Mounting a rear hitch need advice

JFM-jr · 04-29-2012, 08:12 PM

First off I realize it will void the frame warrenty i'm, looking to have some storage for my generators (Twin Hondas) and maybe some spare batteries on a cargo carrier box that goes into a reciever. I have read mounting it on the bumper itself is a no no. I took a pic of the way my frame is and how the current bumper is welded to the frame. I was gonna run a piece of steel across the camper just wondering if I should use the frame of the trailer (blue) or the bumper mounts (red) to weld my cross member too? Or should I ditch this whole idea altogether is this more trouble than it's worth?.

OldCoot · 04-29-2012, 08:19 PM

Looking at the quality of the welding and the thin material, I would scrap the idea and look at the tongue. Re-arranging things there and maybe a rack as long as you watch the tongue wt and don't overload it or your tv.

The bumper has all it can take now with the spare tire bouncing around. A checklist should list checking the bumper for cracks around the mounting surface and where the red is welded to the blue in you pic.

Mine started cracking and I removed the pins in the spare tire rack and bolted it solid on each side and the bottom. Was going to weld the crack and never got around to it and towed it several thousand miles and the crack did not propagate further.

Rod Johnson · 04-29-2012, 08:25 PM

I'd mount it to the frame. I don't know how much room you have. But, if you could burn it to the frame and the bumper, it would make everything stronger.

Did you do the bumper yourself, or is it already part of the trailer?

I built a hitch bumper for one of my trucks, let me see if I can find some pics of the brackets...

New ones on the left, old ones on the right

This is from under the truck, looking back. They're bolted into the frame with (6) 1/2 inch grade 8 bolts.

The truck frame is 3/16" C channel. The bumper brackets are 3/16 or maybe 1/4 inch plate cut and welded together. And believe me, its on there.

googmiester · 04-29-2012, 08:29 PM

You can purchased a bolt on receiver (e-bay, amazon, ect) that fits the bumper and use a hitch cargo basket for hauling accessories, total investment $250. The hitch baskets are also available in aluminum, some models flip up for storing, and most hold up to 500#'s. Hope that helps, Goog.

**Herk7769** · 04-29-2012, 08:42 PM

Goog,

I did this with my FAIL cargo tray mod. It lasted a week and the camper never left my driveway. Not a total disaster; I saved the "dog house" the generator lived in and learned why nothing should be attached to the bumper or frame of ultra light campers. Luckily not the hard way, as I could have watched my 2500 dollar generator; my blue boy; and my cargo tray sliding down the highway.

OldCoot · 04-29-2012, 08:47 PM

Quote:

Originally Posted by herk7769

Goog,

I did this with my FAIL cargo tray mod. It lasted a week and the camper never left my driveway. Not a total disaster; I saved the "dog house" the generator lived in and learned why nothing should be attached to the bumper or frame of ultra light campers. Luckily not the hard way, as I could have watched my 2500 dollar generator; my blue boy; and my cargo tray sliding down the highway.

And into a poor unsuspecting soul following you.

And Herk would be still paying the lawyers.

crocus · 04-29-2012, 09:16 PM

JFM, your main frame I-beams actually look a lot beefier than some I have seen, so there may be hope.
It is the main frame members that you have to worry about, as they are the ones that carry any load you put on the rear. And as the top flange of the I-beams are tied together with the crossmembers that hold the floor of the camper (or at least they should be), it is the bottom I-beam flanges that need to be connected to keep them from flexing sideways under load, so that is where your crossmembers need to be located.
I would run as tall a rectangular tube as possible down the inside of both main frame I-beams. Looking at how much clearance you have above your bumper, you could construct a complete subframe and simply slide it into place, then weld it up solid. Is there anything between the frame rails at the back of the camper?
The only real issue is that if you want to put a fair amount of weight on the rear, the maximum bending moment will occur where the new subframe ends. So, in thory, the subframe should really extend far enough forward to find some kind of support, in this case being the suspension. When I do mine, I will go as far as the midpoint between the axles, as there is a lot of strength in that area.
If you simply beefed up the very rear bumper area, and installed crossmembers all the way to the axles, the I-beams could still fail, depending of course on the load applied.

Could you tell us exactly how thick the webbing and the flanges of the I-beams are, and how deep and wide are they? I could probably give you an idea how much weight they would support.

JFM-jr · 04-29-2012, 09:37 PM

Quote:

Originally Posted by Rod Johnson

I'd mount it to the frame. I don't know how much room you have. But, if you could burn it to the frame and the bumper, it would make everything stronger.

Did you do the bumper yourself, or is it already part of the trailer?

It's a factory bumper. I was thinking of doing what your saying weld a solid beam across to each frame rail then attach to the bumper where the square reciever port would sit tying everything together. I just was not sure if the frame rails would hold lets say 125-175 lb area. I see Herk mentions not attaching to the bumper or frame of ultra lights. My unit is not an ultra light and the frame rails are I beams. Looks like the bumper on that truck is not going anywhere in fact that could probably pick the entire truck off the ground and hang by it.

Dunnc as for the tongue forget it im near the ceiling as it is in fact i remove my batteries and propane tanks off the nose when traveling to save the 220 lbs on the hitch and put that stuff in the front of the bed of the truck. I travel solo as well, im asking alot out of my 1/2 ton chassis with this unit. Tongue weight is the bigger issue than overall weight and was the reason for coming up with this idea in the 1st place. Figured a few pounds on the back would eliminate a few things going into the bed and may counter tongue weight in the process possibly a win win. Ram 2500 with a CTD would end all my woes

.

JFM-jr · 04-29-2012, 09:47 PM

Quote:

Originally Posted by crocus

JFM, your main frame I-beams actually look a lot beefier than some I have seen, so there may be hope.
It is the main frame members that you have to worry about, as they are the ones that carry any load you put on the rear. And as the top flange of the I-beams are tied together with the crossmembers that hold the floor of the camper (or at least they should be), it is the bottom I-beam flanges that need to be connected to keep them from flexing sideways under load, so that is where your crossmembers need to be located.
I would run as tall a rectangular tube as possible down the inside of both main frame I-beams. Looking at how much clearance you have above your bumper, you could construct a complete subframe and simply slide it into place, then weld it up solid. Is there anything between the frame rails at the back of the camper?
The only real issue is that if you want to put a fair amount of weight on the rear, the maximum bending moment will occur where the new subframe ends. So, in thory, the subframe should really extend far enough forward to find some kind of support, in this case being the suspension. When I do mine, I will go as far as the midpoint between the axles, as there is a lot of strength in that area.
If you simply beefed up the very rear bumper area, and installed crossmembers all the way to the axles, the I-beams could still fail, depending of course on the load applied.

Could you tell us exactly how thick the webbing and the flanges of the I-beams are, and how deep and wide are they? I could probably give you an idea how much weight they would support.

I will take more pics tomorrow and take some measurments I like your idea of constructing the subframe and sliding it in. I need to see how far back inside the framerails I can go as you stated the further forward the better. As I stated above I'd be looking at putting 200 pounds as a maximum on this setup and the cargo rack is aluminum and rated for well beyond that.

Dave_Monica · 04-29-2012, 09:59 PM

Quote:

Originally Posted by JFM-jr

in fact i remove my batteries and propane tanks off the nose when traveling to save the 220 lbs on the hitch and put that stuff in the front of the bed of the truck. I travel solo as well, im asking alot out of my 1/2 ton chassis with this unit. Tongue weight is the bigger issue than overall weight and was the reason for coming up with this idea in the 1st place. Figured a few pounds on the back would eliminate a few things going into the bed and may counter tongue weight in the process possibly a win win. Ram 2500 with a CTD would end all my woes

.

Be careful when reducing the tongue weight...don't think you'd want to get it less than 10% of the camper's total weight.

Anyone that's been in that situation with light tongue weight will agree how evil the camper's handling can get!

Dave

transamz9 · 04-29-2012, 10:03 PM

I cut mine off and went with 3/16" tube. I pull my 4,000# bass boat with 400# of tongue weight..........

JFM-jr · 04-29-2012, 10:37 PM

Very nice what does that 3/16 tube attach to?

crocus · 04-29-2012, 10:46 PM

JFM, if you are only talking a max of 200 pounds, I wouldn't think you would have to get carried away. Your main frame I-beams look plenty hefty, much larger and with thicker metal than our lightweights. And I wouldn't think you would have to go too far forward, maybe past that vertical weld a ways, but not that much more.
If you made up a subframe assembly out of 2x4 rectangular tubing, 1/8 wall, and slid it over and tied it into your bumper assembly, I think you would have no worries at all.
But as a precaution, I might add one more crossmember, tying the bottom webs of the main I-beams together, maybe 1/2 way to the axles. That would remove any chance of them flexing under the added load.

My old fifth wheel had similar sized I-beams, and I also pulled a boat with only minor modifications to the frame. As transamz9 didn't show how he connected his heavier bumper, its hard to say if his is adeqaute or not.

Rod Johnson · 04-29-2012, 10:53 PM

If you pick up some 2x4, look for some .188 wall. It'll be a whole lot lighter than .25 wall and still be plenty strong.

Oh, I see Crocus said .125 wall.

crocus · 04-29-2012, 11:04 PM

.125, .188, whatever is available in that range.
I agree that .250 is probably heavier than necessary, as you don't want to add too much extra weight, and no need for the reinforcement to weigh more than the added load!

But I know adding a hitch to the back of my lightweight Flagstaff is going to be a lot more involved, as the main frame I-beams are sure small and slender.

transamz9 · 04-30-2012, 05:30 AM

Quote:

My old fifth wheel had similar sized I-beams, and I also pulled a boat with only minor modifications to the frame. As transamz9 didn't show how he connected his heavier bumper, its hard to say if his is adeqaute or not.

I know , didn't take a picture of the way I mounted it. I used the existing lightweight tube that was factory because it was welded on the inside of the web of the frame. Then I added 3/16" on the outside of the frame I-beam. Sorry for not having the pix. I have been working as a welder for 20 years so believe me when I say that if it comes off it will take the frame rail with it.

crocus · 04-30-2012, 07:32 AM

"if it comes off it will take the frame rail with it."
==============================
That is why I was asking, as with the lightweight frames, if you just welded the tube to the rear of the I-beams, it could very well rip the end of the beams right off. I have seen it happen. The I-beams are simply too thin.
Gussets and reinforcement patches over the top and bottom welds need to be used to distribute the stress over a larger footprint on the I-beams.
Of course, for those with "normal" camper frames, it is not so critical.
Yours is probably a heavier frame.

Rod Johnson · 04-30-2012, 11:09 AM

When in doubt, add more triangulation.

You can even box in a section of that I frame...

Not that I would consider myself a mechanical engineer or a great welder, but these trailers have some pretty crappy looking welds. But, then again, I look at what Detroit was putting out 30 or 40 years ago as state of the art automobiles, and many of those are still around and kicking.

FreedomTracker · 05-01-2012, 03:34 PM

FYI,

I placed a similar thread titled "Receiver for Bike Rack on TT" on 3/22/12. You might want to read the responses... consensus was mostly NO don't do it b/c of potential damage toTT frame.

Since I have a MiniLite TT, I just didn't think it was worth the risk. Since then, I have stored my bikes inside the TT and now that I have truck, plan to put the bikes in the truck bed. Neither of which are probably good options for your purpose...

I have a local welding shop that I contacted with this question. He said that the forces from the add'l weight are multiplied kinda like a person boucing at the end of a diving board. He claimed he could build a receiver that would handle this, but would have to start by replacing the current back bumper with one made of heavier gage steel.

You may also like: