Mounting Generator on rear end

...what is your tow vehicle?

This outfit has bracing struts/brackets designed for various 4" and 6" trailer bumpers. They also have a wide range of load brackets and racks for them also.

https://www.mount-n-lock.com

If you do nothing else, add a piece of angle iron that spans from under the frame to under the bumper (the piece cut off at 45 degrees in pic).
This will support and keep the thin bumper from rotating away from the frame.

It's my understanding that the typical 4" square steel bumpers are rated for 100 lbs. max. That would be static weight too. Dynamic forces from hitting things like speed bumps and potholes will be much higher and sometimes enough to catapult things into orbit. That's a lot of stress that can lead to failure of welds and attachments. What you add there would be on top of the weight of the spare tire too.

The only way I would do it is by adding welded reinforcements and attachments to the I-beams. For an idea how to do it well, look at a Nash TT. Some TT manufacturers offer racks at the back as an option but there's no way I'd trust one. You can't see things hanging off the rear and won't know if you lost it in transit.

Not a good idea, but lots of people hang bikes, BBQs, ladders, gennies and other stuff off the rear. It's fun watching them bounce way up when they hit speed bumps in CGs at just a few mph... :)

JCR-1 wrote:
Posted: 01/31/18 02:40pm
Link | Quote | Print | Notify Moderator

I had to go back and read some of your previous posts to figure out what kind of camper you have. In a previous post you said you have a Coachmen Clipper 17RD (For visual, Click here.)

It's a single axle trailer, which means any weight you add on the back will be noticeable on the tongue. But maybe the trailer is still heavy enough on the tongue, this will not be any issue. Still, this would be my first concern. When the tongue is light, the trailer will get bad sway. But you won't know until you try and see how the extra weight on the back handles.

Next, looking at the many photos on the Google search, it looks like your bumper is a traditional 4 inch metal bumper welded in 2 places to hold it on.

Carefully look at the actual welds and see if the weld runs the entire length of the connecting points, or if it is just spot welded. If spot welded, the bumper will not hold anything but itself. I'd even remove the spare tire in that case.

If the weld is solid along the seam, it will be a much stronger weld and you may have a good chance at success. However, there have been stories of bumpers falling off due to too much weight and inadequate welds. Definitely re-inforce the bumper with additional support before you try adding the extra weight. If it's originally spot welded, have it welded completely. That's an absolute given, must do!

One thing you have to remember, the bumper may be able to support your 200 pounds by simply standing on it. But, if you start jumping up and down on it, what happens then? When driving down the road, the rear of the trailer extends beyond the axle several feet. In the middle of the trailer, bouncing may be only a couple inches. But extend that to back, and the bumper may be moving up and down, being jerked 6 inches to a foot. And the harder the "hit" the more force there is on that bumper. Add additional length and leverage with the carrier hanging on the bumper AND the weight of the generator, and a simple 1 inch bump in the road (could) cause a couple thousand pounds of force bouncing up and down on that bumper.

Bottom line.... yes! Get it strengthened and give it a try. If tongue weight is reduced too much, shift weight inside the camper to compensate.

If it were mine, and I wanted the generator, I'd do the extra welding and support in a heart beat!

You sir are correct.. I checked and the bumper is solidly welded to the frame rail. Weight of the genny is 80 lbs and would be placed centered over the support bracket. As suggested I would reinforce with another bracket to prevent any twisting. The genny would also be 1/2 over the bumper itself and the other 1/2 in air.I think it will work fine. My majopr concern is weight and lightening up the tongue. I dont want to increase too much overall weight as these trailers are speced out without any safety margins. I could add another battery up front to counter the genny . ??

you'll probably want to reinforce the area were the tube is welded. that tube is thin and what will happen is the weld won't fail but the thin metal of the tube will break around the weld. with 80# you should be ok with your tongue weight, 80# isn't much 2 bicyles weigh that much. my information about my gen was incorrect its a 3500/4000 with a weight of 130#. also if your worried about it getting dirty or wet just get a cover for it, I have the Champion cover for mine or you could make one.
Jay D.

Posted: 01/31/18 02:40pm
Link | Quote | Print | Notify Moderator

I had to go back and read some of your previous posts to figure out what kind of camper you have. In a previous post you said you have a Coachmen Clipper 17RD (For visual, Click here.)

It's a single axle trailer, which means any weight you add on the back will be noticeable on the tongue. But maybe the trailer is still heavy enough on the tongue, this will not be any issue. Still, this would be my first concern. When the tongue is light, the trailer will get bad sway. But you won't know until you try and see how the extra weight on the back handles.

Next, looking at the many photos on the Google search, it looks like your bumper is a traditional 4 inch metal bumper welded in 2 places to hold it on.

Carefully look at the actual welds and see if the weld runs the entire length of the connecting points, or if it is just spot welded. If spot welded, the bumper will not hold anything but itself. I'd even remove the spare tire in that case.

If the weld is solid along the seam, it will be a much stronger weld and you may have a good chance at success. However, there have been stories of bumpers falling off due to too much weight and inadequate welds. Definitely re-inforce the bumper with additional support before you try adding the extra weight. If it's originally spot welded, have it welded completely. That's an absolute given, must do!

One thing you have to remember, the bumper may be able to support your 200 pounds by simply standing on it. But, if you start jumping up and down on it, what happens then? When driving down the road, the rear of the trailer extends beyond the axle several feet. In the middle of the trailer, bouncing may be only a couple inches. But extend that to back, and the bumper may be moving up and down, being jerked 6 inches to a foot. And the harder the "hit" the more force there is on that bumper. Add additional length and leverage with the carrier hanging on the bumper AND the weight of the generator, and a simple 1 inch bump in the road (could) cause a couple thousand pounds of force bouncing up and down on that bumper.

Bottom line.... yes! Get it strengthened and give it a try. If tongue weight is reduced too much, shift weight inside the camper to compensate.

If it were mine, and I wanted the generator, I'd do the extra welding and support in a heart beat!

You sir are correct.. I checked and the bumper is solidly welded to the frame rail. Weight of the genny is 80 lbs and would be placed centered over the support bracket. As suggested I would reinforce with another bracket to prevent any twisting. The genny would also be 1/2 over the bumper itself and the other 1/2 in air.I think it will work fine. My majopr concern is weight and lightening up the tongue. I dont want to increase too much overall weight as these trailers are speced out without any safety margins. I could add another battery up front to counter the genny . ??

delete

Keep in mind when you stand on the bumper, the forces on the connections to the frame are almost in pure shear.

If you hang the generator off the back, it gains leverage and becomes a twisting force.

A mount fabricated over the tongue makes more sense assuming it doesn't put you over the hitch weight for the tow vehicle.

Fredetteb wrote:

JCR-1 wrote:
I have a light 21 foot trailer and use a 3100 champion generator for A/C. My question is I would like to mount the genny on the rear bumper with some brackets however the rear bumper is only attached (welded)to each end of the frame with nothing in the middle . I would need to gain more support from the chassis frame i would think. Although I weigh over 200 pounds the bumper does support my weight without bending. I am wondering if I could weld on some angle brackets to the bumper. Seeking thoughts , ideas..Thanks

For several years we had a rear mounted genny on our camper. We were lucky enough to have a friend that fabricated a rear bumper hitch for us. The biggest concern on these rear bumpers isn't so much the static weight but the torsion effect of the weight on the bumper.

If you do decide to add a hitch or carrier to the rear, ensure that the box bumper is reenforced to prevent twisting. We achieved this with a "T" shaped section of angle iron welded from the frame to the underside of the bumper.

I would also recommend the double hitch setup also. We didn't use this and the lateral rocking was very noticeable especially on uneven roads.

this right here! i'm getting ready to do the same thing with mine. I have a 27' and the champion 3100. your going to want to redo the bumper mounting. i'm going to extend my bumper back about 4" so the tube is directly under the gen. its the twisting of the tube with any weight hanging off the rear of the bumper. that a bad design and causes problems. i'm also going to make a davit with a small winch that I can use to lift the gen off and put it back on. it will fit a socket on the tube then store in my storage compartment when traveling.
Jay D.

You might want to run this one by the legal bureau of your insurance company because you are putting yourself in a position of liability operating a MV on a public highway with a fabrication like this.
There is a reason why travel trailer mfg.'s do not offer options like this.