Tubular subframe
 

Some of you may have seen this on "the other" forum, but this forum has grown to be a force in the Miata V8 world, so here goes.

Long ago when I did my 302 Miata, I extensively modified the stock subframe. After lots of effort, I decided that if I ever did it again, I would build a tubular frame from scratch. The fixture requirements are the same, I just needed a good reason and a way to bend tubing. Well, the reason presented itself when I bought a 2002 Blazing Yellow SE with 216000 miles on it, just begging for a V8. So I decided I would put an LS motor into it with a subframe that was just a little different from what I had seen to be available.

As things progressed, a neighbor down the road, Jack Dahlmann, ended up with the prototype. But I am working at a snails pace on another.

So here's some pics of the one he ended up with, the motor mounts are setup for a Ford 302, but the mounts are really independent of the actual subframe, any motor within reason could be accommodated. The feature that sets this one apart from any other tubular subframe is the orientation of the lower suspension mounting "tabs". Mine hang down from the tubes rather than jutting out sideways. That in effect moves the tubes out and opens up a lot of room next to the motor, helping out somewhat with header fitment. The steering shaft is still a problem, obviously, but there may be some opportunities for header routing that couldn't happen with the more conventional arrangement. The first pic shows the fixture in place. I guess I should paint it.

I did some rudimentary strength testing by hanging 50 lbs from the end of a 10' steel pipe secured across the top of the "wings" and measuring the deflection with a dial indicator. The deflection as measured at the steering mount tab was .112" for the tubular and .138" for the stock NB subframe. Average of 5 readings each.

Naturally, all this work shouldn't go unrewarded, so I am entertaining thoughts of building more on demand, I guess that depends on the demand.

Enjoy, Mike

Why anyone WOULDN'T use this for a 5.0 swap being built is beyond me. Looks great!

great works

How much are you looking to sell on for? One with 302 motor mounts already on the frame? Also, if you are still making them, how long would it take to get one made?

That was a great frame. Nice designs. :)

im just starting to put a built sbc 350 into my 99. you still open to building a tubular subframe for me :D

Did we get any further on the SBF tubular subframe? Are they available?

We did get a little further. So far 5 of the "beta" versions have been fabricated, 3 were for the 302, one for LS, one without mounts but destined for a 302. As far as I know, none of the conversions they are on have actually made it to the road. So beta testing is pretty much non-existent.

My original concept was to use these subframes on conversions done by me, but I am about to place an order for 10 more sets of laser cut components of the subframe, so I will entertain sales to individuals with the understanding that they are still "beta" units with the attendant disclaimers.

I'm not sure what the forum rules are for sales of this sort of thing, I don't claim to really be in business at this time; more like a non-profit hobby.

Feel free to contact me, email works better than the pm system for me.

tmmoninger@gmail.com

Mike

Just emailed you!

Boy do I hope this old thread is still valid. I would love to hear how the suspension mods work in the real world.