Diagonal frame bracing

I added the bracing to my spring hangers. Few pics:

Moderator edit to re-size pictures to forum limit of 640px maximum width.

When you say "twisting", I think you mean left/right movement? Many trailers suffer from this. Even though Lippert makes frames for the vast majority of towables, some of their frames are better designed than others. The RV manufacturer has some input on it as well, so there's two parties involved. You should see what the frames look like on some of the ultra-lites because the RV manufacturer wants it as light as possible. There are no industry design standards and they do what they want with frames to lighten them and cheapen them. And when something goes wrong, it's not their fault because you obviously overloaded it or abused it.....

Sharp left/right turns can cause the bottom of the spring hangers to move a lot as in simply turning a corner or backing into a site. This is because the axles have different turning radii and one set of tires gets dragged across the ground forcing movement of the spring hangers and an axle. Over time, damage can occur.

If there is no bracing/strengthening on the I-beams, depending on things like the weight of the camper, there can be excessive lateral (left/right) movement at the bottom of the spring hangers. Tall spring hangers and under-slung axles increase the leverage force.

Some trailers eventually end up with stress cracks in the vertical web of the I-beams. Axles can also get bent. There can also be premature and abnormal tire wear.

Tying the bottom of the spring hangers together can help. The Mor/Ryde X-member is one option but it can easily be fabricated and installed yourself.

I would also look at adding gussets to the outer sides of the I-beams above the spring hangers. These are short lengths of flat steel, maybe 3/16" thick, welded at an angle from the outside edge of the lower beam flange and part way up the vertical side of the I-beam.

Square tubing, say 2x2, can be welded to the underside of the lower flange between the spring hangers.

It may also help to box in the spring hangers on the upper portion.

If you can get access to the underside of the frame by removing the underbelly material, I would look at how the attached the cross-members between the left and right I-beams. Sometimes it's a piece of 2x2 just tacked to the sides of the I-beams. If there is excessive lateral flex in the I-beams, cracks will develop where the cross-members are attached. You can add re-enforcement to spread the load out.

And to keep going with more work and $$, you could look at upgrading the axles to a higher rating. Often the axles are sized to a bare minimum and are more susceptible to damage.

mosseater wrote:
I hesitate to actually believe Lippert frames (or any for that matter) are "engineered" to any large degree. I'm sure they must have someone with a spec or two of knowledge about structural design and stress designing these frames. The truth, however, might give us pause.

That said, I'm not sure I'd be comfortable throwing in extra support willy-nilly because I believed it would be better. True, I have built and repaired many things in my career that have held up quite well, but I'm not an engineer and don't play one tv. When you add bracing that wasn't there to begin with, you change how the frame moves and supports. Unless you know for relative certain that is in your best interest, you may be making a bad situation worse in another area of frame by shifting stress to another point which isn't up to the task of taking it. Word to the wise.

Good advice, as you can introduce stresses that weren't there before to other areas.

I have a diagram and instructions on the repair and strengthening of a cracked frame on a Dexter axle before the frame division was bought out by Lippert. Mine was repaired pretty much as they recommended and haven't had any trouble that I am aware of since the repair. I will be happy to send you a copy. Just let me know.

I hesitate to actually believe Lippert frames (or any for that matter) are "engineered" to any large degree. I'm sure they must have someone with a spec or two of knowledge about structural design and stress designing these frames. The truth, however, might give us pause.

That said, I'm not sure I'd be comfortable throwing in extra support willy-nilly because I believed it would be better. True, I have built and repaired many things in my career that have held up quite well, but I'm not an engineer and don't play one tv. When you add bracing that wasn't there to begin with, you change how the frame moves and supports. Unless you know for relative certain that is in your best interest, you may be making a bad situation worse in another area of frame by shifting stress to another point which isn't up to the task of taking it. Word to the wise.

Ours has straight cross braces between the hangers. At first the factory forgot to install them and on the first trip the front axle moved out of alignment by about an inch. The factory realigned everything and then installed the cross baraces. No problem since...the 5th wheel is 20 years old with over 40,000 miles on it.

If it a new 5er, let the warranty folks take care of these issues. I bet it has a Lippert frame which is not a really strong frame.

Ken