if dave doesn't mind me posting, heres the pictures I took of his rear bar.




if you want me to remove these dave just tell me and I will.



I tried the toe out thing and it rotates well but if you give to much steering input your done. Theres not correcting it, once the rear is gone, its gone! zero toe is what I'm gonna try also.

Now if I could just find a good deal on a "rear" bar.

 

The rule change affects a lot of people, serious or otherwise. I think the intent is to eliminate aero requirements from ST* and allowing enthusiast exceptions created a really gross rule- go read 14.2.F if you haven't. Some cars with aero have been at the top but it has not yet been deemed a must have. I was going to dabble in aero, but not until everything else was sorted. Now I don't have to.

Other than the slightly notched hole on the sway bar bushing bracket and the close proximity to the differential, I'd swear the bar was supposed to be there.

Very very quick calculations puts the Miata bar at ~125lb/in spring rate and ~115lb/deg roll rate compared to the 332/300 of my 06 bar. We fought a bit of oversteer this weekend and your front biased car would have done well in the high-speed elements. The toe-out and rear geometry probably evens most of the spring/bar difference we have.

While we are talking setups, here is my Nationals setup:
anti-roll bars F/R: Gendron 1.25"x0.25"x36" @6/stock
ride-height F/R: 13.5"/13.25"
springs F/R: 850#/750#, 7"x2.5" + helpers
toe F/R: 0"/1/4"
camber F/R: -1.8*/-2.0*

The new setup for Blytheville Tour:
anti-roll bars F/R: Gendron 1.25"x0.25"x36" @6/stock
ride-height F/R: 13.25"/13.0"
springs F/R: 850#/750#, 7"x2.5" + helpers
toe F/R: 0"/1/4"
camber F/R: -2.4*/-2.6*

Notes:
The car didn't put power down as well as it has in the past. It felt similar to softening up the front bar; it rotates better, but throttle caution shows on the clock. The trait disappeared as the tires warmed and the course cleaned up. We increased front compression and decreased rear tire pressure as a bandaid. Pyro numbers were 5-10*F hotter on the inside shoulders for the first time, moreso in the rear. Since we both had to consciously drive around the rear of the car and pyros went from flat to hotter inside we are going to decrease rear camber in an effort to increase rear stability.

 

Josh, thanks for posting some pics. There might be some other angles that might be useful... If there are, maybe I'll just e-mail them to you to post.

Note in the pics that drilling the brackets allowed for more clearance of the diff bolts... and there is a bushing keeper (ring) on the center part of where the bushings are. That had to be moved.

Toe out subject... well, my experience is different than Josh's. It sometimes steps out on corner exit, but easily recoverable (spring stagger is much bigger with my car where his is square). But, thinking that on faster venues, it is better to reel it back a little so I can drive with more confidence without having to catch it so much. My thinking going with the rear bar, negated the need for rear toe out. So.... with rear bar=0 rear toe. Without rear bar=.06 degrees toe out was good.

-Dave

 

Dave, Mark, Shawn and Josh,
Good to meet all of you and compete against you this weekend. See you at an event next year.

Dave,
After driving your car at the Evo Advantage, I agree with the decision to go zero or slightly toe-in with the rear tires. It should help with getting power down earlier on corner exit with out all the drama.

 

What's the email adress or link to the people I need to email on getting a ruling on a "mod." I'm 99% sure my mod counts as a creature comfort since it weights more then the stock and uses the exact same mounting points and has no performance gain what so ever.

 

What mod?

 

I know someone would ask. It's not really a big deal I just had a very respectable autocrosser tell me that I need to check and see if my mod is legal or not.

If you must know...

Ap1 car with ap2 door panels, center concole, and radio door. If anything the ap2 stuff is weights more because of the extra material on the center concole and built in tweeters on the ap2 door panel.

No drama, I just wanna verify that I'm legal. It's a creature comfort correct?

 

The MX-5 rear bar? Just go buy one new. I just ordered one including hardware/bushings from www.mazda-parts-dealer.com for $116 including shipping.

 

It uses the same mounting points and everything


Awesome! Thanks rob

 

Technically illegal, but unlikely that someone would protest you, and less likely that a protest committee would give you a meaningful penalty. But definitely technically illegal.