Lower Johnny Joint control arms with stock uppers?

Nordic

Nordic

TJ Enthusiast
Joined
Jan 21, 2019
Messages
138
Location
Monument, CO
Just a quick question, if I upgrade my front lower control arms to a double Johnny Joint set up while leaving my front stock uppers in, will this place undue stress on the upper control arms and control arm brackets?

Thank you!

Also, does anyone know if the Johnny Joints generally used are the 1 1/4" - 12 thread style or the 1" - 14 style, and what the difference between the two are?
 
Are you going full articulation left to right frequently or is this mostly an onroad Jeep? The design of the uppers mounted closer to the center of the axle will allow them to flex easier than the lowers can. So while there may be some increase in rotational load, unless you are really working the suspension and the uppers are in bad shape, you should be ok. I would still plan on upgrading in the future though.
 
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Goatman said:
Are you going full articulation left to right frequently or is this mostly an onroad Jeep? The design of the uppers mounted closer to the center of the axle will allow them to flex easier than the lowers can. So while there may be some increase in rotational load, unless you are really working the suspension and the uppers are in bad shape, you should be ok. I would still plan on upgrading in the future though.
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Daily driver and weekend warrior, so a bit of both, but that makes sense that they are closer so less rotational load, so hopefully they'll be OK. I do plan on upgrading in the future, just not wanting to drop 600 on control arms all at once hah.
 
The stock uppers won't notice Johnny Joint lowers. What matters is if the shock travel is increased to be more than stock. Then the factory arms will start to complain more. Also, as more lift is added, then less the stock arms will be able to put the axle where it ought to be.
 
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FYI most 4” kits from reputable manufacturers only include lower control arms. The main reason is to maintain pinion angle and to keep the wheel centered in the wheel well. I’ve found this is adequate but not ideal for pinion angle and will be adding adjustable uppers to the rear.

It seems as far as “strength” goes, the stock control arms get a bad wrap. In reality, they are well engineered to handle loads and are about half the weight of aftermarket control arms. It’s only the length that’s the issue when adding lift.
 
jjvw said:
The stock uppers won't notice Johnny Joint lowers. What matters is if the shock travel is increased to be more than stock. Then the factory arms will start to complain more. Also, as more lift is added, then less the stock arms will be able to put the axle where it ought to be.
Click to expand...

Currently my downtravel is limited by my stock lowers hitting the spring perches, but the main reason I'm looking for adjustable lowers right now is because I'm not happy with my steering and my castor is only at 4.9°. Of course long term I want to go to a TT and more lift, so adjustable lowers will be a step in that direction.
 
Nordic said:
... I'm not happy with my steering and my castor is only at 4.9°. Of course long term I want to go to a TT and more lift, so adjustable lowers will be a step in that direction.
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What about the pinon? Ignore caster and keep the pinion happy, unless you are ok with burning through u joints. The caster will be fine.

Regardless, when you start working to refine the various movements and positionings, all things lead towards all 8 adjustable arms and track bars.
 
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jjvw said:
What about the pinon? Ignore caster and keep the pinion happy, unless you are ok with burning through u joints. The caster will be fine.

Regardless, when you start working to refine the various movements and positionings, all things lead towards all 8 adjustable arms and track bars.
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Well if 4.9° is a reasonable amount of castor, do you know what else could be contributing to my bad tracking? I have currie steering I installed and it has >20k miles, my tires are road force balanced, and my TOE in is set properly, however my jeep is still all over the road, doesn't like to go in a straight line. The steering is super tight because of the correctlync, there's no excessive play or anything, it just loves to wander and has a hard time tracking straight. It improved somewhat after I put a new heim in my RE track bar, but still isn't where I want it, and everyone who's driven my jeep agrees it's a handful. Worn ball joints maybe?
 
What is the tire size and pressure?

Mine has a 4" spring with a Savvy skid. The front pinon is right about 0 deg to the drive shaft. By my estimation, it tracks pretty well on the highway compared to other vehicles I have driven.
 
jjvw said:
What is the tire size and pressure?

Mine has a 4" spring with a Savvy skid. The front pinon is right about 0 deg to the drive shaft. By my estimation, it tracks pretty well on the highway compared to other vehicles I have driven.
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33x12.5, 26 PSI. 2.5" SL all around with 3/4" spacers in front. Mine definetly doesn't track well, even my gf's 93 Yj with worn out components and like 1/4 of a turn of play in the steering seems to track better than mine.
 
Ideal toe setting is not fixed in stone. I had 1/8" toe and it tracked like shit. Moved it to 1/16" and it went to amazingly tight and true.
Others have had the opposite effect. The only way to find out is to adjust the toe by giving the adjustment sleeve a 1/4 turn at a time and then see what happened. Better? Try another 1/4 turn. Worse? Go back the other way a 1/4 turn. This is what I ended up doing.
Be sure ALL joints are in good shape first. Tie rods, bearings, control arms, etc. Good load range C tires at correct pressure goes a long way.
 
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