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Suspension setup is neato. I've driven a Miata with a cantilever rear and Busa shocks all around and loved it (Keisler's car). He always wanted to do something similar in the front but never got around to it.
That's a good person to be compared to. That guy makes art.
Subframe is more or less done. I still need to make a bolt on crossmember in front of the front lower tabs. I'll make that when I start on the exhaust as it will probably interfear. I might also add a jacking point in the very back so I can lift the rear end cleanly in one shot.
The thing was a real pain in the *** to make. I was careful. I used a jig. I had almost no gaps and good fitup. It still walked after welding. Usually it wouldn't bother me but 0.1" is a big deal on suspension stuff. I had to spend an ungodly amount of time asjusting and rewelding. Big big pain in the *** but all the arm points are within .020" and it mounts to the the car square and level. It'll do.
Overall I'm very happy with it. It's 43lb even compared to 42lb for the stock subframe. Considering that to run the getrag diff with the stock subframe you need to add the v8r kit (which has a listed shipping weight of 20lb) I finished well ahead in weight.
That is incredible. What does it weigh (rear subframe)?
Originally Posted by 4gordeev
Overall I'm very happy with it. It's 43lb even compared to 42lb for the stock subframe. Considering that to run the getrag diff with the stock subframe you need to add the v8r kit (which has a listed shipping weight of 20lb) I finished well ahead in weight.
Progress has been slow. Machining work, day job, and travels have been keeping me away from the miata. I have finally had time to get a move on the exhaust. The plan is pretty simple. The long tubes dump as dual 3". The idea is to join them into a single 4" which has a slightly smaller area but still plenty (600hp unrestricted flow) for my needs. This single 4 saves me a whole run of tube, a set of resonators and a muffler. Back of the napkin says ~20lb savings. Does 20lb matter on my build? No, but 4" exhaust makes me pretty happy. I started building it working from the hardest point (subframe) going out from there. I decided that to avoid things from clunking about, the exhaust would be attached via 4" grommets at the subframe. This should prevent it from wagging its tail but still be somewhat OK with NVH. Bellows flex couplings to be installed before and after that "hard" mount to provide some give. Bends needed to be fairly tight; ~3" clr; so pie cuts it was.
Finished up the subframe back exhaust. Now that its donem I can add a jackpoint to the subframe and brake line mounts and the subframe is off to powdercoat. An aside, the last photo is why stainless on stainless hardware is a horrible idea. Minimal torque and the nut completely galled up.
Wow. Absolutely beautiful. Please don't paint it. Clear coat the subframe and call it a day.
The exhaust is 304 stainless and will stay as is. As for the subframe, its 4130 which rusts like no other. Clear coat by itself won't cut it if I actually drive the car. Itll get powder coated red ro match the front subframe.
12-16-2018, 09:33 PM
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