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66 Chevelle SS396 & 66 Chevelle 327 Convertible.
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Discussion Starter · #1 ·
Let me first say I have never done anything like this before. I am trying to replace the upper trunk crossmember. I have to remove the spot welds that hold the upper front crossmember brace to the trunk floor and also to the flange that extends from the rear floor of the car. The also are spot welds from the inner wheel house to the end of the crossmember. ( 66 chevelle).

I started on a trial piece and burned though the cutter in removing 4 spots. Not having done this before I did not use any cutting oil, my mistake.

Looks like there are about 10 welds at the front and rear of the crossmember. Is it best to remove these from above? Looks as if my only choice for the spots on the inner wheel house is from the wheel house to the crossmember. I think I will have to patch this area of the wheel house as there are rust holes on both sides. Looks to be about 4 welds on each side.

One I remove all the spot welds holding the trunk floor and wheel housing to the crossmember, there will be spot welds holding the front flange of the crossmember to the flange extending from the rear floor. Do I Just continue to drill though the crossmember to the flange; but how do I locate the spots holding the floor flange to the crossmember, is it just one big spot weld though all 3 pieces. Thanks for your help
 

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1969 Chevelle 2 Door Sport Coupe Malibu COPO clone
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:cool: Take a look at the mechanism of your part removal: If you're going to weld a new part to the piece you're working on, you can save money by using a standard drill bit and drilling all the way through the spot weld that's holding the 2 pieces together. That way you already have a hole to plug weld (assuming you can get at the far side to weld). If you can't plug weld from the "rear" of the "inner" piece, then use a Spot Weld Cutter. Spot Weld Cutters are used to remove the "outer" piece and not to go all the way through the "inner" piece, and should leave a "dot" of metal on the "inner" piece (that will need to be ground off). You'd do well to invest in a "Spot Weld Separator (Wacker)" to help separate the pieces.

Spot Weld Cutters are 5 bucks at Harbor Freight and work just as well as more expensive cutters.

Can't see the little spot welds? Remove all the paint, etc. before you drill. You should be able to tell where the sport welds are once all the paint is removed. There is a wash you can put on the metal that shows up the spot welds, but what it is escapes my addled old brain right now... Hopefully a younger mind can responded with the answer.

8 Steps To Drill Spot Welds and Remove A Quarter Panel on the 66 Mustang | Mustang Restoration
 

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66 Chevelle SS396 & 66 Chevelle 327 Convertible.
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Discussion Starter · #3 ·
Thanks Bruce. Well I actually have to removed the crossmember from my car where I can cut though the rear flange of the crossmember; but not cut though the flange from the rear floor that the front flange of the crossmember sits on. And I have the remove the crossmember from a section of the trunk floor and rear floor of an donor El Camino, so I will have to use both methods. Not found of Harbor Freight tools; but I can test a few out for $5 each.
 

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1971 Chevrolet Chevelle Malibu
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Don't run the cutters real fast it will cause them to burn up faster.
 

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I used the blair cutters at low speed with cutting oil and held up pretty good. I know the exact piece you are trying to replace and it is a PITA to get any good working room. I had to replace the trunk in one piece, so cutting out wasn't as bad as trying to save what is there ( had to replace back seat pan as well). welding in new panel tried my patience until I got the body on the rotissiere. good luck.
 

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I don't know what cutter you guys use, but I did the hood on my 66 with the one from Harbor Freight and it worked like a champ. I didn't use oil and I don't remember how fast the drill was because it was years ago.
 

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Central Iowa
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No it is not one big spot weld through all three pieces.
The cross brace to the rear floor lip seam has a good 40 or so spot welds!...
I am out of space to post pictures easily or I would but that's a whole nother story.
You might be able to see some of them from the underside if you look real closely.
That brace which seems pretty solid to me from what I could see in pictures you posted in the past could be rusted much worse, so you might again want to think
twice about ripping the crap out of stuff if it's really not necessary!

Sometimes what we vision in our heads of the finished product is not what things
sometimes turn out like when we finished and always takes way longer than we think.

Time to move on here, you can now move in the wheelhouse area being you mentioned
there was some rust repair needed. Start small and cut/grind out the area that needs cut out anyway and take a look to see if the ends of the brace are good or easily fixable?
If the ends are good or easily fixable then those areas won't take to long...just twice as long as you might think and maybe three time longer if your a bit anal like some of us. Keep in the back of your mind how much work it is really going to be if your going to replace that whole brace...or maybe just the ends cut from a new brace with cage nuts intact?
If you decide you don't want to rip it up you can easily fabricate 2 really nice and strong
cage nuts and guys here will help with some great ideas for you. You have lots of hours involved in finishing up the damage you have already cut out.

Them spot weld bits are time consuming and a pain! If your going to go gung ho and replace the whole brace I would get out the drill and a sharp chisel.
 

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The way I've tackled spot welds is to strip the area with a polycarbide abrasive disc to find the spot weld, then use a center punch to line up the cutter. Low speed and pressure to get it started so it's located, then you can turn up the speed more with some lube, but I find medium to be as fast as I want to go so I don't ruin the good side. Take your time and don't rush, don't cut all the way through, use a chisel/screwdriver to break the bond and then grind flat.
 

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on my 69 for the pieces going to the inner wheel house I just cut it in half with a sawzall. I was replacing the inner anyway so I did this and then on the other one just cut around the end attached to the inner, removed the wheelhouse, then ground off and removed spotwelds from the other side. if your car is not show quality hack away. have welder so metal can be whatever you need.
I've also used hf spotweld cutters. no cutting fluid needed. it just puts oil on a panel you will need to clean before paint. I've literally cut over 50 normally with each one. then turned the cutter over and got another 50. and I tend to go right through both panels cause i'm a hack. not sure why you burnt up yours. did you take out the little circles you cut out? in a pinch I've used 2 drill bits. one pilot hole and one big one after. I use an air chisel after I get through most of it but you have to be careful as it will slice through panels fast.
 

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I haven't used spotweld cutters in years... I pretty much just use 135 degree drill bits now (5/16 to 3/8'). For a while I was also occasionally using Pilot tipped bit from Dewalt. The pilot portion on the dewalt bits is quite large, so I tend to wobble the bit a bit while drilling so it doesn't break deep into the base. For xmas my boys got me these Milwaukee Shock Wave bits. these have a very shallow pilot tip so they don't go deep into the base metal. Milwaukee Titanium Shockwave Drill Bit Kit (15-Piece)-48-89-4630 - The Home Depot. I hate traditional spot weld cutters since they take too much prep to center, wear out at the worst of times, break occasionally... Drill bits noted above work well, plus very light grinding cleans the base for the replacement panel.
 

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I like the HF cutters too, but they only seem to have one size available. I also have a set of Blue-Point Rotabroaches that I really like, that are great when you need a size larger or smaller than the HF cutter. I have never used oil with these and get good life out of them and the HF cutters.
 

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I changed that brace on my 66 and it is not fun. There are about 50 spot welds on it. The spot welds are not all the way through where it is 3 layers. You have to drill them all out on both the top and the bottom. They are in different places. Use a wire brush in a drill to knock all the paint and seam sealer off first so you can find the spot welds.

My spot weld cutter is an S&G. I think I used 2 blades doing all the braces under the floors. I don't use any oil. If you killed after 4 times, you are going too fast with the drill or have a cheap blade in your cutter.
 

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I use a spot weld cutter from Napa (looks the same as the Harbor Freight one).
I like to try to get a thin blade scraper between the panels close to where I am spot weld cutting.
With the scraper in there it makes the panels pop apart before you start drilling through the second panel.
The other thing to look for when you are drilling through the top panel is just when you get through you will see rust appear in your cuttings signaling you to stop.
I'm assuming it must be the rust that is between the two panels.
 

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Central Iowa
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Jim, I sent a couples pics to your email
You are welcome to share in your thread to show the placement of spot welds from
a look from below so folks can see.sorry a couple pics were not so clear. My upper corners were cut out just like yours. Hope the pics help.
 
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