For Motorsport: Hardtop? Soft top? Or No top?

PT · Postby PT » Mon Jan 27, 2014 8:30 am

So what's the general concensus for Motorsport use. If you have a hardtop do you put it on? Or leave it off to save weight? So then do you put the soft top up for aerodynamics? Or fold it back?

In my opinion the best way to go would be hardtop on but with soft top removed so that you aren't lugging the weight around. That's ok if it's a track car but if it's a road car with both roofs, what do you do?

mazmad · Postby **mazmad** » Mon Jan 27, 2014 8:59 am

The diehards run no roof....rain or shine. Minimum weight. Because I am soft...I run a hard top. Keeps the rain and some dust out, also easier for transporting and storage of the car.

zero00 · Postby **zero00** » Mon Jan 27, 2014 9:03 am

I run an NB8A, only has soft top and run with that down unless it's raining

zossy1 · Postby **zossy1** » Mon Jan 27, 2014 9:07 am

You should check the big forum and mt.net for info on this - it has been done to death. In fact, I think there is some info on here too...

In short, it depends on the track - longer straights (like PI) have a greater need for improved aero and hardtop > soft top > no top. But at tighter tracks like Wakefield, the difference is less.

zossy1 · Postby **zossy1** » Mon Jan 27, 2014 9:09 am

mazmad wrote:The diehards run no roof....rain or shine. Minimum weight. Because I am soft...I run a hard top. Keeps the rain and some dust out, also easier for transporting and storage of the car.

Missed you yesterday Craig - was a good day!

Sorry... [/thread hijack]

mazmad · Postby **mazmad** » Mon Jan 27, 2014 6:54 pm

Looks like an action packed weekend Chris. End of school holidays, family weekend away for me. You were pretty consistent, must be happy with the car!

zossy1 · Postby **zossy1** » Mon Jan 27, 2014 7:11 pm

mazmad wrote:Looks like an action packed weekend Chris. End of school holidays, family weekend away for me. You were pretty consistent, must be happy with the car!

Car's fine, driver needs work! My tyres were ancient old slicks, and in the last race my front left started coming apart. Chris was all over me and it was all I could do to hold him out! Had a blast.

manga_blue · Postby **manga_blue** » Tue Jan 28, 2014 11:40 am

I tried alternating top up vs top down at Sandown awhile ago. Up the back straight the difference was 9kmh - 164 down vs 173 up from memory. Soft top up is much faster, at least for a stockish car.

Teruo tried the same thing at the Island and lost about 4 secs top down.

hks_kansei · Postby **hks_kansei** » Tue Jan 28, 2014 11:57 am

If I recall a thread years ago found:

Hardtop adds top speed (streamlining)
Softop up allows higher corner speed (less weight)

I think the best option was completely remove the softop, then use a hardtop (so you get the streamlining of the top, without a weight penalty)

Magpie · Postby **Magpie** » Tue Jan 28, 2014 7:54 pm

Look at this work by Danny and then decide!

http://mx5cartalk.com/forum/viewtopic.php?f=18&t=35781&p=723899&hilit=Torsion#p723899

Trackphotos · Postby **Trackphotos** » Tue Jan 28, 2014 8:43 pm

Magpie wrote:Look at this work by Danny and then decide!

http://mx5cartalk.com/forum/viewtopic.php?f=18&t=35781&p=723899&hilit=Torsion#p723899

That thread only covers torsional rigidity though, doesn't consider weight and aero effects. I reckon I'll run with the roof up at Lakeside in a coupla weeks and see if my speed through the kink is any better. Maybe I'll wait until we've seeded ourselves through the first session or two, make sure nobody comes sneaking up behind me.