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DC871F

73 240z restoration 904 White

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    Hi all, David in Jacksonville, FL. I am starting a new thread here in build threads. I have my 73 on a rotisserie and just received my goodies from Zedd Findings, pans, front rails and supports. I have a new MIG welder in hand and I'm about to get serious with cutting and welding (which I'm really not a welder) other than stick welding several years ago, so I will be doing a lot of practicing first.

    After getting more detailed inspecting trouble areas, I noticed that the sills on both sides where the vertical pieces (where interior trim is attached to) are sandwiched together and spot welded are rusty, so I was thinking I should probably order the Klassic Fab sills and replace them as well. Along with all that, the front support for the radiator inside "webbing" piece where the oval lightning holes are is pretty crunchy as well, but the rest of the support there is solid inside and out.

    My question is, along with looking for advice, where should I begin as far as keeping the car structurally sound during the process of dismantling? The car currently is being supported on the rotisserie by the rear bumper mounts and the front rails outside where the bumper supports mount. It looks like to tackle the front radiator support beam, that the car will have to be resting on stands and not by the rotisserie up on the front rails. So where should I begin?

    Thanks all.

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    Edited by DC871F

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    Take a better photo (clear and focused with good lighting) of the rust on top of your sills. Is it just a bit of pitting and surface rust? You're talking about replacing the entire inner and outer rocker, which is a major job, for what looks like fairly minor rust. I think your proposed repair is overkill for the amount of damage. I would just spot repair holes and serious pitting as needed, and treat the rest with rust converter.

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    9 minutes ago, rturbo 930 said:

    Take a better photo (clear and focused with good lighting) of the rust on top of your sills. Is it just a bit of pitting and surface rust? You're talking about replacing the entire inner and outer rocker, which is a major job, for what looks like fairly minor rust. I think your proposed repair is overkill for the amount of damage. I would just spot repair holes and serious pitting as needed, and treat the rest with rust converter.

    Its pitting and flaking off in spot. I figured its got to be rusty on the inside as well. Where the spot welds are there some pretty good pitting in between the sandwiched metal.

    Will post some pics.

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    Yeah, yours look better than mine do. I would start with wire wheeling them to see what remains when loose rust, paint, etc, is removed, but broadly, I think they look fine. If you think there's rust between them (beyond surface rust that you'll find in any seam in the body) then you could drill out the spot welds and split them enough to knock the rust out and treat the seam, but I'm not seeing any reason to do anything more than wire wheel + rust converter right now, certainly not replacing the entire inner and outer sills. The spot in the second photo looks like the worst bit, and it doesn't look that bad. Could spot repair it if the pitting is bad enough, but I'd probably just leave it.

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     Grab an implement of destruction (I use an ice pick) and probe everything that is suspect. You'll soon have a better idea of the extent of the damage and what will need to be replaced.

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    35 minutes ago, rturbo 930 said:

    Yeah, yours look better than mine do. I would start with wire wheeling them to see what remains when loose rust, paint, etc, is removed, but broadly, I think they look fine. If you think there's rust between them (beyond surface rust that you'll find in any seam in the body) then you could drill out the spot welds and split them enough to knock the rust out and treat the seam, but I'm not seeing any reason to do anything more than wire wheel + rust converter right now, certainly not replacing the entire inner and outer sills. The spot in the second photo looks like the worst bit, and it doesn't look that bad. Could spot repair it if the pitting is bad enough, but I'd probably just leave it.

    Ok, thanks.

    On a bigger scale, what would be the best place to start as far as pans, front rails and the forward cross member for the radiator support? The radiator support looks like it may need to come out to repair the rear side where the oval lighting holes are (a bunch of spot welds with a few sandwiched metal pieces in there). If so, whats the best method, repair that, or do the front rails first?

    Edited by DC871F

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    34 minutes ago, Mark Maras said:

     Grab an implement of destruction (I use an ice pick) and probe everything that is suspect. You'll soon have a better idea of the extent of the damage and what will need to be replaced.

    Yes, I plan on that method when I get home in a couple of days. Honestly it looks like if I started picking at some of those rusty areas it would be swiss cheese in no time. But I figured locally reparing that area with the way Datsun manufactured the sills it would start to unravel so to speak with the two layers of metal there and the spot welds. Like I said before, i'm no metal smith, so recreating the joint on the sills would seem to me like trying to do open heart surgery with a mexican 9/16th.

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    8 minutes ago, DC871F said:

    Ok, thanks.

    On a bigger scale, what would be the best place to start as far as pans, front rails and the forward cross member for the radiator support? The radiator support looks like it may need to come out to repair the rear side where the oval lighting holes are (a bunch of spot welds with a few sandwiched metal pieces in there). If so, whats the best method, repair that, or do the front rails first?

    I've never done frame rail or rad support repairs, but looking at your rad support, I'd probably just remove the piece on the backside where it's rusted, repair that, and replace it. No sense removing the entire structure if you don't need to.

    What's wrong with the frame rails? They're not obviously badly rusted in any of the photos you've posted. Given that you were looking at replacing the entire rocker structure for what looks like minor rust, I feel I should ask. 

    If you can repair a panel relatively easily with a spot repair vs replacing the whole thing, I'd generally lean toward that. Sometimes replacing the whole panel makes more sense, but rockers and frame rails aren't that easy, especially given that you don't seem to have prior body repair experience. Also consider that aftermarket body panels require fitting, and the quality of them varies - I'd try to stick to original metal when possible. 

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    2 minutes ago, rturbo 930 said:

    I've never done frame rail or rad support repairs, but looking at your rad support, I'd probably just remove the piece on the backside where it's rusted, repair that, and replace it. No sense removing the entire structure if you don't need to.

    What's wrong with the frame rails? They're not obviously badly rusted in any of the photos you've posted. Given that you were looking at replacing the entire rocker structure for what looks like minor rust, I feel I should ask. 

    If you can repair a panel relatively easily with a spot repair vs replacing the whole thing, I'd generally lean toward that. Sometimes replacing the whole panel makes more sense, but rockers and frame rails aren't that easy, especially given that you don't seem to have prior body repair experience. Also consider that aftermarket body panels require fitting, and the quality of them varies - I'd try to stick to original metal when possible. 

    I did mull over just spot fixing them, but the areas I was concerned about looks like it may be rusty on the inside of the rails in a few spots. I was trying to avoid doing a restoration just to see rust in the future and having to go back in.

    Been lurking a few build threads for about 2 years, as an aircraft mechanic and working with aluminum sheet metal for a number of years I feel Im up for the task, albeit it will probably be me measuring about 25 times and then cutting. 

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    I agree rockers and even front frame rails is serious surgery. The car needs to be properly supported. If the doglegs are solid I suspect the rockers are too. The rear section is normally the worst. Are there any holes inside the wheel wells near the doglegs? I would avoid taking the radiator support out. I would probably try to take the rear section with the ovals off and then use that access to treat the onterior. A home run would be to have someone fab you a replacement and weld it back in. I have seen much worse...

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    45 minutes ago, Patcon said:

    I agree rockers and even front frame rails is serious surgery. The car needs to be properly supported. If the doglegs are solid I suspect the rockers are too. The rear section is normally the worst. Are there any holes inside the wheel wells near the doglegs? I would avoid taking the radiator support out. I would probably try to take the rear section with the ovals off and then use that access to treat the onterior. A home run would be to have someone fab you a replacement and weld it back in. I have seen much worse...

    Wheel wells and rockers are solid, rear of the car is very clean.most of the problem are on the pans and supports. Until a few days ago I wasnt even going to worry with the sills until I started inspectinf the sandwiched vertical seem where the door closes. I'm more concerned of trying to repair that seem if the rust is significant. I will be putting new pans and supports in no matter what. I"ll know more in a few days when I start to probe the sills and put a wire wheel on them. Maybe I'm thinking too much on them.

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    Nice rotisserie!  Like rturbo mentioned you need to get all suspect areas down to bare metal so you can see what you're dealing with.  Get an aggressive wire wheel for your angle grinder like the one in the pic.  I think the rad support will come out nicely without removing it, the bottoms of the rockers don't look bad so you might get lucky on those ugly spots on the pinch welds and sills.

    One of those $40 Harbor Freight bore-scopes are great for looking into the rockers and dogleg areas before you start drilling out spot welds.     The floor pans don't look too bad, the transition area where your feet are always needs a custom patch anyway and you might get away with just a section patch on the P/S floor pan rail, you'll know more when you cut it out.

     

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    4 hours ago, grannyknot said:

    Nice rotisserie!  Like rturbo mentioned you need to get all suspect areas down to bare metal so you can see what you're dealing with.  Get an aggressive wire wheel for your angle grinder like the one in the pic.  I think the rad support will come out nicely without removing it, the bottoms of the rockers don't look bad so you might get lucky on those ugly spots on the pinch welds and sills.

    One of those $40 Harbor Freight bore-scopes are great for looking into the rockers and dogleg areas before you start drilling out spot welds.     The floor pans don't look too bad, the transition area where your feet are always needs a custom patch anyway and you might get away with just a section patch on the P/S floor pan rail, you'll know more when you cut it out.

     

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    Ok, look forward to getting out there this weekend to do some cleaning. 

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    On 8/20/2020 at 3:48 PM, rturbo 930 said:

    Take a better photo (clear and focused with good lighting) of the rust on top of your sills. Is it just a bit of pitting and surface rust? You're talking about replacing the entire inner and outer rocker, which is a major job, for what looks like fairly minor rust. I think your proposed repair is overkill for the amount of damage. I would just spot repair holes and serious pitting as needed, and treat the rest with rust converter.

    Got some grinding done today, sills seems pretty good except for a couple holes. Looks like the pinch weld maybe mostly intact!

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    I think I would make some patches and move along

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    That's about what I expected to find. Some rust damage, but nothing major. I agree with Patcon, do some spot repairs and move on. You should do the same with the rust on your frame rails as well to see how much damage is really there. My suspicion is that they can be patched, rather than replaced, which would be significantly easier. 

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    Lower radiator inboard support it toast, but thats the only part thats rusty, the rest of the support is just surface corrosion.

    I think I saw this piece for sale a Z Source or one of those sites for big dollars.

    Check out pin holes in left dogleg (car is upside down on rotisserie), that did not show at all through the paint, and no bondo either, hmmmmm.

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    Adding pics of the car before breakdown, just to shoe what I'm starting with.

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    38 minutes ago, grannyknot said:

    Oops, bad call on that one.

    I'm going to remove the inboard piece right up to the frame rails and weld in a new piece.

    The rest of the radiator support is pretty clean.

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    Started welding, in areas that wont be seen for the most part first, I'm new at this. These are my first MIG welds ever. Small patch panels went well enough, but went to fill in a few holes I uncovered with the wire wheel and started blowing holes, wowzy! Managed to get them filled eventually. I'm guessing some rust must of been hiding underneath.

    Ok, a question for you guys. The last PIC shows some surface rust inside where I cut out the lower sill, right where the lower door hinge bolts up to. Its very solid, just surface rust inside. The question is, can I just treat this area with rust converter and move on and hope for the best, or does it need to be cut out?

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    If it's only surface rust, no metal replacement is necessary. Metal replacement is only needed when the metal loses structural integrity. 

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    8 hours ago, rturbo 930 said:

    If it's only surface rust, no metal replacement is necessary. Metal replacement is only needed when the metal loses structural integrity. 

    Awesome, I'll keep that in mind going forward.

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    Are these welds happy? I'm getting penetration, but sometimes it doesnt want to fill in the seem, meaning the spot weld builds up right up to the edge of the seem and it takes 2 or 3 times to get it to jump the gap.

    How about a grinder that fits into the convex curve of the door jamb? Anything has to be better than my angle grinder trying to get in there.

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