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Location:
Melbourne
Registered:
November 2003
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Rear spoilers on FWD cars
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Wed, 03 March 2004 09:36
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Do they actualy DO anything good?
Or do they just slow 'em down?
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I supported Toymods
Location:
melbourne
Registered:
June 2002
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 Re: Rear spoilers on FWD cars
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Wed, 03 March 2004 09:39
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why?
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Location:
NSW
Registered:
September 2003
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Re: Rear spoilers on FWD cars
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Wed, 03 March 2004 09:45
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I havent seen an Excel yet that can go fast enough to actually create any useable downforce with those rediculous wings they all have. 
Yeah... like 160kmph is like putting an extra 8kg's of lead in the boot to hold the back end down.
100ks... a bag of spuds on your back seat.
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Location:
South Australia
Registered:
July 2002
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Re: Rear spoilers on FWD cars
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Wed, 03 March 2004 13:52
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It's very similar to adding a wing to a rear-wheel drive, it pretty much does nothing for most street purposes. When you get on the track it will make a small difference through some of the higher speed stuff. There is no real difference in what it does whether it's on a rear wheel drive car or a front wheel drive.
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Location:
Melbourne
Registered:
October 2003
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Re: Rear spoilers on FWD cars
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Wed, 03 March 2004 14:01
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| FWDboy wrote on Thu, 04 March 2004 00:52 |
It's very similar to adding a wing to a rear-wheel drive, it pretty much does nothing for most street purposes. When you get on the track it will make a small difference through some of the higher speed stuff. There is no real difference in what it does whether it's on a rear wheel drive car or a front wheel drive.
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You serious man?
I think evidence speaks to the contrary.
How would 100kg over the rear wheels help a FWD car?
Now think of a RWD car with the same?
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Location:
South Australia
Registered:
July 2002
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Location:
Melbourne
Registered:
October 2003
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Re: Rear spoilers on FWD cars
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Wed, 03 March 2004 14:30
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yeah, thats more believable.
However with the grand prix in town it gives me a pretty good example of where a rear wing does serve a BLOODY massive purpose.
So high speed is the only real application for them.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Rear spoilers on FWD cars
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Wed, 03 March 2004 16:13
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theres two different things here..
a 'spoiler' does just that, it upsets the air leaving the surface of the car that would other wise create turbulence directly behind the car and slow it a little.
a 'wing' actually creates downforce.
one big difference between them is that a spoiler is meant to reduce drag (a proper one that is) but gives little downforce, whereas a wing increases drag significantly but provides downforce.
for the F1 cars they produce around 2 tonnes of downforce as a total package (front and rear wing, slick belly very close to road etc) but this is only at high speed, maybe 300km/hr++
for sports sedans, they might generate a coupel of hundred kilos of downforce at 200km/hr, but they have significant drag and that makes the car slower down the straights!!! (but faster in corners)
the Lotus Exige has more bodykit than the normal Lotus Elise, BUT, it only generates either 50 or 80kg of downforce at 160km/hr and not much at all below abotu 130-140.....
what would help on a FWD is to have a 'cat-cutter' with maybe an inch ground clearance, and sideskirts to match.. the idea being to stop any air going under the car from in front, and keep it out..
rear 'wings' and 'diffusers' and 'spoilers' on any street car look pretty lame, and do sfa, until you are well beyond legal speeds.
LOL, "fooly siik 5 way adjustable BLING brand double blade wing" hand me my chequebook!!!!!!!! 
so, original question. they can slightly decrease the drag co-efficient if designed and implemented properly.
the normal 'add-on' ones just increase drag and slow themn doen (at high speeds )
basically zey doo nussing 
Cya, Stewart
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Club Member
Location:
sydney
Registered:
May 2002
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Rear spoilers on FWD cars
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Wed, 03 March 2004 23:24
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Getting back to the original question, in some cases a wing on a FWD car can be beneficial.
It can compensate for bad suspension design. - a lot of manufacturers try to compensate for the natural understeering tendancy of FWD cars by installing a rear anti-roll bar. Unfortunatly in some cases "corollas" they go too far and they end up being tail happy which is not really desireable in a FWD. In my opinion you are much better just getting the suspension sorted properly.
Can reduce fuel consumption - a well designed and installed wing on a hatch back can reduce the drag wake. This then means that you need less power to maintain speed and consequently less fuel.
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Toymods Club Treasurer
Location:
Sydney
Registered:
May 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 02:02
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Rear wings can be effective, and at speeds less than 160km/h. Seen a rally car flying through the air with its nose heading towards the sky?
A lot more drag though, & for a street car very pointless.
My wagon (although it has more metal in the back, therefore more weight to keep the rear end down) has got a 24mm swaybar on its stiffest setting. I can get it unsettled if I'm really hamfisted with cornering, but generally sticks like glue.
So, I'd recommend getting springs, shocks, and swaybars matched for better handling.
The rear "spoiler" on my car (a factory item added after I bought the car) is only good for keeping crap off the rear window, but may have some slight effect on downforce cause it forces air to stay straight after it comes off the car instead of getting sucked behind the car.
I only added it for 2 reasons:
1. it looked better
2. it got rid of the brake light out of the rear window which was blocking my vision.
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Location:
South Australia
Registered:
July 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 02:06
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| Quote: |
the natural understeering tendancy of FWD cars
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I think that statement (natural undeersting) is a bit of a myth - but I'll let it go this time 
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Location:
Melbourne
Registered:
November 2003
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 03:10
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I mean for racing. As I understand it, spoilers only realy start to do anything at about 90kph, and only do anything meaningfull at around the 120 mark, depending on the type of wing/spoiler.
On a rear wheel drive, a wing provides down force. This forces the rear wheels into the ground giving you better traction. On a front wheel drive... What the crap does it do?
Or have I got my info terrably wrong?
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Club Member
Location:
sydney
Registered:
May 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 03:12
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Rear wings can be effective, and at speeds less than 160km/h. Seen a rally car flying through the air with its nose heading towards the sky?
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if youve ever jumped a motor bike, and know what acceleration and braking does to a rotating mass and what its attached to then youll know that the wing has very little to do with it, no matter how big the wing and how fast your travelling. Do some reading on forces applied to centrifugal rotating mass if you want get into the engineering of it. Although this is only a small part of the equation of what happens, rally cars produce incredible torque and so this is still a factor at the take off point. The major factor of course is the weight location and centre of gravity
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Getting back to the original question, in some cases a wing on a FWD car can be beneficial.
It can compensate for bad suspension design.
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are you serious??? a wing will never compensate for suspension, firstly it has to have a fair amount of force ( something a oem spoiler will never produce ) to even affect the spring or shock.
Think about when you lean on a car, if you weigh say 70-80Kg's then the car, ( with reasonbly new suspension ) will barely move. Lets guestimate that youre putting roughly half your available weight on the one spring point, so say 40Kg, now multiply that by two to have any affect over a front or rear section of the vehicle, thats 80Kg, now think about how much air flowing over a well designed wing will produce that much downforce....in most corolla setups youd have to be doing over 150kmh to get close to 80Kgs of downforce and even then youve barely affected the suspension.
secondly the spoiler is only affecting sprung weight. nuff said right there.
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Can reduce fuel consumption - a well designed and installed wing
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most OEM wings are NOT well designed to reduce drag, they are merely a marketing gimmick to sell more cars.
In some rare occasions, especially during the fuel chrisis in the 70-80's then there were a lot of companys making the effort to reduce drag co-efficients,in fact I recall one car getting down to a co-efficient of 0.2!!! but i think youll find now days there is little emphasis on that, when was the last time you read a new car brochure that stated its drag rating
EDIT: to clarify my point on the jumping of rallycars, the subaru is an incredibly balanced machine with lots of torque this is why they are one of the few rally cars built to have been able to maintain a nose up attitude in flight, being 4WD with lots of rear weight also helps
and Mr Subaru said...
if you build a wing big enough it will work 
[Updated on: Thu, 04 March 2004 03:20]
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Location:
South Australia
Registered:
July 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 03:30
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It just seems like a poor question...
FWD cars are very rarely used for racing above 200km/h, so basically if you see a big huge spoiler/wing on a FWD car, you are looking at a complete tosser.
There are reasons for having rear spoilers, but it's not ENTIRELY because the power happens to be at the rear wheels.
It's moreso because the rear wheels are slipping (when too much is asked of them) because the *large* portion of aerodynamic downforce acts on the front wheels and not the rears (look at the wedge shaped design of most cars please). However, by adding a rear wing you can increase (or achieve greater balance of) downforce at the rear, and even when the power is not used (for example into and up to about the middle of the corner so this affect would help front or rear wheel drive cars) your rear end doesn't oversteer to oblivion.
Of course rear wheel drive cars will get benefits from increased downforce at the rear-end when coming out of a corner...but the FWD has tonnes of downforce on it's front-end as well regardless.
I think that about covers it.
There's so much more to it though...go read "Race Car Vehicle Dynamics" (I know I should).
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 03:43
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are you serious??? a wing will never compensate for suspension, firstly it has to have a fair amount of force ( something a oem spoiler will never produce ) to even affect the spring or shock.
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As for what my comments were about, we weren't talking about OEM wings at all, all they are good for is mounting a brake light. And yes a properly designed wing will produce measurable downforce and will aid rear end grip of any car, front or rear wheel drive. I don't think anyone here will argue with that.
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secondly the spoiler is only affecting sprung weight. nuff said right there.
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Lets see, if you increase sprung weight on a spring, you compress it, shure but you also increasing the force on the unsprung weight by the same amount. If you want to talk about engineering, draw a free body diagram of the spring.
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most OEM wings are NOT well designed to reduce drag, they are merely a marketing gimmick to sell more cars.
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See my first comment in this post.
And for all the punters out there, if they provide no performance advantage then why were they used on the supertourers.........to increase drag.........yeah right 
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Location:
Sydney
Registered:
May 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 04:00
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Its all about finding that balance with a race car
On a road car most wings are a WANK. Remamber the most Important Function of a wing is to help increase Cornering speed
by putting more Force (G) on the tyres as they are whats in contact with the road..Which has nothing to do with which wheels it is being driven from.
As a rule of thumb the more you give area the same amount you take away from another.
IE. If you increase the front wing on a car you will increase the amount of grip to the front making the car oversteer and you loose rear grip, If you increase the rear too much you will find the car understeer taking grip from the front. Again this is all assuming that the dampers you are running are very hard because any downforce will apply preassure to the dampers first then the tyres. And dont even get me started on other factors like tyre compounds/bump and rebound rates/springs/rollbars etc etc.. which are more likely to increase lap times then wings.
Ben
AE86 Trueno (with a WANKY wing) 4AGE
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Toymods Club Treasurer
Location:
Sydney
Registered:
May 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 04:46
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Exactly the same, provides downforce to keep the rear wheels on the ground.
Ever had an unexpected tailslide in a front wheel drive?
I've just trained myself to nail the throttle instead of the brake when this happens, it seems very unnatural.
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Club Member
Location:
sydney
Registered:
May 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 05:26
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Oh dear
seems a technical discussion has been taken the wrong way again....
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we weren't talking about OEM wings at all,
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sorry my mistake...up till now i diddnt see anyone mention a properly designed performance wing
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And yes a properly designed wing will produce measurable downforce and will aid rear end grip of any car,
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agreed.. but it still doesent improve suspension
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if you increase sprung weight on a spring
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increaseing weight and the affect of downforce do not act the same way, weight is linear, downforce is not.
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draw a free body diagram of the spring.
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drawing a diagram wont show the affects of downforce on suspension, youll need to test it in a wind tunnel ( f1 do it every day ).. and i still smaintain it doesent improve suspension. In your last post you seemed to concerntrate more on the wing affecting grip and handling which i agree with, still cant see how it improves suspension though, please feel free to educate me , im always keen to learn how to improve my performance.
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why were they used on the supertourers
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because it improves there high speed handling.. supertourers regularly are at speeds in excess of 150Kmh, and there are a large number of tracks in Australia that have high speed corners, eg Eastern Creek where the wing has the greatest affect, these wings would be pretty much useless on a road car that wont have the same G forces applied in 90% of the time spent driving, the only time i can see it being beneficial to a road car is going down the highway in excess of 150kmh. In most cases they gain better effects from the front splitter around the track than the rear wing anyway.
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Its all about finding that balance with a race car
On a road car most wings are a WANK.
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Amen to that
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Remamber the most Important Function of a wing is to help increase Cornering speed
by putting more Force (G) on the tyres as they are whats in contact with the road
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which is mostly done at high speed, as thats where the most force from any air effects is applied to the tyres.
some sites that might help provide some insight to it all are....
http://www.hanleyinnovations.com/racecarpack.html
http://www.allianz.com.au/internet/allianz.nsf/doc s/MCFOFE+Wings
http://www.nas.nasa.gov/About/Education/Racecar/ae rodynamics.html
http://www.racer.nl/tutorial/wings.htm
youll notice that when people talk about downforce they use the term "high speed" a lot
[Updated on: Thu, 04 March 2004 05:26]
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Location:
Sydney
Registered:
November 2003
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 05:31
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has anyone seen that yellow civic with the yellow t-wing on the roof... thats just plain silly...
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 05:43
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Lets look at a case study then:
Scenario, a FWD car on a track (cos you can't do it legally on a road) with a wing.
Low speed corners - wing is not effective. Want maximum grip on front tyres for corner entry and exit. Stiffen rear anti roll bar to maximise weight transfer at the back wheels and maintain maximum grip at front.
High speed corners - Wing is effective. You don't want a stiff rear end making the rear wheels slide all over the place reducing cornering stability. The wing adds downforce on the rear, increasing rear grip.
Thus a wing is useful on a performance FWD car.
The question was:
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Do they actualy DO anything good?
Or do they just slow 'em down?
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The answer is YES
Is it going to be noticeable on a road car...doubtful....particularly with a poxy little brake light holder that you get as "OEM" equipment.
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Club Member
Location:
sydney
Registered:
May 2002
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 06:27
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Excellent design.
Function over form.
When this Civic is hurtling along at 300 kph, the driver can rest assured that it will be planted firmly on the ground.
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Location:
Lost in the K hole
Registered:
May 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 07:23
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The only road cars that I can think of where it may make a difference are cars like McLaren F1s, Ferrari F40s etc ie - a seriously fucking fast car.
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the mclaren didnt use wings, it used a ground force undertray. the wing simply created too mucg drag, and looked athetically displeasing.
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At the front you would need a "cat cutter" ....I think what you are referring to here was commonly called ground effect
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michael - from my understanding 'ground effect' underbody design actually has a 'scoop' type front, deliberately bringing air in under the body... then the shape of the uderbody (like a venturi) accels, then decels (sucks) the air out of the back of the vehicle through a outward tapering rear diffuser.
the simple cat-cutter splitter is designed to redeuce the total amount of air under the chasis generating a simple low pressure zone = downforce. a lot more simple than the ground effect design
cheers
ed
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Location:
adelaide
Registered:
April 2003
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 07:41
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| Shraka wrote on Thu, 04 March 2004 14:10 |
I mean for racing. As I understand it, spoilers only realy start to do anything at about 90kph, and only do anything meaningfull at around the 120 mark, depending on the type of wing/spoiler.
On a rear wheel drive, a wing provides down force. This forces the rear wheels into the ground giving you better traction. On a front wheel drive... What the crap does it do?
Or have I got my info terrably wrong?
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sounds to me like you dont really know what you are talking about
ab
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Location:
Sydney
Registered:
March 2004
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 10:35
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one word that explains it all
RICE
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Club Member
Location:
sydney
Registered:
May 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 10:46
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| Quote: |
michael - from my understanding 'ground effect' underbody design actually has a 'scoop' type front, deliberately bringing air in under the body... then the shape of the uderbody (like a venturi) accels, then decels (sucks) the air out of the back of the vehicle through a outward tapering rear diffuser.
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Ed as far as F1 cars go you are correct, later variations on high perfomance motor cars like ferrari and lamborghini actually used diffusers with large vents in the front sorta like what the front of a V8 super car has but smaller, these vents directed air primarily under the car to create as you correctly put it the venturi effect. F1 could not use these designs as they created more restrictive forces than was acceptable for aerodynamics thats why they use the front wing to guide the air under the chasis.
if you read some of the links i posted it goes into it there.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 10:58
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GT that 'pink thing' has one hell of a boot closer...
i wonder if they've tried the adjustment points and come to the conclusion one of them is better LOL 
i guess if i was going shopping in a civic or an excel, i'd wanna make damn sure that boot stayed closed 
Cya, Stewart
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Rear spoilers on FWD cars
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Thu, 04 March 2004 21:29
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I think you will find that F1 doesn't use venturi undertrays because the rules have been carefully written to ensure that they can't use it. It was being used in the late 70's, but there was concern that it was allowing them to maintain really high speed in corners (about 3-4ton of down force). The reason for banning venturi undertrays was a safety concern.
These undertrays are used a lot in sports car and prototype racing now (eg LeMans). It is a very efficient way of creating downforce, however it is very sensative to ride height and pitch, which is why two mercs flipped at lemans a few years back.
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Club Member
Location:
sydney
Registered:
May 2002
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Re: Rear spoilers on FWD cars
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Fri, 05 March 2004 05:02
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Yes Mr webber certainly changed his undies that day
i used to have a link to the MPEG of those flips .. cant seem to find them now 
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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