I really like the support your giving the axle. I hope it works for you. I have one question to ask. 

The picture of the support were its lying on the vise you have a bolt with a spacer. When mounted on the rpod you just have the holes without a bolt. Why are the holes in the support?  Thanks for sharing.

Looks great so far though. 

Were you able to get the axle recambered? Was the axle tube being bent the only issue you found?

Thanks

How do you intend to attach this to your axle? I don't see enough space on it for U bolts. Drilling through it and bolting would work since the place where it would attach would be the same place that the internal part of the axle would need to move for your suspension to work. Even drilling and using short screws would not work since the screws would also very likely interfere with the internal movement of the axle. Welding it to your axle is also not feasible as it would cook the rubber inside that provides your suspension support. The slideshow on the Lippert page shows what a cross-section of the axle looks like in the 5th and 6th slides (see dots below picture).

https://www.lci1.com/torsion-axles#about - https://www.lci1.com/torsion-axles#about

Edit:

I got to thinking more about this and it might work but it would require modification of your design. In brief, add wings to each side of the bracket and then either use a "V" bolt or fabricate another section of channel with similar wings to the top piece and then use bolts through the wings to attach the bracket to the axle. Here is a line drawing of what I think would work (I don't claim to be an artist):

I disagree. From what I can see, the bracket on the frame has a bolt and the axle bracket has a bolt and there is going to be some sort of jack screw between them. This is not rigid, but will be able to swivel on the hinge bolts. That means that the axle bracket will slide along the axle since it would not be fixed to the axle Toyanvil mentioned bolting to the axle. That is why I offered my suggestion and just edited my prior post to suggest a solution to the problem of how to attach it to the axle so it won't slide.

Originally posted by Toyanvil That's a good guess,  as that is the plan.   I hope to have them welded up tonight after work. My axle has lost it's camber, it is now almost flat with less then an 1/8 inch of arch with no load.

I look forward to seeing how they look after you get them finished. Even if I take the other tactic of using angle iron, I think that welding some tabs for bolting to the axle tube would be a good method to attach the angle to the axle.

Since Toyanvil is planning a pin joint I agree with you, it will want to rotate and the axle attachment needs to be tightly clamped so there is enough friction that it doesn't want to creep outward over time. So there should be a gap between the clamps and the bolts should be torqued pretty tightly. 

In the angle reinforcement approach, I think the u bolts work fine. The u bolts themselves are not in direct contact with the axle and the nut plates are really thick material and a bit over an inch wide. All the forces are vertical so there isn't any tendency for things to creep or move laterally. You are only clamping the parts together, not trying to develop friction to resist a sliding force.

I re-read the posts and realized that you are doing the welding yourself. Nice work! I have a wire-feed welder that I got at Harbor Freight. I'm not sure if it would handle a job like this. I think so, but I will need much more practice before I can do a weld as nice as yours are.

Do you do your own powder coating? Once everything is done, are you going to put some sort of sheet rubber between them and the axle to both pad them and to increase the gripping strength so they would be even less likely to slide and to help keep moisture out?

The coefficient of friction (cof) of steel on steel is about 0.7 so that clamp should develop a sliding resistance of 4 * 8000 * 0.7 = 22000 lbs. The max lateral force on it from a 3g bump load on the axle is going to be something like 5000 lbs if the new support took all the load and the axle tube took none. So you'll have at least a 4x safety factor against sliding. In less technical terms I don't think its going to go anywhere. 

With 11000 lbs on each side of the clamp I do believe you are correct about needing the gussets. I wouldn't recommend putting rubber in between the parts, I doubt the rubber will take that much compression and the cof of steel on rubber is about the same as steel on steel anyway, so it won't really improve things. 

Here's a couple useful links if you want to look at the numbers:

https://www.engineeringtoolbox.com/bolt-torque-load-calculator-d_2065.html - https://www.engineeringtoolbox.com/bolt-torque-load-calculator-d_2065.html

https://www.engineeringtoolbox.com/us-bolts-tensile-proof-load-d_2066.html - https://www.engineeringtoolbox.com/us-bolts-tensile-proof-load-d_2066.html

https://www.engineersedge.com/coeffients_of_friction.htm - https://www.engineersedge.com/coeffients_of_friction.htm

Toyanvil: I guess I figured out how you came up with your user name.  Nice work on those parts. They look really nice and so does the completed trailer. Now that leads to the question of what is that car on the trailer?

Offgrid: Thank you for that additional information. It is good to have someone who knows the engineering end of things.

I found your thread on the MX5 Sunbeam build on the Miata forum. Awesome work. Your Sunbeam is the best of both worlds, classic looks but with a real drivetrain that actually runs. I used to drive and maintain Spridgets so I know a bit about crappy post war British drivetrains. The RX7 and MX5 were revelations when they came out, I owned one of each.  I really like that valve cover and airbox.

For you other seniors out there who might not recall, here's the program that made Sunbeams famous:

https:///www.youtube.com/watch?v=Kv3kcnI72Ec - https:///www.youtube.com/watch?v=Kv3kcnI72Ec

It has been a looooooong time since I have seen a "Get Smart" episode. I don't think I ever paid attention to the make of the car he was driving. I did have the opportunity to drive an MGB which was similar in size. It was fun.

Yes, the clamp arrangement is coming along very nicely. It will be very interesting to see the completed job and to hear how well it works.

When you recamber it I'm curious to find out if the shop finds a bend on the axle tubes immediately outboard of the frame attachment points. You axle arch flattening in itself doesn't sound like its really bad enough to cause the negative camber in your photos. 

That is exactly what I want to know. I am no engineer, but it has to be relatively easy to flatten out that tiny arch than to bend the last foot of the axle tube at the frame attachment point. BTW, the welding skills shown in this thread are top notch!

Thanks

Great!! 

What do you think of my suggestion for fabricating the upper brace using an L bracket with the bottom part sitting between the frame and the riser and the top part resting against the frame side (kind of like your design), with the axle mount and the adjustable support being the same as your design?

But, I'd avoid it for a couple reasons. First, the frame rails are really thin, 0.1 inch. Second, if you do twist them you would be really sorry. its one thing to pull off an axle and repair or replace it, much more difficult to do that with a frame rail when the trailer box is attached to it. 

Okay. I see now. The torsional effects of the bracket in your design would be on the riser. I would like to install something to keep mine from losing camber again. In order of difficulty, Offgrid's design is the easiest, Marwayne's is harder and Toyanvil's is the most complex. As for effectiveness, so far, it appears the outboard brackets are very effective. Hopefully, the other two designs will be effective also.

How expensive was it to fabricate the Toyanvil system? It is not something I could do as while I have a wire-feed welder (from Harbor Freight), I don't think it would be capable of making the welds strong enough to not break under the forces they would encounter on the road. I also don't have lathe nor the skills needed to fabricate such a system. About the only system I could do myself would be Offgrid's angle reinforcement.

As I said before, driving a few hundred miles without problems doesn't prove anything one way or the other with any of these fixes. How many miles did you drive on your original axle before you had a problem? And a large majority of rPod owners never have a problem. 

You're trying to determine whether a specific low probability event is reduced or eliminated by a given change. There are 3 ways to do that:

Statistically: hundreds of trailers for thousands of miles with no failures would be required. Not practical.

Experimentally: do a controlled load test with and without the change in place and show that the result is different. Not advisable.

Mathematically: calculate the force required to reach the yield point of the material with and without the change and show that you have increased it substantially. That is how engineering is done. Very practical and well proven, it ain't rocket science. If you don't have confidence in that approach then I'd suggest staying off any steel bridges and out of any steel structure high rise buildings 

So, I chose door number 3. Both mine and Toyanvil's solutions should work fine in reinforcing the axle tube, resulting in at least a 50% improvement. Toyanvil's has a small chance of causing frame twisting that I didn't look at, but I expect it to be minimal. Unfortunately, Marwayne's design does not address the underlying problem for the reasons I've explained. 

Check out the other active thread on axles for a couple of conversations I had with the sales techs at Lippert last fall. Most companies won't let consumers speak directly to their engineering staff, they keep them in the back room and feed them peanuts.  Why? They have nothing to gain except increased liability if the engineer says the wrong thing. 

I slightly object to the implication of the term "real" engineer. I am a real live engineer, worked as one  for 40 years. There are other engineers on this forum as well. We're not all that unusual you know, you could pass us on the street and not recognize us for what we are unless we forgot to remove our pocket protectors. 

That response from the guy at Lippert is exactly why most companies keep their engineers in the back room and feed them peanuts. 

Lippert is the manufacturer who made that axle with that support spacing and its Lippert's label on the axle rating it at 3500 lbs. Not FR's. So Lippert is in the end responsible for fitness for use, they can't claim FR "forced" them to do it. 

I'm speculating but most likely what really happened is that the FR sales account executive at Lippert won the internal argument to accept that order at that price point and that required Lippert's engineering dept to reduce their normal axle load safety factor.  That safety factor is not regulatory as far as I can tell so its whatever they think it needs to be. its not a black and white thing. That kind of thing is very common in manufacturing companies especially ones that service a few large OEM's.  Its the old sales vs. engineering battle and sales usually wins. Duh, the engineers aren't the ones bringing in the cash. 

The safety factor on that axle isn't way off the mark either, looked like around 2.5 to 3x when I checked it, meaning you'd have to have a 2.5 to 3g bump load or around 4000 lbs per wheel to get a failure. That does happen but not commonly.  So while its no consolation to those that have had an axle failure, its not clearly that bad either. The actual failure rate isn't that high or there would be hundreds or thousands of folks reporting axle failures. 

And, axle problems are not by any means limited to rPods. If you do a web search you'll see these kinds of issues and concerns cropping up with many different makes and models of trailers. Weak axles seem to be endemic in the travel trailer industry. 

An interesting project might be to get something like this and stick it to an axle to monitor actual bump loading accelerations. You can get an accelerometer app for smartphones but I'm not going to strap my iphone to my axle.

www.amazon.com/Bluetooth-Accelerometer-Triple-Axis-Acceleration-Transducer/dp/B01MRPKDV9/ref=sr_1_1_sspa?gclid=CjwKCAjwk7rmBRAaEiwAhDGhxHekWdTW6ZDHHkE74oFgWlLnJmUxkNfSmeP6D0hHexgd5C5QhWtC9RoCXaoQAvD_BwE&hvadid=153659459887&hvdev=c&hvlocphy=9009855&hvnetw=g&hvpos=1o1&hvqmt=b&hvrand=1951565213553423548&hvtargid=kwd-15395111&hydadcr=18031_9433042&keywords=accelerometer+sensor&qid=1557052264&s=gateway&sr=8-1-spons&psc=1

When that dealer told you you couldn't put a different or modified axle under there what he meant was that HE as an authorized dealer couldn't do that. YOU as the owner can do anything you want as long as you're not wanting to make a future warranty claim. The way you did it does give you a fresh warranty on your new axle, if that's any consolation to you. 

Great! It sure looks like more in the photo, shows how deceiving those can be. That's encouraging because your negative camber was really bad and its fixed by just recambering the tube, no other damage. So hopefully our axle end reinforcing fixes should solve the problem....