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Flyin' Miata butterfly brace v2.1 upgrade

Flyin' Miata butterfly brace v2.1 upgrade

Regular price $449.00 USD
Regular price Sale price $449.00 USD
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Note: This kit allows you to upgrade your v2.0 FM frame rails to the full butterfly specification. It is not compatible with the older frame rails. It cannot be mounted to a car without a set of frame rails.

If you don't already have a set of v2.0 frame rails, you're looking for the full butterfly brace.

The butterfly brace "closes the box" for improved chassis rigidity.

First, why do you want chassis rigidity? Because a stiff structure allows the suspension to work better. If your chassis flexes, it's basically a big undamped spring that changes your suspension geometry under load and shudders every time you hit a bump. A stiff chassis will give your suspension a solid platform to work from, leading to better, more predictable handling as well as improved ride quality. There really is no downside. Chassis stiffness is usually measured as torsional rigidity - resistance to twist - because that's how loads usually travel through a car.

When it came time to update the design of our popular and effective butterfly brace, we did it properly. We tested Miatas in a variety of configurations, from a high mileage 1990 to a late NB with the full Sport bracing. Here are some of the highlights:

  • The new design is stiffer than the original design 
  • The new design ties right into the front subframe mount points
  • Fuel/brake lines have more room than with the original design
  • The new design fits a wider range of cars and exhausts
  • The new design includes mounting points for attaching a flat undertray (not currently available)
  • The new design is dramatically easier to install and remove for service. 

Ground clearance is unchanged from the factory Sport bracing. The new design gives more clearance for various exhaust configurations and is easier to remove if you need to do work like dropping the trans. It's fully compatible with factory front and rear subframe braces. Cars with the "Sport" undercar bracing will have to remove two cross braces in the center. It's made of stainless steel so there is no concern about rust.  The butterfly upgrade adds 19.5 lbs to the car, low and in the center of the car.

The butterfly brace upgrade adds the center section to an existing set of 2.0 frame rails. If you have our older frame rails then they're unfortunately not directly compatible without welding in some mounting plates.

The differences between the 2.0 and 2.1 butterfly brace designs are minor, and they are interchangable. The primary modifications have been for more consistent quality.

Stiffer. Easier to install. Lower price. Now that is progress.

Miatas with stock headers will likely need to cut the heat shielding off to prevent interference. This is a relatively easy modification. 



Ships free in the US.

Shipping restrictions: None

What does it fit?

Fits: 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, 2000, 2001, 2002, 2003, 2004, 2004 MSM, 2005, 2005 MSM


Emissions do not apply.


1 year



Customer Reviews

Based on 6 reviews
Steve W.

I bought the frame rails when V2 was introduced but I did not do the Butterfly Braces until now.

Easy install, and the car feels even more stable and tight. Another great product as far as I am concerned. Not the cheapest but very effective.

v2.1 Braces

I've been waiting for the butterfly brace to become available since I purchased my frame rails last year. As soon as I noticed the new version was available and in stock I placed my order.

Order was shipped right away, and received within 3 business days from my order. As soon as I received them, went to the garage to install them. The install video recommended using a jack to hold the braces up while installing, but I didnt find that to be needed. There is some heft to these, but it isnt unmanageable for a single person to do without additional help.

Everything lined up perfectly, as you'd expect with an FM-engineered part. All-in-all install took about 15mins once the car was on jackstands. Only issue I've experienced is the rear brace makes contact with my Roadstersport V3 catback, and the front brace contacts the heatsheild on my stock header. This is likely due to my original 27yr old exhaust hangers, so I've ordered polyurethane replacements to help.

First drive after install blew me away. Car feels much more solid when going over normal road bumps, cracks, dips, etc. Hard to quantify, but it was a noticable difference. Car just feels solid now. First track day of the season is coming up this weekend and I'm excited to see how the car performs compared to last season.

Buy these, you wont be disappointed.

It works

Like they said, you can definitely feel the difference in seat of the pants. Makes the car absolutely flat. Gives me more confidence
in cornering.
I noticed a big improvement once I installed the V2 frame rails, and with the cross braces, another magnitude of stiffness has been added.

Version 2.1

They look so much better than the previous version. Super happy I waited for these. Awesome!

Must have if you have the frame rail braces

Really nice fabrication. Super easy install if you put the frame rail braces in correctly. Took all of 15 mins.
100% better than the rail braces alone. Recommended.