Miata Hard Dog Roll Bar Installation
By John Kuykendall
Roger, our region’s President, has been doing some local autocrosses lately, and I guess he got to thinking about what MIGHT happen if he tried jumping a curb at full-tilt like he did one time (ask him about it sometime) and got it upside down! So he decided to install a four-point roll bar and a racing safety harness. We took some pictures during the roll bar install to help you visualize what’s involved.
The bar that Roger installed in his car is what’s known as a Hard Dog Hard Core Double Diagonal Hard Top. Wow, that’s a mouthful! More often, it’s just called a HDHCDDHT for short. What all that means is that this particular roll bar is made by Hard Dog (HD, actually Bethania Garage, Bethania, NC). It’s the Hard Core model (HC), and it’s made of 1 ¾” diameter tubing which generally meets the requirements for SCCA Solo I racing (timed events with a single car on the course at a time). The Double Diagonal (DD) part means that it has two, shorter diagonal braces, rather than the standard single diagonal, which supposedly provides better rearward visibility.
Most types of roll bars will reduce the visibility through your rearview mirror, but the diagonal braced types limit it even more. The Hard Top (HT) designation means this bar is about 1″ shorter than the standard Hard Core model, so that it will fit under the Miata’s OEM hardtop – the standard Hard Core will not. There are many other makes and models of roll bars, to fit many other needs, from style to pure racing. You should do your research before buying a roll bar, keeping in mind what your particular requirements might be. Be aware that for most on-track driver’s schools or driving events, the organizers will require a “four-point” type roll bar for all convertibles, with “substantial rearward bracing”. The Hard Dog Sport and Hard Core Models both meet this requirement. Style bars (such as those by Racing Beat) and other two-point mount bars do not. In most cases, an OEM hardtop is not an acceptable substitute for a 4 point roll bar.
All that said, it’s my opinion (and that of many others) that a roll bar is an essential safety feature for any convertible, whether you’re planning on doing competitive events or just driving on the Parkway. It’s not that you intend to get in an accident or roll your car over, but, as the saying goes, those things happen, even on the street.
So, let’s see just how difficult it is to install a four-point roll bar in a Miata:
SOME PARTING NOTES ABOUT THIS AND OTHER MIATA ROLL BAR INSTALLS:
• Despite what it may sound like, this is not a really hard installation to do, as long as you have the proper tools and an assistant. I think what we found was that having someone who has done at least one installation before makes the process go MUCH faster, as there is less mystery to the instructions and the process (“Why do they do it that way?”). Our install took about 3 ½ to 4 hours, not including the preparation time Roger took to put his car on jack stands, remove the trim and carpeting, and remove the rear wheels. It also does not include the time required to carefully cut the carpet and plastic trim to fit. That time will vary in direct proportion to how careful you are and how good you want it to look afterward! Tools you really should have on hand: Open end and socket wrenches to fit all hardware (OEM and roll bar), a long 12-18″x3/8″ drill bit and power drill, a Dremel tool with metal and plastic cut-off bits, and a power metal cutting tool such as a sheet metal nibbler. Other sheet metal tools will do in a pinch, as the sheet metal is fairly light guage (why do you think the Miata is so light?)
• As mentioned earlier, this install was for an M1 Miata. The install should be very similar for 99+ Miatae, but the Hard Dog roll bars for M2’s have slightly different rearward brace bars since they have to clear the non-folding glass rear window. Consult the instructions for differences. NOTE: For those who may have installed aftermarket convertible tops with glass windows on M1 Miatae, there may be a problem with installing a four-point roll bar! Check with the manufacturer.
• Note that in order to use your OEM convertible top boot (or a tonneau cover), you’ll have to modify the boot (or tonneau) to fit around the rear brace bars of a four-point roll bar. This can be done by any upholstery shop, or you can probably do the boot yourself, by simply splitting the sewn seam along the bottom. Fit the boot in place and you’ll be able to see where the seam needs to be split. Once properly modified, your boot or tonneau will fit around the bar, and the cover can be closed around the bar using velcro closures that will allow it to be removed again.
• You should really, really think about installing some type of padding on your roll bar, so you don’t knock yourself senseless in an accident (or near miss). Hard Dog sells a leather roll bar cover with padding that fits their Sport but not their Hard Core bar. Racing parts places like Racer Wholesale sell closed-cell roll bar padding foam in several colors, which can be used alone or you can have it covered with leather or vinyl by your friendly neighborhood upholstery shop. You can attach the foam padding with long zip-ties.
• With the four-point bars in M1 Miatae, you will no longer be able to unzip and lay the plastic window flat when you fold your convertible top, since the rearward brace bars will be in the way. What you can do instead is carefully fold the window as you drop your top, using a rolled towel or foam pool noodle inside the folded window to maintain a 2-4″ diameter bend in the plastic, preventing kinking or breaking the plastic. Don’t drop your top when the temperature is below about 45 degrees F, since the cold plastic is more likely to crack when bent. You don’t really drive with top down when it’s below 45F, do you?
• SCCA Legalities: Hard Dog Hard Core bars are listed as legal for SCCA Solo I competition. This is somewhat dependent upon your height, as the top of the bar must clear your helmeted head by at least 2 inches. There also appear to be some questions about the configuration of the diagonals on the Hard Dog bar, since they do not connect into the main loop, as required by SCCA. But, a roll bar is NOT required for most classes of Solo II (autocrossing). Real road racing requires a roll cage, which is something else entirely, so get a copy of the SCCA rule book if you’re thinking about that. As mentioned earlier, if you are considering doing any kind of event on a race track, whether it be a driver’s education school or just an open-track day in your Miata, you will likely need at least a four-point roll bar.
That’s all! Go out and install a roll bar in your Miata, and stop worrying about your head!