1997 Mazda MX-5 Miata: Blackbird Fabworx GT3 6-Point Roll Bar
June 28, 2011
Want to bring your Miata to a track day? You'll need a roll bar. With few exceptions, the organizers of such events won't allow convertibles to run without one.
But let's step back a bit first. Track days aren't the only reason to install a roll bar in a Miata, and some roll bars offer more than just rollover protection. Roll bars like the Blackbird Fabworx GT3 6-point, for instance.
Consider that a stock Miata's chassis stiffness is, shall we say, tapioca-like. Then consider that steel is plenty stiff, and that roll bars are comprised of lots of the stuff. A standard 4-point roll bar does a pretty good job of stiffening up the rear bulkhead area, but this is not the area of lowest-hanging fruit in shoring up a Miata.
The Miata's structural Achilles' heel is the part it doesnt have a roof. A hardtop "closes the box" of the car's flimsy open-top layout, and in so doing enhances chassis stiffness a tad (whether Mazda intended it or not).
Still, first-gen Miatas are flexy flyers, and we want to further tie the front end of Project Miata to the rear. Door bars have been high on my to-do list for Project Miata. So when I came across the Blackbird Fabworx GT3 6-point bolt-in roll bar that integrates the door bars to the roll bar, I was intrigued.
Moti, proprietor of Blackbird Fabworx, explained the various options the roll bar or cage offerings are customizable in bracing, wall thickness in certain sections, even color and shortly thereafter we dropped Project Miata off at his shop in Northridge, CA. There, he fabricated and installed the GT3 roll bar.
The process was quick, efficient, friendly, even fun, as Motis knowledgeable in a broad swath of automotive interests. One day well show you his one-off bike-engined car thats nearing completion.
Ill post more info on the Blackbird Fabworx GT3 6-point roll bar in a followup post, but for now, heres a peek of Project Miata during Blackbird Fabworx' fabrication process.
--Jason Kavanagh, Engineering Editor
Blackbird' Fabworx GT3 roll bars are compatible with plastic-window soft tops, although Project Miata is hardtop-only.
The rear package tray sheetmetal is trimmed to accomodate the roll bar's rear legs, which bolt through the sturdier trunk floor to backing plates.
Note that the harness bar is not yet welded in. Blackbird Fabworx customizes the height of the harness bar depending on the driver and the seat.
That's because the shoulder harnesses of a race harness, to function properly, need to sit somewhere between horizontal and 20-degrees, where the bar is lower than your shoulder. Angles greater than 20-degrees compress the spine and put loads into the seat that it was not intended to support, Here, we're at 7.6 degrees, which is goodness. We also did a test-fit with one of Moti's race seats for when we finally ditch the stock seat and confirmed the goodness.
Door bars make the difference between a 6-point roll bar and a 4-pointer. They also make a hugenormous difference in chassis stiffness in a Miata. The plastic armest will be sectioned to make room for the door bar; a small price to pay.
This is where the door bar will be welded to the main hoop. Very nice looking welds all around.
The forward end of the door bar is bolted to a proprietary receiver mount that Blackbird welds into the car. This unique placement sets the Blackbird Fabworx GT3's door bars apart from other ones, for reasons I'll detail later.
Clearances to the chassis are consistently tight and uniform everywhere on the GT3 roll bar. This is something you can't get in a mass-produced roll bar. Blackbird Fabworx' services are available to anyone within driving distance of Northridge, CA. Sorry, Tennessee. On the plus side, southern California is a high-density nexus of Miata enthusiasts.
The seats retain full travel despite the presence of the door bar, which just touches the bolster at the seats' full rearward reach. Clearance of the door bars to the door cards is paper-tight and consistent. It's remarkable; sitting in the car, you don't even know the door bars are there.