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Never really hear much (if any) talk about downforce on this forum.

Does anyone else have problems driving on the highway in high wind / wet conditions.

Ive never had any problems in other cars (apart from a van).
Just the mx5 seems to squirm around and in the wet, it becomes scary over 90kmh.

So ive narrowed it down to two things: Poor wheel alignment & lack of downforce in such a light car.


Do you think the addition of a rear wing & front spoiler will help? If so how effective is the stock wing (it doesnt look very). What can i add to the front?


Cheers

Eric

most convetibles will feel 'floaty' at high speeds due to poor aerodynamics obviously. especially a car as light as the mx5...

if its really bad though...check wheel alignment, buckled rims, wheel balance and any bent suspension components.

I wouldnt say the MX5 has bad aerodynamics (except with the roof down), they're almost like a bullet, being so much smaller and lower they have considerably less frontal area to create drag.
The lower the car and addition of front spolier etc can cause more air to pass around and over the car sucking it down to the road better at higher speeds.
But i do agree with ducktape though, due to being so light they do float around abit and are affected alot more by road undulations.

but the fun factor still outways this!

Edit: Sorry i for got to say, i dont believe the stock spoilers and wings would do anything useful for downforce, unfortunately i think the only useful downforce from wings u can get is from proper inverted aerofoil wings mounted higher off the boot.

Tyres and alignment. My car is stable as a rock.

I must admit that over 160km/h (on a track, of course) that my SP does tend to get a bit light and floaty, but below that speed, it feels well connected ot the road.
I've thought about putting spoilers on the car to eleviate the problem, but I just hate the look of spoilers on a car.

tyres, tyres & tyres kitkat

AJ wrote:tyres, tyres & tyres kitkat

Aint the tyres, they are great in the wet!!!

Will try a wheel alignment when i get some new tyres in a couple weeks.

I think I read on a UK MX5 website that the front factory lip spoiler helps with this as it is actually an airdam forcing the front down.

Ben

kitkat wrote:

AJ wrote:tyres, tyres & tyres kitkat

Aint the tyres, they are great in the wet!!!

Will try a wheel alignment when i get some new tyres in a couple weeks.

it's squirming at 90 kmh in the wet, yet the tyres are great in the wet???


a cosmetic piece of plastic stuck on the front won't help that matey

AJ wrote:it's squirming at 90 kmh in the wet, yet the tyres are great in the wet???

plenty of grip in the wet!!!

Driving in the wet is fine until i hit the highway on a windy day. The car even squirms in the dry when its really windy...


Ill see what a wheel alignment does, if it does nothing ill look into a decent rear wing with a proper lip on the back spoiler... just have to find something that looks stock or somewhow modify a stock spoiler.

My bmw is planted in the wet, same tyres, 200kg heavier but has both front and rear spoiler. The front spoiler prob doesnt do much but the rear most definetly does. That car hasnt had a wheel alignment since i bought it also.

take some of that ridiculous rear camber out might help too

I wouldn’t bother with a rear boot spoiler. The little boot lip spoiler might looks cool but is totally useless. Most factory rear spoiler’s are just for show and provide little if any down force. They are simply not high enough or angled aggressively enough to create any down force…what they do create is more unnecessary drag. You need a large GT style wing like the Mania race car to get some decent down force at high speeds.

If the alignment doesn’t give you the stability you are after try a front lip spoiler. The little OEM one might help a “tiny” bit but something like the Garage Vary or an “air splitter” would be better (but you might not like the look). The front lip spoiler doesn’t really give you any down force but they can help reduce the amount of air that travels under the car - that creates lift. ‘”Deep” side skirts also help reduce the amount of air that goes under the car (to a lesser extent).

Their isn’t much you can do apart from tyres + alignments + lower your car to improve high speed stability if you want it to still look “stock”.

I remember seeing a wind tunnel picture of the MX-5 on miata.net. The MX-5 has an awful drag coefficient - a lot of air turbulence around the top rear of the car (with the top up). The fact that it looks sleek… like a bullet, is deceptive.

The fact that it has a short wheel base and a relatively narrow track + being light weight doesn't help us with high speed stability.

The MX-5 handles great... that's about it

My standard vehicle has no problems up to around 120 (I try not to make any mistakes and exceed this if I can). I used to find my old MG used to get 'light' above this figure (as you might expect) but no such feelings in the MX-5..there again I'm not using it on a track....

I do find sitting in the silly seat of an RX-2 at 170 on the dirt (on a special stage) gets my spine tingling though.....

i havent sat in any mx5 that feels 'planted' over 120(maybe the NC's may be different?)...

our cars DO have really bad aerodynamics with or without roof on unfortunately...but i guess that all goes out the window when u can see the stars when ur driving gotta love topless driving

Mine feels OK. How old are your shocks?

JUles