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Thread: '73 240Z Ground Up Rebuild

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    Default '73 240Z Ground Up Rebuild

    I'm neck deep into a complete ground up rebuild of my '73 240z. I thought it's about time I started a thread on this car and started sharing my "experiences"

    I just finished replacing the passenger side floor-pan and decided to start working on the battery compartment area (it was completely rusted out). After cutting away all the sheet metal I got a better view of the condition that the passenger side frame rail is in. I new that I would have to cut parts of it out and replace with good metal but after getting a good look at it I think I'll just replace the whole thing.

    Before I cut it away completely from the body I decided to take a closer look and try and devise a way of keeping everything in place so my alignment and so on would still be good after the replacement. This is when I noticed that some road damage had bent the frame rail toward the outside of the car. No wonder the floor pan seemed to tight going in (ahhh!). I was able to move the frame rail back toward the inside of the car a little with a 4X4 block and 5 pound sledge. This would have probably been easier with the floor pan out but oh well. It's a little late now.

    Before I continue further and do anything I seriously regret I thought I would try and see if any of the resident Z gurus could steer me in the right direction. I have 2 specific questions:
    1) What methods can I use in my garage to get the frame rail straightened before I replace it?
    2) How do I keep everything true when replacing the frame rail?

    Please keep in mind that the logistics of getting the body down to a shop with a frame straightener make that option almost impossible.

    I've attached some photos of my recent progress. If you look a the top of the frame rail you can see where it is bent.

    Any advice is greatly appreciated.
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  2. #2
    Registered User J Shara's Avatar
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    Im in the same boat man im doing a ground up restoration on my 73 too. I took mine to a body shop though.
    1973 HLS30-129971

  3. #3
    Registered User conedodger's Avatar
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    Where are you at? I have a trailer and I have just set unibody cars on 4X4's before for the trip to the body shop. Probably the most accurate frame straightening is done on something called a Celette bench. They want the engine and suspension off the car for that though. Not cheap and not every shop does it. The one I know of is Yeaman Autobody in Palo Alto.
    Rob
    2000 BMW R1100 RT-SE (for sale)
    1999 Toyota 4Runner Supercharged
    1975 Porsche 914 stroker motor autoX car
    1973 Datsun 240Z Restoration project. New paint in original white. E31 head on 2.4 block. Nissan Motorsports header. R200 with Nissan motorsports LSD.

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    Quote Originally Posted by conedodger View Post
    Where are you at? I have a trailer and I have just set unibody cars on 4X4's before for the trip to the body shop. Probably the most accurate frame straightening is done on something called a Celette bench. They want the engine and suspension off the car for that though. Not cheap and not every shop does it. The one I know of is Yeaman Autobody in Palo Alto.
    Modesto, CA

    I don't know anyone around here with a trailer. If I did I would probably take it to get it straightened. The suspension is definitely off the car. Actually, there is nothing at all on the car. It's just an empty shell. 2 guys can lift and walk it (with a bit of effort of course).

    Do you know any way I could do it myself? I have a 230volt continuous MIG so fabricating something wouldn't be a problem as long as it is simple.

  5. #5
    HL S30 151764
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    If you're real handy, and have lots of time on your hands, you could always follow this guy's lead and build a 240Z chassis jig.

    http://www.vord.net/cars/240z/chassis-jig.htm

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    I will tell you from experience that the frame rail had little to do with the difficulty of installing the floors. The Zed Findings floors are not plug and play-which it looks like you found that out. As far as the frame rail, is it damaged from a collision? Even with a sledge, it would hard to "move a frame rail". You also have mentioned rust, how rusted is the frame rail? It doesn't look bad from the pics, but it is hard to tell.
    The area you show that is "out of line" probaly would not affect alignment that much. If the crossmember sits on there square, then I think it would align fine. Replacing the frame rail is a big job, maybe bigger then the floor you just put in. My frame rail was also bent at one time from a collision, I guess it was bent up over 30 degrees. The rail was bent back by the PO and besides cosmetics, it was fine. Maybe a tad weaker, but since it wasn't rusted all to hell, it was fine.
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    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    Quote Originally Posted by pwd View Post
    If you're real handy, and have lots of time on your hands, you could always follow this guy's lead and build a 240Z chassis jig.

    http://www.vord.net/cars/240z/chassis-jig.htm
    Hey thanks for the link! I just might do that.

  8. #8
    Registered User conedodger's Avatar
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    Joe,
    I do know someone more in your neighborhood with a trailer. I am in an Eastern suburb of Sacramento. As has been said, you aren't going to move a frame rail by hand. Nor would you want to be able to. It is stiff and beefy for a reason. My friend is in Antioch but that is close enough for Govt. work. He would help you if I asked him, but you should probably help him out with something to even up the karma. He is a 914 guy.
    Rob
    2000 BMW R1100 RT-SE (for sale)
    1999 Toyota 4Runner Supercharged
    1975 Porsche 914 stroker motor autoX car
    1973 Datsun 240Z Restoration project. New paint in original white. E31 head on 2.4 block. Nissan Motorsports header. R200 with Nissan motorsports LSD.

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    Quote Originally Posted by madkaw View Post
    I will tell you from experience that the frame rail had little to do with the difficulty of installing the floors. The Zed Findings floors are not plug and play-which it looks like you found that out. As far as the frame rail, is it damaged from a collision? Even with a sledge, it would hard to "move a frame rail". You also have mentioned rust, how rusted is the frame rail? It doesn't look bad from the pics, but it is hard to tell.
    The area you show that is "out of line" probaly would not affect alignment that much. If the crossmember sits on there square, then I think it would align fine. Replacing the frame rail is a big job, maybe bigger then the floor you just put in. My frame rail was also bent at one time from a collision, I guess it was bent up over 30 degrees. The rail was bent back by the PO and besides cosmetics, it was fine. Maybe a tad weaker, but since it wasn't rusted all to hell, it was fine.
    Thanks a lot for your reply. It's good to know that the mods I had to make to the floor pan were normal. It took a lot longer than I thought not just because I had to modify it but because when I cut the old one out I had to cut quite a bit of rusted metal out right in front of the seat belt housing and other places like the trans tunnel and weld in new. I'm getting used to new "surprises" every time I remove some sheet metal. I'll post some pictures of the back passenger rocker to show you what I mean.

    The frame rail has definitely lost some of it's structural integrity. I was able to move it over by about 1/8 inch or so with the sledge and wood block. Battery acid and rain water really did a number on it during a time when it was sitting outside for a few years. It wasn't bent from a collision, rather something was driven over that hit it pretty hard from underneath. I did some really hard driving when I was younger also without knowing that it was weak and it's possible that just the cornering forces moved it a little.

    This car is definitely a long term project so I plan to do everything right regardless of time. I think I have another year to go at least. The reason the frame rail doesn't look that bad is because the black primer covered up all the rust. If you look closely though you can see holes in the top. The metal is pitted and week for about 6-8 inches back from the firewall. Rather than cutting pieces of it off and attempting to patchwork it back together I thought it would be better to replace it.

    I measured the distance between the two frame rails and they were square all the way back to where the cross-member bolts up. After that the passenger side gradually drifted toward the outside until it was about 1/8 further out. After some additional blows to the frame rail later today though it's pretty close to straight now. It's good to know that as long as the cross-member is square I don't have much to worry about.

    I was going to weld in new sheet metal in the batter tray and kick-plate area before attacking the frame rail but was afraid that something might move when I removed the inside part of it from the firewall. Short of creating a jig, if you can think of an easier way to keep things straight I would love to know.

    Thanks again for your reply.

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    Default Floor Pan Work

    Here are some pics of some of the floor pan work for you your entertainment.

    I had to cut away some rusted areas and rebuild them with new sheet metal. Painted everything up in POR-15 before I decided to grind it off and use weld-thru primer instead.

    In one of the picture you can see how far gone the passenger side kick panel and frame rail bottom were/are.
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    Quote Originally Posted by conedodger View Post
    Joe,
    I do know someone more in your neighborhood with a trailer. I am in an Eastern suburb of Sacramento. As has been said, you aren't going to move a frame rail by hand. Nor would you want to be able to. It is stiff and beefy for a reason. My friend is in Antioch but that is close enough for Govt. work. He would help you if I asked him, but you should probably help him out with something to even up the karma. He is a 914 guy.
    Wow! Thanks a lot for the offer.

    I'm hoping I can figure out a way to do this myself since I'm going to be doing all the work and will need a few weeks to get it done. My guess is a shop probably wouldn't let me come and do my work over at their place.

    I was actually able to get the frame more or less straight and have been reassured by madkaw that it probably won't mean a problem with alignment anyway. This just leaves for me to figure out a way to hold everything in place while I'm doing all the cutting and welding work. I may have to bite the bullet and build a jig but am eager to here if anyone has an easier way.

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    Default Other Pics

    Here is a photo that gives a better view of the kind of condition that the passenger side frame rail is in.

    There is a photo of some more carnage near the back of the passenger side rocker panel and wheel well. This will be the next up for surgery after the battery tray and frame rail.

    I also included a pick of the body so you can see the "big picture".
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