prwdmd

I have been noticing a mid-high pitch whir that happens just as I get the car moving in first gear. It only lasts for a few seconds and then disappears. It isn't loud... I hear can only hear it when the window is down and it sounds as though it is coming from the rear of the car. Does anyone have any idea what this could be?

Peter
997 S, Black on Black, PCCB

99firehawk

its most likely normal but without hearing it its hard to say
general rule of thumb, if you have a noise that only happens sometimes, over6 inch potholes, pulling out of driveways with 60 degree grade, on tusdays at 3:03 or when you take off from a stop in 4th gear (all are real complaints ive gotten from customers btw)...................ect its probaly normal

mal28

at what RPM's do you here it?

prwdmd

I guess it only occurs sometimes... most of the times that I've noticed it, was possibly when car wasn't warmed up yet. When I do hear it, it's right when I get the car moving, so under 3k RPM's and under 10 mph.

Lotus350

Is it just when the car is getting off the line? Like, when the clutch engages? Or, do you hear it even with the clutch fully engaged and the car moving.

911Dave

You're probably noticing the gear whine, which is normal.

Gerg

Mine whines all the time.

dstrimbu

Yes, the whine is noticeable and actually sounds kinda sexy, in my opinion... :-)

From the 997 Technik manual:

3908 Drive set

The gear set has been constructed as a hypoid drive. That means that the
centre axis of the crown wheel is positioned above the centre axis of the drive
pinion. Hypoid drives with the same crown wheel size can transfer higher
torques due to the sturdier construction of the teeth of the drive pinion.
The changed crown wheel position can also be used for decreased deflection
angles on the drive shafts.

The drive pinion is hollow, in order to reduce the weight and to enable
lubrication. The drive pinion incorporates cross holes for the purposes of
lubrication.

So, the hypoid gearset + the hollow transmission drive shaft (with R, 1st and 2nd fixed gears) + the hollow pinion drive shaft + the aluminum trans / diff case probably all contribute to increased gear whine.

Just MHO.

-d

prwdmd

I only hear it when the clutch is engaging, after it is fully released and the car is moving, the noise disappears. About the gear whine... I think I know what you're referring to... isn't that something that you hear in every gear and all the time. This is more of a whir that doesn't happen all the time and only in first gear when I do hear it.

Peter

500

Drive another 997 and comp it...

911Dave

I only hear it at low speeds which usually means I'm in 1st gear. Once you get going the sound is masked by road noise, exhaust noise, and wind noise.

InTheBayArea

prwdmd : did you figure out what that sound was? It just started on my 997 Carrera as well, after the car is warmed up, when I put it in first gear or change from first to second on low rpms, I hear a whirring sound like something is spinning at the rear of the car. The dealership can't replicate it but I hear it almost all the time now. Any suggestions?

rotesAuto

might be the low speed ground to ground missle system, it took me a while to figure out I could just use high velocity missles at low speeds to reduce traffic, good luck