Miter vs Bend

[slvrbullet]

Hello All,

I'm working on a suspension project that I will need to put a bend or angle into one of the arms to clear the frame. Usually I would put a bend but I'm not sure a bend is right in this scenario. I was looking back at some of Dumps old post and noticed he was a fan of miters I also know some other guys are also fans of them

I'm thinking the mitered joint would be stronger in this scenario if I properly cap the tubes and lay down some decent welds. My fear with doing a bend is, the bend weakens the material and the bend is inline with the frame so my fear is the bend could continue to bend over time when the car bottoms out even with bump stops.

Thoughts?

 

[biggjim]

It would depend on where the bend is I suspect. Its pretty popular in the UTV world to build lower control arms as "High Clearance"...We do so with a bend. If and when you do bend 1 its usually further down the line. Also out bend is not on the Load arm/Shock arm

 

[slvrbullet]

This bend would be on the lower A-Arm inner frame pivot of a UTV. The bends near the tire don't worry me to much, but the leverage that inner pivot see concerns me.

 

[biggjim]

This bend would be on the lower A-Arm inner frame pivot of a UTV. The bends near the tire don't worry me to much, but the leverage that inner pivot see concerns me.

Can Am? Our can am arm has a bend real close to the inner rear pivot. So far it has not been an issue. I dont really see any way around it due to the chassis/suspension design.

 

[isdtbower]

Options to test: CroMo/etc. Go up a size in tube? Bend and Heat treat.
Stuff with another tube inside or outside wider than the bend. Fab and heat treat.
If the bend is "slight" stuff inside with 7075-t6+, bend and fab.

 

[43mod]

so lets take this to roll cage joints if you don't mind. a / b pillar to halo miter w proper overlapping gussets . What are the general thoughts on this ?
I am looking for tighter windshield to roll cage ,leading edge of roll cage to roof advantages , possible more head room ,better vision, more room for lights under halo bar, better egress ,and simplicity of build.
My thoughts are it is stronger and better.

 

[slvrbullet]

"Can Am? Our can am arm has a bend real close to the inner rear pivot. So far it has not been an issue. I dont really see any way around it due to the chassis/suspension design."

Yep X3, I looked at it yesterday and I think your right there's really no way around it and I'm not even sure a miter would work in this spot.

 

[slvrbullet]

so lets take this to roll cage joints if you don't mind. a / b pillar to halo miter w proper overlapping gussets . What are the general thoughts on this ?
I am looking for tighter windshield to roll cage ,leading edge of roll cage to roof advantages , possible more head room ,better vision, more room for lights under halo bar, better egress ,and simplicity of build.
My thoughts are it is stronger and better.

I think if the miter joints are done properly and welded right it shouldn't be an issue. In this scenario though I'm wondering if it would be better to build the cage without bends and have everything cut and notched into each other.

 

[Zambo]

"Can Am? Our can am arm has a bend real close to the inner rear pivot. So far it has not been an issue. I dont really see any way around it due to the chassis/suspension design."

Yep X3, I looked at it yesterday and I think your right there's really no way around it and I'm not even sure a miter would work in this spot.

If you're talking about the bend in the lower A-arm itself, you don't need one. Just offset the notch where the arm lands on the tube boss for the bushings. My CT chromoly lowers have no bend at all in this area and they clear.

 

[Ryan Sims]

To bring it around to a general discussion, what are peoples thoughts on the strength of a correctly done miter joint vs a bend? Say on either a 45 degree bend & a 90 degree bend using dom tubing?

 

[43mod]

its not that hard to build a device to test this. A hyd jack can do wonders to supposedly fixed objects.

 

[Zambo]

To bring it around to a general discussion, what are peoples thoughts on the strength of a correctly done miter joint vs a bend? Say on either a 45 degree bend & a 90 degree bend using dom tubing?

I'm not a certified welder or a metallurgist but I'd figure that the more you bend the tube, the weaker it gets. And I'd figure that correctly mitering a joint with an internal bulkhead disc and proper welding technique would be as strong as you can get. But it would also be a ton more work, so you would just have to evaluate the situation.....how strong does it need to be and how much work is involved. And also evaluate the chances that the weld has a flaw which might compromise the joint.

 

[isdtbower]

Typical on main frame tubes, are interior bungs and outer fish plates. They can be done to really increase the strength above the base metals and can be artsy -craftsy also. No reason you couldn't hammer up a fishplate to cover the sides of a round miter...and maybe some straps. All of that is probably why the pro's buy a bender.

Many supercars today are built with straight short tubes and "billet" corner nodes. The welding or bolting to the nodes takes only little stress. That minimizes the heat affected zones and associated heat treating/tempering etc.