GT3CupCarRandP

Just went back to stock exhaust for smog, and was wondering what is up with these drivetrain noises. I understand that the GT3 trans has "straight cut" gears and more noisy, but thanks in advance if you listen to this recording.

Auto_Werks 3.6

Hard to tell from laptop speakers, but it sounds pretty noisy. does the whine continually increase with vehicle speed, regardless of gear changes? If so it's related to the differential, and mine is actually somewhat noisy. Mine also gets quieter as it's fully up to temp. I have no individual gears that are noisy, and no clunking into gear. They aren't quiet stock for sure. You didn't mention if you have aftermarket shift cables or engine / trans mounts, single mass flywheel. Those can all contribute to noise in the cabin. Is it actually a cup car, per your screen name?

GT3CupCarRandP

thank you - no just a cup car ring and pinion - but does have numeric shifter.
yes increases with speed regardless of gear changes,, and instantly silenced with clutch in
other wize street stock 2007 gt3 that has been modified with cup car gearing, numeric shifter

and embarrassingly - do not know if single mass flywheel as prior owner did the build - but noise does not appear at idle and stops with clutch in

Auto_Werks 3.6

I'd have to do some research, but I think the cup car ring and pinion is different than the 3.8RS parts that I swapped into my base GT3. The lowest gear ratio has some life limit to it because it hits the same spot on every revolution or something like that. Might be worth changing the trans oil and seeing what the metal content looks like, or confirming which part number was swapped in. For sure I wouldn't go back to stock, The shorter gears are a huge win on these cars.

sirringo

Numeric shifter - I assume you have the Numeric cables as well? If so, this is normal in my experience - solid cables transmit a LOT more of the diff (and other) noise. I heard similar noises from a mechanically perfect drivetrain with Cup cables; once I reverted to OEM GT3 cables, they went away.

RAudi Driver

I don't think our 997 Gt3's have straight cut gears. I hear no noise to tell me they have them. However, your car sure sounds like you have straight cut gears in them. Sounds like normal straight cut geared car.

JpCrp

I have the cup car 8:32 ring and pinion in my car, to me it doesn't sound much different than the stock R&P gt3's I've driven. I believe mine was installed around 20k km ago, by the previous owner, so it's not exactly new. I have read the 4.0 R&P can become noisy as it ages, but that hasn't been my experience. Your's does not sound at all like mine.
I'll also note I have oem shifter cables, oem dual mass flywheel and clutch.

FLT6SPD

Cup cars have straight cut gears, street cars do not. Sounds like a bad pinion or carrier bearing, best practice to change both.

Did the sound start right after the ring and pinion change, or gradual?

https://rennlist.com/how-tos/a/porsc...n-noisy-386587

FLT6SPD

Probably best to contact Bill and discuss

https://billradermotorsports.com/gearboxes

Spyerx

First, ensure it's not NVH.
1. put car on lift, pull the center pan, and check your transmission mount. I had mine fail and prior to it failing it was getting more NVH / gear whine than I recall and also thought it was a trans issue. it 100% was not and going to a new factory mount fixed it. It sounded not terribly different than the recording. The design of the mount has a large bold through rubber that suspends the transmission at the nose cone. If the rubber collapses the bolt/mounting will rest on the mount itself and transmits a ton of noise.

2. if you're using solid shift cables you get more NVH, although this more than I experienced using cup cables for many years (I'm not back to street cables and a 997.2rs shifter)

Check those before you pull the box and send it off to Rader or Copans. I've used Rader to build a couple boxes and he obviously does quality work.

GT3CupCarRandP

thank you very much. Feels like I may be shopping for a built trans or looking for availability for rebuilding. Even though shifting and syncros are perfect.
I didn't even know Copans https://www.copanstransmission.com/ or Rader

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sirringo

I suspect you're more worried than you need to be - dan's post from the For Sale thread feels especially relevant . You didn't say if you have Numeric cables (or Cup)?

The solid cables transmit a TON more noise, especially from the diff, than the OEM cables. Yours sounds very similar to mine (stock trans, Guards diff) did with the Cup cables - now that I've reverted to OEM cables, all the noises are gone - and the car is mechanically perfect.

GT3CupCarRandP

probably very gradual. PO did the swap - seemed to have some miles without noise. And noise accelerating in the last 30 miles now stabilized. I strongly suspect your suggestion is correct. And oddly it seems to come mostly from the passenger side.

GT3CupCarRandP

did that - thank you very much ....
Sending car to him

RAudi Driver

Could it be as simple as a ring pinion adjustment?