Flexiride axle attached to 1/8" tube?

[nelsonrx]

Long time lurker, and finally built a modified widget (pictures coming shortly), that I am now remodeling. Besides a series of internal changes to accomodate two adults + two children, and adding a potty-room (it's going to be a tight squeeze in there), I'm also changing from leaf springs to a Flexiride axle. I already have the axle, but my main question is do you guys think directly bolting to the 1/8" thick main rails will be study enough? There's an image below of my current setup. It's an old pop-up frame axle. In a nutshell, the main rails are composed of two 1/8" C-channels where one has been placed inside the other with open sides facing, thus making a tube. The picture below will hopefully make that more clear - I drew some circles where the two mouting holes per side would go for the flexiride. Do you guys think I need to beef up the attachment point for the Flexiride to something thicker than 1/8"? In essence, the two vertical faces are 1/4" thick since the one smaller C-Channel is welded inside the larger one (each one has 1/8" walls). I was going to use really big washers to spread out the load. My widget weighs around 1400 # so I'm using a 2k Flexiride.

Thanks!

[KCStudly]

I can't really tell what I'm looking at from just that one angle/perspective. Is the C-in-C main rail above and the axle perch on a bracket that sticks down from it?

It looks like some of the stiffening flanges next to where your circles are have been cut away.

Okay, I think I see it now. The floor extends to the left of the double channel rail and there are additional plates scabbed on that have the turn out lip extending down; and that is the part that was previously cut away, right?

So are you asking if it is okay to just drill and tap up into this 2 layers, or do you plan to somehow fish bolts into the "tube"? I'm not a big fan of tapping into two layers, seems kind of sketchy to me. If you can fish nuts or bolts with anti-rotation washers thru the frame, or a window in the frame located in a less stressed area, using the pull wire technique, and that really is a double wall on three sides, I would think that it would be structurally adequate (TLAR method). However you might run into trouble getting the nut to bear flat if it lands on the edge of the inner C toe.

If you can't find a way to get fasteners inside, then maybe you would be better off welding in weld nuts; or perhaps making a scab plate with nuts welded to the top side. You would drill clearance holes into the bottom of the frame at the nut locations, fit the scab plate with the nuts up inside of the frame, and then weld the scab plate along the edges.

[KCStudly]

I can't really tell what I'm looking at from just that one angle/perspective. Is the C-in-C main rail above and the axle perch on a bracket that sticks down from it?

It looks like some of the stiffening flanges next to where your circles are have been cut away.

Okay, I think I see it now. The floor extends to the left of the double channel rail and there are additional plates scabbed on that have the turn out lip extending down; and that is the part that was previously cut away, right?

So are you asking if it is okay to just drill and tap up into this 2 layers, or do you plan to somehow fish bolts into the "tube"? I'm not a big fan of tapping into two layers, seems kind of sketchy to me. If you can fish nuts or bolts with anti-rotation washers thru the frame, or a window in the frame located in a less stressed area, using the pull wire technique, and that really is a double wall on three sides, I would think that it would be structurally adequate (TLAR method). However you might run into trouble getting the nut to bear flat if it lands on the edge of the inner C toe.

If you can't find a way to get fasteners inside, then maybe you would be better off welding in weld nuts; or perhaps making a scab plate with nuts welded to the top side. You would drill clearance holes into the bottom of the frame at the nut locations, fit the scab plate with the nuts up inside of the frame, and then weld the scab plate along the edges.

[nelsonrx]

Sorry KC - yeah, it's a bit difficult to explain in words what would be so much easier with a picture. I drew a schematic below of what the main rails look like if you were looking down the length of the trailer. In other words, this is a cross-section if you were to take a slice of the main rail. The upper c-channel in blue and the lower c-channel in black are both 1/8" thick, so the side walls of the main rails are actually 1/4" total. My concern though is that the bottom face that is horizontal with the floor is where I want to bolt in the Flexiride (you'll see my image of a bolt there), but that is only 1/8" thick. My plan is to fish the bolt in there since the bottom c-channel actually doesn't span the entire length of the main rails, only where the suspension gear goes. I'm not so worried about that part. I think I've seen other posts on here where folks have bolted their axles to 1/8" angle, so I'm thinking I'll probably be okay, but I'm wondering if I need to beef up that area by welding in some angle that would span the bottom face and one of the sides.

Ideally, I'd like to just bolt the sucker on the bottom existing face without any modification, its the thickness that worries me.

[KCStudly]

Ah, I get it now. 1/8 inch does seem a little thin for a bolted joint like that. Is it just two bolts per side on the axle mount?

If you have the ability to fab and weld in a thicker piece, why wouldn't you? I'm usually not one to grossly over build, but this is one area where you don't want to have problems. How was the original axle attached? Something to do with where those flanges were cut away?

[nelsonrx]

That's what i figured - why not beef it up since it would be so easy to. Funny enough, the original leaf spring suspension was bolted to this same main rail; although, in a horizontal fashion with a big bolt - like all leaf spring systems. I'm thinking I'm going to weld on some 2x 1/8 angle and then bolt up through that and the existing c-channel. Thanks!

[Tomterrific]

The frame rail sits on the axle plate, correct? It seems the axle plate would be supporting most of the load. You could have an angle piece bent to fit even further over the frame than the axle plate.
Call Flexride and see if you can talk to an engineer. They probably have answered this question many times.
T