Help me find a Miata based Locsot frame: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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May 5, 2010 1:52 p.m. fifty Reader

EDIT: or would that be LOCOST... pardon the typo.

I've got a line on a complete Miata 1.6L drivetrain - it includes the rear subframe, diff and axles.

My first thought was "Locost!". I read the Ron Champion and Keith Tanner books several years ago and I'm familiar with the stock frame and the plus sized McSorley frames.

I've been perusing the www.locostusa.com forums to get some frame ideas - if someone info on a frame that is 2 inches wider than the "book" frame and incorporates the Miata subframe, I'd like to hear about it. Also, if you have some tips for stiffening the frame, such as using round DOM tubing to make the transmission tunnel, I'd like to hear it also.

I'll be welding this myself, just looking to get some good ideas before I dive into it.

Thanks, Iain
May 5, 2010 2:05 p.m. Dr. Hess SuperDork

Do the Aussie Mods to stiffen it up.
May 5, 2010 2:09 p.m. Keith SuperDork

I think the Gibbs book has a Miata-friendly option. I'm not sure.

Keep in mind that a "book" frame is already larger than a Lotus Seven, and a +2 is a really big car by these standards. The smaller frames are stiffer.
May 5, 2010 2:21 p.m. fifty Reader

Thanks guys. Being an ex-pat Aussie, I like the doctor's prescription!

Keith - what dimensions are the CMC frame that you have? Same as the Ron Champion book frame?
May 5, 2010 2:24 p.m. Keith SuperDork

Yes, my frame is a "book" frame with some alterations at the rear for the IRS and a (poorly) widened front track.
May 5, 2010 2:45 p.m. kreb Dork

Bear in mind that even a generously sized Seveneque like the Stalker has rather narrow butt wells. Make sure that you fit what you build. That sounds basic, but I can think of a couple of builders who couldn't
May 5, 2010 3:07 p.m. Dr. Hess SuperDork

Iain, if you venture west a few hours, you're welcome to come look at my build. From what I understand, a Miata drivetrain should fit a book chassis, no problem, with no need to go "plus size." My build is a book frame with Aussie Mods, up to the back end, then my own IRS design, plus my own suspension location points at the front. Dave Hempy did a Miata based build and just kinda hung the rear end up in the air and built frame around it until it all tied in, from what I understand. I saw his car in KC a couple years ago. The CMC Miata based frame "had issues." Of course, CMC "had issues" and that's why there's no CMC anymore.