has to be rubber axle side uca. lca's would be flex joint axle side and rubber frame side. good combo of flex and comfort with this set up.

Bryson said:

I would put the bushing side on the axle side of the arm. The reasoning is because it allows any vibrations to be absorbed by the bushings before transfering through the control arm. If you flip the control arm, you are essentially increasing the unsprung weight of the front axle. More unsprung weight = more weight transfer to the chassis and a more uncomfortable ride.

Your ability to flex won't change either way it's mounted.

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i don't care how how long you were in school for advanced hypermolecular engineering sciences or whatever you call it, that makes no sense.

LMAO !