porschegrp5

2001 Porsche Carrera which has a rattling noise coming from the transmission in neutral only. When I push the clutch in the noise disappears, however during cold starts there is NO noise. The car shifts good, there is no noise while driving. The manual calls for 75W 90 gear oil, but I am hoping to use 75W 140 light weight shock proof gear oil. The car does have a light weight fly wheel with a racing clutch. I am hoping this will eliminate the rattling noise.
Any suggestions are welcome.
Thank you in advance.

Macster

There are only 2 approved transmission lubes for that tranny both are 75w-90.

By switching to a 75w-140 "light weight" gear lube (I fail to understand how a 75w-140 gear lube can be called light weight compared to a 75w-90 gear lube) you risk ruining the transmission in an attempt to eliminate a noise that is normal in a healthy car as it came from the factory and which as I touch upon more below has been modified in such a way to make the noise worse.

The noise is normal (my 03 Turbo does this when everything is up to temp) and in your car's case has been exacerbated by the removal of the stock flywheel with its dual mass feature which in some way also acts as a crankshaft dampener and replacing it with a lightweight flywheel.

The normal high frequency difference in engine rotation speed causes the rattle. Ensuring the engine is in a good state of tune will reduce the high frequency variation in idle speed which may reduce the noise but probably not eliminate it.

If the noise really bothers you switch back to the stock flywheel and clutch. While this might not eliminate the noise it will reduce it.

And it doesn't require you run the wrong fluid in the transmission and risk its health in an attempt to deal with a self-inflicted problem.

KrazyK

What Mac said. I have tried a few different brands and nothing shifts as smooth as the "Porsche" brand. Dont fall for the BS about the others, Royal Purple, Swepco, Delvac, etc. I wasted money on other brands before I gave up and bought the Porsche fluid from Suncoast.

I repeat, NOTHING works like the Porsche oil. If someone could just get the secret formula to make it cheaper. The Porsche stuff is too $$$ but I have to admit, its worth it.

PS, you light weight flywheel may not be a good thing.

porschegrp5

I really appreciate your input on this subject.I bought the gear oil but I was reluctant to changing it.I guess I will have to live with the noise. Another person that had a lightened flywheel Told me that this is a common problem, Don't worry about it just drive the car.
Thank you again,