Mk2.5 Roll Cage / Roll Bar

Technical Area Motorsport & Trackday Preparation
2

I know there are plenty of threads about roll bars and cages (I read them), but there are none that fit my individual situation. Apologies to anyone who thinks this question has already been answered. My car is a Mk2.5 - so far manufacturer specs though intend upgrading to improve handling and BHP.

I bought the car to be a track day focused second vehicle. However, having bought it I now love open-top motoring and want to ensure it remains road legal and road practical.

My original thoughts were that I should get a roll cage as this is the safest option and will allow my trackdays to progress into competition (or at least give me more protection if I end up in the runoff). However, roll cages don’t really enhance practicality or aesthetics. A sunny Sunday drive to a country pub wouldn’t quite be the same if I have to climb through a roll cage - not to mention the issues with whether soft tops or hard tops would still fit.

So I am tending towards a roll bar, though I am still a little concerned as this clearly isn’t the safest option. I am presuming that if I buy a bolt-on roll bar, it could be removed and replaced with a cage at a later day if need be? My understanding is that the bolt-on options are not as safe as welded versions but at least they leave the option for an upgrade to a cage at later date? Are any roll bars sufficient for competition driving?

From reading other threads and Googling my thoughts so far are either

  • [Mx5 GCR3 Roll Bar - GC Fabrications](https://gcfabrications.co.uk/product/mx5-gcr3-roll-bar/)
  • Or the TR lane GPVWHB [MAZDA MX5 SPECIALIST - MX5 ROLL BARS](https://www.trlanefabs.co.uk/MX5-ROLL-BARS.html)
I wondered whether anyone on here had been through the same process and whether my thinking makes sense to those of you with experience in these matters?

Thanks in advance.

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When fitting a rollbar, or cage, something that gives some people pause for thought is what happens in a rear or side impact, which is more likely than on a track. If your unprotected head hits a hard steel rollbar, you will suffer a head injury. If the rollbar is “properly” padded, even that material may cause a concussion to the unprotected head.

And for “competition”, what were you thinking of, in a Mk2.5? Autotests; no rollbar is needed. AutoSolo; no rollbar is needed.

https://www.youtube.com/watch?v=uMyGPT9oauQ
https://www.youtube.com/watch?v=_pdZO919qHU

Sprints; short track, two laps, you won’t actually be going that fast, no other car to bash into. I would say, having been through it, if you turn up in a road going class, intending to drive home afterwards, you don’t exactly go full chat like the others (I never got out of 2nd in sprints, and barely made it to 3rd in a hillclimb), and its just a bit of fun. If the car is turned into a dedicated competition car, then what a rollbar/cage looks like is moot. Ditto hillclimbs. For both, I’d say the chances of rolling the car are no different than on the road, and the only reason you are putting in a bar is because a regulation requires it. And not all competitions will insist on a rollbar. Others are happy with a hardtop for instance. Others, I know, will pass a stylebar. Whether they should is another matter. And I know of no car to car competition that includes Mk2 or 2.5s. Its all either Mk1 or Mk3, and they stipulate the cage that is fitted, which doesn’t include any bolt in rollbar.

There is a danger of overthinking things when it comes to these. I suspect if you were contemplating proper competition, you’d be binning that car, and getting something for the job. If you are panicking about rolling a car on a sprint track, then probably you are worried about rolling the car anywhere.

4

 

I did a bit of sprinting last year and fitted a GCF2 bar - I didn’t go for the R version as I was concerned about my head making contact on the road having looked at a few cars fitted with the R version.  That said, this is not so much of an issue now I’ve fitted bucket seats, so with bucket seats I’d possibly now chose the R version…   

 

I also picked the ‘2’ version after speaking to GCF as they said the ‘3’ version won’t work with a glass rear screen as per the Mk2 (despite what it says on their website). I also considered the other bar you mentioned but went with the GCF one as it was ‘MSA approved’ in terms of materials used and welding (whatever that’s worth).

 

However…

 

For me at 6’2”, once fitted my head was way over the bar when wearing a helmet, rendering  it useless.  So, unless you’re fairly short, assume you’ll need to fit a race seat (and associated harness).  

 

You’ll possibly still need a hardtop to pass scrutineering - with a Tillet B6S seat fitted in my car my head is below the bar without a helmet, but a bit above with.  

 

Also, food for thought…

 

SCCA (not that I think you’re going to compete in the US) mandate the hardtop on a MX5 being bolted in palace, so my next step is to get fixings so I can bolt my hardtop in place.  (It’s seems fairly likely to me the standard clip-on hardtop will fly off in any sort of major roll).

 

Ultimately the MX5 is a small road car and making it safe for the track / sprinting will compromise it on the road.  

5

 

I’m slowly coming to this conclusion too (guilty as charged too).

 

To the OP - you can do the club sponsored Japanese Sprint Series with just a hardtop, so maybe that’s an easy option to try first.

 

However, to contradict myself, having had race seats and harnesses fitted to my car I wouldn’t want to go back to using a three-point seat belt for sprinting, and to use a harness safely you need race seats and a rollbar that is above your head.  

 

Lastly, I’ve also seen some awful harness mountings (where the harness is anchored to the floor so it will probably crush the driver’s spine in an accident) so if you go with a harness get it fitted properly.

 

 

6

Thanks for all the replies, I had a good think about this - and read lots of forum debates on both MX5 and other vehicles. Some of them get quite heated!

Ultimately, it seems to be a matter of personal choice. There are enthusiastic recommendations on both side of the fence - roll bar or no roll bar, but no hard data.

@Super_7 - I was thinking of bucket seats too and wondering if that might give protection against contact with the roll bar. We could do with someone who could fabricate a device which sits between the seats to prevent heads flying into a roll bar.

Despite the expressed concerns regarding the roll bar when on the road, I am tending towards installing one. Plenty of other things to do in the meantime so I will hold off for the time being and overthink it some more :slight_smile:

7

A seat won’t protect you from the bar, but you will likely sit lower, and because the seat is thinner, you likely will find the seat is adjusted further forward. The trade off is that a race seat tends to be not that comfortable. eg. a Kirkey.

Obviously lots of MX5s have had rollbars fitted, and used on the road. Most of my MX5s have had Jap rollbars, though the best of 20 years using these bars has knackered my right knee, as Japanese rollbars preclude setting the seat back (they bolt to the floor), so currently sans any roll over protection (I took the roll bar out of my S-Spec 2 about 5 years ago).

I think there is a mindset question here. Fit a rollbar because you have to (regulations), fit a rollbar because you like the look of them, but fitting a rollbar because you feel unsafe in a MX5? Fitting a rollbar address one perceived issue, but the original car was designed to bear its own weight on the A-pillers. The sort of crash that flattens the A-pillers but leaves the rollbar standing, isn’t the crash you are going to walk away from without wearing some sort fo head protection.

What I am saying is, if you feel the MX5 is inherantly unsafe because its a soft top, I don’t think fitting a rollbar is going to remove that doubt. If you think the MX5 is perfectly safe, adding a rollbar is not going to change that mindset.

You started the thread, walking back from a full cage, welded in rollbars, bolt in rollbars. Most owners who fit a rollbar just get a 4-point item, bolt it in, and be done with it. With your Mk2.5, you will NEVER be involved in competition that will REQUIRE you to fit a welded in rollcage. There is no Mk2.5 racing series, and I doubt there ever will be. There are Mk1 racing series, and Mk3 racing series. Except for what Mazda did 20 years ago, they skipped the NB shape.

To rollbar or not to rollbar is a debate thats been going on in the MX5 community for at least 23 years (the number of years I’ve been involved). There is no easy answer, though it doesn’t help if you ask a complicated question.

8

I fitted a rollbar (a GCF2) to pass regs for sprinting. The danger with a bar is your head can make contact on the road without a helmet. With the standard seats my head was quite close so I fitted impact foam. With Tilletts fitted there is much more room and I don’t think impact is likely.

So bucket seats do make a big difference in my experience of fitting Tilletts to a MK2.5 in terms of space between the bar and seat. My car is currently at Roddisons being worked on – I’ll post a picture when I get it back showing how much space there is.

Overall, I don’t think you’re likely to roll an MX5 (possible but unlikely is what I’m told by people who would know) however if you do, you’ll probably wish you had a roll bar fitted.

Also, having fitted seats, harness and bar to my car I feel regs that allow you to sprint with just a three-point lap belt and a clip-on hardtop are not stringent enough. I spoke to the driver of a MK1 that was written off on a club track day at fairly low speed and he was fine but had a harness on, his passenger hurt their leg but was only wearing a standard lap-belt.

@BRG_blur - I’m planning to be at Donington Historic Fri and Sat infield in the club parking area. It’s a long way in the future but you’re very welcome to come and sit in my car if you’re still thinking about options.

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The paradox is without a rollbar present, there is no chance of your head hitting the rollbar.

Which is more likely, your head hitting the rollbar, or tipping the car over? There isn’t an easy answer. I’ve head butted rollbars plenty of times, including wrecking an Arai helmet. Never tipped the car over, yet.

Risk = Hazard x likelyhood (simplistically)

Does fitting a rollbar lower the hazard, but does it also increase the likelyhood (the controversial, you’re more likely to press on with a rollbar, because of the perceived extra layer of safety you have). I expect most to say “no”, but maybe they are not being honest with themselves.

This extends to sprinting/hillclimbs. You might drive to a hillclimb, sign on. And see that other cars in the same class are arriving on trailers, with a selection of tyres. The cars are often covered in dents, and the bar-minimum-interior-trim-they-can-get-away with. A lot of them will seem to be owned by scrap metal yards etc, ie. easy supply of shells etc. Do you drive as hard as them, or actually, more likely, you will back off a bit, because you don’t really want to scratch the car up, you would like it to get home in one piece, for the morning commute.

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@Super_7 There’s a very good chance I will still be overthinking it by then, so that would be great thank you.

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No prob - it’ll be the blue MK2.5 with Tilletts. Once it’s back from Sheff I’ll post a pic showing rollbar / seat clearance so youll have an idea of the space you’re likely to have. :+1:

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Hi @BRG_blur as pomised a couple of shots of the space between my Tillett B6S seats and the GCF2 bar fitted to my MK2.5. I think there could potentially be less space with the R-type bar, which is more intrusive, at the side especially. And to give you a comparison, below are a couple of pictures of the same bar in my red car showing the standard seat’s position relative to the bar in that - not a great pic but the best I have. I think head contact wit the Tilletts is much less likely. I’ve only just got it back from its sojourn in Sheff, hence the delay in posting. The Tilletts sit much lower than the standard seats too.

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thanks for posting these. Sorry about the delay in replying, I must have missed the notification.

My car is still in the garage being slowly de-rusted, but hoping to have it operational again soon, and I will have to make a decision about the rollbar.

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Is it an option to have your “sunny Sunday trip to the country pub” car and another dedicated, caged track day/ sprint/ hillclimb etc car?

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Ah yes, of course that is the ultimate plan. Just two potential issues: 1) Drive / garage space 2) Wife.

16

Understood. You can rent storage but wives are a bit more tricky!!!

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She did buy the first one for me, so really only has her self to blame. One MX5 leads to another, as everyone knows.

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I have been hillclimbing for a few years, I am on my third road / competition car. The first one had a supercharger and a TR Lane roll hoop, I have the other two in the garage at the moment neither of these has any roll protection, one is stock the other has ITBs and 169 BHP I always compete with the hardtop fitted which makes the car a closed coupe as far as the regulations go. Both cars are in fully trimmed roadgoing condition, I compete for the fun of it not to win.
My other other car that I Hillclimb does not even have seatbelts !! Its still fast enough to get the tail out.
67.97 seconds up Wiscombe in a 750cc side valve car thats 85 years old ( 52.2 in the Mazda )
Its a 1934 Austin Sports so I feel really safe in the Mazda

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19

This is really helpful. I did have a track day booked at Donnington in January until Boris spoilt everything with the lock-down. The guys organising the day weren’t worried about me not having a roll bar, but I think ultimately I will look to have a roll bar, though perhaps a hard top would be an interim measure.

I have never partaken in a hill climb, but perhaps it is time I gave it a shot. We at least once i have got the back bumper back on and have treated the rust on the underside of the car, fitted a performance exhaust and air intake (just for the noise), performance brakes and an adjustable suspension :slight_smile: