Hey Billy,

What would you recommend to help increase the structural rigidity of our First Gen cars? I had noticed some references to the Flying Miata's Butterfly crossmember with reinforced central frame rail sections in a post on the RX7Club.com forum, but I'd like to hear first hand from somebody with the knowledge and experience you (or anybody else that autox's or road course races these SAs/FBs) have. Would any type of subframe connectors or a "butterfly" style cross brace help improve the cornering and rigidity of these cars?

Besides a front strut tower brace or a front triangulated strut bar brace, what else would/could you recommend for an FB that could greatly improve the rigidity of these unibodys?

I've drawn up similar frame rail reinforcements to what FM sells (their "butterfly" cross brace), but I'm not sure exactly how much of an improvement this would addd to our cars. What do you guys think about this style or just general sub-frame connectors for our cars?

How about urethane bushings for rear suspension control arms and urethane watts-link bushings (and/or possibly stronger than stock adjustable rear control arms made with turnbuckle style drilled and tapped DOM tubing) and what other modifications to the chassis/suspension system would be in order or would you recommend to maximize modifications such as these?

I'm after the best handling street suspension/application with my '83 GS ('85 SE suspension-strut housings and rear axle) that may see occasional use on the track (but not currently bound by any class rules or restrictions); I just want a solid street car that can handle like it's on rails...

Any and all help, info, input, or criticizm is greatly appreciated...

Sincerely,
-Adam Collins

Adam,

I am not sure that the "butterfly" or sub frame connectors would actual do anything for first gens. If you try it I would like to see the data you collect testing it.

As far as urethane bushings for the rear amrs and watts. We do have them listed here ->
http://mrcmfg.com/catalog/index.php?cPath=112_41_91

As far as the upgraded rear arms. We also have those listed ->
http://mrcmfg.com/catalog/product_info.php...;products_id=67

If you have not painted the engine bay yet I would suggest seam welding to obtain the stiffness you are looking for. Hit the strut towers, front frame rails, rear shock mounts.

Post some pics of your build when you get a chance.

-billy

I've read of filling the frame rails with urethane foam. Not the insulating stuff but something heavier. Not sure of how well this works but I plan to try it, if I get around to it. The list is long, the memory is short.