Floor failure!!! - R-pod Owners Forum

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Olddawgsrule View Drop Down

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Topic: Floor failure!!!
Posted: 15 Aug 2019 at 7:32am

Originally posted by Toyanvil

If you add a frame rail you will not want to continuously welded it, it will be stronger to stitch weld it.

Thanks for the info on this. For what I've read so far the stitch weld is used so you do not compromise the parent metal. Which makes a lot of sense to this simple mind! Especially if the parent is .1 and the child is .187..

It also sounds like it's very specific in pattern. Like, 2" weld, 2" space. Did I read that correctly?

They also spoken of back-stitching. I thought it interesting that the spaces (in my example above 2") was filled/welded in the opposite direction. I never thought of a weld having directional strength. Does it truly?

Mind ya, I have no intention of doing this myself! My welding skills are close to non-existent.. It's my curious mind.

Byways no Highways
2017 Tacoma
Truck Camper Build
2004 F150 My Overlander

offgrid

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Posted: 15 Aug 2019 at 5:20am

Originally posted by Toyanvil

If you add a frame rail you will not want to continuously welded it, it will be stronger to stitch weld it.

Thank you Toyanvil, that is what we needed. I understand the structural requirements but I'm not a welder.

I always thought that continuous seam provided the strongest joint and stitch welding is done where that isn't needed or to reduce heat distortion. Maybe that's the case here? Is there something on the web you can point me to on this where I can learn more about when one is used vs. the other?

Olddawgsrule, just for clarity, here is the formula for section modulus of a rectangular tube the "hard way" that I'm using:

Z=(b*d^3-h*k^3)/6/d where b is the outside base, d is the outside height, h is the inside base, and k is the inside height.

I'm suggesting another 4 inch tube (but with thicker walls) under the existing one because the taller the tube the stronger it is for a given weight per foot, and also because 4 inches is more or less the same height as the standard riser kit.

For example, a 2x4x.1875 has a section modulus of 2.11 in^3 and weighs 6.9 lb/ft while a 2x3x.25 has a Z of 1.7 and weighs 7.1 lb.ft. Either way if you use two 3 ft sections you'll be adding about 42 lbs to the axle load but with the 4 inch tube you'll be 73% stronger while the 3 inch tube will only give you 39% more frame capacity.

Sometimes things can work out and you can kill two birds with one stone (in this case gain ground clearance and reinforce the axle to frame attachment at the same time). Like the old saying goes, if you're handed lemons, why not make lemonade? Thumbs Up

1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold

Toyanvil

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Posted: 14 Aug 2019 at 7:12pm

If you add a frame rail you will not want to continuously welded it, it will be stronger to stitch weld it.

GlueGuy

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Posted: 14 Aug 2019 at 5:10pm

A good welder can fix that, and give you a built-in riser at the same time. Convert your 182G to a Hood River and repair your frame at the same time.

bp
2017 R-Pod 179 Hood River
2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost

Olddawgsrule View Drop Down

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Posted: 14 Aug 2019 at 2:51pm

[/QUOTE]

Section modulus of that shape is only 0.55 in^3. Not enough especially if you can't depend on there being any strength left in the original tube. I think you'd want at least a 2x4x.1875 tube which has a section modulus of 2.1. But you don't have to run them the whole length of the trailer. About 3 feet should do it. Shouldn't cost much at all for the steel.

[/QUOTE]

I need to fix my spreadsheet formula.. The numbers never match yours.. Yet I did come up with 56% less.. Thank you for confirming.

I did run a 2x3 .25 steel and found 43% increase. I do wish to see it lifted and have no idea way I'm debating the amount...

My mind is spinning..

Byways no Highways
2017 Tacoma
Truck Camper Build
2004 F150 My Overlander

offgrid

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Posted: 14 Aug 2019 at 2:42pm

Originally posted by Olddawgsrule

What's your thought on 2x2 .125 steel tube. I still have some around here. Actually enough to run both sides end to end.

1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold

Olddawgsrule View Drop Down

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Posted: 14 Aug 2019 at 2:37pm

Update: Just heard from the Dealership. It has been looked at.

They are deciding upon approach of repair. The floor bend/fix seems to bother them the most right now. I 'guess' that's good... the frame doesn't seem to bother them as much.

The journey continues..

Byways no Highways
2017 Tacoma
Truck Camper Build
2004 F150 My Overlander

Olddawgsrule View Drop Down

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Posted: 14 Aug 2019 at 1:36pm

Originally posted by furpod

[QUOTE=Olddawgsrule] [

Where were you blasted? I will admit I try to check in every day if possible, and I have not seen it. Feel free to PM me if needed about any issue with the site or our members.

Not in this group! Another Rpod group..

Byways no Highways
2017 Tacoma
Truck Camper Build
2004 F150 My Overlander

Olddawgsrule View Drop Down

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Posted: 14 Aug 2019 at 1:31pm

[/QUOTE]

Suppose that all the shop does is straighten the existing frame rail and doesn't even weld it up. Then, the shop welds another 2x4 rectangular tube to the bottom of that rail, but this time its say a 0.1875 thick tube. This new tube extends well in front of and behind the axle attachment point and is continuously welded to the old tube. Then the axle is attached to the new tube. The new assembly will be much stronger than the old tube was even if there is zero capacity left in the old tube. Since the peak loads on the frame are at or near the axle attachment and drop off rapidly in front of and behind that area the 0.1 inch tube is fine to carry the loads as long as you extend the new heavier tube a foot or two from the axle area. So, the 0.1 inch tube can stay there and not cause a problem because you're not counting on it to take any load in the axle area.

And the floor and body of the trailer doesn't need to be removed to do it.

[/QUOTE]

What's your thought on 2x2 .125 steel tube. I still have some around here. Actually enough to run both sides end to end.

Byways no Highways
2017 Tacoma
Truck Camper Build
2004 F150 My Overlander

furpod

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Posted: 14 Aug 2019 at 1:07pm

Originally posted by offgrid

Originally posted by furpod

Switch to discs.. popular mod in a couple other groups I am in..

Yeah, i looked at doing that. Not only would I need to switch to discs but I'd need an electric over hydraulic actuator. Probably around $1500 in parts IIRC. So the operative word here is prefer. But that preference isn't worth $1500. Let me know if anyone in the other groups has found a cheaper way.

Barring that, I'd probably be more inclined to switch to a 5200 lb axle with drum brakes, that would both be cheaper and would provide more headroom on axle capacity as well as more powerful braking.

Yeah, the dual axle kit, which includes everything needed is around $2k.. But the guys who have done it swear it's worth every penny.. Of course this is on Lances and Airstreams...