jmaisch

I would like to de-automate the rear spoiler on my 99 c2 coupe, i.e., make it
so that I control the deployment of my rear spoiler instead of the car. I looked
though the posts here and it appears that I can simply swap out the stock deck
lid wiring harness with an alternate (part # 996.612.070.51)

My question is:
1. Will installing this wiring harness prevent my stock spoiler from deploying
at 75 mph AND prevent any warning lights?

2. Would I still be able to deploy the spoiler manually using the button under
the dash?

My apologies if this has already been discussed, but I could find anything
that addressed this specific issue.

Thanks in advance for any advice you can offer.

-Jason

Marc Gelefsky

Ok, I have to ask... why do you want to do this?
There is a reason the spoiler deploys.

Also, I am pretty sure that wire harness is for the Aero kit rear deck like on my car and will remove power from the spoiler so it will not work, you also will not get a warning light.

Robin 993DX

One idea I have would be to manually disconnect the speed signal wire to the spoiler control module. This way the control module always think you are stuck in traffic.

jmaisch

Yeah I know it sounds weird. I think the car looks
so much better with the spoiler down.

Asquared

I could see wanting to deactivate the automatic deployment at speed. It just points out to everyone that you are speeding.

I will say that when I was driving my Targa well in excess of the posted speed limits, I would often push the button to raise the spoiler manually even though it was already raised (like I said, i was exceeding the legal limit) so that an officer couldn't use the fact that the spoiler was raised to demonstrate that I was speeding. I know it never made a difference, but I did it anyway.

jyoteen

so vain.

Edgy01

Just recall that when the rear air spoiler is up it produces additional drag on the aerodynamics of the car. If you don't need it for its downforce, you will pay a mileage price to keep it up.

jyoteen

all the rear spoiler on the C2s will do is negate lift at the rear axle. The 996 Turbo produces something like 20 lbs of positive downforce.

Don't know if my numbers are actually accurate though.

racer

The spoiler, in the open position, also increases airflow into the engine compartment. It also reduces rear lift which aids in handling. Is the spolier visable when up on a 996? My only ref point was my boxster where I couldn't tell if it was up or down when inside the car.

rwiii

Without wind tunnel data I think the rear spoiler is a total gimmick and does nothing to improve aerodynamics. Ever see a race car with a chump 12" spoiler (or whatever it is) like we have? No way. Either a huge spoiler that dominates the rear end or no spoiler at all. Somebody with data jump in here and get you some. Tell me I'm wrong 'cause I'm with they guys here who think "whatever".

BruceP

You're confusing a spoiler with a wing. They do different things. A wing generates downforce. A spoiler just prevents lift by disrupting airflow (the 911's profile is decidedly wing-like, which is why every fast 911 since the 70s has had a spoiler). They aren't meant to be "aerodynamic". Quite the opposite.

Edgy01

It definitely makes a significant difference. As a 911 driver from the pre-tail days I can tell you how incredibly unstable these cars are at speed without them. They did a study (Porsche) some time back measuring the downforce of the various tails (duck tail, early turbo tail (Carrera RSR) and then the whale tail with the integrated heatexchanger) and the numbers are significant. Without the added downforce the cars handle very differently and are substantially less safe.

htny

I've run mine manually down at real speed, it is not a fun feeling. I do have a center radiator and last year added the gt3rs front spoiler (thank you Bruce!), and have 315 rubber out back, all of which would impact airflow in one way or another, but even on the 17 inch lightweights without the front lip it didn't feel right without the spoiler up past 90-100

Also, don't ask me to go into details on why I spent a week hypermiling this thing over a bet with a tree hugging crazy ex girlfriend, but I've actually gotten marginally better fuel economy with the wing in its deployed position (vs. manually lowered), again likely attributable to a host of factors beyond an implied effect on Cd or our preconceived notions of the spoiler's effect on the fluid dynamics or the lift vectors.

One thing I'm sure everyone's noticed, the coolant temp and intake air temps drop fast when that thing goes up. And is it just me or does yours have a mind of its own? I'll notice that it's raised after extended WOT even if I pulled back well short of 75, and when it's hot out, well then I've seen it in my mirror at 50mph.

And for those who think it's vestigial, I will present the following logic: If it were as useless as some newer members have purported, the same value engineering that gave us the much bemoaned integrated headlight assembly would have rapidly eliminated the need for something with such a huge financial impact on wind tunnel time, fuel economy testing, and structural integrity, and with as many electronic, electrical and mechanical considerations as an active spoiler engine lid, which the driver practically never sees.

Best,
Hans

goliver

I'll have to check my Porsche library in the AM but in a book I have it clearly states it does change rear lift and that the engineers/designers couldn't meet design goals without the spoiler. They proved it to the bean counters and were begrudgingly allowed to proceed with the spoiler as part of the design.

I have had several older Carerras with and without spoilers. The '84 without was a handful at speed. The '85 with front and rear was majorly planted at trip digits. More so than my '99. It feels floatly in comparison.

Colpitts

I was actually wondering the same thing as the OP...

Running this car in the winter, with a build up of ice and snow on the rear of the car ... I can only imagine this will lead to issues with the spoiler deploying? (I know... I know... Clean it off)