Roll bar, yay or nay?

[warped head]

Red Firecracker said:

warped head said:

Reason Insurance Co's and the rozzers dont like cages in road cars is very simple.

My insurance company were overjoyed, to the extent of not charging me any extra, when I enquired about and subsequently told them I had, installed a roll bar. They deem it a safety device and were most welcoming of the modification.

How odd, When i informed my insurance co of my uprated brakes which do stop my car about 5-10 foot before standard they raised my premium saying it would encourage me to go faster, and there for im more likely to have an accident.

to say i want pleased is an understatement!!

[Bill]

300bhp/ton said:

I don't follow that. Surely if you are in a bad enough accident to hit your head on the roll hoop. You either weren't strapped in. So no hope would result in just as bad or worse. Or you'd have hit your head on the ground.

In a rear 3/4 crash (either being hit or spinning into something solid the combination of seat flex and your head movement could easily result in a hard impact with the upright.

Those hoops (IIRC Munter posted) look like the best solution IMO, but this from the same company look slike a liability:

[Red Firecracker]

I purposely went for one that entirely sat behind the seatbelt posts.

[Gibby78]

Mr Will said:

Doesn't have to be a rear end shunt, you could spin it and hit something while travelling backwards.

But you do get thrown around a huge amount in a crash, even with a seatbelt on. What do you think side airbags are for?

Not all cars come with side airbags though do they, same could be said of hitting the door pillars, side windows and so on, as this is an MX5 and more than likely won't have side airbags his head could get thrown out of the side of the car and hit the armco, anything can theoretically happen, all I know is In a crash/rollover I'd rather have more structural rigidity, in a crash hard enough to throw you into a roll bar if it wasn't there you'd probably hit something else anyway, and with less structural rigidity it'll be closer to you.

Edited by Gibby78 on Friday 5th February 11:36

[Munter]

Modern cars in a roll over test(s). See those guys get thrown around!
http://www.youtube.com/watch?v=K6h7wqLqJ0U&fea...

Rear impact on an unsupported seat. (e.g. the MX5 has a bulkhead that'd stop the seat back going so far)
http://www.youtube.com/watch?v=9xoauIutCmc

He does move up the seat a bit. If the seat moves less would he move more...or less...I don't know.

[speedtwelve]

Chap I knew barrel-rolled his Mk1 Eunos Roadster after an unplanned car/tree stump interface. He had a non-structural style bar fitted, which took enough of the weight of the car to enable both occupants to walk away with minor injuries. Note the state of the windscreen:

[The Wookie]

Ozzie Osmond said:

The Wookie said:

If you're just a tootler who never gets near the limits, then it's more likely to cause you injury than save you

Well viewers, if you can understand that leap of logic you're doing better than me......

If you're just tooling around in it, are you more likely to put it on it's roof, or get hit up the back and smack your skull against a solid bar that wouldn't otherwise be there?

[paulmnz]

Interesting debate which has raged over the internet for years... I can only provide my opinion, as frankly there is no *real* facts one way or the other in terms of improving your 'survivability' - it's all mostly conjecture. Evey accident is different and so contributing factors will be vastly different as well.

My *opinion*:

I have one of the orginal TR Lane MX5 bars in my MX5 (I commissioned it with TR-lane to get it as close to the MSA specs as we could and still fit a roof (which as noted in one of the other posts, you can't actaully do with an MX5 as the bars would be within the MSA stipulated 20cm bar-head). The MSA requirement might be due to the higher speeds (and therefore impact energy) experianced in racecar crashes - Not sure on that.

My MX5 is primarily a road car. my bar sits quite far behind my seats (which are FIA sparcos) and I use a 4-point road harness.

I also have a rollbar / half cage and my road-legal track Integra, but my head is a million miles from that bar (I use FIA seats and 6-point harnesses in that car).

You are much more likely to roll a car on a track than on the road due to higher cornering forces and gravel traps catching cars sideways.

However, I wouldn't drive an MX5 quickly on the road without some kind of roll-over bar. For me to hit the bar behind me in an impact would be difficult (not impossible I'm sure) as FIA seats are designed not to bend/move as much as a conventional reclining seat, and I use harnesses rather than inertia-reel seatbelts. The OP mentions he has recaros, not sure if they are bucket types, but regardless, recaros tend to be crash-tested and 'safer' than OEM generic seats.

I would feel safer in a standard MX5 (standard seats and belts) with a roll-over bar as well.

Plenty of road accidents end with a car on it's 'roof' even if the roll wasn't part of the initial accident. the rollbar will also significantly strenghten the MX5 across the car - which would help in a sideways impact.

Mine is a 'goalpost' style, the dual hoop-time might be better for a roadcar as less head-bar impact posibilities.

Ultimately, the decision to have a bar in the car is a 'personal' one as it depends on your driving style, and definition of 'risk'. if you are considering a rollbar, it is likely your a keen driver, so it may be right for you to have one.

As for insurance - if you mention it is a 'rollover bar' rather than a 'rollcage' you should find most mainstream insurance companies are OK with it - esp if your car is standard otherwise - they will consider it a safety feature. If you have aftermarket suspension etc then the insurance company will be more concerned about it and see it as a liability.

[paulmnz]

Pics of my rollbar:

[groomi]

That looks much better.

[pbirkett]

Right, this has been an interesting debate, and certainly there seems to be an argument each way for going for one.

Personally, I'm kind of on the side of getting one at the moment, but only provided it is well enough designed so that it is not too close to my head, had it not been for this thread, it is something that may not have occurred to me before.

It does seem like some designs will keep the bar far enough away so that may not be an issue.

To the guy asking about the Recaros, my Recaros are kevlar fixed buckets so the seats wont bend back as I can't adjust them anyway, so I reckon the seats would be safe.

[GravelBen]

groomi said:

That looks perilously close to the side of the head. Even with a helmet on, I'd be wrapping foam around the side of that bar - without a helmet you're better off without that bar.

I think its mostly the angle of the photo which makes it look that way, the bar is behind the line of the seat backrest rather than beside it. I think you'd be about as likely to hit your head on the B-pillar of some normal cars, and you'd have already hit the window of the MX5 (with the windows up) before your head got that far.

That said, taller drivers/passengers than me frequent the car at times too, so I think I'll accelerate my plans to get some decent buckets in it - thanks for bringing the point up.

Edited by GravelBen on Sunday 7th February 05:09

[aww999]

I'm going to chime in with a quick note about roll bar padding. My Fury has a roll bar that is close enough to the seats to be used as a head rest! The first thing I bought for it was some FIA-approved roll bar padding, this has a curved face on the back to fit around the bar, and a square face on the front to spread the impact if you headbutt it. What surprised me was how hard it is, it's not some squishy cushion thing, it has a properly rigid foam structure that can't be dented or manipulated by hand. It's designed to spread the load of a helmet striking it with some force during a big accident, and would give little or no cushioning during a head/bar interaction at lower speeds without a helmet. You can get squishy padding which looks a lot like domestic water pipe insulation, but from what I've seen you would need it to be several inches thick to provide any sort of protection in an accident, and is best viewed as decoration in my book.

Needless to say, I always wear a helmet when driving my car, even with the padding, and I'm giving serious thought to changing the seats to move my head away from the bar. Those people who cannot imagine how a strapped in occupant could hit their head on the cage need to watch some crash-test clips - unless your neck is wider than your shoulders, your head will display the same range of motion as a bowling ball attached to a bungee cord in any sort of big impact! A local chap was killed a year ago round here when a fast (80mph) barrier impact on a motorway gave him such severe whiplash-type motion that both arteries in his neck were damaged internally and his brain died due to lack of blood.