Rear lower control arm upgrades - good or bad idea?

[bloc]

I would just find the right size spacer and push that bushing out before the welding. Visible damage like that is definitely going to impact durability.

 

[audyssey]

Will be on the list of things to watch. This is definitely out of my normal comfort zone of things I've done before, but half of the fun of learning is making mistakes.

 

[kcjaz]

Yes, there was a little bit of heat damage. Should have slowed down and let them cool, but we were being impatient. We'll see how long those bushings hold up.

where did you cut the OEM arm? In my head, cutting near the frame end is better and if you're going to weld on the ends anyway, just cutting an end off then sleeving seems like the way to go. If you are not going to remove the OEM bushings, cutting closer to the frame end would at least put the cut in a place that isn't the middle of the arm where it is likely to bend but you still need the arm to work in tension so the sleeve has to have enough spot welds to accomplish this.

 

[turbo8]

With a 20 ton press, I couldn't press the stock bushings out. I had to cut them out. Febest makes aftermarket oem replacement bushings. I do not know how long these will last.

 

[CharlieS]

where did you cut the OEM arm? In my head, cutting near the frame end is better and if you're going to weld on the ends anyway, just cutting an end off then sleeving seems like the way to go. If you are not going to remove the OEM bushings, cutting closer to the frame end would at least put the cut in a place that isn't the middle of the arm where it is likely to bend but you still need the arm to work in tension so the sleeve has to have enough spot welds to accomplish this.

With all of the people that have done this, I think there would be more cautionary tales if it didn't work. One of our metallurgists could probably provide good information, but I suspect that the sleeve takes over the responsibility for rigidity and resistance to bending, and the cut stock part is mostly for alignment.

Also, if you take your time and stitch then let cool, rotate the part, stitch then let cool, etc., I suspect you can weld the circumference without putting a lot of heat into the bushing.

A continuous bead is bound to put a ton of heat into the workpiece.

I've done the stitch technique with seam welding a vehicle and that worked great to minimize the amount of heat in the work piece.

 

[kcjaz]

With all of the people that have done this, I think there would be more cautionary tales if it didn't work. One of our metallurgists could probably provide good information, but I suspect that the sleeve takes over the responsibility for rigidity and resistance to bending, and the cut stock part is mostly for alignment.

Also, if you take your time and stitch then let cool, rotate the part, stitch then let cool, etc., I suspect you can weld the circumference without putting a lot of heat into the bushing.

A continuous bead is bound to put a ton of heat into the workpiece.

I've done the stitch technique with seam welding a vehicle and that worked great to minimize the amount of heat in the work piece.

Yes, I agree that the cut in half the sleeve must work. It for sure results in an arm that is stronger than the OEM one. All I am saying is that cutting it means you are now only relying on the sleeve to resist bending, at least at the point of the cut. If you can sleeve it and end up with the ORM tube and the sleeve welded to the bushing housing then you get the strength of both tubes. Do you need that and is it worth the effort? IDK but over engineering to me is like mud to a pig. I like it.

 

[audyssey]

I followed the same steps for sleeved RLCAs on the 100-series forum where the instructions were to cut in half, then wield the 6 holes on each half with pools (12 total per RCLA) and then a complete bead across the top. We were too eager to get it done quickly on completing the bead and not allowing for anytime for the bushing end to cool. If I were to do it again, I would try to see if doing half the bead, then waiting for the end to cool down before completing would have prevented bushing damage.

The original RCLA bushings had 11years and almost 200K. What symptoms would a bushing failure present for RLCAs? What do I need to look for?

 

[bloc]

, but I suspect that the sleeve takes over the responsibility for rigidity and resistance to bending, and the cut stock part is mostly for alignment.

This exactly. Dom especially will be much stronger than the stock stuff, and eventually you do approach the point where you transfer the forces to less robust parts of the system.

Cutting in the center keeps the weld from the stock tube to the end intact, and this plus the new weld from the sleeve to the end does a great job of preventing shear forces.. like when you set the truck down on the link near the frame end. Then you add those to the welds from the holes in the sleeve to the stock tube and have extra tensile strength compared to stock.. not that that is much of an issue.. other than cutting the stock tube into two pieces anyway.

With a 20 ton press, I couldn't press the stock bushings out. I had to cut them out.

It stalled the press? Or was it an issue of being able to get forces applied to the thin edges of the sleeve?

The fact that new ones go in to the same location makes me wonder if Toyota crimps or glues the stock ones in place.

 

[landtank]

I stumbled on this thread by chance and thought I would reply. I offer very stout lower control arms for the 80 and 100 series truck. They have over sized ends to help protect the frame and axle mounts and are made with 1.5" solid rod. The 100 series arms might work depending on the bolt size, bushing width and the arm's length. If they don't and somebody is interested in working with me to help me with the specs I need, I could make some.

 

[kcjaz]

So I went down the engineering rabbit hole and did some math (while digesting turkey) on different methods of stiffening a RLCA.

The resistance to bending is based on the strength of the material and the cross sectional area and shape of a member. The term for the geometry part is Area Moment of Inertia (I). You can calculate this for different shapes and axes. If you are interested in the math, there are many online calculators that allow plugging and chugging or give you the formulas for basic shapes. If you are a real geek, you can do the calculus to develop the equations but I digress... I put some references below for those interested.

The table below shows my results:

	OEM Tube	OEM Tube	Solid Round Bar	Solid rectangle	Larger DOM tube (Sleeve)	Larger DOM tube (Sleeve)	OEM Tube
OD/h	1.3563​	1.3563​	1.3563​	1.3563​	1.7500​	1.7500​	1.3563​
ID/w	0.9813​	0.9813​		1.3563​	1.3740​	1.3740​	0.9813​
Ix	0.121​	0.121​	0.166​	0.282​	0.285​	0.285​	0.121​
Relative I	1.0​	1.0​	1.4​	2.3​	2.4​	2.4​	1.0​
Additional bar added to bottom
h	0.5​	0.25​			0.25​	0.5​	0.5​
w	1.75​	1.35​			1.75​	1.75​	1.25​
I	0.018​	0.002​			0.002​	0.018​	0.013​
d (A2 distance from RLCA axis)	0.928​	0.803​			1.000​	1.125​	0.928​
Axis adjustment (A2D^2)	0.754​	0.218​			0.438​	1.107​	0.538​
Ix	0.893​	0.340​			0.725​	1.411​	0.672​
Relative I	5.4​	2.0​			4.4​	11.7​	4.0​

Conclusions:
1. The "sleeve" method results in a RLCA that is 2.4 times stiffer than the OEM RLCA and so are the aftermarket tube designs that use 1.75" 0.188 DOM tubes.

2. Welding a 1/4" thick x 1.35" flat bar to the bottom od the OEM tube would give you 2x stiffness. Make it 1/2" x 1.75" wide and you get 5.4x. Conceptually, you could probably make something 10x if you wanted to.

Welding a flat bar to the OEM tube would seem easier than sleeving. For grins, I also did the math on welding angle to the OEM tube. Using a 1.5" x 1.5" angle welded to the OEM tube results in 2.7x stiffness. Seems like the old guys back in the day had this right and I'd bet they didn't do any math...

Disclaimer: no guarantee my math is correct, if anyone is so inclined, please check my math.

Here's a good video on the topic.


And here is a calculator site:

Second Moment of Area Calculator

 

[kcjaz]

just called Olathe Toyota parts. Its as I thought, you can not buy OEM bushings for the 200 RLCAs. You have to buy the complete arm. I may try to press out one from my bent arm but suspect it is crimped and won't press out.

 

[turbo8]

It appears Whiteline has bushings for the 200 series coming out soon.

If these were available a couple months ago I would have purchased them.

I used Whiteline bushings on my 4runner and don't have any complaints after 3 years. They ride well, no noise, and flex as good as stock bushings.

 

[turbo8]

Got my parts for my lower arms.

 

[kcjaz]

Got my parts for my lower arms.

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Very nice! If you can provide the detailed dimensions for the “skid plate”, I’ll run some numbers on the area moment of inertia/ section modulus. My guess is your design is stronger against bending that the typical sleeve approach.

Also stainless is a good choice for general rusting caused by scrapes on rocks but 304 is not so great against chlorides (salt). 316 is better for that. If you are in the rust belt, you may want to paint the skids. If chloride attack happens, it will show up as pitting on the surface.

 

[turbo8]

Very nice! If you can provide the detailed dimensions for the “skid plate”, I’ll run some numbers on the area moment of inertia/ section modulus. My guess is your design is stronger against bending that the typical sleeve approach.

Also stainless is a good choice for general rusting caused by scrapes on rocks but 304 is not so great against chlorides (salt). 316 is better for that. If you are in the rust belt, you may want to paint the skids. If chloride attack happens, it will show up as pitting on the surface.

Yeah, that would be cool. I'll PM you the exact dimensions tomorrow and send you a set for your own, for your work. Good info on the material choice. I live in the desert so no rust issues for me.

 

[Tex68w]

You should definitely sell these once you've figured out the proper material.

 

[dusty2]

i did the same thing with my 80 series LCAs years ago. go slow with the welder around the bushings and they wont get smoked.

That said i have changed the front radius arm bushings on an 80 and the job can be done with a 20 ton harbor freight press

Why not just tack weld some 1 inch by 3/8 wall angle on the bottom of the LCA and be done? i have seen that work very well.

 

[kcjaz]

Why not just tack weld some 1 inch by 3/8 wall angle on the bottom of the LCA and be done? i have seen that work very well.

Agreed. my math exercise convinced me that welding on some angle is the easiest fix and is stronger than sleeving. I think that given bending one isn't typically a catastrophic situation and that I carry a spare just in case, I may just do that. First though I want to do the beam stress math to see how strong you really need or could easily build. I think it is possible to build a RLCA that could support the weight of a rear corner in the middle of the arm, without bending, for less money than the aftermarket arms. I'm just curious to how "bullet proof" you could make it.

 

[RET2]

KISS solution

 

[turbo8]

Put them on tonight.