Alright, so here's the story on the broken tire carrier.
I took the rig to the car wash the other day and like always, I looked it over before I got started. I always check the items on the tire carrier to make sure they are secure. When I gave the tire a tug, much to my surprise, it moved.
Once I got home, I pulled the tire down and this is what I found:
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I'm not sure whether there was a weld there or not. I was ready throw the damn thing over the fence, so I didn't take a lot of time to study the failed joint. Notice in the picture below that crack in the metal is not a straight line, and has a curve near the middle. I also noticed that the edges of the two separated parts were pretty straight and square. Finally, the metal didn't have the nice, consistent thickness at that bend that it does at other locations where the metal was obviously bent on a brake. IMO, it looks like the seam was welded, and then ground smooth.
Notice in this picture where the weight of the tire was causing the upright face to jump the diagonal face, leaving marks in the powder coat. I tried to force this to happen by hand, but even with the broken weld it was difficult. The rigidity of the top section of the tire mount resisted the downward motion, and the seam was still tight enough that the upright face had to come outward a bit to get over the diagonal face. I don't think there was an immediate danger of the tire falling off, but over time the remaining metal would have fatigued and cracked as well, dropping the spare on the road. I'm glad I caught it right away.
So, not many pictures were taken after that. I figured that while I had it cut apart I would take care of another issue with the CBI tire carrier: departure angle clearance at the spare tire.
To illustrate what I mean, on the obstacle pictured below, I was dragging the spare tire on the rocks behind the rig.
While the tire carrier on the CBI is height adjustable, I really wanted to move the tire inward, toward the body of the rig. I settled on moving the tire 3 inches inward, and 4 inches upward.
A few pics from about the halfway point...
And this is where it sits as of today. I still need to add a few more gussets, specifically another upright gusset to support the face of the tire mount, and a couple along the top outside bend. I'm also going to weld the wheel mounting studs in place, rather than using star washers to secure them.
Once I moved the spare inward, the inside lip of the wheel contacted the tire mount, preventing the mounting surface from sitting flush. I had to notch the mount to make room for the lip of the wheel. With less backspacing this would be less of a problem (my wheels have 4" BS).
If you refer to the first picture of the tire mount, above, you'll see a triangle shaped hole in the bottom diagonal face of the mount. I welded a piece of steel over that hole to provide additional support and offset the reduction in strength from notching that part of the mount to accommodate the inside lip of the wheel.
I also used another piece of steel to create a tie between bottom diagonal face and the main upright structure of the mount.
Finally, I tied everything together with a vertical gusset. This should prevent any future separation of the joint that failed. I will be adding another identical gusset on the other side of the lower mounting stud.
I welded the seams on both sides wherever I could fit the gun. Also, in case you're wondering, all of the welds are covered in Vaseline. I had to put something on them to prevent rust, because I had a trip planned the day after the initial failure and had no time to get the mount painted before leaving.
At the top, I welded the seam top and bottom, ground the top weld flush, and welded in two chunks of steel parallel to the primary welds. These got rusty because I forgot to put Vaseline on them.
And the results...
Before (the tire looks goofy sticking way out there, not to mention creates a ton of leverage on the swing arm, which leads to the tire bouncing around while the vehicle is in motion...which probably contributed to the stress failure I experienced with my tire mount)
After
Departure angles...
Before (notice that the bottom trailing edge of the tire is right in line with the departure angle from the tire to the bumper... if you drag the bumper, you drag the tire)
After (the tire is tucked up and in... drag the bumper, and the tire stays clear)
3/4 view....
Before
After
Anyway, that's about it. I'll post a few more pics when it's finished and painted. Thanks, [MENTION=64712]CBI OffRoad Fab[/MENTION]
anda:
: Thanks for the compliments, I'm glad to be able to contribute to the forum. To ensure that I complied with your instruction, I believe I had 3 beers on the night of your post.
