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Discussion Starter · #1 · (Edited)
Hello all. I'm in my very long process of fixing the rip in my frame that is front of the rear boxed frame area under the passenger door. The story is people may lift the car wrong or get hung up on cement creating a rip in the frame etc. Anyway, I've drilled my rip end to stop the rip, completely cleaned out the rip creating a space for full weld pool. welded the cleaned rip. Then I created a fish plate. I'm about to prime the pictured frame section/spot with SEM'S "weld through primer" . My question is my fish plate is going to cover the factory hole in the frame. What's it for? And, I'm covering it up because I feel like replicating a hole in the plate to have it there is only another place for water to get in between the fishplate and the frame. I don't think that's good. I'm planning on sealing the outside frame side between body with a putty knife and some sort of material spread to finalizing sealing. There is not much space there if you understand my spot. it's somewhere just under a 1/4 inch on my car. Am I having the correct idea welding the fishplate over the hole? If not, what's a better reason to leave the hole there collecting rain water between the plate and frame to have this "original" hole there? Notes/info: Ive went past the hole with the fish plate because bringing it up to the hole seems a weaker repair to me. Do I really need the hole? Thanks always.
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Usually the holes are for access to bolts. You can do anything you want, but you may suffer the consequences at some future time.
 
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Discussion Starter · #4 ·
I have a question. I purchased 1/4 inch hot rolled plate to use as the fishplate patch because I don't want to grind the weld on the frame flush. I feel like leaving the weld a little keeps it stronger-plus I don't want to grind any material around the weld weakening the surrounding existing frame material while performing the grinding of the weld itself. The second reason I chose quarter inch is because it gives me enough material to mill a groove in the fishplate backside to give for the weld to lay in. I've milled around the seen perimeter of the front side of the patch to make the weld material a closer match to the parent material (frame) for easier welding around the patch. So my question is this. I've read people saying that fishplates are not suppose to be very thick because they need to flex with the frame twist. And, thick fish plates will maybe cause a new stress point. Would this be true on my design? My patch is only 5 1/4 inches long total. I state this as "only 5 1/2" because I feel like such a short patch may not really matter on the thickness vs a long thicker plate for example on a long stretch of frame rail that needs to twist on an offroad application. I hope I've asked my concern correctly. do you guys think this repair is good? I have not welded my patch yet. I'd like some feedback on leaving my weld beefy slightly ground back and my grooved plate. Also feedback of my 1/4 thick patch. Is a 1/4 inch thick patch (short legnth) too thick? Would I be asking for trouble doing this? I feel like it will be strong but don't want to be wrong. I feel like it's worth it to not patch it at all to test my weld itself that way if it rips again, I can simply weld it again
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While I get the tapering off deal , i would be would be welding into the rear frame section just to the rear of your repair.
I would also making the piece flanged at tge bottom to tie into the bottom edge where the crack started.
Even a small boxing piece flange to flange maybe.
Would taper off as you did at the front still.
 

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As Gerry said, the only purpose I have ever seen for those smaller holes is reference points for frame measuring, but i'm not entirely sure that was the factory's intended purpose for them or if they used them for something else during the assembly process. Who knows. In any case, covering one shouldn't be any issue at all as long as you never have to measure your frame on a tram.

I repaired a few of these frames that cracked at the same location. Never went too crazy with it, just drilled and welded the crack and fish plated it with 1/8th steel about about 6-7" across. One of the cars I repaired was my own daily driver, I drove it for 5 years after that on the terrible NY roads (most likely the worst in the country lol) and never had an issue.

I think yours will be fine. Your weld looks good, and I think the 5" fishplate will be more than adequate. The only reason for going larger is because that area of the frame obviously sees some stress where the boxed section ends which is why the cracks form in that area to begin with, so going longer in my mind helped to reinforce that area which becomes sort of a fulcrum point, but I don't know if it really matters that much. I've never seen another crack reform after repairing one anyway. Always wondered if maybe swapping to poly body bushings would help a bit to keep the frame a bit more rigid and prevent those stress cracks. I ended up completely boxing the frame on my 96, but I did that for performance reasons, not because I was worried about cracking.
 
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I don't want to grind the weld on the frame flush. I feel like leaving the weld a little keeps it stronger-plus I don't want to grind any material around the weld weakening the surrounding existing frame material while performing the grinding of the weld itself.
Maybe I didn't read enough, other than for cosmetics in body panel work, I don't think any structural weld should be ground... And hopefully your welding does not make them look that ugly else i'd question their integrity.
 

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Maybe I didn't read enough, other than for cosmetics in body panel work, I don't think any structural weld should be ground... And hopefully your welding does not make them look that ugly else i'd question their integrity.

As long as the weld is sound, it shouldn't be a problem.You have to grind it flat to fishplate it, and the fishplate will do more to prevent the weld from failing than leaving leaving the weld intact by a long shot.

Interesting note about grinding welds down, Weldcraft Racing, the company that widened my wheels, offers a service to finish the welds and grind them flush. This is a pretty large scale company and a wheel is a pretty critical component. In some applications it is actually favorable to grind the weld to reduce stress risers.
 
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Discussion Starter · #10 · (Edited)
Thanks for all the replies. It's mentioned to have the fishplate reach over into the boxed area. I thought about that but feel questioned if it's such a good idea. Because, the space needed to work isn't quite available. The angle of the camera makes it look like there is more space for the torch to weld the fishplate into the boxed area but where my picture with the fish plate held over the weld is, is as far as I can go keeping the MIG torch positioned"at least" 90 degrees or perpendicular to the weld in that area. If I put the plate any closer to the boxed area I'd be aiming the torch in the opposite direction away from the fishplate. I'm not saying It won't work but should or can this work? Normally when people weld a lap joint the torch/wire is aimed into the joint or at most 90 to it -not away from it. I don't know if I should try it. For example, I'd be kind of dragging the torch over the root especially at the very end right of the plate. I'm interested knowing if others fishplate went into the boxed area. Any special techniques? Any special flex head torch etc? Here is an annotated picture showing how I can place the torch neck tube in the boxed area where that half circle is cut out of it. And for me to have at least a 90 degree torch angle to work surface the plate has to be "at the least" a 1/2 inch away from the seam line. I'll say that a 1/2 inch is pushing it. I'm also asking anyone if this welding angle should be something to worry about? I weld myself but don't claim to be a welder and am wondering the strength of the weld if It's welded in the contrary position. Last note. Then there's the thickness of the plate. The thinner the sheet of fish plate helps but This thing is .250 thick. I milled down the edges to about .120 The purpose for the milled down edge was to insure not blowing a hole in my frame while welding thick stuff to thin and getting proper penetration on both pieces. I'd be upset. Just a reminder for anyone. Make sure you weld test pieces to get a feel for how long you can weld on a surface before it gets too hot. I made sure to practice every angle on scraps that way I'm not practicing on my car. it has to be done right the first time. I went as far as sticking a mocked up lap joint piece of sheet and plate up in there at the same angle and welded from the right of the "to be" plate downhill to the center bottom there. I didn't try any further from the boxed area right of the seam. I don't know how possible it is
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