Dusterbd13
Dusterbd13 MegaDork
10/1/24 12:07 p.m.

1999 miata. Getting fully reworked for another challenge run, and to be a NICE street car after the challenge. 

Its stitch welded per fm directions. Frog arms,  harddog m2 bar, 2x2 square tube welded through floor as subframe connectors to front and rear fram rails and tied in heavily. 

Ohlins coilovers, big front bar, hard s rear, 15x7 wheels with 225 45 15 rs3 tires

250rwhp turbo six speed drivetrain. 

 

Im trying to figure out what else i should do to the chassis for stiffness sake. I have the 04 factory butterfly brace and strut tower bar. I dont k ow if they are worthwhile at this point, or wasted effort. Same with a three point brace from rear subframe to the ppf/diff bolts. Or a triangulated strut tower/firewall brace. Or....

 

No door bars. Its destiny is as a nice street car. Days of being a track rat are over....

 

Picture because we all love pictures. 

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
10/1/24 12:19 p.m.

Don't tie the PPF to the subframe, there's supposed to be movement there.

 It's worth bracing from left to right on the shock towers in the engine bay, but you gain nothing from trying to triangulate it because that's not the direction of the forces and there's no structure at the top of the firewall anyhow. The factory 2004 unit is a good one. https://youtu.be/aNYQ4VKWtmo?si=EN6NRa1eqpCNpGEd

Underneath, there's definitely some rigidity to be gained with a cross (butterfly) brace. The factory stuff is meh but better than nothing.

Put some sound deadening under the rear deck and bulkhead :)

When setting up those Ohlins, pay attention to your compression and droop travel. They're short on overall travel so it's walking a fine line to get it right.

Dusterbd13
Dusterbd13 MegaDork
10/1/24 12:54 p.m.

In reply to Keith Tanner :

I didn't know if it was going to be a law of diminishing returns thing at this point with everything else I had done. I'll put them in! Is there any other bracing or chassis stiffening I should add while I still have the welder out and before I get to paint and body? And I will definitely pick your brain when it comes time to fine-tune the olens when I swap them over from the wrecked car

RacingComputers
RacingComputers GRM+ Memberand HalfDork
10/1/24 6:40 p.m.

"It can never be too stiff"  to quote Mae West

Dusterbd13
Dusterbd13 MegaDork
10/1/24 8:04 p.m.
RacingComputers said:

"It can never be too stiff"  to quote Mae West

You're not wrong!

Just want to focus my time, money, effort amd weight on what will get me the best results for my use case. 

Im sitting here tonight looking at pictures of the fm butterfly brace vs the factory piece and comparing to my subframe connectors. Trying to see if there something i could fabricobble that would be as good as theirs. Or at least better than stock and fit my challenge budget. 

So far everything has been heavy, cumbersome, with too manybwelded points of potential flex.....

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