Why do you have a rollbar? Road or track?

[Mr Morlock]

Its been discussed before but from a use point of view and construction of bent tubes it is a space and convenience negative for an already small cabin. Its not even a certainty it improves the safety of the vehicle especially if the driver and passenger cannot maintain a safe distance between head and bar. Personally I think it also detracts from the cars inherent and svelte looks and a plumbers nightmare is hardly aesthetic - others think it looks cool. For track use it is somewhat different in a number of ways.

[manga_blue]

The biggest advantage I've found with the rollbar is that it means you can carry stuff or lash stuff to it, like surfboards, kayaks, fishing gear, timber, dogs, golf clubs, anything really.

[rascal]

Gives you somewhere to mount the camera...

[Magpie]

It is like a front strat brace something to lean on , use as a cable tie point and for hard parking points. I think I will get mine powder coated to match my eyes (hazel).

[lightyear]

The seatbelt towers provide structural rigidity but are basically a U-shaped brace so the tops can twist in opposite directions.
Put a brace across them, such as the meaty torque box built into the MX5 Plus roll bar, and this twist is reduced significantly (imagine two fence posts; add a beam across the top and it's much harder to "wobble" them from the top).
In an NA/NB, this brace is essentially the only significant horizontal brace above the floorplan (the NC has much better chassis stiffening - it was recognised as a deficiency in the NA/NB).not a believer in it adding any stiffness. Seatbelt towers are above a wall. The wall is the brace

The hardtop is definitely NOT a brace. i believe it is

PS: I've never dríven around with the doors wide open so cannot verify that the rollbar makes a difference with/without the doors wide open.[/quote]
no need to drive, just look at the chassis.

the aftermarket is full of chassis braces for the MX5, I use none, and seem to be doing competitive lap times considering the chassis should be at a disadvantage. I don't even use aftermarket suspension bushes. Just drive faster

[hks_kansei]

I still disagree with the whole hardtop is a brace thing, my reasons are below:

Hardtops flex easily, you can twist them by hand with minimal effort.
That latches still allow a little movement by design.


Now I know that Danny did some measuring etc and found that the top reduced body droop or something, and I don’t doubt his figures. BUT, from memory the difference was a few mm, and was also measured statically.

My theory is that the top did indeed help the car to not droop as much, however I would contend that it was more the top helping in regard to tension (ie: the rear latches pulled down, which in turn pulls on the windscreen header reducing droop in the passenger area)
Since the OEM latches only pull, I would contend that under any compression (ie: what you actually see when driving, other than maybe cresting a hill at speed) the top would simply squish against the rubbers and do ƒü¢k all for stiffness.

I would say the hardtop is as useful for chassis rigidity as tightening a ratchet strap from the windscreen header to the seatbelt shoulder mounts. With the car on the jacks it will support weight via tension and reduce the body droop, but for actual driving I’d say nothing.

Cliff notes:
I think the HT adds some support, but to an area that has no use in 99.9% or all driving.
And that it only adds a tiny amount.

[lightyear]

The hardtop create a diagonal brace. I have dríven MX5's with the wobble at 100km/h. Top up or down. Put on a hardtop, and it's gone.
The hood bows on a soft top add no diagonal support. Even one of my c.f thin lightweight ones stop the wobble.

[93_Clubman]

Danny did some measuring etc and found that the top reduced body droop or something, and I don’t doubt his figures. BUT, from memory the difference was a few mm, and was also measured statically.

For anyone interested in Danny's test results:
viewtopic.php?f=18&t=35781&p=723899&hilit=results+are+in%2A#p723899

[StillIC]

The hardtop create a diagonal brace. I have dríven MX5's with the wobble at 100km/h. Top up or down. Put on a hardtop, and it's gone.
The hood bows on a soft top add no diagonal support. Even one of my c.f thin lightweight ones stop the wobble.

I agree with your comments about the hard top, because I disagree with your comments about the soft top!

I have never dríven a hard top, but I don't doubt they stiffen up the chassis in torsion (and bending, as shown in the research above). I am pretty sure of this because putting my soft top up stops my windscreen wobbling left/right. It definitely stiffens the chassis in torsion to a noticeable degree, but most likely less so than a hardtop does.

[kalt]

I got mine so it enhances the racecar experience when I go vroooom while driving to work.

I also have the heavy (fiberglass??) glass window hard top and support lightyears' comments, without a doubt.

Maybe the carbon fibre hard tops are more for weight saving and aerodynamics, rather than stiffness?

[Geordie]

Hi folks. I don't track my NA8 but I have been wondering if I should get a proper rolls bar (not one of those cheap stylebars that offer no safety.) I see quite a few MX5's on here, if not out on the road, with roll-bars intact, and wonder if people only get them because you go on track?
Would you get one for a road only car?

I know they technically make the car safer, but they areexpensive and I think they really ruin the shape of the car. Seem so heavy-handed on a sweet little NA.

Interested to hear opinions.
Thanks

I am installing an mx5 plus to my SE as it both stiffens the chassis and will protect my sons head when he does Motorsport. Automotive plus do not have any in stock but we are doing a bulk order of three for WA so it might be worth ordering while he is cutting and welding ours.. Talk to Dave at Automotive Plus, he is very helpful.

[madkeen]

Such great feedback (and some funny smartarses). All good! Thanks guys. There's seem to be as many positives to installing one for road use, as negatives. In which case, I think I'll just keep saving my coinage.... for now

I might make a similar post seeking opinions on ceramic coating extractors for road-use next!!

[Jeo]

ceramic coating extractors for road-use

Do you like spending money? If so, yes.

[bensale]

If you do get a roll bar please as a minimum upgrade the seats, particularly if you're on the taller side (NA6 NA8 N8BA are all bad - NB8B onwards and most aftermarket race seats are better). You're far more likely to be rear ended on the street than roll the car and you can imagine where your head will end up in a large impact....

[speed]

My bar dresses up a spare bedroom nicely. Mazda speed, Shiney and no diagonal bar. Is also lighter than the plus bar but obviously not as rigid.

Safety wise, I hope that I never have to find out.

Ps I think Nevyn72's entire car looks awesome. The bar looks even better in real life too. Oh man, now I'm thinking how comfy his seats are...