Weight capacity for TT bumper

May be a bit tricky to calculate precisely, but the force of a few bounces going down the road would increase the load on the bumper welds. Just something to keep in mind.

I've not seen ANY 4" square RV bumpers that are truly "heavy duty." Bolting a hitch receiver to the bumper creates a fulcrum/lever situation and the 90 lbs. of generator and whatever the rack weighs become much, much more in terms of torsion (ft. lbs.) as the RV bounces down the road. There are countless stories on this and other forums about people who have set things up this way and end up dragging bicycles, generators, and other gear down the road by one end of the bumper or just the locking security cable they used. The only truly safe way to do things is to have a receiver hitch bolted or welded directly to the frame. Leave the RV bumper to what it does best: carry the stinky slinky.

Rob

Second Chance wrote:
I've not seen ANY 4" square RV bumpers that are truly "heavy duty." Bolting a hitch receiver to the bumper creates a fulcrum/lever situation and the 90 lbs. of generator and whatever the rack weighs become much, much more in terms of torsion (ft. lbs.) as the RV bounces down the road. There are countless stories on this and other forums about people who have set things up this way and end up dragging bicycles, generators, and other gear down the road by one end of the bumper or just the locking security cable they used. The only truly safe way to do things is to have a receiver hitch bolted or welded directly to the frame. Leave the RV bumper to what it does best: carry the stinky slinky.

Rob

100% agree.

OP, take a look at the thickness of the bumper as you may find it is actually very thin. Many reports of the metal peeling away with the type hitch installed you have mentioned. It is much safer to have a hitch welded to the TT frame then chance a RV bumper with hitch bolted to it. Of course all RVs are not created equal but willing to bet yours is not any different than the average cheap RV bumper.

You guys convinced me. I cancelled the bumper mount hitch order.

The portable generator I bought is only 1 inch too tall to fit in the pass through. It would be nice to get it in there but not sure I want to modify the handles to make it fit. I will look at options.

Lots of people do it. There is no standard for RV bumpers, so it is difficult for us to say you will have no problems. My advise is only put items on that bumper you are willing to lose.

Something that attaches to the frame would be better.

There are two options for this if you truly want to use the bumper to carry something. The first option is a pair of these.
The second option requires some fabrication with materials you can get at any home center. You get some 2" angle iron, grade 8 bolts, 1 1/2" long by 5/8" diameter, washers, lock washers, and nuts. These are used to secure the angle to the frame, one on each side. You get a 4x4 to slip inside at each frame member, a piece of 3/16 plate, or cut the angle in half to place against the face of the bumper and then get 5" long grade 8 5/8" bolts, drill all the way through the bumper, 4x4, and angle, and secure them with washers, lock washers and nuts. You can use grade 5 bolts if you like, I prefer grade 8 for heavy duty things like this, I replaced the hardware on my Husky WDH with grade 8.

Neither fix will be as strong as a purpose built frame attached hitch as previously posted, but will support loads under 200# hanging off the back end. The former I was going to do, but thankfully looked at the actual attachment points and realized they would never work since my stabilizers are against the bumper, but option #2 would work fine, in fact I was looking around and found that I have 3" x 3/16" angle in my garage that would work fine, and since my stink pipe wont fit in the bumper, it is no loss of room for me, I have my hose in its own container that is sealed. That frame attached hitch wont work on my trailer, due to the stabilizer position.

Here is the real problem, the wall thickness of the bumper is thin, even with a perfect weld to the frame, given enough trouncing, eventually the metal around the weld will tear, and cause the bumper to fail. By using the plates, blocks, bolts and angle you can secure the bumper front the back, or back to front depending on how you look at it, and that weight then is transferred to the frame. Instead of a few welds, you would have 12 heavy bolts securing the bumper to the frame. While not perfect, it would be a whole lot safer than just putting the receiver on the bumper and hoping for the best.

Acdii wrote:

snip..

Here is the real problem, the wall thickness of the bumper is thin, even with a perfect weld to the frame, given enough trouncing, eventually the metal around the weld will tear, and cause the bumper to fail.

^^^^THIS^^^^ IS THE PROBLEM!!!

I almost lost two bikes not realizing just how thin the bumper metal is!

MOST RV bumpers are 14 gauge steel (about 1/16" thick), that is only a couple gauge sizes thicker than the sheet metal of a vehicles door skin (typical automotive sheet metal is 18 gauge!).

The 14 ga steel will simply tear away from the welds when it is twisted (which is what happens when you put bike racks on the bumper).

This leads to the fact that MOST RV bumpers do not have ANY weight rating for the bumpers..

SOME RVs do use a thicker wall bumper which will be 1/8" inch thick, with those the manufacturer of the RV will typically give a weight rating..

No weight rating from the RV manufacturer, do not attempt to put any weight on the bumper..

I worry about those spare tyre carriers bolted to the bumpers, got rid of mine
spare is in the pass thru

stevemorris wrote:
I worry about those spare tyre carriers bolted to the bumpers, got rid of mine
spare is in the pass thru

If you bolt the carrier around the frame attachment point, then the chances of it failing are very very low. Also the type of carrier makes a big difference. The short ones that put the tire a couple inches away and near center of the bumper are the best. Those that are hinged and sit the tire high are the ones not to use, they would stress the heck out of the bumper.

I had a few ideas on my way home from work (hour fifteen drive gives lots of thought time), and was thinking that a rack mounted on top of the bumper, close to the back wall would work to have a stable load to mount a generator back there as it wouldnt be leveraged out, so when I got home I measured my generator, then went back to the trailer and found, eh, wont work either, bumper is too close to the wall, the generator is 18" wide, so 2/3rds would overhang the bumper. Even though the mass would be low on the bumper, it would also be cantilevered out too much to be safe, so nixed that idea as well.

I also took another look at the attachment points. There are 1/8" angles welded to the frame and the bumper. They are well done, but as mentioned before, the wall thickness is too thin to support much weight. I was going to mount a truck box back there, even installed a bolt on receiver, but after looking everything over, decided not too, that and it would block the water heater outlet.

Bottom line, to brace the bumper to be strong enough to support overhanging leverage would add too much weight to the trailer, and a ton of work to make it strong. Not worth it.

The problem with most stock bumpers are that they aren't substantial enough to place heavy object back there. While they can support the static weight of the objects, they also have to support the dynamic weight of the objects bouncing around. You end up with a very effective hammer back there. My trailer came with a warning stick on the bumper that said the max weight was 135 lbs. The bumper can support much more than that, I know because I've stood and bounced on it. However the manufacturer is accounting for the hammering effect.