The Frame Crack

Yep, my poor baby blue RC had a frame crack. I discovered it a couple months after returning from it's first trip to Moab Utah. I was installing new front shocks when I spotted the crack in the side of the frame behind the right front shock mount. The crack was several inches long, and actually wrapped under the frame rail. The lower end of the crack was about 1/2" from reaching the edge of the frame.

I spoke to several people, and gathered as much advice as I could. I planned to fish plate the frame rail, but I was unsure what the proper welding layout would be. This portion of the frame is also unusually shaped, and a simple plate wouldn't exactly fit.

I concluded that vertical welds were undesirable as the heat affected brittle seam in the frame that would provided a path for the frame to crack again. Also, the lower edge of my RC's frame was in the most danger of breaking again, so I intended to provide extra reinforcment for that area. I wanted to use a single, bent plate to reinforce the frame, but the shape of the frame just didn't lend itself to that.

I came up with the best compromise solution I think.

I used a wire wheel in my die grinder to clean the frame area so I could find the ends of the crack. Then, I drilled a hole at the ends of the crack so that it couldn't propagate any farther. I used the cutting wheel on my die grinder to grind the crack open so that the weld could penatrate deeper for a stronger repair.

Next, I fit up my reinforcing plates. I used 1/4" plate steel. One large plate was used on the side of the frame, and a 15" long piece of 1.5"X1/4" strap for the bottom of the frame. I also drilled two 3/4" diameter holes in the strap steel, one on each side of the crack. These holes were for plug welds.

Finally, I talked a buddy into coming over to do the welding for me. These are critical welds, and I didn't trust my welding for this. While I phoned in the order for one large pizza, he welded the crack, then ground it flush. We fit the patch plates back on the frame, and welded the side plate on the top and bottom only. Next, the bottom strap was fit into place and it was welded down both long sides, the ends were not weled. Finally, the 3/4" holes in the strap were plug welded.

I sprayed a sloppy coat of paint all over the repair area to minimize rust. I also siliconed the ends of the plates where they weren't welded to hopefully keep excess moisture from getting behind the plates and accelerating rust. I think this repair will hold for a long time.

PLEASE SIGN MY GUESTBOOK!

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