99 4964 Frame Crack Suggestions

Going through doing some minor maintenance to my new-to-me truck during the off-season, and I notice that both sides of the frame have a single horizontal crack right behind the torque arm mounts. Given this truck is a single frame OTR converted to dump I'm not surprised, it obviously has a little more body roll than originally intended. One side appears to be within the last year, but the other side has been poorly covered up by a fool with a MIG. I've included pictures of the two cracks. I checked the rest of the frame and these are the only 2.



So what should I be doing to fix? I've read through everything I can find and the general consensus seems to be that if I'm going to attempt repairing it via welding I'd do the following:

-drill 1/8 on either end of crack to prevent spreading
-v groove entire length of crack on outside
-root and cap with 7018
-v groove entire length of crack on inside into newly welded material
-root and cap with 7018
-post stress relieve entire joint by reheating and slowly bringing down over 45 min or so.

One question I have is what I should be doing to reinforce the section after. Most repairs I've seen involve installing an inside channel 2-3 ft either side of the repair, however that would require removal of quite a bit of hardware.

Since the cracking seems to be from the torque rods pulling on the frame channel, I'm wondering if a long 3-4ft plate bolted (not welded) to the outside of the frame would be a more suitable option. It would be fairly easy to fit in (nothing other than bag mounts in the way, and would certainly provide ample reinforcement in my opinion.

Any input from those who have been there before would be greatly appreciated. The next MVI for this truck is in April, so I'll be getting on it very quickly.

Thanks in advance!

 

Thanks for the quick reply, I value your input!

Any reason why inside? My thoughts with putting the flatbar on the outside was that the torque rods would have to pull the new plate through the frame rails to fail again, if I put it on the inside its putting more pressure on the bolts.

 

Wow....I'm an idiot. I didn't even think about them pushing outward.....good thing I didn't try to fix it today.... Thanks for the patience lol.

 

Thanks for the reply. Looking at the failures a little closer I feel the crack partially because of twisting, but mostly because the torque rod mounts are fairly small and the bolts tight together...there's not much space for things to flex and over time it will open up when being loaded.

I will look and see how much would need to be removed to add a frame insert. The first picture is near the dump pivot so access is limited, the other side is between the drivers so no issues there.

Either way we're talking about a difference of a half day's work vs. several days. Equipment and time isn't the issue, I just don't want to do an overkill repair if unnecessary.

Thinking about it, both the fore and aft crossmembers would have to be shortened, as well as both torque arms. That's kinda why I was more in favor of plating the exterior of the frame.

 

Following up on this. Installing an insert wouldn't be terrible, but it would be very hard to get it to extend past either of the crossmembers. They are thick 3/8 or 1/2 box section crossmembers with flanges. No tubing to shorten.

Your thoughts? I would be happy with welding the cracks and bolting inserts in as far forward and back as I can without hitting a crossmember. Keep in mind these are horizontal cracks, not vertical. Torsional load doesn't seem to be a problem at this point.