[Motor31]

I guess my rig was telling me it did NOT want to leave the cool temperatures of Washington State.

We got parked in Kansas just 30 miles south of KC at Rutladers park, a nice friendly big rig style place. I unhitched the rig and happened to look at the pin box. What I saw was a big BIG crack on the top of the box right behind where the shock mount connects to the top jaw of the pin box. It went all the way through the pin box and the front of the same area was pushed or dished in towards the trailer. I was not happy about that.

I called Trail air and the nice lady informed me that I was out of warranty, no kidding! DUH!! it was just past the 5th year anniversary date. She asked me some questions about the pin box.

Does the crack go through the pin box?
Does the front end look "pushed in"?
Does the front edge of the top of the pin box have a curved "lip" on it.

The first 2 were yup and the last one was nope. She said that I had an "early model" pin box. Later units have a curved lip on the bottom edge of the upper jaw behind the shock. That gives additional strength when they are used on bigger heavier rigs (like MS trailers). This is most common in "L" model pin boxes. Mine is an M18 or medium length. In any case, it is not uncommon.

The solution is simple, weld the crack and install some gussets to reinforce the forward lip and shock mount area and you are good to go.

I called a welder in the area referred by a local mobile RV tech. He set up a time and date to do the repair onsite. He said he would have a few gussets made up to be ready to install. In the mean time I removed the air bag to clear the area for welding. Simple, just deflate and remove 2 bolts on top.

When the welder arrived we also removed the lower jaw. Two bolts and tap the "axle" out. We used a hydraulic jack to push the front end of the pin box back out straight as it was to begin with. Then he welded the crack. Since this was a medium length pin box there was no place to weld the gusset inside the jaw so it would not wear on the air bag. We decided to place it on the top outside. I now have a velociraptor pin box with a crest. Pix are below. Fairly inexpensive and easy repair. You can see there is no curved lip on the forward edge of the pin box.

He also added to the welds on both sides of the upper shock mount as the original welds were a bit of "cold welds" and not really professional quality. Lots of spatter around the bead. That was another comment made by the lady at Trail air as well.

Check the front of the top pin box and see if there is a curved lip. If not, consider getting some gussets made to reinforce the box especially if you have an "L" model pin box on the rig.

If yours does crack remember that it's the lower jaw that holds the push pull forces. The forward shock mount just deals with the up and down motions so it will not just break apart and send the trailer on it's own down the road.