1.5x120 DOM ucas bending


Apr 5, 2022
So check this out, I’ve always ass-u-me’d that 1.5 120 DOM should be fine for some upper arms on a more basic front “kit” do you all agree or think it’s a little undersized? We have never seen this happen before so I’ve always figured all is well. Well this dude comes to us and bent one of his arms, so I made him another. He bent it again. I’m kinda thinking the heims are letting it turn into a parallelogram easier than if it was on bushings? Have still made many arms even from 1.25” on lighter trucks with heims and no bad results. Y’all think this is a fluke or do I need to rethink everything? (I already am) looks like it happened from braking forces to me.


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I’m running 1.5” DOM on my truck, going on 10yrs old now. I bent one arm slightly when I lawn darted tough trucks many years ago. Hasn’t gotten any worse though.
Has your boy been standing on the brakes going into whoops/holes?

I don’t think bushings vs Heims effect it much. A bushing will deflect a lot still letting the arm bend imo
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That’s what I’m thinking. The way it’s bent forward like that almost has to have been from braking forces. It’s hard to get the whole story from people though.
Looks like Mr trophy truck driver is mashing the brakes into square edge hits.

“Here’s a new arm, next time you drive stupid, it’ll cost you”

Seriously though, square/boxed sections of the same height are around 1.5 to 2 times as strong in pure bending like that’s seeing.

@michael_gonzalez thoughts?
Is it stronger if it has a sharp bend/miter in it at the same spot though? I’m definitely no engineer. Haha
I had some 1.5 x .120 dom uca bend on my second race truck forward the same fashion. I was also racing and front end was in the air landing on the breaks. Truck was moving probably 15-20 mph with tire stopped and breaks were obviously stronger than the UCA causing it to bend forward. Rebuild with .240 sleeved tubing and never an issue after that. I never considered breaking force being that much but people told me back then the breaking force on UCA is a lot when moving and tire is stopped.
Well, thanks for the replies. It’s really easy for me to start thinking the worst and I don’t like my parts falling. I will have a talk with the owner and tell him his driving style definitely needs some work.
Phrase it as he’s a badass driver and should upgrade to a full race kit so he can drive to his “full potential”
Well, thanks for the replies. It’s really easy for me to start thinking the worst and I don’t like my parts falling. I will have a talk with the owner and tell him his driving style definitely needs some work.

Yeah he drives so fast and awesome he needs a race kit because of people think everyone needs them and king Kong bypasses.
I found some old photos on Photobucket of my old UCA before and after the bend.


The Failure. Landing on the breaks into big holes on a corner made this failure


You can kinda see how I fixed it with 2 bends closer to pivot and the outer uniball tab area. Also these were 1.5" sleeved with 1-1/4" tubing as well so .240 wall thickness.

Yeah. I need to start doing YouTube stuff again and show people how I screw stuff up and how I "fix" it. Everything doesn't have to be perfect to get the trucks done and out in the dirt. If someone said they've never had anything fail they're lying to you.
Installed one of your kits on a customers 88-98 chevy and he bent the frame before anything bent on the kit lol

This guy must be doing something very wrong.
That’s what usually happens, I’m kinda thinking since these chevys have about the shortest spindle of any truck, plus he’s on 37’s and has 4 piston brakes as well… I think those might all be contributing factors. Made him some boxed arms and told him to stop stabbing the brakes when the going gets rough.


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funny enough, I never bent my old 1.5' mild steel upper arms when my truck was still a armed, but I did rip the lower pivot sleeve in half from braking forces, I thought for sure a failure would come from just plain abuse before ever taking into account the braking forces and how they are applied to the suspension.