Rear lower control arm upgrades - good or bad idea? (1 Viewer)

[82SC]

Just thought I’d add these to your list in case you bent your diy LCA. Nice work BTW

Ironman Rear Upper and Lower Control Arm Review plus Panhard Bar. #ABUSED!!!!🤯

I did a "longish" term review on the @Ironman 4x4 USA UCAs a months ago after I put them through the wringer and now Its time for my Rear Lower and Upper Control Arm and Panhard review. If you follow me you know ive had constant issues with bending rear control arms and panhard bars. The rocks...

forum.ih8mud.com

 

[kcjaz]

Put them on tonight.

View attachment 2858610

looks good. looks like there could be interference with RLCA guards on the frame mounts if you ever added those. Probably wouldn't be too hard to resolve though.

 

[turbo8]

looks good. looks like there could be interference with RLCA guards on the frame mounts if you ever added those. Probably wouldn't be too hard to resolve though.

It is close, I think I'll remove about an inch from the length.

 

[kcjaz]

Just thought I’d add these to your list in case you bent your diy LCA. Nice work BTW

Ironman Rear Upper and Lower Control Arm Review plus Panhard Bar. #ABUSED!!!!🤯

I did a "longish" term review on the @Ironman 4x4 USA UCAs a months ago after I put them through the wringer and now Its time for my Rear Lower and Upper Control Arm and Panhard review. If you follow me you know ive had constant issues with bending rear control arms and panhard bars. The rocks...

forum.ih8mud.com

thanks for posting this. I was not aware of this thread. Great real world testing. It does make me scratch my head a bit though. From a geometry point of view the "area moment of inertia" of a solid 32mm bar is about the same as the OEM 34.5 mm tube. So whatever is making the Ironman arm more bend resistant, its not the change to a smaller OD sold bar. This is why people use tubes as they end up being stronger per lb of material. The OD is the big geometry factor. Bigger is better, solid or tube. There are lots of other factors though the actual steel used and overall quality are probably being the biggest.

In the end, @ga12r1 testimonial is pretty good. In the photos of all the carnage of other parts of his truck, the Ironman RLCAs clearly held up, but I don't see a lot of obvious scratches or evidence that they really banged against the rocks either. Its one photo, and I'm not saying he didn't hit them on the rocks but maybe after bending the OEM arms repeated every time he went out, he magically picked better lines after installing the Ironman arms...

 

[turbo8]

thanks for posting this. I was not aware of this thread. Great real world testing. It does make me scratch my head a bit though. From a geometry point of view the "area moment of inertia" of a solid 32mm bar is about the same as the OEM 34.5 mm tube. So whatever is making the Ironman arm more bend resistant, its not the change to a smaller OD sold bar. This is why people use tubes as they end up being stronger per lb of material. The OD is the big geometry factor. Bigger is better, solid or tube. There are lots of other factors though the actual steel used and overall quality are probably being the biggest.

In the end, @ga12r1 testimonial is pretty good. In the photos of all the carnage of other parts of his truck, the Ironman RLCAs clearly held up, but I don't see a lot of obvious scratches or evidence that they really banged against the rocks either. Its one photo, and I'm not saying he didn't hit them on the rocks but maybe after bending the OEM arms repeated every time he went out, he magically picked better lines after installing the Ironman arms...

Maybe it was the extra 1.25mm of clearance that got him over the rocks without contact.

 

[ga12r1]

thanks for posting this. I was not aware of this thread. Great real world testing. It does make me scratch my head a bit though. From a geometry point of view the "area moment of inertia" of a solid 32mm bar is about the same as the OEM 34.5 mm tube. So whatever is making the Ironman arm more bend resistant, its not the change to a smaller OD sold bar. This is why people use tubes as they end up being stronger per lb of material. The OD is the big geometry factor. Bigger is better, solid or tube. There are lots of other factors though the actual steel used and overall quality are probably being the biggest.

In the end, @ga12r1 testimonial is pretty good. In the photos of all the carnage of other parts of his truck, the Ironman RLCAs clearly held up, but I don't see a lot of obvious scratches or evidence that they really banged against the rocks either. Its one photo, and I'm not saying he didn't hit them on the rocks but maybe after bending the OEM arms repeated every time he went out, he magically picked better lines after installing the Ironman arms...

Yeah, I dunno. Ive been wheeling them for the better part of a year now. Moab again in August, and about 5 more trips to Windrock, plus some front range and San Juan action in Colorado. They are still going strong. As far as obvious damage theres really only a thin deep scar running down the bottom of the arms. I guess cause they are round?

Edit: I went out and dropped and arm to check. They have been through hell but sure don’t show it.

 

[kcjaz]

I finally found some time to do the math on @turbo8 bolt on skid design. His skid design does add significant stiffness to the stock RLCA. My calculations say that the stock RLCA plus the skid is about 2.5 times as stiff as the stock RLCA by itself. That's about the same increase in strength against bending as the traditional sleeving method or the beefier aftermarket options. Given that is a bolt on, it seems like a good solution.

 

[RET2]

I'll stick with the stock ones, easier to replace than mounts or frame damage.

 

[ga12r1]

I'll stick with the stock ones, easier to replace than mounts or frame damage.

It gets old replacing stock arms every time you wheel.

I can’t see a stronger arm cause frame damage. If you are somewhere where that could happen you are probably gonna have a lot more to worry about then control arm mounts.

 

[kcjaz]

I'll stick with the stock ones, easier to replace than mounts or frame damage.

While anything is possible and there is truth in the idea that strengthening one part will potentially make the next weakest link break, in this case I think damaging the RLCA frame mounts by strengthening the arms is unlikely. While I don't know what kind steel Toyota used in thee frame mounts, common low carbon steel has a shear strength of about 40,000 psi. The RLCA bolts are 1/2" diameter (I think) and the thickness of the frame mount plate is about 1/8". The are 2 bolts (one on each end), and two mounting bolt holes per bolt. This means that if you support the truck in the middle of one RLCA (and the three other tires) the load on the arm would be ~2000 (8000/4). That would put 1000 lb on each mount and 500lb on each of the mounting holes. This works out to 500/(.5)(.125)=8000psi which is a lot less than 40,000 psi.

 

[RET2]

That's the beauty of it (so far) we all can do whatever or not we feel like unlike some of the European regulation/limitations. If I want to go boulder hopping I'm not going to take a 4 ton tank.

 

[ga12r1]

That's the beauty of it (so far) we all can do whatever or not we feel like unlike some of the European regulation/limitations. If I want to go boulder hopping I'm not going to take a 4 ton tank.

I hear ya. I bend arms on blues at Windrock. I wouldn't call that boulder hopping, but it is a good possibility I just don’t know how to drive

 

[CharlieS]

I hear ya. I bend arms on blues at Windrock. I wouldn't call that boulder hopping, but it is a good possibility I just don’t know how to drive

I've started to ignore online comments like "should have picked a better line". At least we're out there using our 200s and having fun offroad, regardless of how perfect the line. Something has to give when a several ton object meets an immovable surface like a boulder or ledge. All things considered having it be the LCA is a fairly economical option.

 

[04UZJ100]

While anything is possible and there is truth in the idea that strengthening one part will potentially make the next weakest link break, in this case I think damaging the RLCA frame mounts by strengthening the arms is unlikely. While I don't know what kind steel Toyota used in thee frame mounts, common low carbon steel has a shear strength of about 40,000 psi. The RLCA bolts are 1/2" diameter (I think) and the thickness of the frame mount plate is about 1/8". The are 2 bolts (one on each end), and two mounting bolt holes per bolt. This means that if you support the truck in the middle of one RLCA (and the three other tires) the load on the arm would be ~2000 (8000/4). That would put 1000 lb on each mount and 500lb on each of the mounting holes. This works out to 500/(.5)(.125)=8000psi which is a lot less than 40,000 psi.

Have some commentary. Been a while since I studied Mechanical Engineering…….

- you’re assuming static loads only, not the dynamic loads of the weight of the truck dropping down on a rock etc

- you’re assuming 3 other points of contact which might not be the case

- you’re assuming the 2000# is distributed through the entire circumference of the mounting point when It is not. The load will be focused on one half or less of the mounting hole - due to the nature of the vertical component. For example, I bent my lower link mounts by using a floor jack at that location.

- you can reference the 300 series frame details. It’s likely Toyota uses UHS steel at these mounting locations (>120,000 psi yield strength)

 

[RET2]

I've started to ignore online comments like "should have picked a better line". At least we're out there using our 200s and having fun offroad, regardless of how perfect the line. Something has to give when a several ton object meets an immovable surface like a boulder or ledge. All things considered having it be the LCA is a fairly economical option.

Guess it all comes down to is the juice worth the squeeze?

 

[kcjaz]

Have some commentary. Been a while since I studied Mechanical Engineering…….

- you’re assuming static loads only, not the dynamic loads of the weight of the truck dropping down on a rock etc

- you’re assuming 3 other points of contact which might not be the case

- you’re assuming the 2000# is distributed through the entire circumference of the mounting point when It is not. The load will be focused on one half or less of the mounting hole - due to the nature of the vertical component. For example, I bent my lower link mounts by using a floor jack at that location.

- you can reference the 300 series frame details. It’s likely Toyota uses UHS steel at these mounting locations (>120,000 psi yield strength)

Yes, I made many assumptions. The static load and 3 other points of contact are big ones. When I bent my RLCA, I’m sure I had a front passenger lifted and I was moving (until wasn’t) and I tried over and over.

The 40K psi yield strength was also a low ball assumption adding some conservatism. If Toyota used 120 ksi steel, there is a lot of safety factor built in.

All my analysis is trying to do is sanity check the idea that strengthening the arms will endanger the frame mounts. While the risk isn’t zero, I don’t think that specific risk is very high.

Now, SHOULD you try to take a 4 ton tank bouncing over rocks, is an entirely different question…

What I'm personally doing is just having fun. I like figuring out what my truck can and can not do. I like making the mods and thinking abut how to better protect against the last thing that broke something. I like fixing things that break. Almost all of my mods have be after some kind of mistake or accident. Most of my trail damage has occurred at local off road parks while out with the local club. Most of the rigs in the club are dedicated trail rigs trailered to the park. When rolling with those guys, I find my self in some places that maybe a 200 really shouldn't go. Its fantastic experience that I will be able to use when overlanding when judging "should or shouldn't I". On my last trip out, I got myself out of a self induced stupid situation requiring my winch and rock placement (while being supervised by an ever growing group of ATVs gawking at the stuck SUV on a trail meant for side by sides). I'm learning what I can go through or over and also learning what I can get out of if I judge wrong. So what is my "use case" and what am I modding my 200 to do? I don't really know the exact answer to that question. I'm figuring that out as I go and just enjoying the ride.

 

[CharlieS]

Whether the juice is worth the squeeze is something everyone has to answer for themselves.

I enjoy driving my 200 offroad and seeing other people use their 200s offroad too. I'm consistently amazed at how capable they are, with the main limitation being driver skill (at least in my case). So for me, the answer is yes, it is worth the squeeze, for me.

I also like figuring out what could be improved and am constantly making minor tweaks to improve it for the way I use it. I get bored when I run out of projects (just bought my son a land rover that is keeping me busy lately).

Thanks for posting your experiences @kcjaz . I've been enjoying mine both on and offroad, and I think we may be at a similar point in the learning curve.