"boxing" lower control arms

[SUPER_NOVA_71]

I'm installing a 3 inch lift. I am keeping the stock lower control arms, I can box them for more strength. However I do not rock crawl. I DD and run mostly in dirt/mud/snow trails.
Is this worth the time and effort? or should i just leave them the way they are.

 

[Nuke Proof]

IMHO anytime you can add strength you should. Keep in mind that mud bogging and snow wheeling can create just as much if not more stress on suspension systems than rock crawling.

just my .02

 

[winkosmosis]

I don't know if it's warranted or not but I'm more concerned with the stress on the uniframe from the control arm angle with 3". In an IFS system, the wheels move back when they go over a bump. With a stock Jeep solid axle, they go up, and then go slightly back. With a lift, the wheel has to go forward over the bump, and the greater the lift the more it pushes into the bump and the more energy gets transmitted into the uniframe.

 

[slcpunk74]

Cheap lowers are a bit over $100 and they will do much more for you in strength then just boxed stock 16 ga oe lowers

 

[Love2Ride450]

Don't box them. It's actually a hinderance. They are strong enough the way they are, and the fact that they aren't boxed allows them to flex which reduces stress at the uniframe mounting points.

 

[asp]

the stock ones are made to twist some. boxing them will create big stress rises and the joints. you can fairly well beat the crap out of stock LCA's. look for a set of used tubular LCA's. doesn't have to be fancy or adjustable, just make sure the bushings are ok. they can be found pretty cheap. that will also move your front wheels a bit farther forward so they don't rub the body too...

 

[userbmx1315]

get some lowers off of a zj. they are boxed and are bent so the tires dont rub

 

[MoparManiac]

get some lowers off of a wj. they are boxed and are bent so the tires dont rub

Fixed it for ya

 

[Nuke Proof]

wrg

 

[Nuke Proof]

Don't box them. It's actually a hinderance. They are strong enough the way they are, and the fact that they aren't boxed allows them to flex which reduces stress at the uniframe mounting points.

Now wait a second, if the factory arms are designed to flex to absorb some of the forces to protect the uni mounts; then one would assume that all of the short arm kits out there are too rigid and therefore would damage the uni frame mounts.

 

[slcpunk74]

get some decent lca's stock sucks for how cheap it is to buy better ones...

http://www.rjroffroad.com/warrior-lower-control-arms-jeep-wrangler-cherokee-offroad-c-572-p-2-pr-16857.html

 

[scorpion]

The factory mounts are designed to twist and/or flex? I think you're mistaken. What I think they are is as thin (cheap) as they can possibly be without failing under normal driving conditions. If you look at them you'll notice that the edges distant from the axle tube are rolled on them making them stucturally stronger than if they were flat tabs made out of the same material. The benefit is similar to using a dimple in a piece of thin gauge plate. When you see the LCA box flex, you are actually seeing the lower control arm brackets "working" on failure.

Adding a skid like plate to the bottom of them will add strength to the box itself. It will also increase the weld surface area between them and the axle housing. As far as options go, it is a distant second from repalcing them with a stucturally superior reinforced LCA box made from thicker material but boxing them will be far better than nothing.

 

[Dave41079]

The factory mounts are designed to twist and/or flex? I think you're mistaken. What I think they are is as thin (cheap) as they can possibly be without failing under normal driving conditions. If you look at them you'll notice that the edges distant from the axle tube are rolled on them making them stucturally stronger than if they were flat tabs made out of the same material. The benefit is similar to using a dimple in a piece of thin gauge plate. When you see the LCA box flex, you are actually seeing the lower control arm brackets "working" on failure.

Adding a skid like plate to the bottom of them will add strength to the box itself. It will also increase the weld surface area between them and the axle housing. As far as options go, it is a distant second from repalcing them with a stucturally superior reinforced LCA box made from thicker material but boxing them will be far better than nothing.

Pretty sure the thread here is about the arms themselves, and not the mounts. But very good info nonetheless.

 

[WB9YZU]

I'm installing a 3 inch lift. I am keeping the stock lower control arms, I can box them for more strength. However I do not rock crawl. I DD and run mostly in dirt/mud/snow trails.
Is this worth the time and effort? or should i just leave them the way they are.

Don't bother. The holes the bushings are pressed into will wollow out before you get a chance to damage your stock LCAs. IMO, the CAs that are the weakest are the uppers.
Once you get to much over 4 inches, the suspension angles get a bit extreme and I have seen a few bent uppers because of it. Not under street use mind you, but when you are really punishing it.

 

[beer_goggles_009]

I would definetly recommend replacing the stock CAs if you are going to wheel it. I bent my upper CA on the road while driving on unplowed streets in ~6-8" of snow. Others peoples experienes will vary, some will wheel hard on the stock pieces. The relatively low cost of CAs will be well worth it when you don't have to figure out a way to get your jeep back home after breaking your control arms in a location inaccessable to a trailer.

 

[fubar XJ]

I'd leave the lowers as they are, for the reasons listed. If you're not happy with them, aftermarket LCAs are pretty cheap.

 

[scorpion]

Pretty sure the thread here is about the arms themselves, and not the mounts. But very good info nonetheless.

I sometimes have a hard time switching between surfing (more like skimming) and reading for content. Sorry.

I think the same concept applies to the control arms though. The formed arms are designed to be strong for what they are - thin sheet metal designed for driving only. They were never designed to come into contact with anything and there's a slight chance that they are designed to fail on front impact though I don't honestly know that for fact. Though automobile manufacturers seem to get direction wrong all the time (like underpowering the JK), they do their homework on everything else. Thier purpose is to build a vehicle as inexpensively as possible while keeping it safe and, if you inspect the factory control arms, you'd see that they are a perfect example of this.

Boxing them will improve their strength as it will turn the design into a tube instead of a channel. It isn't a bad low-buck option if you have or have access to a welder but, as others have stated, the entire arm assembly (even boxed), isn't really up to the task of wheeling unless you reinforce the entire thing at all points There are quite a few companies that sell affordable replacement lowers that would be a much better idea as a whole. The factory bushing isn't a bad one. The bonded polymer concept works well at offering some flex and a nice ride. Going to poly-bushings will be much stronger but give a little bit of a rough ride when compared to the factory style (or any rubber version).

As geometry changes, so does the impact on the control arms. Any vehicle over a couple inches of lift is a good candidate for long arms or drop brackets IMO.

 

[wannajeep]

Don't bother. The holes the bushings are pressed into will wollow out before you get a chance to damage your stock LCAs. IMO, the CAs that are the weakest are the uppers.
Once you get to much over 4 inches, the suspension angles get a bit extreme and I have seen a few bent uppers because of it. Not under street use mind you, but when you are really punishing it.

Yup, at 3" no worries, anything over that, uppers gotta go and the lowers are too short. I destroyed 2 set of uppers after adding a 1" spacer to my 3" springs. With the 3" they suvived many years of wheeling.

 

[Love2Ride450]

Now wait a second, if the factory arms are designed to flex to absorb some of the forces to protect the uni mounts; then one would assume that all of the short arm kits out there are too rigid and therefore would damage the uni frame mounts.

I never said they are designed that way, just that is how it ended up. I'm just saying there isn't really any benefit (in my opinion of course) to boxing the stock lca's. Do what you want, but I built some beefy adjustable arms and used a johnny joint to keep it from being rigid.

Maybe I could have used more solid joints, but when you see this picture, you will understand why there needs to be some flex. This picture is of my LCA at the body end while fully drooped.

Also, I don't believe my setup would flex as nicely without the flexible joints.

 

[Nuke Proof]

I can appreciate that your custom made one off arms that are equipped with JJ's flex and do not allow for the forces of the suspension to be placed on the mounts. However I was simply stating that most of the mass produced arms out there create the very problem that you stated boxing the factory arms create by stiffer design, material and poly bushings...this is just my opinion