Weld on radius arm extensions

[justeveryoneelsesparts]

Hello, need a bit of advice. I purchased a set of weld on radius arm extensions. whoever made these, they appear to be thick Dom tube with a bolt tig welded in one end, these are not the kind that were machined out of a solid piece of stock. they are supposed to slip on the factory arm, not thread on.
My question is, the female end that slides onto the factory arm appears to be too small of diameter to slide over the arm. it appears I need to have someone lathe out the inside of these to properly slide over the arm, so either that's just the expectation or they are made wrong?
Looking to see if anyone has used these in the past and if I am going about this correctly or not?
Thanks

 

[Steve83]

...if I am going about this correctly or not?

No, asking a technical question without posting pics of the problem nor a link to what you bought isn't the correct way to go about this.

 

[DirtDonk]

Yeah, it doesn’t sound like any of the brackets I’m familiar with.
Pictures, or a link to them on a website, would be very helpful.

 

[bigmuddy]

Personally, I never understood taking an old arm which has seen considerable stress and adding a longer leverage point to it. Just seems like a bad idea.
Good time to save up for the Duff arms or similar IMO.

 

[DirtDonk]

While I agree that longer arms are the better solution, I’m not sure I see in my mind how adding a longer mounting bracket adds any stress to the arm itself.
Certainly more potential stress to the frame, and mounting hardware, if not welded, depending upon the input.

But the threaded stem and shank on the arm should actually be under less stress, at least in one form, because now the neutral angle is back to being more natural. No built-in stress from the additional angle imparted by the lift.
Any forces put into the arm from the vehicle weight pushing down, shouldn’t be multiplied by the longer mount, I wouldn’t think.
Is that about right, or am I missing a big part of this?

 

[DirtDonk]

The negatives of using drop brackets are still there.
Less ground clearance
More stress on the frame mounting point.
Changing the angle of the pinion even further, in addition to any C-bushing offset.

 

[bigmuddy]

While I agree that longer arms are the better solution, I’m not sure I see in my mind how adding a longer mounting bracket adds any stress to the arm itself.
Certainly more potential stress to the frame, and mounting hardware, if not welded, depending upon the input.

But the threaded stem and shank on the arm should actually be under less stress, at least in one form, because now the neutral angle is back to being more natural. No built-in stress from the additional angle imparted by the lift.
Any forces put into the arm from the vehicle weight pushing down, shouldn’t be multiplied by the longer mount, I wouldn’t think.
Is that about right, or am I missing a big part of this?

I am assuming he is talking about adding length to the arm itself in an area that usually has corrosion and is quite a bit smaller in relation to the rest of the arm.
While I agree I can see that it's possible to have less stress if the arm is lowered I frankly still don't see it as being very safe over the long term but maybe that's me being overly conservative?

 

[DirtDonk]

Ahh, lengthening the stock arm! Duh!
I was completely off the rails with my comment then. My first instinct was extensions on the radius arm brackets. That was what my comments about stress were based on.
And also why I couldn’t understand what the heck kind of a bracket they were talking about!
Given the original description, they would’ve been some pretty funky radius arm drop brackets!
A description that was obviously about extending the radius arms!
Disregard my previous comments!

 

[Steve83]

...an old arm which has seen considerable stress...

Stress doesn't accumulate over time. If the arm had ever been stressed to failure, it would have failed then - not decades later. If the stress wasn't high enough to deform the arm, then it was insignificant/irrelevant.

...adding a longer leverage point to it.

The radius arms aren't levers; they're struts (loaded axially only).

...I frankly still don't see it as being very safe...

It's not. The suspension is critical to the brake & steering systems, so it shouldn't be modified without GOOD engineering & installation.

 

[bigmuddy]

Stress doesn't accumulate over time. If the arm had ever been stressed to failure, it would have failed then - not decades later. If the stress wasn't high enough to deform the arm, then it was insignificant/irrelevant.

The radius arms aren't levers; they're struts (loaded axially only).

It's not. The suspension is critical to the brake & steering systems, so it shouldn't be modified without GOOD engineering & installation.

Well considering I have spent a lifetime of looking at infrastructure that is in progress of being stressed and has yet to fail. But given enough time, loading and or environmental conditions they will eventually fail and yes it may even take a decade to do it.
I will respectfully disagree on stress not accumulating over time.

 

[Steve83]

...I have spent a lifetime of looking at infrastructure that is in progress of being stressed and has yet to fail.

You're comparing things that were very precisely engineered to balance strength, weight, available assembly techniques & equipment, cost, & other factors against things that were simply overbuilt to avoid all those calculations. Yes, a bridge accumulates stress because it's so close to failure all the time. But not a pre-finite-element-analysis truck part. It's never so close to failure that stress fractures appear & grow. My assertion was only within the context of this discussion - not everything everywhere ever.

 

[bigmuddy]

You're comparing things that were very precisely engineered to balance strength, weight, available assembly techniques & equipment, cost, & other factors against things that were simply overbuilt to avoid all those calculations. Yes, a bridge accumulates stress because it's so close to failure all the time. But not a pre-finite-element-analysis truck part. It's never so close to failure that stress fractures appear & grow. My assertion was only within the context of this discussion - not everything everywhere ever.

Its applicable to both. All items manufactured have a calculated stress over time until potential failure.
While there are plenty of bridges, over passes, structures in general that are failing are degrading as we argue there are plenty that are not remotely close to failure. Same with automotive parts.

Bridges are not close to failure at all times, I don't even know what to say about that comment.

Me thinks you just like to argue?

 

[Steve83]

Me thinks you just like to argue?

Me thinks I'm not the only one. How many automotive suspension parts fail when hit by an object with 1/1000 the mass of the vehicle? And how many bridge members fail when hit by something (like a truck) with ~1/1000 the mass of the bridge? That's what I mean by "close to failure". Modern bridges are being designed with more redundancy, but MANY old ones will collapse & have collapsed when 1 member is bent or broken. Automotive suspensions - not so much. Not even automotive suspensions with millions/billions of stress cycles &/or amateurish modifications. That's what I mean by "doesn't accumulate". Can you argue that? I'm sure you can. But it won't change the fact that the OP hasn't come back to this thread, so we're both just killing time.

 

[SDlivin]

Classic Broncos .com - Tech: Longer Radius Arms for 66-77 Early Ford Bronco https://share.google/1L23SjAF5ak4zRZa8

 

[SDlivin]

Use an angle grinder with a metal sanding disc, clean up the imperfections on the stock arm, take off just enough material so you can pound on the extension and then weld it up.