downforce on stock 1999 996

just wondering if anyone can tell me the specs on front downforce of a 1999 996 c2? my car handles fine, but at higher speeds the car doesnt feel 100% planted, could this be another issue?? again, its not terribly obvious, but enough to wonder if an aftermarket bumper with better downforce design is worth it. also, the tires have less than 1000km on them (Michelin super sports) and all the parts under the car are in great condition, very little wear except the stab bar bushings.

Akshun, those of us that have changed the suspension to a lowered more sporty/firm stance have found that the "floaty feeling" you mention has completely cured. I suppose that an aero package or aggressive lower front lid under the bumper may work to some extent, but the suspension is really the trick. Pete

Also looks like an aftermarket front bumper and side skirts on the car. Maybe add ons for the bumper...but great Pete's think alike. Suspension is where the truth is.

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Stock, it doesn't have enough downforce to negate lift. 996.2 restyle cut the amount of lift in half from the 996.1. BTW, it was not just the front bumper that cut it down, the rear quarter panels are actually slight different on the 996.2 as well as the lower rear bumper contour helped reduce lift significantly. Consider investing in a 996.1 GT3/aerokit front bumper, side skirts and rear decklid/wing...or just sell it and upgrade to another car (996.2, aerokit car or GT3).

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I would agree with Pete...and Pete for that matter on the suspension front, but like...well...Pete mentioned, it looks like you've added front and side downforce, but no added downforce to the rear(at least from the angle of your photo). Now I don't know at what kind of speed you're experiencing this "not planted" feeling, or if its front end lift or the back end is dancing around(perhaps you could expand on this), but without providing some compensating downforce to the rear end you are throwing off the overall aerodynamic balance that Porsche engineers worked a lot of hours in the wind tunnel to create. Just because there is a lot of weight hanging off the back end, doesn't mean that things won't get a bit hairy at 120+ when the car is biased towards front downforce. Just something to consider in the discussion.

Does the 996.2 require a suspension upgrade, to improve downforce? or does the new front bumper and rear enough?

I didn't do any aero changes on my 99' C2, but did change out the stock suspension to the US MO3O which did not lower my Porsche, but did improve the 'floatiness' mentioned.

I have a Guards Red 996.1 Taco wing i could sell. This wing negates lift. See link in my signature. I have upgraded to a full CUP wing.

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+996 Change the suspension and the difference will be huge.

-Maybe I have not spent enough time at speed, but never noticed any floating of mine.....

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Agreed. Mine was rock solid and planted, even before I added the aero kit.

I'm also looking into suspension lowering What is the least expensive Version ?

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I put H&R sport springs on my '00 C2 and these lowered it by about 1" all around. This is the cheapest route, unless you want to go with coilovers. DO

Ok, so far great responses and much appreciated info. I originally said "planted" and i guess my wording was a little off, i should have said "floating" feel in the front end at highway speeds(120km and up). it is mild, but still, i m not getting the rock solid feel that some have mentioned. My suspension is factory original and lm guessing that after 14 years it wont perform the same as it once did. I am not the original owner, so i wouldnt know. I have considered the ROW M030 suspension, which has been advertised for really good prices, or the Bilstein Pss10's. I have heard good things about both set-ups, but i like the fact that Bilsteins are adjustable as i have 19" wheels and i really dont want to lower the car and have it rub against the tires. im adding some new bushings to the stabilizer bars this weekend and hoping i feel some improvement.

Akshun, From the picture in your avatar, I can 100% confirm that the front spoiler lips and side skirts are from TechArt and were an add-on by a previous owner when the car was relatively new (Tech Art has not offered these pieces for quite some time). I can confirm this because I have those same exact pieces on my '99 coupe. The recommendations from above to get a rear spoiler are also spot on correct. You have a LOT of front end down force now, which is NOT being compensated in the rear so the car is "floaty" at high speeds. Sadly, the offer made above to sell you a Taco spoiler will prove incorrect. Not because there is anything wrong with the advice or the spoiler or the individual who offered it. The factory Taco spoiler will absolutely NOT work on a cabriolet. Porsche never offered it because the metal convertible top "boot" rises up and back when cycled, and would contact the spoiler very hard. Porsche offered a 'Basket Handle" rear spoiler for cabriolet owners who wanted an aero kit. It was lower and thinner than the Taco spoiler. Yes, the suspension ideas offered will also help plant your car even more, but they probably won't give you enough clearance for the 19" wheels. You will likely have to pick one or the other. Your real issue is needing a proper rear spoiler, or removing the front spoiler lips.

least expensive is the right one FIRST most expensive is the cheap one followed by another, and another only to be frustrated and frankly not safe M030 and ROW are just fine - for most girls I know X73/74 - is a man's set up PSS9/10 - serious goodness and there are others like JRZ and IDK... adding a rear wing needs to be balanced with a front lip now - what I want to know is how fast (at what speed) does it get floaty - and at your next track event (and I mean sign up if you have not) - ride in some instructors cars and get the feel of different cars at speed - start thinking, ask questions and THEN but parts trust me on this one

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From his post..... "i should have said "floating" feel in the front end at highway speeds(120km and up)." Mine feels planted at more than twice that speed.

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Not sure what your trying to say Except , your a girl ? Hard to tell by your post

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What IVANGENE is saying is that in his personal opinion there is no gray - either a high dollar, full-on track suspension or nothing. He also ignored the OP posts and the picture of his car in the avatar showing an aftermarket front spoiler but no rear spoiler, and a cabriolet... with 19's. and the OP's desire to maintain those 19's and still have enough clearance. IVANGENE is aboslutely correct in saying a big mistake would be to spend lots of money chasing the problem. Go with the obvious. And what may feel like a front end lifting and floating may actually be a squirrely rear, causing the driver to have to hunt with the steering to keep it straight. Below is a picture of a SAMPLE "basket handle" spoiler for cabriolets. There are other designs. And I am guessing that spoiler is a whole lot cheaper than a new suspension.

When I bought my car with aerokit it had a stock suspension....no 030. It road fine at highway speeds. I did a DE and at 120+ it floated all over the place. I decided I needed some better suspension parts. that led me to a X74. At track speeds the car is solid....but it was solid at highway speeds before the X74. Most cars that are not tracked won't realize the aerodynamics. My point is wings and spoilers look great but are not felt until higher speeds are met. Just my 2 pennies.

Great feedback guys! i never thought that the "floaty " feeling would possibly come from the rear, but it makes sense. i have considered many things, new coil overs, smaller wheels(18") and now a spoiler. I know that the car was not designed to run 19" rims, but i like the look and get lots of compliments when im out on the town, i never thought the aero kit would have much of an effect, but i guess it does. Right now i have a couple of options,,,,, i can set a budget and install new bilsteins, a rear spoiler, 18" wheels and tires and possibly a new front bumper. Or i can sell it and look at a higher performance model. what would you do???

My '99 with stock suspension feels floaty at 70mph. I attest it to the suspension. Since you want to keep the big wheels, why not go for a set of coilovers? It would firm up the ride and allow you to have the perfect ride height.

ive been thinking about a set of the Bilstein, pss10's. What about stabilizer bars? will it make a difference if i replace the stock set? I have heard Gt3 bars work well. Bilstein Pss10- $3000 Stabilizer bars and bushings- $600 Adjustable camber and toe links- $550 so for under 5K i can improve the handling of the car safely and reliably. I also like the look of the cabrio rear wing.