GVWR>GAWR and Stabilizer Issues
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Topic: GVWR>GAWR and Stabilizer Issues
Posted By: Vikingr
Subject: GVWR>GAWR and Stabilizer Issues
Date Posted: 04 Jan 2019 at 8:53am
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Hi, Recently purchased new r-pod (172) and I wanted to ask about 2 issues. The first concern I have is around the cargo capacity due to low axle rating. I neglected to notice the low axle rating at dealer/assumed it was 3500lb but in actuality: GAWR/Axle rating is only 3000 GVWR is still listed as 3243 The dry weight (from door tag) is 2459 Cargo Capacity listed as NTE 767, or 468 after subtracting fresh water weight. Although remaining 468 is limiting enough, with GAWR it appears I should actually be limited to 225. The only way I can make sense of GVWR exceeding GAWR is if they somehow deducted the tongue weight from the GVWR and considered that to be within the 3000 rating-- but from what I have read around DOT regs, the GVWR should never exceed the GAWR (indeed will often be lower based on other factors). Are these ratings reasonable/do the listed ratings (GVWR>GAWR) make sense to anyone? The second, more amusing issue is that my trailer appears to be shedding the stabilizers, particularly at the rear. The first time I used them, I found half the bolts connecting them to the plate under the frame on the ground the next morning/sheared off at the point they connect to the mounting plate. I was very conscious of not raising the trailer too much, only made a few turns beyond what could be done by hand. Is it possible I did not raise it enough and the additional movement allowed by the trailer being “inadequately” stabilized caused them to break? The stabilizers where set on an uneven asphalt driveway, perhaps combination of poor quality bolts, angle/stress? (Do stabilizers need to be set on "perfectly" flat surface?) Any advice on these issues would be appreciated. v/r, Andrew |
Replies:
Posted By: Billy Bob
Date Posted: 04 Jan 2019 at 10:13am
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I will check my stabilizer bolts, but bolts I've lost are the ones holding the steps up. replaced them with stainless steel and blue locktite. I'm not the brain you want for your other issue. ------------- 2019 RPOD 190 2017 Chev Colorado 4 X 4 Yellow Lab and English Springer Spaniel |
Posted By: GlueGuy
Date Posted: 04 Jan 2019 at 10:20am
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If you load the trailer to 100% of the GVWR (3243), you should have at least ~~ 324 lbs (10%) on the tongue, or as much as 486 lbs(15%). I would try to put weight "forward" of the axle to increase the tongue weight. All of the weight on the tongue is weight that is relieved from the axle. Therefore, your axle weight should be in the range of 2756-2919 lbs. Now if you have a WDH, some of that tongue weight (usually about 1/3 of the tongue weight) will get transferred back to the trailer axle. In that case, I would try to shift to a little heavier tongue to get some more margin. It will be close. As for the stabilizers, they have been known to get scraped off when you go through short dips, like when going into a driveway or something like that. The typical way people deal with this is with a Save-a-Jack ( https://www.amazon.com/SAVEAJACK-scissor-jack-quick-release/dp/B005CJOR1M - https://www.amazon.com/SAVEAJACK-scissor-jack-quick-release/dp/B005CJOR1M ) ------------- bp 2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
Posted By: Vikingr
Date Posted: 04 Jan 2019 at 1:00pm
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Thanks Glue Guy-- So I agree that with the tongue weight it technically brings it under GAWR but it still seems at least a little playing shenanigans/wasn't sure if this is typical (or within regs) for calculating GVWR. My limited research on this indicates it's atypical, and I am having trouble finding the authoritative regs (assuming they exist). Do any of the other models list GVWR as greater than the GAWR? (or put a 3,000 axle on for that matter, from the posts I've read on this site it seemed 3500 was the norm...)
Just to clarify on the stabilizers-- I had them in the down position/wasn't moving the vehicle when they snapped-- but thank you for the link, I'll certainly consider a quick removal system for the future/to gain clearance. Billy Bob-- Thanks for the note on the steps-- I'll check those next. (blue locktite was also one of my first purchases-- went to immediate use on the faucet...) |
Posted By: GlueGuy
Date Posted: 04 Jan 2019 at 1:28pm
------------- bp 2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
Posted By: Vikingr
Date Posted: 04 Jan 2019 at 1:37pm
| Cool-- knowing that others are near, at or over their axle rating somehow makes me feel better (although I know it probably shouldn't...) Thanks again. |
Posted By: Tars Tarkas
Date Posted: 04 Jan 2019 at 6:02pm
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It's hard to imagine why your stabilzer bolts would break while extended. I'm not sure what you mean by tightening them just beyond hand tight or if this is relevant, but the stabilizers are only that; they aren't meant for lifting the Pod at all. Extend them to the ground firmly but certainly don't try to use them for leveling the Pod. TT ------------- 2010 176 FJ Cruiser |
Posted By: offgrid
Date Posted: 05 Jan 2019 at 8:03am
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The DOT regs limit the manufacturers to a trailer GVWR no higher than the GAWR plus the manufacturer's lowest listed figure for tongue weight. For my 179 that is exactly what is on my sticker. Manufacturer's listed tongue weight numbers are often unrealistically low. In reality depending on which trailer and how you load it tongue weight can be significantly higher, in my case its almost double. Also, empty weights are stated for a 'standard" trailer with no fluids (water in tanks or water heater, propane) and no batteries. At the other extreme, low tongue weights can be very dangerous, there have been cases of rPods exhibiting sway at tongue weights around 10% or lower. For all the above reasons, I highly recommend that you actually weigh your fully loaded trailer axle and tongue so you know what you really have. If you don't have a tongue scale you can use a public scale to do this. Weigh your tow vehicle separately, then the whole rig (no weight distribution hitch) axle by axle. The tongue weight will be the difference between the tow vehicle weight with and without the trailer. I was surprised the first time I weighed mine, you might be too. There have been some (a few?) cases of bent axles reported on the heavier rPods, so being near or over the axle rating can indeed be a issue. Also be aware that the OEM tires and wheels typically aren't rated as high as the axle. A system is only as good as its weakest link, and while I haven't heard of any catastrophic axle failures, tire blowouts can be pretty ugly events. ' ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: GlueGuy
Date Posted: 05 Jan 2019 at 9:53am
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Back to the original question about the stabilizers. So your stabilizers are coming apart, or are they separating from the trailer? What we do with our stabilizers after we've leveled the trailer: I use my Milwaukee drill set to "2" on a 15 scale, and walk around the trailer twice and run it until the clutch slips. The first time gets it close; the second time adjusts for any shifting. Bottom line it is snug, but not tight. ------------- bp 2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
Posted By: Happy Tripping
Date Posted: 05 Jan 2019 at 10:14am
Actually, this has been a chronic and significant issue for years, including with lighter r-pods. I am not aware that the axle rating is actually as low as 3000 lbs, 3500 seems to be 'industry standard', but that still leaves an inadequate margin, as seen in the many axle problems that Forest River and other manufacturers conveniently dismiss as 'you actually hit...' - you fill in the blank, rut, tree, mountain, whatever. I would love to see a class action lawsuit about this, but in reality, most people just accept that they will have to go thru a set of tires annually due to the increased wear from the bent axle, or do as some and replace it with a heavier rated axle. This is not FR alone, but as I say, it appears to be 'Industry Standard'.
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Posted By: offgrid
Date Posted: 05 Jan 2019 at 11:23am
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I just checked the current rPod specs and the 171 and 172 do appear to have a 3000 lb GAWR. All the rest of the product line is 3500 GAWR, and the GVWR is in all cases the stated (low) tongue weight plus the GAWR, following the letter of the DOT requirements. So there might be a difference in the actual axles on the 171 and 172, or it might be purely specsmanship. By stating a lower GVWR FR can more easily sell the lighter trailers to folks with lighter tow vehicles. So there is a strong motivation for manufacturers to derate both tongue and axle weight. Or it might be limited by tire and wheel ratings. Someone with a 171 or 172 might be able to confirm by looking at the axle sticker and the OEM tire stampings. Regarding numbers of customers that have actually experienced bent axles, I'm not so sure its really a high percentage, You're going to tend to hear from the folks who have had problems, not the thousands who haven't. It would be interesting for someone to take a count on this forum and see what the incidence here has been. I certainly do agree that the axle is not as heavy as it could be. OTOH, if a heavier axle was selected, the trailer empty weight would also go up, which would either limit CCC or tow vehicle selection. This is a typical engineering problem, you reengineer to remove one constraint and another one gets worse. Like playing whack-a-mole. There ain't no free lunch... For this reason and because I don't view a potential axle failure as a safety issue, while I know I have a heavy 179 I opted not to change the axle, but I did upgrade tires and wheels, which I see as a significant safety improvement. The upgrade caused little or no weight penalty. I'll see if that was the right decision over time. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: mjlrpod
Date Posted: 05 Jan 2019 at 2:18pm
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I have a 2017, 172 and I haven't had any issues. I usually put more weight toward the tongue. The bunk area tends to be a great place to put stuff, and it tends to stay put. Especially since the large storage space is under the lower bunk. So far, I bring whatever I want. I also have the truck bed I pack up also, and if i really need to, I can throw a travel bag on the roof racks, although I haven't ever done that. My biggest issue is when i bring my sewer caddy. If i am over packed in the truck bed, I find it fits perfect right ontop of the tonneau cover, tucked right up to the cab. I use a ratchet tie down that goes under the tonneau cover and hooks onto the tie downs in the bed. I've never had issue with my stabilizers, maybe they dragged on an uneven road. If you go up, or down a small rise on the road, or a parking lot, they can hit. Good luck and camp the hell outta your 172, i LOVE mine. ------------- 2017.5 Rp-172 2020 R-pod 195 2015 Frontier sv 4.0L 6cyl I'll be rpodding |
Posted By: lostagain
Date Posted: 05 Jan 2019 at 5:20pm
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Our 172 appears to have a 3000# axle. The gross cargo capacity is stated to be 920 lbs. with a maximum weight of 3179 pounds. We generally travel with tanks empty, but when the tanks are kinda sorta full [black is nearly always empty], it doesn't make any noticeable difference in handling except the mountains seem to be a little steeper. We run D range tires, a swap out from the C's that were on it, but that was more for ride comfort, speed, and economy than cargo capacity. We load the back of our TV, which has a wedge roof camper shell on it, with most of the heavy stuff like extra propane and gasoline [I hope we never catch fire], fire wood, extra drinking water etc. I've never had the trailer feel overloaded or on the edge of comfortable control. As stated in prior posts, we've removed the upper bunk, raised the lower one with more storage below and have done some other things to lighten the load as we live simple lives when traveling. ------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: GlueGuy
Date Posted: 05 Jan 2019 at 5:45pm
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Everyone knows that FR de-rates the actual axle capacity by 500 lbs because the mount points are ~~ 8" inboard of the normal mount points? I think it would be reasonable to fab a support that attaches to the frame, and just wraps around the outboard 8" of the axle. It doesn't need to be welded to the axle, juts have a yoke that wraps around the top. I'll try to draw something up. ------------- bp 2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
Posted By: Vikingr
Date Posted: 05 Jan 2019 at 9:10pm
Thanks Offgrid, This is exactly what I was trying to confirm. Also good to hear from other 172's that they too have the 3000lb and this is iaw spec from FR, although it appears earlier 172s have 200 lbs more cargo capacity, I'll chalk that up to the #!@*^& microwave... (no need to correct me on this). I expect an upgraded axle will be required since I am already at limit, considering the destinations and resulting punishment I hope to put ours through, also an eventual enclosed basement for 4 season camping. I read the 6000 or 6500 lippert may allow for the same wheel/bolt pattern as my TV (16"/6x5.5 lug), so will look into going as high as that if it presents no other issues. Please let me know if anyone else has done this heavy an axle. Regarding class action, would assume a number of similar issues would certainly be required given FR is, at least on paper, within ratings allowed by DOT. I hope not to be one of those statistics, but will certainly speak up if anything occurs. Lastly regarding the stabilizer issue I had-- yes the bolts broke at the trailer mounting location, if I had to guess my driver clutch rating would have certainly been less than 5 on scale of 20, but I did it old school/with 2 turns of the wrench after stabilizers made contact. It was literally my first time putting them down and I was overly cautious to not lift. Looking at the bolts again where they broke, there is a good deal of pitting/appeared to be very porous/low quality material-- so at this time will assume that was primary factor and not my incompetence (didn't hear from anyone that the stabilizers required a level ground to avoid additional stress). |
Posted By: Happy Tripping
Date Posted: 06 Jan 2019 at 7:48am
Ooops. My bad (memory). I crawled under, our 171 is also 3000# (Just to keep the record straight) ------------- "There comes a time in the affairs of a man when he must take the bull by the tail and face the situation" - W.C. Fields |
Posted By: offgrid
Date Posted: 06 Jan 2019 at 7:58am
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During my original discussion with Lippert on this issue I was told that they could sell me a 4400 lb axle which was identical except the label to our 3500 lb ones. I guess perhaps not surprisingly, when I called back to confirm I got a different sales engineer and a different answer (nothing higher than 3500 lbs unless I went to the next size 5200 lb) axle. The second person also made the comment that they had been told not to tell people that a 4400 lb version was available. Hmmm. So if indeed the first sales engineer was correct then there are really only two sensible explanations: 1) the axles are really good for 4400 lbs and are being derated to 3500 for reasons of specsmanship or 2) the mounting points on the rPods are resulting in the derate from 4400lbs to 3500 lbs. StephenH, I believe you have been given explanation 2 by FR? So it that is correct than we could potentially pick up 700lbs of load capacity. Regardless, from an engineering perspective I think GlueGuy's proposal is a good one if we can make it work. The axle is a essentially a double ended cantilever beam with equal loads at the ends of the overhanging supports. The stress calcs for this load case are here: https://www.engineersedge.com/beam_bending/beam_bending7.htm What we see is that by reducing the overhang (c) we can make the axle bending stress lower, in fact with zero overhang the stress goes to zero. Interestingly this is true both for the axle sections outboard and inboard of the mounting points. So, this is one of the few design changes in engineering where you're not just moving the problem somewhere else, its all to the good, for the axle at least. We do have to consider that we would be applying a new torsional stress to the rPod frame rails (because the new axle brackets would need to carry load back to the frame rails), but box tubes are very strong in torsion so that's probably not going to be much of an issue. I'm still puzzled though about the 3000 lb axle rating for the 171/172. Lippert's lightest torsion axles appear to be the 3500 lb units so is there really any difference in the actual axle and/or mounting points on those trailers or is the 3000 lbs just a derate for specsmanship? e
------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: lostagain
Date Posted: 06 Jan 2019 at 10:01am
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I should clarify my comment that " our 172 appears to have a 3000# axle." That is a number I found on the data plate in two places. The print was so small and worn that I cannot be sure the 3000 number is really what it seems to be. I took a picture of the data plate and here it is: https://postimg.cc/BPXChkvB">  Unfortunately, my line cleat obscures one segment of the data plate, but I don't think it was the critical info. ------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: michaeln
Date Posted: 06 Jan 2019 at 1:16pm
Here is the label from my 16-171: ------------- --- Avery, CA |
Posted By: lostagain
Date Posted: 06 Jan 2019 at 1:40pm
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So, if you weigh the tongue weight with one of those little Sherline tongue weight scales, and weigh each wheel weight with same, you'd have the total trailer weight by adding the results? Seems that for the price of that scale, a lot of uncertainty could be clarified and you could easily balance the trailer if you were in doubt about the balance and total weight. In my imagination, which is very fertile, one could complete this process much faster than going to a public scale. Ok, our Pod Board engineers, will this work, or do I need to lay off the arguardiente again? michaeln, our posts crossed in cyberspace. So, how come your data plate looks so nice and new. Could it be my trailer is a 2009 and yours is nice and new?
------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: StephenH
Date Posted: 06 Jan 2019 at 2:08pm
Actually, I was considering that myself. I was not told that by FR. It makes sense that the additional distance between the mounting points and the wheels means more force able to be exerted on the axle beam than if the mounting point were closer. In addition, I saw this video that indicates the same thing: https://www.youtube.com/watch?v=FtXRGOadTKU - https://www.youtube.com/watch?v=FtXRGOadTKU
The video shows one solution, but it also included not only fabricating a new support bracket and welding it to the frame, but ordering a new axle with mounting brackets closer to the wheels. e
[/QUOTE]
------------- StephenH Happy is the man that findeth wisdom,... http://www.rpod-owners.com/forum_posts.asp?TID=7712 - ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS |
Posted By: David and Danette
Date Posted: 06 Jan 2019 at 3:37pm
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Do you think Timbren Axle-Less Suspension would work on the a r-pod?
------------- 2018 Vista Cruiser 19BFD (2018- 2012 Vibe 6503 (2014-2019) 2009 r-pod 171 (2009-2014) Middle Tn 2014 Ram 1500 Quad cab |
Posted By: StephenH
Date Posted: 06 Jan 2019 at 3:44pm
------------- StephenH Happy is the man that findeth wisdom,... http://www.rpod-owners.com/forum_posts.asp?TID=7712 - ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS |
Posted By: offgrid
Date Posted: 07 Jan 2019 at 3:53am
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+1. The Timbren solution won't work on an rPod without adding a structural weldment to mount it to, which would need to extend laterally across the trailer to take the torsional loads. That would negate the claimed benefit of having an "axle-less" design. StephenH, I saw that video too, but because it requires a new axle its only a solution for an rPod owner who already has a bent axle so has to buy a new one. GlueGuy's concept would allow us to reinforce our existing axles before they fail. I'll try to take a couple measurements today and see how much bending load reduction we might expect to get with GlueGuy's approach. If anyone either knows or has access to an old axle they can cut open, the wall thickness of the axle tube would be useful for that calculation. lostagain, using a Sherline tongue scale would work for what you're suggesting and also allow someone to measure the side to side weight imbalance of their trailer. mcarter suggested that several months ago in another thread. You would need to jack up one wheel at a time and lower the trailer onto the scale while raising the opposite wheel so the trailer winds up level side to side. Should work as long as you're careful. In my case, I've obtained my tongue weight and axle weight the cheap and lazy man's way using a public scale, so its really only the side to side imbalance that's a question mark. I'm not sure I want to spend $125 just to know that. It's really only a one time measurement. But if any folks here want to split the cost of one I'd be game. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: offgrid
Date Posted: 07 Jan 2019 at 4:04am
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The problem with going by the label on the side of the 171's/172's to determine axle rating is that the 3000 lbs listed there could easily just be derated from what's really the same 3500 lb axle used on the heavier rPods. There should be a sticker on the axle itself with the manufacturer, a weight rating, a part number, and a "variant number". If someone wants to take a photo of that and post it I can compare it to the data on my 179 axle. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: offgrid
Date Posted: 07 Jan 2019 at 8:37am
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Well that was interesting. I measured the overhang of the axle.spindle and the distance between axle attachments, and also took a look at how much it might be possible to reduce the overhang. I assumed that the wheel loads are applied at the midpoint between the inner and outer bearing races. I get an overhang of about 13.75 inches and a distance between supports of 60.5 inches. I also was able to see the axle tube wall thickness at the ends. I couldn't get my micrometer in there but I estimated it to be 3 inch box tubing with a 3/16 wall thickness. That gives an axle bending stress of about 12ksi (12000 psi) for a 1750 lb load on each wheel. Mild steel has a yield strength of about 35 ksi so that would imply the axle could take a bump load of just under 3g's. From what I've seen on vehicle design, a minimum load factor of 2.5-3 g's is pretty typical, so the current design is right in there, about as light as you'd ever want it to be for the loads it takes, but not severely under designed either. Its worth noting that this stress is uniform over the whole axle tube if the same load is applied to both wheels, so if you were to generate a high bump load on both wheels (say by going over a speed bump too fast) you could end up bending the axle anywhere along its length. If you went over a bump on one wheel only then it would of course be likely to fail first on that overhang. It also looks like by extending the axle attachment points outward we could get the overhang down to about 6.75-7 inches, which would reduce the axle bending stress by a factor of about 2! I think that's well worth exploring further. One thought I had on an easy way to improve this would be to simply strap a 2.5-3 inch steel angle to the full length along the bottom of the axle. I'll take a look at the numbers on that and report back. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: lostagain
Date Posted: 07 Jan 2019 at 9:50am
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offgrid, thanks for the info on weighing each bearing point with the Sherline scale. I was thinking of doing an initial tongue weight check with the trailer in it's mostly empty state state [just the normal junk we keep inside such as pots pans], then use it when loaded to get an idea where, relative to for and aft, the weight was shifting. It wouldn't take but a few minutes to check this with the trailer parked. Since we use a WDH the actual axle weight on our truck and trailer would change everything around, but if the rig is basically straight and the truck is balanced fore to aft, then we should be ok. For us, going to a public scale is would take over an hour round trip and I figure I can get the basics using the little Sherline scale in about half that time. And since we travel with relatively light loads in the trailer, I hope [maybe more accurately, fantasize] that we will not be overweight. From experience, the heaviest loads we've carried have never presented any driving anomalies which would be of concern. Indeed, driving with the trailer attached is smoother than without, though we certainly won't win a drag race. ------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: Vikingr
Date Posted: 07 Jan 2019 at 10:16am
Below is axle sticker on my 172. Also, assuming it makes a difference, it's mounted in a diamond, not square, configuration.
 |
Posted By: offgrid
Date Posted: 07 Jan 2019 at 2:34pm
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If your axle is like mine it should be a 3 inch square box tube oriented at 45 degrees. Looking at the part numbers I'm highly suspicious that there isn't any actual difference in load capacity. Both start with the same series of identifiers, which I think mean that the axles are 3500lb nominal Lippert torsion axles with 89.5 inches hub face to hub face and 59.25 inches inside attachment bracket to inside attachment bracket. The only difference other than the suffix on yours that says Cap 3000# is that your 6th identifier says 220 while mine says Zero. I think that is specifying the starting angle of the swing arms which controls how much lift the axle is providing. It shouldn't effect the load capacity. I'll bet that both axles can carry the same loads. Here's my label.  ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: offgrid
Date Posted: 07 Jan 2019 at 3:30pm
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I took a look at the effect of just adding a 3 x 3 x 3/16 inch steel angle along the bottom of the existing 3 inch axle box tube. It got a bit beyond my ability to readily recalculate the combined section modulus of the two parts, but if I did it right I got about a 75% increase in load capacity. This would be a pretty easy mod, just cut a piece of angle to the right length and clamp it to the bottom of the existing axle with say 3 or 4 heavy duty stainless hose clamps at each end. Those should be enough to handle the transferred load which is only going to be about 1000-1500 lbs at each end. I don't think it would be necessary to clamp it between the axle attachment points because the axle tube will press down into the angle in the middle under load anyway. Added weight would be about 25 lbs. I might give it a try, couldn't hurt anything I don't think. To mitigate corrosion I'd drill some holes in the bottom of the angle so it doesn't collect water in there. Paint it and seal the edges with caulk. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: StephenH
Date Posted: 07 Jan 2019 at 4:28pm
Would there be a difference if you clamped the angle to the top of the tube so any water would tend to drain out? Am I understanding that this is only done on the portion of the axle between the mounting brackets and the arm on each side? ------------- StephenH Happy is the man that findeth wisdom,... http://www.rpod-owners.com/forum_posts.asp?TID=7712 - ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS |
Posted By: David and Danette
Date Posted: 07 Jan 2019 at 5:05pm
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When our axle or wheel was bent it didn't look like the axle itself was bent but I guess would be called the hub. Only one wheel was at a angle, my thinking strengthening the axle would not prevent the hub from bending. I am no mechanic or a mechanical engineer, I don't understand why only one wheel would be bent on a angle. If the axle bent wouldn't both wheels be bent on a angle. If I remember correctly I was told the axle was bent and the entire assembly was replaced under warranty with a stronger axle and a larger wheel size. This was on our Vibe with the same style axle and fenders on the outside of the camper as a r-pod.
------------- 2018 Vista Cruiser 19BFD (2018- 2012 Vibe 6503 (2014-2019) 2009 r-pod 171 (2009-2014) Middle Tn 2014 Ram 1500 Quad cab |
Posted By: GlueGuy
Date Posted: 07 Jan 2019 at 5:08pm
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That sounds like it could help. I would still worry about the large moment arm between the frame and the spindles. If Stephen could get access to his old/bent axle, we would have a better idea where the bending is happening. I think there is about a 50/50 chance that the bend happens outboard of the frame. ------------- bp 2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
Posted By: offgrid
Date Posted: 07 Jan 2019 at 7:04pm
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If the force is applied to both wheels equally and simultaneously (like when going over a speed bump) the bending moment is the same from just outside one mounting bracket all the way to just outside the other bracket. So the failure ought to be equally likely anywhere along the axle tube between those points. But if one wheel gets more load than the other (like going through a pot hole) then the worst case occurs just outside that mounting point. The bending force drops as you move outward from the brackets toward the ends of the axle, so its less likely that an axle failure would occur there. Its like if you have for example a piece of rebar sticking out of a wall and you push on it it will bend right at the wall. So because potholes are more common than speed bumps I think its most likely that just outside the mounting brackets would be the point of failure, and most likely the slide side because we know that side of the larger trailers is heavier. If the axle is indeed what is failing. If David and Danette are right and the failure could be outboard from the axle itself then reinforcing the axle wouldn't help. But the starting premise here is that the reason for the failures is because the axle attachments on the rPod are too far inboard. And it sure looks like that has a very large effect on axle capacity. Put another way, moving the attachment points doesn't change the loads on any parts outboard of the axle, so if the failures are somewhere other than the axle than they have nothing to do with the rPod axle mounting points. StephenH, from a beam load perspective there is no difference if you clamp the angle on top of the tube or on the bottom, but practically speaking you can't because the axle mounting brackets would interfere with running a continuous angle. The angle needs to be continuous or it will leave a weak spot right at the mounting brackets. The bottom of the axle tube is clear from one end to the other. GlueGuy, consider that adding brackets outboard to bring the loads back to the rPod frame rails will do the same thing as adding an angle under the axle, its really just two different ways to stiffen the axle in the critical area. Either way would work, its a matter of selecting bracket extensions or angles that are stiff enough to do the job. We know both by calculation and field experience (we don't have massive numbers of immediate axle failures) that the existing design is not that far off what's needed, so we don't have to go crazy I don't think. I'm more concerned that the hose clamps won't do the job at which point a weldment and bolted clamp arrangement that fit around the axle ends would probably be needed. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: GlueGuy
Date Posted: 07 Jan 2019 at 7:18pm
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Consider also that FR (or Lippert) decided to de-rate the axle capacity because of the inboard attach points. I would be concerned about the hose clamps being strong enough. Maybe if there were 6 of them or something.... ------------- bp 2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
Posted By: offgrid
Date Posted: 07 Jan 2019 at 8:18pm
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Here's a link that lends some hope that heavy duty hose clamps could work. http://www.jcshi-torque.co.uk/just-strong-jcs-clamps/ Another perhaps better approach might be to use two square U bolts at each end to clamp the axle and angle together, one placed on each bottom face. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: lostagain
Date Posted: 07 Jan 2019 at 8:40pm
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So, let me see if I understand the concept of strengthening the existing axle. Given that the greatest point of stress is just outboard of the attachment point on the frame, one proposal is to run a piece of angle iron [3x3x3/16] for the entire length of the axle on the underside as that has a clear space from one end to the other. Then, the idea is that the angle iron will provide additional support at the stress point, thus increasing its resistance to breakage. How'm I doin' so far? Since the angle iron, if its subject to the stress at the outboard axle connection point, will try to resist that stress, it will effectively get pushed away from the fracture or bend site unless it is securely held to the axle with some kind of fasteners. So far it's not clear how much stress those fasteners will subjected to, but it is clear that hose clamps will have to be numerous and sufficiently strong. Am I still there? So, a question: Why don't you use some kind of U clamps appropriately sized to fit around the axle and the angle iron that wouldn't stick down far enough to interfere with ground clearance? Aren't they pretty strong? Just wondering from a lay person's point of view. Seems to me with 2 or 3 spaced on the inboard and outboard sides of the axle to frame attachment point, they'd fit the bill. Ok, when you get up off the floor after falling down laughing, help me understand or I'll just be lost again. ------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: StephenH
Date Posted: 07 Jan 2019 at 8:55pm
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What about these? http://www.hoseclampkings.com/prod-21-1-476-74/breeze-hi-torque-htm-1800-17-1-4-18-1-8-inch-range-5-8-304-ss-band.htm - http://www.hoseclampkings.com/prod-21-1-476-74/breeze-hi-torque-htm-1800-17-1-4-18-1-8-inch-range-5-8-304-ss-band.htm Although the U-bolt idea also might be good as those can definitely be very heavy duty.
------------- StephenH Happy is the man that findeth wisdom,... http://www.rpod-owners.com/forum_posts.asp?TID=7712 - ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS |
Posted By: offgrid
Date Posted: 08 Jan 2019 at 6:35am
Ha Ha lostagain. Not laughing at your idea of using square u bolts, just laughing 'cause I beat you to it by 22 minutes  .The reason I was mentally resisting them at first is because with the diamond orientation of the axle you need to have two of them at each point to symmetrically hold the angle to the axle, so its a little weird. But it should still work I think. The holding capacity of each u bolt in the direction of force is derated to cosine(45 deg)= 71% so two together would be about 1.4x the the holding force of a single u bolt used normally. The only issues I'd take with your summary of the situation is first that there isn't just the one weak point, the stresses on the axle are continuous. The points just outboard of the axle attachment brackets are most likely to see the most stress over time but that doesn't mean they're the only points to worry about. Second, I'm not sure what you mean by "get pushed away from the bend site"? The bending forces are upwards on the wheels so the axle ends are getting pushed upwards while the midsection of the axle is getting pushed downward. By clamping the to the axle at the ends the two parts should stay in intimate contact over their whole lengths under load. You could add more clamps inboard if you wanted to but I don't really think they're necessary. StephenH, I think the hose clamps you found should work but I'm now leaning toward trying square U bolts if we can find the right size. They would probably need to be 3/8 inch to have enough thread area to carry the load and have a 3.5 inch opening to slide over the 3 inch axle plus the 3/16 in angle. These would probably work. We'd need bolt plates, nuts and washers as well. https://store.uboltsdirect.com/SecureCart/ViewCart.aspx?mid=0D3EC8DE-C0FA-487C-81A3-BB423F37A886&sctoken=164be636ce8a4f7da159cd2aa91502b4&optionId=1012189971,&bhjs=1&bhqs=1 ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: Pod People
Date Posted: 08 Jan 2019 at 6:59am
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This discussion brings me back to a question I asked a while back--does the axle bend up or down ? it would seem to me that you could weld the 3x3 angle to the axle and it would stop the bend regardless of the directin. Is it not possible to weld to the hollow axle instead of U bolts? Vann ------------- Vann & Laura 2015 RPod 179 https://postimg.cc/0zwKrfB9"> 
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Posted By: offgrid
Date Posted: 08 Jan 2019 at 7:05am
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Nope, you can't weld to torsion axles. There are rubber cords inside there that would burn up. When Lippert and Dexter make them all the welding is done before inserting the rubber. The rubber cords are compressed and frozen (in liquid nitrogen I think) then everything is inserted and allowed to warm up. The axle ends bend up under load, the center section of the axle between the frame attachments bends down. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: StephenH
Date Posted: 08 Jan 2019 at 7:43am
It would be nice if there were such a thing as a V bolt used with a V plate, washers and nuts. I don't know if such a thing exists, but it would make things easier, I think.
When I look at the new axle, I can see a little upward bend in the middle section. Would an angle iron need to be bent to match the initial shape of the axle? Would adding a straight piece of angle iron tend to start a bending stress on the axle if an initial matching of the shape is not done?
I saw the 3/8" deep nuts and washers offered as an option. I like the idea of the deep nuts as they would have more threads. ------------- StephenH Happy is the man that findeth wisdom,... http://www.rpod-owners.com/forum_posts.asp?TID=7712 - ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS |
Posted By: lostagain
Date Posted: 08 Jan 2019 at 8:10am
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ummm, errrr, I just went out into the pre-dawn chill to confirm what I recall, that my axle is round. I was actually thinking of standard U bolts, not square ones like you'd find on a leaf spring. The round part would rest against my round axle and the retainer plate passing over the angle iron. The issue I had with that was that the retainer plate wouldn't fit up against the angle iron completely as it would have to be bent with a right angle in it to touch the angle iron and would need additional bends where the bolts go through at 45º or so. Or am I, once again, trying to put round pegs into a square hole? Another dumb question: Has anyone calculated the various potential sizes of angle iron and what additional strength they would impart to the axle once installed securely? For me, if I were to engage in such a modification, I would not be looking to significantly increase the load capacity of our 172, but to give it a little more strength for forest service roads and such when loaded within the defined limits. If I put a 1 1/2 inch angle with about 1/8th thickness angle iron would I be wasting my time or would it add enough strength to make it worth the bother. It's a lot of work wallowing around under a trailer for an old geezer my age. ------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: offgrid
Date Posted: 08 Jan 2019 at 9:33am
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StephenH, I've never seen a v bottomed U bolt but yes if there was one that would be good. Or you could weld up some custom clamps but I'm not convinced its necessary. If your axle is crowned you'd probably want to crown the angle a bit to match. We'd probably have to ask a metal shop what that would cost to do. Angle iron gets bent all the time but I've mostly seen it bent parallel to one of the flats. I don't notice any crown in my axle but I haven't looked carefully. Could be mine has already started to fail, or its got more weight on it. About how much of a center crown do you have? I calculated the 3/8 bolt size based on only a single thread engagement, so it's really way overkill even with standard nuts, but more threads can never hurt. lostagain, interesting that you have a round axle. Vikingr's 172 has pretty much the same axle as StephenH and I do. Who is the manufacturer? With a round axle you might be better off thinking about using a piece of steel pipe cut in half lengthwise rather than an angle to reinforce it. What is the OD of the round axle? You should be able to buy off the shelf u bolts to clamp it. I just looked at the 3 x 3 x 3/16 angle, which seems about right for reinforcing the 3 x 3 x 3/16 inch Lippert box tube axle, while not adding a lot of weight. Your case might be totally different, your configuration might or might not even be subject to axle failure. Have you had any signs of it?
------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: StephenH
Date Posted: 08 Jan 2019 at 9:41am
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I did find some online, but none of the correct dimensions for this purpose. I did not measure, but there was a little bit of crown visible. I don't think it was more than about 1/2", but I would really have to measure to be sure.
------------- StephenH Happy is the man that findeth wisdom,... http://www.rpod-owners.com/forum_posts.asp?TID=7712 - ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS |
Posted By: lostagain
Date Posted: 08 Jan 2019 at 9:55am
My axle is about 3" inches in diameter. Since I broke my arm at the end of Dec., I'm in no condition to crawl under and measure it right now.  I have no idea who the manufacturer is, except to say it's likely to be one of the two common brands. When the weather warms up and my arm heals, I'll take a gander below and see if I can find a label. Maybe I should just call FR and see what was originally installed. Since it's probably never been replaced, that should answer the question.Where would I find a piece of steel pipe split in half without getting into going to a metal fabricator to cut one for me? Would the round half pipe configuration be sufficiently resistant to bending to make it worth it? ------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: offgrid
Date Posted: 08 Jan 2019 at 9:59am
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If you do go to the trouble to measure it I'd suggest lifting the trailer off its wheels first so you can get the crown dimension with the axle unloaded. Then if you crown the angle to match things should line right up under load. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: lostagain
Date Posted: 08 Jan 2019 at 10:19am
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Sounds like a plan. But then I'd have to get the metal guy to not only cut the pipe, but to bend a crown into it? Right? ------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: offgrid
Date Posted: 08 Jan 2019 at 11:37am
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lostagain, it would depend on whether or not your axle was crowned. StephenH's is which makes me think that that is the way the Lippert ones are made. But your's and mine might no longer be crowned or yours might never have been crowned to begin with. If your axle isn't crowned and you're not getting uneven tire wear from too much negative camber then I wouldn't try to change its camber by strapping it to a crowned reinforcing element. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: lostagain
Date Posted: 08 Jan 2019 at 1:42pm
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Thankfully, my tire wear is phenomenally even. It is easy enough to measure the crown, when the weather gets nicer and my arm recovers, simply by stretching a string from one side to the other. ------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: offgrid
Date Posted: 08 Jan 2019 at 2:03pm
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Yep. But as you've had your 172 for awhile and knowing that its a lighter rPod, and you keep it light, and have no uneven tire wear to date, I don't think you really have any pressing need to do any axle reinforcement. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: offgrid
Date Posted: 08 Jan 2019 at 2:39pm
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BTW, I think the reason that FR/Lippert appear to be deliberately derating the axles on the lighter rPods could be to mitigate the risk of a customer encountering trailer sway. It's going to be difficult to load a lighter rPod's axle to anywhere near 3500 lbs without also winding up with low tongue weight as a percent of total trailer weight. There is quite a bit of evidence that rPods with tongue weights at or below the industry standard minimum 10% figure can sway. To load a 172's axle to 3500 lbs and still be at least 10% on the tongue the trailer would gross out at at least 3889 lbs and have a tongue weight of 390 lbs. That's a crazy huge load on a trailer with a dry weight of 2338. There's just no sensible way or reason to load a 172 like that I don't think. On a 179 that's not an unusual load at all. By limiting the axle to 3000 lbs the gross weight is 3333 with a tongue weight of 333 to keep within the 10%. Much more sensible on a 172. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: lostagain
Date Posted: 08 Jan 2019 at 3:15pm
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No, I am not planning on any axle reinforcement any time soon. At least not until I discover gold on one of our trips and have to haul out giant nuggets. I'm sure that will happen eventually, but I'm realistic enough not to count my nuggets before they're found. And since the dry weight on our 172 is only 2259# I'd have to carry some of the gold on the tongue to keep it all balanced. ------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: offgrid
Date Posted: 08 Jan 2019 at 3:48pm
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You might need to remove your battery to make room for the gold. Changing lead into gold would make you a modern day alchemist. But do let me know when you've got that gold sitting on your trailer tongue. Sounds like it would be a good time for a midnight campsite visit.... ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: lostagain
Date Posted: 08 Jan 2019 at 4:27pm
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It was a sad day when science discredited alchemy. My favorite was phlogiston. You would be most welcome to drop by when I've loaded the trailer with gold. I'll need someone to help me calculate the trailer and tongue weight ratios. ------------- Never leave footprints behind. Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
Posted By: offgrid
Date Posted: 08 Jan 2019 at 4:50pm
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Be happy to help. I've even volunteer to take some gold off your hands to reduce that tongue weight to a more reasonable level... ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: David and Danette
Date Posted: 08 Jan 2019 at 4:54pm
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Has anyone visited the Dexter or Lippert website for axle specifications. Would you be able to find the axle that is on the r-pods and compare a 3,000 lb axle to a 3,500 lb axle to see if there is a difference, perhaps they would list the weight of each axle. At one time I was on a website comparing their axles and I believe it gave the weight. I would think a 3,500 lb axle would be heavier than a 3,000 lb. axle if they are the same weight then it may be true they are same axles just labeled different. But if they are different in weight there must be something different in their construction not just labeled different. Does all this make any sense.
------------- 2018 Vista Cruiser 19BFD (2018- 2012 Vibe 6503 (2014-2019) 2009 r-pod 171 (2009-2014) Middle Tn 2014 Ram 1500 Quad cab |
Posted By: offgrid
Date Posted: 08 Jan 2019 at 5:18pm
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Yes it makes sense, and I tried to find Lippert axle weights because I wanted to know how much more the 5200 lbs ones weigh. I couldn't find anything on their website. I'm pretty confident that Vikingr's and mine/StephenH's have the same actual load capacity because the part numbers are identical except for the one set of digits that defines the starting angle of the torque arm, which shouldn't effect load rating at all. And, if I was FR I wouldn't want to state the 172 axle rating any higher than 3000 lbs anyway, for the reasons I mentioned above. Anyone can feel free to call Lippert and ask. Frankly, after I got two different answers to my question from them on two phone calls I'm not going to waste my time anymore. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: GlueGuy
Date Posted: 08 Jan 2019 at 8:22pm
------------- bp 2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
Posted By: StephenH
Date Posted: 09 Jan 2019 at 2:27pm
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I was able to get outside and measure my axle with a string and tape measure. There is a definite 3/8" crown to the axle. This is with the wheels on the ground but only partially loaded (no water, groceries, clothing, etc.) with only non-perishable items such as dishes and cookware. I don't really have a good way to lift it up off both tires at the same time to measure that way.
------------- StephenH Happy is the man that findeth wisdom,... http://www.rpod-owners.com/forum_posts.asp?TID=7712 - ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS |
Posted By: offgrid
Date Posted: 09 Jan 2019 at 3:15pm
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I’ll take a look at mine and see what it’s crown is. My trailer is more or less empty right now too.
Just to be clear deflection is a different analysis from yield stress. Beams will deflect under load and return to their original positions. Think jet aircraft wings. The reason the axles are crowned is so the wheels don’t end up with too much negative camber when loaded. If a beam doesn’t return then it has been overstressed. I’ve not yet looked at the axle deflection calcs yet. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: offgrid
Date Posted: 23 Jan 2019 at 3:53pm
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Things finally warmed up and dried out enough out here on the OBX for me to crawl under my rPod and measure the crown in my 179 axle for comparison to StephenH's new axle. I have a definite crown in the axle center too, about 1/4 inch, so my crown is a little less than StephenH's. I probably have a bit more weight in mine that StephenH does (mostly some canned goods), or it could be that my axle has started to fatigue a little bit, or it could simply be measurement error. I took a look at the deflection calcs and get about 0.1 inch for an unloaded trailer and 0.14 inch for a fully loaded trailer, so there really isn't a whole lot of change as the axle loading changes. Based on this I think if we did proceed to add reinforcing angle to the bottom of our rPod axles we probably should try to get the angles made up with a 3/8 inch crown in them to match StephenH's axle. That way there would be no impact on a new axle's crown or bending stress under light load conditions when we clamped the angle to the axle. But in reality the deflection changes are going to be small enough that if the crown ends up slightly off its probably not a big deal. StephenH, what are your thoughts. do you want to proceed? We live close enough to each other that we might get a benefit by finding a shop to make up two angles for us. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: SC for Huskers
Date Posted: 14 Mar 2019 at 6:21pm
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Fellas, I have tried to speed read seven pages of axle bending. Sunday I had my 172 home to spring flush and noticed the tires, both sides wearing on the inter part. Taken trips from Charleston SC to SD, CO, and three to GA. Not a whole lot for 2017. I use equalizer sway bars and carry a heavy suit case, a Cushman Scooter, 2 alum ramps, 2 Hyd. Jack, 2 tool boxes, lawn chair, food for 2 weeks, CD and DVDs. I know I am transferring some of the weight in the pickup back to the camper. What you have said, if I read correctly, I shouldn't have used the equalizer bars because FR didn't build a sturdy camper.  One thing bothers me. No one has said the rubber in the axle is bad. Rubber doesn't become dis-formed around the inter part of the axle? Second, How do you measure the hump in the axle? Thanks to all of you, ------------- Happy Traveling, Tom 2017 172pod 2011 F150 STX |
Posted By: michaeln
Date Posted: 14 Mar 2019 at 8:02pm
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I am betting that reinforcing the axle is just going to transfer stresses to some other part, and that will end up bending or breaking. ------------- --- Avery, CA |
Posted By: podwerkz
Date Posted: 14 Mar 2019 at 8:06pm
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You guys got me curious, so I went and looked and the axle on my new 171 actually has "CAP 3500#" printed on the label. The sticker on the trailer has 3000 for the GAWR. ------------- r･pod 171 gone but not forgotten! |
Posted By: offgrid
Date Posted: 15 Mar 2019 at 1:43am
Sorry to hear your having axle problems. When you say equalizer bars I assume you mean a weight distribution hitch? If so then possibly you could have transferred more weight back to the trailer axle than you really should. It would depend on how much tension you put on the wdh bars. I suggest that you load up, tension your bars as you normally do, then run through a public scale and get the individual axle weights. That way you'll know exaclty what you're putting on the trailer axle. To measure the crown/arch/camber on your axle, run a string line between the ends of the axle tube along the bottom of the tube from one side of the trailer to the other and measure the gap between the string line and the tube in the middle. Yes, I've read that the rubber cords on these torsion axles can get flattened and go bad. But, this would make the wheel on one or both sides sit low, it shouldn't change the wheel camber angle, so shouldn't cause the inside of the tires to wear more, which indicates you have negative camber. That's most likey to be a bent axle tube. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: offgrid
Date Posted: 15 Mar 2019 at 1:47am
Yep, makes sense. I'm pretty confident that the lighter rPods are using 3500 lb rated axle just like the heavier ones, they've just derated them to 3000 lbs to limit the total published load you carry. Consider yourself lucky to have some extra margin we don't have on our heavier ones. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
Posted By: offgrid
Date Posted: 15 Mar 2019 at 1:59am
How much do you want to bet ?Seriously though, in this particular case it doesn't work that way. The axle loads are proportional to the distance between the wheels and the axle mounting points, meaning that if you can support the axle tube farther outboard things get better for the axle tube. That includes the section of axle tube between the supports. That's not going to change the loads on the spindle or torsion arms, or rubber cords or any other parts outboard of the axle tube supports, which will see the same loads as before. So if any of those were the failure point before (and they for sure could be in some cases) then they still would be after reinforcing the axle tube. ------------- 1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |