Our original butterfly brace was a very popular upgrade for NA and NB Miatas. Now it's better in every way! It's lighter, it has more ground clearance, it's more effective, it's easier to install and it costs less.
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:
- our frame rails alone increased rigidity by 17.5% over the late NB (without bracing)
- our butterfly brace took that improvement to 29%
- the butterfly is 11% stiffer than the stiffest NA/NB Mazda ever made - the late NB with Sport bracing
- the new design is stiffer than the original
- the new design is 10% lighter than the original
- 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)
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. Naturally, it's made here in the US. Total weight is 27.5 lbs, low and in the center of the car.
The butterfly brace includes our frame rail kit and supplements it with two cross-braces. If you already have our version 2.0 frame rails (the ones with Flyin' Miata cut through the sides), you can add the butterfly brace upgrade. If you have our older frame rails then they're unfortunately not directly compatible without welding in some mounting plates.
Lighter. Stiffer. Easier to install. Lower price. Now that is progress.