DUKW frame doesn't fit

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DUKW frame doesn't fit

Postby uglydukwling » Mon Mar 06, 2017 6:31 am

I'm re-assembling a DUKW that had the frame removed for sandblasting and painting. The problem is that the bolt holes don't line up. With the front of the frame hard against the front hull cross-member, the bolt holes at the front are off by a couple of hundredths of an inch. With a little more hammering, I can probably get them to fit. The problem is at the rear. With the front in place, the rear holes are mis-aligned by as much as 3/16". (the hull is now shorter than the frame.)

I doubt that welding shrinkage is the explanation, since almost all the patching was finished before the frame was removed. Another possibility is that while the frame was out (for a couple of years) the hull was supported better at the ends than in the middle. That would cause the ends to be pushed up relative to the middle, and that would move them inward. Given the quality of the war-time finish, the slight amount of wrinkling this would cause would not be noticeable. To test this theory, I have supported the middle on pallets and put weights on the ends. It's been that way for a couple of weeks, and so far there's no visible movement. I could add more weight, but obviously I'm afraid of breaking something.

If worst comes to worst, I could make the holes align by reaming them, but I know I shouldn't, and I hope it doesn't come to that.

Has anyone else had this problem, and if so, what did you do about it?
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Re: DUKW frame doesn't fit

Postby renovate7 » Sun Mar 12, 2017 9:58 am

Try taking a big punch with a long tapered shaft, putting it in the hole and driving it in with a hammer to get the holes to line up. If you can line up the one hole then holes close to it should also line up. It may be a bear to get the punch out, you'll have to be able to hit the small tapered end with a hammer to drive it back out, after putting some penetrating oil on it. You can also try putting some channel locks or vise grips on it and twisting it as you mightily pull. I just had to do this when reinstalling the frame member that the transfer case hangs from. With the holes lined up on one side the other side was off by 1/8". Don't know if the frame spread or what but the big punch lined them up just fine.
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Re: DUKW frame doesn't fit

Postby uglydukwling » Tue Mar 14, 2017 6:24 am

Driving in punches was the first thing I tried, but I couldn't apply enough force that way. The bolt holes were starting to distort and the frame still hadn't moved.

The next thing I tried was to lift the frame at the front so the front of the frame cleared the front hull cross-member. This allowed the frame to slip forward far enough to get bolts in some of the bolt holes at the rear of the frame. I tightened the bolts while I drove the front of the frame down. Amazingly, the front of the frame didn't hang up on the top of the cross-member as I drove it down. I now have almost perfect alignment. Unfortunately, with the front of the frame raised, there was a slight angle between the frame and the hull, so I was only able to insert 1/2" bolts instead of the proper 9/16". When I replace the bolts with 9/16", I'll probably have to ream the holes to get perfect alignment, but they're a lot closer than they were. Close enough so I'll feel a lot less guilty about reaming them.

There's one more thing I plan to try as I replace the bolts. The problem with tapered punches is that they're tapered. That means that when the punch comes tight in the first layer (the frame), it's still loose in the layer behind it (the hull). This means the holes can still be mis-aligned. Maybe enough to worry about, maybe not. So I made some punches that have a straight 9/16" section above the tapered part. If I can drive them in past the tapered part, so the straight part fills the hole in both layers. they should give me perfect alignment. I'm afraid I'll have the same problem I had when I first tried to align the holes using punches, that is that the required force will be more than I can apply with punches, but it's worth a try.

I won't find out for a while. I can't put the final bolts in until it gets warm enough for the sealant to cure, and it's snowing now.
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