Rollover Safety

I'm considering gearing up to try a couple of new things, track days and rallycross. My current funmobile is an NB Miata. I've never worried much about rollover on the street or at the occasional autocross, but for these activities I'm more concerned. Plus it seems some HPDEs and all rallycross events want a top of some kind. The two paths open to me are to:

1. Get a roof and rollbar for the Miata, or
2. Get a hardtop vehicle such as an AW11.

My question is whether the Miata so equipped is similar in rollover protection to a hardtop vehicle, or whether there is still a big gap. A second question is whether all Miata hardtops are created equal as far as protection is concerned. Are the aftermarket ones similar to factory in this respect?

A rollbar will offer greater rollover protection than a typical solid roof car. The reason is because cars are designed as a system: the roof absorbs some impact (and crunches down some) while your reclining seat and three-point seat belts provide give for the occupants. A rollbar doesn't give. Any. This will suck impact-force-wise but that's okay if you're strapped into a proper 5- or 6-point harness, seat, and neck restraint. I would not run race harnesses or a non-reclining seat without a cage in a solid roof car.

A rollbar without a roof is slightly sketchy but okay. Your biggest risk will be the bar "digging in" to the dirt while you're upside down. Any Miata hardtop will solve this, OEM or otherwise, as long as it's bolted in well enough to survive an impact or two with the ground (after which you've dissipated enough energy that it shouldn't matter).

A rollbar without SFI padding, a proper race seat, and harness solution is suicide. Nothing ruins your day/life more than banging your head against the roll bar, or the ground, or both. Plus, the bar means no crunch zone so you better be strapped in well to allow that force to act through you, not on you.

I am not an engineer so YMMV.

So keeping the Miata safe as a daily driver with a rollbar installed means using the harness at all times? Makes sense. Hadn't thought about the potential danger of a harness w/o cage in a roofed car.

The biggest risk with DDing a car is getting rear-ended. If you're in a lowered racing seat, there's better odds of not rebounding your skull onto the bar. If you have SFI padding (which is honestly meant for helmeted heads), there's better odds of getting a concussion instead of a split skull were you to make contact. The only way to eliminate the risk is always wearing harnesses and a helmet. Many (myself included) feel the risks are alleviated enough with a lowered seat and padding.

I completely disagree with the need for harnesses in a street driven Miata. The safety police will tell you it's instant death to step in to a roll bar equipped Miata without a race seat, helmet and 5/6 point harness. I say empirical evidence doesn't support that. Go goggle for people injured on the street by a Miata roll bar compared to the number of pics of rolled street Miata's where people have been saved by a roll bar. Last time I looked I think I found one anecdotal example of someone hitting their head after being rear-ended but with nothing more than a bruise, but you can easily find dozens of roll over shots.

Also I present these as evidence to the bar. Millions of these out there with simple foam padding, the OEM padding from the 80's and 90's was very thin, nowhere close to SFI rated padding.

And look at the Tracker, no padding at all next to the metal B pillar to stop your brain jelly escaping on impact.

I don’t' recall seeing ambulances chasers setting up class action law suits for Suzuki/GM or Jeep selling dangerous products guaranteed to kill you. These vehicles probably have a far higher chance of an incident where you can/will hit your head on the bar/pillar than a roll bar clad Miata.

If I ever get another NA Miata it's getting a roll bar for sure and no race seat or harness outside a race track environment.

Adrian_Thompson wrote: I completely disagree with the need for harnesses in a street driven Miata. The safety police will tell you it's instant death to step in to a roll bar equipped Miata without a race seat, helmet and 5/6 point harness. I say empirical evidence doesn't support that. Go goggle for people injured on the street by a Miata roll bar compared to the number of pics of rolled street Miata's where people have been saved by a roll bar. Last time I looked I think I found one anecdotal example of someone hitting their head after being rear-ended but with nothing more than a bruise, but you can easily find dozens of roll over shots.

The cynical view is that the people who smacked their heads on the roll bars are dead, and thus couldn't post about it. :)

That said, keep in mind that people post stuff that's interesting/dramatic and rollover shots are very dramatic.

I hit my head on the (padded) roll bar in a rear-end freeway collision. It wasn't a high speed impact (required replacement of rear bumper cover, but that was it), and the results of the hit weren't much more than a minor sore spot/headache for an hour or two. At the time it had factory seats & belts, now I've got Recaros and harnesses, although I still use the factory belts with the Recaros on the street.

As for the original question, the answer to which is safer is going to depend on a lot on the details of whatever incident occurs.

I wouldn't worry about a roll bar on the street as much as a rollcage. A rollbar sits behind the seat and should never contact your skull. A rollcage that has the side bars above your head I could see as being dangerous without a helmet.

I'd love a roll bar in my miata, but with the stock seats I wouldn't be able to even touch the headrest. I'm all torso. So until I can get lower (foamectomy/racing seat) it's no roll bar for me.

The difference with the jeep is how much higher the bars are - pretty low risk of bashing your head on it.

I drove my brother in law's miata for a few weeks with a rollbar and stock (foamectomy) seat, and got a few good whacks just going over bumps.

cmcgregor wrote: The difference with the jeep is how much higher the bars are - pretty low risk of bashing your head on it. I drove my brother in law's miata for a few weeks with a rollbar and stock (foamectomy) seat, and got a few good whacks just going over bumps.

Fair point on your BIL"s Miata.

With the Jeep and the Tracker I'm not talking about the top of the bar, I'm talking about the B pillar / bar being right next to you head. Trust me in both of those vehicles you get tossed from side to side a hell of a lot, more so than a Miata doing hard cornering.

I can't comment on the relative safety of any of your options, but I can tell you that for Rallycross, the rulebook states that a convertible must have a factory hardtop, making an aftermarket Miata lid a bad choice for a rallyx car.

In reply to Adrian_Thompson:

Ah, point taken. I guess the verdict is that no matter what you do, someone out there is going to tell you you're sure to burst into flames at any moment...

As for the OP - If I were you, I'd just keep the miata and go with a factory hardtop/rollbar. The devil you know, and all that. As far as I understand it, the hardtop doesn't do much of anything for roll protection, being made out of fiberglass. But to wae's point, the SCCA requires a factory top, so a factory top is what you must get.

Don't forget hundreds (thousands?) of people in other parts of the world race Miata's with no hard tops.

Real rally cross, not dirty solo with no hard top

And 'Lanes rallying' (Think a road rally or 'TSD' but with American Rally Cross style stages between road sections) No bar or top.

Not a Miata, but you get the 'drift'

I say get a bar, drive it on the seat with the stock seats. Possibly lower them by removing the sliders and or a foamectomy. Then get the cheapest hard to you can find for rally cross and track days.

Also rember that not all Miata roll bars are the same, but all require making safety compromise on a street car. Some are taller but closer to your head, while others are further from your head but shorter. Personally, I prefer having a bar, but also won't run one of the taller bars without at least the factory high back seats from 01-05. Earlier factory seats, even with a foamectomy, are a shorter bar only proposition for me. But it's up to each driver as to which safety compromises they are most comfortable making for themselves and their passengers.

Thanks for all the advice guys. Now I am going to go spend an hour learning about lanes rallying. All those pics of racing Miatas have my blood pumping!

wae wrote: I can't comment on the relative safety of any of your options, but I can tell you that for Rallycross, the rulebook states that a convertible must have a factory hardtop, making an aftermarket Miata lid a bad choice for a rallyx car.

That's an excellent bit of advice. I am now regretting not picking up a cheap one from CL that was in my rareish body color for only $750.

DLC wrote: Thanks for all the advice guys. Now I am going to go spend an hour learning about lanes rallying. All those pics of racing Miatas have my blood pumping!

Don't forget it's in Ireland not here.