Greetings:

Both of my pods had and have 14 inch wheels.  The newer pods come with 15's and they are set higher so I don't think that a lift kit is needed any longer.

Crankster78

Well, if GlueGuy is correct, their not anymore. Well, at least not factory installed..

The issue is frame wall thickness. This picture shows where the stress occurs and happens to be where my fracture occured. By just adding the same size lift kit really doesn't help a existing issue. 

As a few of us determined we have 12gauge or .10 steel thickness. According to the dealer during repairs, I may actually have 14gauge steel or .075.. Either way fairly light gauge for what it's meant to do. 

OffGrid has a plan, as do I as how we'll lift our trailers. Differences are basically height and maybe thickness (thinking weight). I will probably match his length of tube. 

Greetings:

Why would Forest River sell lift kits if this was any sort of a problem?  

Crankster78

Greetings:

I've owned a 171 and now a 179 that I bought in 2015.  I have around 10,000 miles on this one and have had a lift kits under them from day one.  I have had 0 problems with the frame and have traveled down many a bumpy 2 lane road, plus gravel.  I often travel with a full tank of fresh water.  I just don't see how installing the factory lift kit would add stress to the frame.  I have seen some other makes of TT's that have a much lighter frame than the pods.

Crankster78

GlueGuy mentioned them re-clocking the torsion arm.

I have not yet inquired with Forrest River, but I would like to find out what they did to increase the height. Spacer, rotate axel, thicker frame?

My 2015 has 14" tires

Vann

That made me curious if any of the rPods now sold still have the 14" tires? My east coaster of 2017 is on 15".

  

I'm not sure, but I think the Hood River editions also have 15" tires instead of 14" on the east coast versions. this add a minimal amount(1/2"+/-) to the height/ground clearance.

Vann

[/QUOTE]

 I get an increase in section modulus of 39% 

Curious if I'm doing all this right.. I have 1.421 as the modulus for the 2x5x.1 frame

Whups, I found a boo boo in my calc. I divided the moment of inertia by 2 for the 5 inch tube rather than 2.5. Correcting that I get an increase in section modulus of 39% not 74%. The 195 axle is rated at 4400 lbs so that's 26% higher than the smaller rpods. So there is still some headroom there but i don't know how far the rear of the trailer frame overhangs the axle which would be the other factor we'd need to take into account.  

A failure due to the walls of the tube bulging would be considered a buckling failure. Interesting question as to when a tall thin wall tube in bending would be subject to that. There are equations for bucking of slender columns in compression that I've looked at before but they're not really applicable here.  My gut feeling is that we aren't close to a buckling failure yet at 5 inches and 0.1 wall thickness, but I could be wrong. 

What stumps me is that many members here drag their Pods all over the country with zero issues with the frame or axles. I have to wonder if the few failures we have seen are caused by poor metallurgy or installation errors? 

Greetings:

I've owned 2 pods, a 171 and now a 2015 179.  I have had the factory lift kits on both.  I have driven many miles on rough 2 lane roads in MN and WIS plus gravel and hayfields for dry camping.  I've had no problems with the frame or axle on either pod. I try to avoid running over curbs etc. but have at very low speeds.  I have dual LP tanks and a group 27 battery, and usually a full tank of water.  Several pod owners have gone to Alaska and back with pods.  I do think the axle is a bit light.  I've looked at some other RV's similar to the pod that had frames with smaller square tubing.  I wonder how they work out.  

Crankster78

Scary, I had 71% 

Curious, I see the 2x5 having greater strength the 'hard way', yet wouldn't the added height (without added thickness) make it more susceptible to bulging? 

a 2x5x0.1 tube is 74% stronger in bending than a 2x4x0.1 tube so without having done all the detailed equations for the 195 I think it's frame would probably be no worse if not better than a smaller rPod's.  

All this material is going to be fabricated from mild steel for cost reasons so there isn't any reason to be concerned about the strength of the lift kit compromising the frame because of that. The lift kit does add to the stress on the frame from hitting a curb or from hard braking, see my post above.  

I offer my statements due to the frame failure I have incountered. Adding the additional support to the frame is a minor cost and reduces the chance of failure. 

Axle failure and replacement is much easier than what has to happen to mine. I do wish I had caught it sooner or knew what I do now earlier.

The lift kit won't add more force but it will add more moment (think torque). The vertical load on the frame from gravity or from getting lifted by a bump or dropping into a hole won't change.  The moment from the arm of the torsion axle getting pushed up also won't change. What will change is the moment caused by braking or by hitting a curb. That is because torque is force x distance. The distance is the height difference between the contact patch and the frame, which is increased by the lift kit. If it helps to visualize this imagine the extreme case where you bolt 10 foot stilts on your trailer and then you run it into a curb. The stilts would act as a long lever and immediately twist the frame where it is attached.

Is it a significant increase? With my lift kit the distance from the contact patch to the frame is 14 inches. Without it it would be 10.5 inches, so it adds 33% to the stress on the frame from braking or hitting a curb. So yes it is significant. 

Is it enough more to cause a frame failure? The only reported frame failure I know of is Olddawgsrule's and he doesn't have a lift kit on his trailer. There are lots of owners who have lift kits, including all the HRE's until FR started increasing height by changing the start angle on the torsion arm, not sure when that was. So I'd say that there is no hard evidence that adding the lift kit increases the stress on the frame enough to cause frame failures in the real world. 

For me, if I can come up with a simple and inexpensive way to reinforce the frame at that weak point I will just do it rather than risk a failure, but I'm not giving up my lift kit.  For where I camp the standard height trailer is just too low to the ground. 

Well the sizing is better, thickness still low. 

Your modulus #'s are 1.421

Mine (2x4x.1) is 1.001

Your are also at 4740 max weight.

What axle is under there?

I’m no engineer, but I’m a curious how raising the height would add more force?  Perhaps a smidge of downforce (original height times 1.X where X equals additional height?) but I wouldn’t think it was even measurable.