Axle truss tech

[Oddball]

Maybe I havent searched hard enough, but I'm not finding answers to my questions regarding the ins and outs of an axle truss. I see the aftermarket make nice looking blingie units. But to me, it seems like the designer was an expert in CAD and not fabricating or wheeling ( just my asshat opinion ) What I want to know is why the truss doesn't extend to the yokes (Cs). Instead, they terminate to a place that is difficult to weld, right before the yoke. Secondly, They are not exactly "light weight" although advertised as such. I feel like thinner material could be used to acheive nearly the same ridgidity. A D60 is already a heavy unit, does it actually need a 1/4 boxed truss its full length? I'm building a custom axle, so a custom truss will be in my future. Edit looking again, I see there are 3/8s top plate 1/4 side and 1/4 top plate 3/16 side versions. I was thinking about possibly going even lighter.

 

[gt1guy]

The axle truss has only one job.....to help keep the axle from bending.

I tried to run mine out as far as I could to the ends of the axles. Which for me was tying into the C's in front and into the actual spindles on the rear.

Also went with the boxed type out of 1/4" rather than the style that looks like a "T" sitting on top.
I don't like the "T" style. To me it's putting all it's strength into a narrow line down the top of the tube. The box style has twice as much vertical material that is tied into the tube just above 3&9, so it's parallel with the wall thickness.

That was my thought process for the trusses anyway. Ive had retarded thoughts before though. So, interested to hear what others say.

 

[Oddball]

I'm wondering if I can get away with 1/8th verticals and 3/16ths cap. With a little more internal ribbing like a roof truss. I'm not an engineer, but I do know some guys on here are well versed in structural mathmatics/ fabrication.

 

[AgitatedPancake]

It's hard to have a one size fits all blanket statement about the strength of stuff like this, when you can be talking to someone with a 3k lb 150 hp moon buggy and someone else with a 6k lb 1000 hp behemoth in the same breath. And IMO, that is one of the reasons that most aftermarket options we have are as heavy as they are. Everyone is going to hear about the one that breaks under the extreme rig, but not many are going to complain about the one that weighs a few lbs extra.

That being said, depending on your application I think a 3/16" top with 1/8" sides as you noted would probably be sufficient. I've built a handful out of all 3/16" and have been satisfied with the outcome. Also agreed with you and gt1 about making the truss as wide as possible, no reason to leave a bottleneck right at the end if you can avoid it.

Also I think gt1s point about box style being superior to T style needs to be said again. Not just for the stress he describes, but the fact that you are guaranteed to curl your axle tube as you weld that top seam with a T style, it's inevitable. With a box truss landing near 3 and 9 on the tube, the heat input balanced between the front and rear of the tubes balance out and minimize warping a ton IMO.

You can make them prettier than these, but I just decided to keep them simple and sealed

 

[WaterH]

I'm wondering if I can get away with 1/8th verticals and 3/16ths cap. With a little more internal ribbing like a roof truss. I'm not an engineer, but I do know some guys on here are well versed in structural mathmatics/ fabrication.

I’m sure it could be engineered. The problem with 1/8th in my eyes, is a little bit of rust pitting and you don’t have any strength left. Also, even a good strong log could bend 1/8” steel if you hit it right.

 

[Treefrog]

I'm not as informed as many of the guys here, but the style the uses an upper tube with shorter tubes connecting to the axle tube always seemed like a good approach to me, especially on the front axle.

 

[Sean]

It's hard to have a one size fits all blanket statement about the strength of stuff like this, when you can be talking to someone with a 3k lb 150 hp moon buggy and someone else with a 6k lb 1000 hp behemoth in the same breath. And IMO, that is one of the reasons that most aftermarket options we have are as heavy as they are. Everyone is going to hear about the one that breaks under the extreme rig, but not many are going to complain about the one that weighs a few lbs extra.

That being said, depending on your application I think a 3/16" top with 1/8" sides as you noted would probably be sufficient. I've built a handful out of all 3/16" and have been satisfied with the outcome. Also agreed with you and gt1 about making the truss as wide as possible, no reason to leave a bottleneck right at the end if you can avoid it.

Also I think gt1s point about box style being superior to T style needs to be said again. Not just for the stress he describes, but the fact that you are guaranteed to curl your axle tube as you weld that top seam with a T style, it's inevitable. With a box truss landing near 3 and 9 on the tube, the heat input balanced between the front and rear of the tubes balance out and minimize warping a ton IMO.

You can make them prettier than these, but I just decided to keep them simple and sealed

Those two are super clean. Great job!

 

[AgitatedPancake]

Those two are super clean. Great job!

Thanks man. I know the D30 one is less pretty because it has even less shape to it, just a box . WJ's just happen to have super tall coil buckets that aligned well with the UCA, pumpkin, and sway bar height, so I gave it what it wanted and just ignored the aesthetics lol. Once the steering is in place the truss hides itself pretty well like the other one though.

Also offers another nice opportunity, if you're coil sprung with a tall coil mount and OTA track bar, you can tie the coil bucket into a raised track bar mount for tons of added rigidity. Though that's probably more a niche thing that won't apply to most in this thread

 

[Oddball]

It's hard to have a one size fits all blanket statement about the strength of stuff like this, when you can be talking to someone with a 3k lb 150 hp moon buggy and someone else with a 6k lb 1000 hp behemoth in the same breath. And IMO, that is one of the reasons that most aftermarket options we have are as heavy as they are. Everyone is going to hear about the one that breaks under the extreme rig, but not many are going to complain about the one that weighs a few lbs extra.

That being said, depending on your application I think a 3/16" top with 1/8" sides as you noted would probably be sufficient. I've built a handful out of all 3/16" and have been satisfied with the outcome. Also agreed with you and gt1 about making the truss as wide as possible, no reason to leave a bottleneck right at the end if you can avoid it.

Also I think gt1s point about box style being superior to T style needs to be said again. Not just for the stress he describes, but the fact that you are guaranteed to curl your axle tube as you weld that top seam with a T style, it's inevitable. With a box truss landing near 3 and 9 on the tube, the heat input balanced between the front and rear of the tubes balance out and minimize warping a ton IMO.

You can make them prettier than these, but I just decided to keep them simple and sealed

Thanks for the info and examples. I think your logic is spot on, welding at 3 and 9 is best. I like the sealed up look and will work to make mine like yours. The axle is a 06 sd60, the truck is a 90 yota with 5.3.