Rear Control Arm Mod

[Zane]

Many of you have done this already so this is nothing new other than I couldnt find one place that gave any details about this mod so i figured i would write something up to help others out. This is a VERY simple mod that will beef up your rear control arms. As I understand it, they have a tendency to bend when bashing them on rocks. This makes plenty of since due to the weight of our rigs. I dont claim to be an expert on this, but I would think this mod should make them close to bullet proof.

Attached is a picture of one of the control arms finished up. I pulled the control arm, welded in the steel, cleaned it all up, primed and painted and reinstalled the control arm all in about 30 minutes.

When I do the drivers side in the next day or so, I will take step by step pictures including how to remove your rear control arm and update this post.

oh ya.. this mod only cost $14.00

 

[farinvail]

Looks good. Welds look great.

 

[yoter100]

Would welding weaken the control arm????

 

[Kanaljen]

I'm definitely no expert but I would like to toss in some food for thought..

The additional 90 degree metal strip would definitely add to the strength of the ctrl arm.. But would it be enough to eliminate the possibility of bending the arm if it would rest on/hit a rock and the mass of our LC tank would rest on it?

Any would you want to?? Weakest link idea; it might not bend but something [now] relatively weaker (and likely more expensive and complex to repair) would give in instead.

For example, on my 330i (BMW), the lower wishbone (by many referred to has the ctrl arm) is purposely made rather weak.. So weak in fact, that if a tow truck uses it to pull a car up on a flat bed, they would bend.. Or, if you bump/slide into a curb, they would bend very easily.. Or, if you race, ride they outside bank/curb a bit, they could also bend; that's how weak they are made..

The thought behind this is that they would deform before the subframe and mounting points would..

Thoughts?

 

[Trunk Monkey]

No it won't weaken the metal by welding it.

I can't think of a way that you'd get the entire weight of the vehicle on one control arm, but they do hit rocks. I bent both of them on my 80. Reinforcing them like this is just like a slider for the rocker panels, you're just adding armor.

Weakest link? On either side of that is the axle housing or the frame - the control arm is still the weakest link.

Don't go overthinking this simple mod.

 

[1loudLX]

do mine do mine!

 

[Zane]

This mod is not indented to make it the strongest part of the rear suspension. Saying Bullet proof may have been a bit much unless i add that the frame and the axle housing are missile proof... ha... Its intent is to protect the control arms from bending if they bump into a rock or ledge at very slow speeds. Remember, we are not traveling at high speeds over obstacles. Most of the time its at a snails pace and with a good spotter you would know if you are going to drag a control arm, but sometimes the line you take can change quickly and the extra protection is nice to have. I would agree that the control arm is still the weakest link even after this mod.

This concern is not a new one as I have read other discussion around similar modification to the control arm in a few other threads, but I have yet to hear anyone bring it up when someone adds Slee's heavy duty units made from 27.4mm solid K1045 metal. Those I would assume are much stronger than what I am getting out this mod.

 

[AutoCraft Aus]

We use flat d scollop it to the eyes on each end as well when we do them that way.

We also do 50 x 25 RHS onto heavier eyes, and with bolt in high quality uniball diff end, so bush stops any noise back to chassis, to allow the flex of the arm more readily.

The angle welded on would actually be stronger if one flat was horizontal, and the other vertical.

 

[Adventure Teq]

Don't go overthinking this simple mod.

But what else do we have to do?

Good to see a closeup of it and hear it was a 30 minute job. Nice job.

 

[e9999]

I can see the bit about the angle being stronger "vertically" but there is something appealing about sliding on a knife's edge on the rocks....

 

[LandCruisers4Life]

Would welding weaken the control arm????

No, not if you just let it cool off on its own. Don't ever throw water on a weld !

Zane take your other pics before you paint everything BLACK.... can't see a thing except your welds (which look passable). Good job!

 

[Taildragon]

Time to update the sig! Nice work Z

 

[Skidoo]

A lot of folks also reinforce the front mount when they do the tube. A 3/8" plate is welded to front face of mount. There is a vertical weld seam in middle of face so you end up with thick welds. If you have access to a hydraulic press, plate can be given a slight bend to give it a great fit. A welding shop near me did welding , supplied steel for plate and tube all for $85. For tube they used 1" angle steel 1/8" thick.
A couple of photos.

dQyRl

 

[Zane]

Adding some steel to the control arm hanger is the perfect next step for me in this project. As I understand it the hangers get hung up on stuff really easily and tend to be the thing that gets beat up fairly bad.

 

[Zane]

Well, I did my drivers side control arm last night and I hate to say it, but my wife and I couldn't find our digital camera to take all the pictures that I wanted to for this write up. Sorry guys...

I did take a few pictures of the control arms before paint with my BlackBerry. Not the best pictures, but I think you get the idea along with the other pictures Skidoo posted up.

I also used 1" angle at 1/8" thick. When removing the control arms you will want to loosen the bolts from the NUT end, not the bolt end. Jack the rig up from the rear axle, support the frame with jack stands and lower the axle back down so the tire is resting back on the ground. I chalked the tires and set the emergency brake. Once nut and washer are removed the bolt slipped out and control arm easily drops out.

 

[hoser]

Zane, you asked about the torque spec for the lower control arms fasteners. FSM says 110 ft/lbs on the nut. Be advised, the FSM also says the nut itself is a non-reusable part.

 

[Zane]

Zane, you asked about the torque spec for the lower control arms fasteners. FSM says 110 ft/lbs on the nut. Be advised, the FSM also says the nut itself is a non-reusable part.

AHHHH good to know! I will order up 4 new nuts today. Thanks for the torque specs. I was guessing it was 100 ft/lbs so I was not too far off. I will tighten up tonight and then replace the bolts once they come in.

Thanks Hoser!

 

[hoser]

The FSM directly points to the nut itself as non-reusable but I'm not sure if that also means the bolt has to be replaced. Of course, it would be best to replace both but I'd still like to know the correct interpretation of the FSM.

 

[Trunk Monkey]

That's because of those hash marks that "lock" the bolt in place. I've reused them on front control arms, but also know of one person that had one back out, but he'd reused it a few times.

 

[hoser]

So, you are saying just the nuts need to be replaced and not the bolt nor washer?