NB Miata structural repair parts?

So, because I have the skillz and am too cheap to buy a nicer car, I'm wanting to proactively (before northeast tinworm creeps any further) replace the front sections of the Miata "frame rails"... They're a boxed element in several sections, and I need to cut out the bottom and two sides from the front of the shock tower stamping up to the back of the front bumper mount.  It's actually more straightforward than it sounds, but what I can't tell is exactly which part numbers I need in the diagram below... for sure I need #9, but do I *also* need #8 and #10, or are those just "subsections" of 9?  Remember I want to leave the "top" and replace the sides and bottom of the rails...  Anybody know better than I?

#8 appears to be the inner layer of #9 and #9 is "buried" behind the spring perch. When I repaired my Miata I just cut out the area between #11 and the spring perch, then welded in flat plates that were around 3/32 thick . Trying to get that entire #9 piece out will require a lot of dismantling.  If you do go ahead and do it post lots of pictures. I have a second one to do, so a tutorial would be nice.

To your original question, I think #10 is the top plate, which shouldn't need replacement. To retain the strength of the original tub I think you need 8 & 9. Good luck , whatever you do.

I did mine kinda like this.

I'll bet you want #7. Some of these parts may be NLA (or his friend NWA, Never Were Available), I found that out when trying to order a bunch of them as part of testing the 2001 rigidity improvements.

I priced up the parts to do this a few years ago, so my memory might be off, but I thought that you could substitute the NA rails which would be a single layer.

Plan is to section in #9 the same way we'd have shortened/sectioned frame rails, long 45 degree cuts with plenty of weld length, nothing perpendicular to any loads.  I don't need to replace anything rearward past the spring perch as far as I can tell.

Hopefully #7 isn't the only way to get it (that one includes the spring perch, which is intact... and expensive!)

8 plus 9 sounds reasonable, about 190 bucks shipped assuming they're not NLA. If they're gone I'll try the fabricated sections from that UK outfit, they have all the captured nuts etc in place, but are more money than the oe stuff at current exchange rates.  Only NA style "single" layer though.

In reply to Gearhead_42 :

When I did mine the inner side of both rails was fine, so I just welded in the outer sides and bottoms. The sway bar mounts were welded back in place and large self tapping screws held the plastic bits to the heavy gauge repair material I used. I may get some 3x3 or 3.5x3.5 tubing and make up repair parts for the next one. That area is roughly 80mm x 90mm, so an exact fit with standard tube won't be possible.

Keith Tanner said:

I'll bet you want #7. Some of these parts may be NLA (or his friend NWA, Never Were Available), I found that out when trying to order a bunch of them as part of testing the 2001 rigidity improvements.

I’m glad you specified Keith, that isn’t the NWA I was familiar with. 

There is another alternative that you might consider. What you see in the picture is the front of a Miata chassis separated from the tub at the firewall.  The entire front of the Miata pretty much unplugs from the firewall once you drill out a few spot-welds. This came apart with a drill and maybe a bit of pounding with a hammer, but it was not a ridiculous effort to get done. The  cost of a donor front clip will probably be less than buying a few of the repair parts you are looking at. I can see doing the entire clip swap in a week-end if you stay with it.

Few holes to drill on the side, but not many

I'm surprised the parts might be NLA/NWA. Apparently you can buy a new floor pan for a 1976 Mazda Cosmo. There were maybe hundreds of those things brought over here and I suspect there may be only be 2 remaining.

Snrub said:

I'm surprised the parts might be NLA/NWA. Apparently you can buy a new floor pan for a 1976 Mazda Cosmo. There were maybe hundreds of those things brought over here and I suspect there may be only be 2 remaining.

I know where more than 2 are.

Amazing how little really holds these things together.  If I lived anywhere but the rust belt I'd go with that front clip plan, but anything local would be a crapshoot as to condition. 

'Course if I lived anywhere but the rust belt I wouldn't have this problem to start with, would I?

In reply to Gearhead_42 :

They are out there to be found.. I live in a rustier belt than you and found a rust free donor shell. Have you looked into the cost of a front cut from the south?

Then again, if the front half is this rusty, why not just order up a whole shell from FL or Texas and be done with it? Pretty much impossible to beat rust t it's own game.

Pete