Reverse & 5th gear "sing"

My 1972 911T which has the 915 transmission "sings" in both reverse and 5th gear. Is this typical or something as simple as low gear oil or ...? Both gears are used infrequently as I don't see as much open road that would take advantage of 5th gear as I would like.

It is probably low gear oil level, and hopefully no bearing damage has occurred! The gear oil level is checked with the car level, at normal driving ride height, on the driveway, or on a lift. If you are small enough to fit under the car without it having to be jacked up, crawl under in front of left rear tire, with 19 mm six-point socket and large ratchet, or the lug wrench in hand. The filler plug is forward of the axle on the left side of the transaxle. Once the filler plug is out put one index finger in the hole and check for fluid level ... it should be level with the bottom of the filler hole. If the oil is black, dirty, or gritty ... it needs to be changed, and oil that has been neglected should be changed twice, in short succession, say 200 miles apart with a good, high-quality oil such as Valvoline, Castrol, or favorite brand SAE 75W-90 gear oil. SWEPCO 201 is the preferred oil for 915 transaxles for long-term use, but a neglected transaxle should be 'flushed' out first with two changes of 'inexpensive' oil first! This is not a trivial matter with Porsche transaxles, as most are neglected by owners!!! Please read the following threads recently posted:

http://www.pelicanparts.com/ultimate/Forum3/HTML/001015.html

http://www.pelicanparts.com/ultimate/Forum3/HTML/001037.html



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Warren Hall
1973 911S Targa