Offroad Trailblazers and Envoys

Custom Upper Control Arms

Any special projects involving a decent amount of fab work (bumpers, sliders, roof racks, etc)

by bartonmd » Sun Jan 12, 2014 5:54 pm

JamesDowning wrote:
bartonmd wrote:Cool! Is 1/2" stronger the weak direction than the factory box construction?

I wasn't worried about that direction and never did the math. The area right near the pinch plate is much stronger than the neck down, but as you get a little closer to the coupling nuts it might be closer to equal. Not sure. Its something i'd have to FEA to really tell you, and I'm not going to put the time into modeling the stock UCA.


Yeah, I wouldn't be really worried about it, but was just curious if you'd done the FEA.

JamesDowning wrote:
bartonmd wrote:Also, no way, no how, would I take on the liability for making suspension pieces, even with the REAL business insurance that I already have, that costs $2k/year. Making a spring spacer or something is one thing, but something that if it breaks, involves the suspension coming apart and a loss of control, no thanks!

I kinda figured. There's a lot more risk with suspension stuff...


Yep. Even rear end stuff is different than front end stuff...

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by ErikSS » Sun Jan 12, 2014 6:51 pm

Looks great James! I'm just wondering if a U shaped 1" wide piece of 7 gauge welded on end to the top of them would reduce any risk of bending.

Sorry, I'm not sure how else to explain what I'm picturing. I'm thinking on it's side, to create vertical bending resistance.
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by DustinC1989 » Sun Jan 12, 2014 7:13 pm

ErikSS wrote:Looks great James! I'm just wondering if a U shaped 1" wide piece of 7 gauge welded on end to the top of them would reduce any risk of bending.

Sorry, I'm not sure how else to explain what I'm picturing. I'm thinking on it's side, to create vertical bending resistance.


I understand what you're saying, seems like it would prevent any flex and strengthen it even more.

But I'm not a engineer. ..
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by The Roadie » Mon Jan 13, 2014 12:15 am

Think about the stresses put on the Uca. Fore and aft. In and out.

There isn't any resistance to up and down. No need for a vertical web.
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by Trail X » Mon Jan 13, 2014 12:31 am

Thanks for the thoughts Eric. I'm really not worried about it. The only bending put into the plate is from the slight moment arm of the ball joint, and the strength against bending of my new arm is much stronger than the ball joint rod/stud. So if something were to fail, the ball joint rod would break before the UCA ever will. I haven't ever heard of one of the ball joints breaking on these trucks, so I see no real reason to design any more strength into the arm.

And Mike, yeah, I agree. The rear end arms are simple compression and tension, not cyclic bending on 2 axis.
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by The Roadie » Mon Jan 13, 2014 12:52 pm

The lowered guys with the misdesigned DJM arms were breaking ball joint shafts, but only because they were binding up and had to withstand bending stresses.

When Greg lost his UCA ball joint mount, the pinch section casting broke.
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by HARDTRAILZ » Mon Jan 13, 2014 12:58 pm

Other than greg have there been other failures. I could not recall or find any.
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by mikekey » Mon Jan 13, 2014 1:31 pm

Mario was the only other person I could find, but from the looks of his photos, I'd say rust + time did his in.

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by Trail X » Mon Jan 13, 2014 1:48 pm

The Roadie wrote:The lowered guys with the misdesigned DJM arms were breaking ball joint shafts, but only because they were binding up and had to withstand bending stresses.

Hm, I don't think I had heard of that. What was the design flaw by DJM? And why/how did the people installing the arms not notice the issue?

mikekey wrote:Mario was the only other person I could find, but from the looks of his photos, I'd say rust + time did his in.

Well rust and time can't be the only factors, a force of some sort has to actually break it. But your point is that, maybe if it's properly coated against rust that it might survive the beatings we give it? I don't know, hard to tell. The really strange thing though, is that both failures were on flat road, not off road. Which, to me, means its gotta be a long term fatigue failure, and they were really just lucky enough to not have the failure at high speeds or deep off road.
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by mikekey » Mon Jan 13, 2014 2:09 pm

mikekey wrote:Mario was the only other person I could find, but from the looks of his photos, I'd say rust + time did his in.

Well rust and time can't be the only factors, a force of some sort has to actually break it. But your point is that, maybe if it's properly coated against rust that it might survive the beatings we give it? I don't know, hard to tell. The really strange thing though, is that both failures were on flat road, not off road. Which, to me, means its gotta be a long term fatigue failure, and they were really just lucky enough to not have the failure at high speeds or deep off road.[/quote]

My assumption was that it may have been a contributing factor. But the same can't be said for Greg based on the photographic evidence presented.

I'd often wondered about the DJM arms, I know Norcal SS was modifying them for the lowered guys

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by NC_IslandRunner » Tue Jan 14, 2014 12:56 am

Would they be stronger if you just cut them out of a single piece of steel and powder coated it? save on buying the Johnny Joints and no welds that can break?
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by DustinC1989 » Tue Jan 14, 2014 2:05 am

NC_IslandRunner wrote:Would they be stronger if you just cut them out of a single piece of steel and powder coated it? save on buying the Johnny Joints and no welds that can break?


Without the Johnny Joints, they wouldn't be adjustable.
But even then, it seems like there would have to be welding no matter what because you would still have to have the connector for the ball joint.
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by Gordinho80 » Tue Jan 14, 2014 6:31 pm

Amazing! Good to finally see it all together! Great job!!!
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by Trail X » Tue Jan 14, 2014 9:11 pm

NC_IslandRunner wrote:Would they be stronger if you just cut them out of a single piece of steel and powder coated it? save on buying the Johnny Joints and no welds that can break?


Like make the whole thing 1" plate? 3 issues I see with that.

1: it would be very heavy, as is each side prob weighs 15 lbs. Solid 1" plate would easily double that
2: you still have to weld on some sort of mounting bushing to the plate. You can't just have a hole drilled in that a bolt goes through.
3: the pinch plate is welded on separately so the angle can be set on two axis, to make the ball joint angle correct. If it was 1 solid flat plate, it would likely be off more than the stock arms are, maybe slightly better.
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by Trail X » Tue Jan 14, 2014 9:14 pm

mikekey wrote:I'd often wondered about the DJM arms, I know Norcal SS was modifying them for the lowered guys



Wow, I hadn`t seen that picture before. Looks like the pinch plate bore wasn't the right bore, or they didn't use a thick enough plate for the pinch. I'd like to know what norcal ss was doing to modify those arms.
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by mikekey » Tue Jan 14, 2014 9:18 pm

JamesDowning wrote:Wow, I hadn`t seen that picture before. Looks like the pinch plate bore wasn't the right bore, or they didn't use a thick enough plate for the pinch. I'd like to know what norcal ss was doing to modify those arms.


According to himself:
Here's the difference compared to regular DJM a arms
Arms will be notched to clear the spindle area.
Balljoint hole will be drilled for a 7/16 sized grade 8 bolt and nuts/washers included (this depends on holes drilled from djm if stock bolt will fit in there snug will not need to be drilled for bigger bolts)
All zerk threads will be checked.
Bushing sleeve fully drilled.
Balljoint hole area cleaned for easy fitment.
4 zip ties included to strap brake sensor line on top of a arms.
Over past 6 years not 1 arm has failed.
Bolt in deal nothing to modify check or buy.


Source: http://gmtnation.com/f75/djm-modified-u ... eeded-399/
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by Trail X » Tue Jan 14, 2014 9:50 pm

Very odd... sounds like the UCA was actually hitting the knuckle?
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by dvanbramer88 » Tue Jan 14, 2014 10:17 pm

Image

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by Trail X » Tue Jan 14, 2014 11:10 pm

Wow, that is quite a poor design.
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by NC_IslandRunner » Wed Jan 15, 2014 12:57 am

JamesDowning wrote:
NC_IslandRunner wrote:Would they be stronger if you just cut them out of a single piece of steel and powder coated it? save on buying the Johnny Joints and no welds that can break?


Like make the whole thing 1" plate? 3 issues I see with that.

1: it would be very heavy, as is each side prob weighs 15 lbs. Solid 1" plate would easily double that
2: you still have to weld on some sort of mounting bushing to the plate. You can't just have a hole drilled in that a bolt goes through.
3: the pinch plate is welded on separately so the angle can be set on two axis, to make the ball joint angle correct. If it was 1 solid flat plate, it would likely be off more than the stock arms are, maybe slightly better.


A friend of mine said he could make it in one piece with bushings, or with adjustable johnny style joints but the pinch plate would be build it and cut at the angle you wanted, the whole thing wouldn't be 1" thick. I knew he had a shop that customized cars and truck for show, but I just found out he bought another shop that builds custom suspensions. If I thought it was worth it I'd put him to making a long travel suspension but a SAS would be cheaper than a full custom IFS, plus my wife would kill me!
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