Chin Spoiler on 911

[DANNOV]

I considering the installation of a chin spoiler on my 1985 911 Targa. I do not have a rear wing spoiler and do not want to install one. It seems that everything I read states that the factory recommends running with both spoilers; if not, you run the risk of having an unstable car at high speeds. I can see how having a rear spoiler without the chin spoiler can cause a problem by creating a light front end at high speed. But, I can't see why running with a chin spoiler only will create any problem, if anything it would seem to make a rear engine car more neutral by giving the front end more grip. I use my car in DE events with the PCA. I drive at Road America with this car and there are two places on that track where where I get over 135+ mph. The last thing I want is instability. Has anyone run a 911 at high speed with only the chin spoiler?

DANNOV
1985 911 Targa
1995 Corvette
1999 VW Passat

[R22tech]

Don't do it if you are running high speeds- a light a$$ on a 911 is a recipe for disaster. Maybe you should buy a rear decklid w/ a carrera tail and just put it on when your at the track.

[Vipergrün]

To the contrary, Wayne's book clearly indicates it is ok to run JUST the chin spoiler w/o the rear. I just installed one this weekend based on that. Car seems much more stable at 120 MPH now. A definative answer would be great

cheers
-Brad
80SC

[Saffs]

My '75 911S came with one on it - the PO had fitted it with no rear tail. I drive the car a lot at around 80 - 90mph on the (UK) Motorways. I've driven in high winds and snow. I've been at about 130 in it and it doesn't seem unstable or difficult to control. I can't contrast it without the chin spoiler, but can only conclude that it does not appear unstable. Ironically, I'm going to take it off, as it doesn't suite the car (wouldn't of had one originally). I'll see if it becomes even more stable then.

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'75 911S Targa
'81 BMW Alpina C1 2.3

[thabaer]

Using the chin spoiler alone is not a problem, the imbalance caused by running the the carrera or turbo tail without the front spoiler could make the nose light at high speeds.

The front spoiler by itself helps keep the nose down and doesn't contribute to a cushion of air under the body.




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Charlie Baer
'79 Euro 911SC

[makaio]

When I purchased my car it came with just a chin spoiler, no rear tail except the deck lid. I noticed that at 90 mph and above the car seemed kinda loose, compared to my wifes VW Passat. So I purchased a Ducktail, and the car is much more planted now at high speeds. And since I like the look of the car more without any rear spoiler, I just left the tail the black fiberglass color, and only put it on when i go to the track, or feel like a different look. I picked my Duck tail up for $150 from Rich at Jerry wood's shop. It was brand new, never installed.

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Matt Chamblin
78 911 SC

[old_skul]

A good solution would be to pick up a retractable 964 decklid and put that on.

I think Jack has one for sale. Jack?

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Mark Szabo
1986 911 Targa 3.2
1987 Escort 5-speed 1.9 RIP
The Porsche Owners Gallery

[thabaer]

Matt,

Did you ever remove the chin to see how unstable the car felt without either one installed ?

I may be biased, but I think SCs are much better looking with the chin + carrera tail.

Makes 'em look less like a stink bug ( flame suit on!! )


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Charlie Baer
'79 Euro 911SC

[emcon5]

There are some numbers in this article that disagree with Wayne. The source of this data is listed as: The Porsche 911 Story 4th Ed., Paul Frere.

http://www.pelicanparts.com/techarticles/911_speed_prep/914_speed_prep.htm

excerpts:
"Wind tunnel tests run on a car equipped with the front air dam, without a rear spoiler, saw an increase in rear lift to 320 Lbs. "(from 255 Lbs).

"Installation of a chin spoiler without a matching "whale tail" could be equally dangerous, inducing premature oversteer, especially in the event of a throttle lift while negotiating a high speed bend. With the reduced lift on thefront, the rear is correspondingly light. In the same left turn, the rear end may decide to swap ends, with the front end coming around to the rear in a spin"

On the other hand, in the "Parts and Technical Reference Catalog, 911 Models 1974-1989" the page with rear spoilers warns that a chin spoiler "For aerodynamic balance, a front spoiler must also be installed" The page with front spoilers has no similar warning.

I don't know if this is really an issue, I am just reporting alternate views.

Tom

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82 911SC Coupe

[speeder]

I always thought that the reason 911's have oversteer problem was because of HEAVY rear-end. Like a rock on the end of a string or a dart thrown feathers first, the heavy end wants to go first. Anything that makes the rear-end of 911 lighter(within reason), should improve the dynamics of a fundamentally un-balanced car. Porsche 911's are an extreme example of "engineering triumphing over design".

[DANNOV]

I might have found the answer to my own question. In the 7/2001 issue of 911 & Porsche World there is an article about wings and spoilers. I will quote a small section: "The first production 911 to feature an aerodynamic aid was the 911S...early 1972. But this model didn't have a rear spoiler, merely a neat air-dam incorporated into the front bumper...it was said to reduce front-end lift by no less than 40%...Unfortunately, however, the air-dam accentuated the behavior of the 911's already rather wayward rear end and many drivers soon began to complain of excessive high-speed oversteer"
The last thing I want is excessive high speed oversteer. I consider this case closed, I will forget about the chin spoiler unless I also add the rear wing. The suggestion about adding the retractable wing from the 964 is interesting. Is there anyone out there that has done this? Will the 964 lid fit onto a 1985 Carrera?
DANNOV

[jsmarcus]

How often are you going to run at speeds that it really makes a difference?

Really?.....

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Josh
'84 Carrera Coupe

[MarkY]

Originally posted by jsmarcus:
How often are you going to run at speeds that it really makes a difference?

Really?.....

The original poster said that he runs DE and gets up to speeds in excess of 135 MPH.

It only takes one time. Really...

[89Targa]

I believe the late model Carreras (88-89?) came from the factory with the front rubber chin spoiler as standard equipment. The rear spoiler was an option. Why would the factory deliver the cars this way if it caused a handling problem?

Tom

[carnut169]

DANNOV- I am w/ you. I like the look of the chin spoiler but it is not worth spinning my car over.

I will say that on my first 911 (86 coupe) I had the whale tail removed- I also like the clean lines w/o a tail- and the handling did suffer. It felt much (MUCH) looser w/o the whale tail. I did spin it (without damage) in the first week following removal. This was on a corner that I drove everyday at the same pace.

Oh, to answer your question yes, you can mount the later wing. I think it is Jack Olsen that has done this w/ his "Black Beauty?" Looks great but what a PITA!
Here is a photo of Jack's car:




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Sean O.
Atlanta, Ga.
87 Carrera Cabriolet

[This message has been edited by carnut169 (edited 10-23-2001).]

[This message has been edited by carnut169 (edited 10-23-2001).]

[This message has been edited by carnut169 (edited 10-23-2001).]

[Bill Douglas]

I'm now feeling a bit concerned about my car. My SC has a chin spoiler and no wing at the back and I drive around 135mph often. And not just high speeds on straight roads. My car feels as solid as a rock, and the faster I go the better it feels. It is a lower than stock euro.

I suspect the chin spoiler just keeps excess air from being forced under the car and the actual downforce is created by the sloping front of a 911.

Bill '79SC

[speeder]

I would love to know at what speed the benefits of spoilers really kicks in. I have no doubt that at extremely high speeds,(130+), front+rear would be desirable, but below 120 I would think small chin spoiler would be OK. And yes, Porsche did sell them this way. I am a little incredulous about 911 feeling "much looser" w/out tail; at what speeds? 140?

[Eric Coffey]

You guys that prefer the chin spoiler with no rear tail might try the following for more piece of mind concerning high speed over-steer:

Wider rear wheels/tires.
Lower ride height.
Equal/even ride height (less rake).
Slightly lower rear tire pressures.
Smaller rear sway bar.
Softer rear torsion bars.

Just some suggestions.

-Eric



[This message has been edited by freefly (edited 10-24-2001).]

[Randy W]

I don't have my referece handy, but a ducktail's effect of reducing rear end lift is actually measurable at 35mph. I have driven slmilar cars with and without the ducktail, and I don't think it is really felt in every day driving until about 65mph. However, I agree with Jack that it's benefit at a track with elevation changes in the middle of curves is noticable at 50mph and makes a big difference in your confidence level at 80mph and higher! IMO, a Carrera front spoiler without the tail is OK for highway use and occasional DE (but not the other way around). Dannov, I would also put a tail on at Road America.

Randy Wells

[This message has been edited by Randy W (edited 10-24-2001).]

[pwm74]

did you guys ever see the race car, I think it was a chapparal from the late 60's, he had a adjustable wing. he would adjust it for downforce on turns and bring it up in the straights for less resistance, I read he nearly killed himself when he forgot to put down on a turn. I also saw pics of a vacuum bottomed racer, now thats downforce( it was banned because of shooting debris from the vacuum exhaust. Road & Track had a shootout and someone brung a snowmobiles engine vacuumed go-cart that pulled like 3G's.
Wished I had pics