Hard top on mx5 race car

alex k · Postby **alex k** » Sat Oct 18, 2014 1:33 am

Hard top on mx5 race car is there a need ,dose it serve a purpose ?

davekmoore · Postby **davekmoore** » Sat Oct 18, 2014 1:48 am

Maybe aerodynamics on a fast track,

Just added weight otherwise.

david_syd_au · Postby **david_syd_au** » Sat Oct 18, 2014 6:50 am

A hard top does help with aerodynamics, and is generally accepted to offer about a 1 second improvement at Wakefield Park over an open car.
It is also useful as a .... cloaking device, if you are marginal on the mandated 5cm clearance to roll bar/cage

mazmad · Postby **mazmad** » Sat Oct 18, 2014 7:13 am

I refer you to viewtopic.php?f=18&t=65689 for evidence as to how much protection it offers ;)

I am on my second car, swapped the soft top for a hard top on the first, an NB. For the last 6 months I have not had one on the new car. I have actually enjoyed racing topless.... But cannot wait to get my hard top (this week hopefully). For security when the car is on the trailer, dust and crap on track if you or anyone nearby has an offload excursion. And yes for rain (yeah yeah yeah been told to htfu already...).

So for me big plus. But not for supposed handling (rigidity) or aero benefits.

Postby **Boyracer** » Sat Oct 18, 2014 7:22 am

Makes a huge difference at Phillip island, maybe a bit at Eastern creek, if you want to run a wing it will also help...I hate them...

greenMachine · Postby **greenMachine** » Sat Oct 18, 2014 8:01 am

It goes without saying :lol:

that if you run the HT, you lose the soft top ... and as for weight, get a carbon one with plastic window if that is a worry.

:mrgreen:

Magpie · Postby **Magpie** » Sat Oct 18, 2014 8:21 am

CAMS minimum requirement for any window is meets AS2080.

Plastic/Perspex etc normally bumps you into a higher class, at least in time attack.

Not sure on the implications for road registered vehicles.

oztrackdays · Postby **oztrackdays** » Sat Oct 18, 2014 8:46 am

It really should be 7 plus cms clearance for safety of you have seen the stretch in a harness during blue green blue moments I wouldn't be happy with 5. I think I have about 15 in mine.

alex k · Postby **alex k** » Sat Oct 18, 2014 4:30 pm

All good points , i just need some help parting with the $2000 for carbon top.
Thanks guys.

SKYHI · Postby **SKYHI** » Wed Oct 22, 2014 8:22 pm

Another point to note, it will keep you dry in the event of rain

lightyear · Postby **lightyear** » Wed Oct 22, 2014 9:10 pm

2 seconds at Phillip Island.

ManiacLachy · Postby **ManiacLachy** » Thu Oct 23, 2014 8:30 am

I remember reading somewhere that the hardtop added stiffness to the chassis. They weren't actually expecting much if any change in ridgidity, but they used a machine to test it and were quite suprised by how much it added. Not sure where I read it, and of course now I can't find it!

93_Clubman · Postby **93_Clubman** » Thu Oct 23, 2014 12:00 pm

ManiacLachy wrote:Not sure where I read it, and of course now I can't find it!

Perhaps this: viewtopic.php?f=18&t=35781&start=75

lightyear · Postby **lightyear** » Thu Oct 23, 2014 12:43 pm

Even a lightweight carbon fibre hardtop stiffens the car. I would have put money that it would make no difference. But after having an NB with scuttle shake (soft top up or down), then drove with a c.f hardtop to find no more scuttle shake. I think it has to do with a folding roof adding no diagonal bracing. I wouldn't run on a track without a roof, unless you were just doing it for fun.

mazmad · Postby **mazmad** » Thu Oct 23, 2014 5:04 pm

Jury is out as to whether the hard tops add stiffness on road cars.

If its going on a race car then it has a full cage and hard top will do stuff all for added stiffness, cage has already done that job.

Oh.... And.... My carbon hard top went on the car yesterday, looks amazing.