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Frame and core support replacement


DatsunRod

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Looks like my zmw will only need the front subframe and rails from 4" in front of the strut towers forward. 

My question is this.. can I cut it off and use square steel to replace it with and not gain points or will I have to replace it with a front cut off another 280z ?

Basiclly the frame of square I have to make will hold the front of the fenders on, the radiator in place and the hood hinges will bolt to it. 

 

Thanks 

 

Rod

20180408_092821.jpg

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While only tech can answer for sure, my advice would be, tech guys are racers, you show them these photos, and as long as they dont perceive your alterations as a performance advantage you will be covered under 

 

4.7.6. Teams may replace any worn, broken, ventilated, impaled, defective, or bent-beyond-all- recognition parts on their car without affecting their total points so long as it’s an OEM or OEM- equivalent part for that car’s specific model.

 

If you do a front cut, and replace with tube frame, you would probably want some pics of the weight removed vs weight added, to show you put on a similar amount...  As long as you are repairing, your fine.

 

my guess is no mater what you do, you will be adding weight trying to make it reasonably as stiff as the unbent OE stamped part.  so nothing to see here. 

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I would cut the damaged rails off on the bottom and see if you can bend the rest back into shape. Weld square tubing back in. 

 

If simply welding similar square tubing back in doesn't satisfy a reasonable attempt at replacement for 0 points i would be very surprised (and disappointed).

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Right, even if you cut it off, weld on a plate, and put some tube coming from that plate to re-create the front, I suspect using .120 wall tube or so would be at least as heavy if not heavier by the time you add some gussets and brakckets.. and re-create the bumper support....   if you show chumpcar that your fix, while maybe pretty isnt really a performance improvement (ie doesnt remove weight or somehow magically add crazy stiffness in a place where you didnt have it, you would still be fine...   

 

the only way I would go with square stock, was if you could somehow slide it into the existing frame rail and use some bolts further back to help position it (like use those subframe bolts), but at the end of the day, I think that would remove the factory crush point, and your next front end hit would take out your subframe...  I think you want to ensure the factory crush point is still in front of that subframe.

 

I would do like I said above, cut it, plate it, and weld a tube to the plate.  Keep the pictures and maybe throw what you cut off on a scale to offer as evidence its a "repair"

 

 

Note, before I cut anything, i would spend some time with some come-along's between a few trees in the yard, you would be amazed what you can probably get that back into...  assuming the subframe is still in a decent location, you may get away with adjusting the front till the hood fits, and just adding a few plates to reinforce the crinkled metal.

Edited by Xph
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When I finally get off work I plan on taking it apart. Once I can figure out what's bent besides the frame horns in the front, I can get a plan together.

I've built a tube front clip 280z before and know how to tie it all together correctly.  I just don't want the extra points. 

Thank you for the input 

 

Rod

Edited by DatsunRod
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15 hours ago, DatsunRod said:

When I finally get off work I plan on taking it apart. Once I can figure out what's bent besides the frame horns in the front, I can get a plan together.

I've built a tube front clip 280z before and know how to tie it all together correctly.  I just don't want the extra points. 

Thank you for the input 

 

Rod

 

Yep, if you dont want to take extra points, it needs to not look like a tube front end.  IE you are convincing another racer (tech) you repaired it, and it needs to look like something he / she would want to race against.

 

if you need to replace the horns, using rectangular steel vs DOM tubing will help...  if you cut it all at the firewall expect to take points (unless you are welding back uni-body to what you cut)

 

Now no one would say you need to increase your weight, hence my suggestion that if you weigh what you cut out, vs what you put back...  you should be able to get away with some general "prettyness" before you run afoul of the "tube frame" rules.

 

Good luck

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Here is a right front strut tower and frame rails.

I need to cut it off where the blue line is.

The top red arrow is showing forward direction. 

The bottom red arrow is pointing at the 2 bolts that hold the sway bar on place. 

I basiclly need to cut it off.  Cap the end of the frame box with 1/8" plate.  Then run 2" square forward off the plate to tie the front together.  Then bolt the sway bar to it and run tube up off it to mount hood hinges to it and a cross bar to tie the radiator to. 

Kind of a simple repair.  

20180410_190335.jpg

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