High Pitch ringing while in Gear

[Porschecool]

Hello guys I need some help, while driving my 1975 911 I noticed a high pitch ringing coming out of the back part of the car this happened while the car was in gear but as soon as I shifted to neutral the noise disappeared, I did it a couple of times and the result was the same; I dumped the transmission fluid and there was no metallic shrapnel, i changed it with kendall transmission fluid but the high pitch ringing is still there while on gear, any thoughts on this issue?
Thank you for your help

[2stroke]

Throw-out bearing?

[Porschecool]

Originally Posted by 2stroke

Throw-out bearing?

When i changed the transmission oil I notice that the transmission breather was pointing to the back of the car and the fluid was coming out of it, could it be that the fluid that spilled out is causing the throw out bearing to sound like that?

[kodioneill]

How many miles on the trans? 120k+ It maybe the pinion bearing race spinning in the case very common. Search for trans noise and you can search for peter zimerman (sp) posts he's the go to guy along with steve from rensport and mat monson. Not sure if I spelled their names correctly but do some searching and you'll find their posts.

[Porsche2217]

How many miles on the trans? 120k+ It maybe the pinion bearing race spinning in the case very common. Search for trans noise and you can search for peter zimerman (sp) posts he's the go to guy along with steve from rensport and mat monson. Not sure if I spelled their names correctly but do some searching and you'll find their posts.

No the car only have 66000 miles.

[Matt Monson]

Same noise in all gears? Wheel speed dependent? Then likely the ring and pinion or a major bearing.

[Jerome74911S]

What Matt said above. My R&P 'sings' all of the time when there is a load on it. The trans was rebuilt, but there are over 100k miles of wear on the R&P. Very annoying, but R&Ps are not cheap.

[Porsche2217]

Yes it sounds in first and second gear but the total miles for the car is 66000 miles is that common in a low miles car? I read in another thread that the problem for the noise was the shift selector for nuts were loose. I will give it a try

[Jerome74911S]

My trans was rebuilt because a previous owner ran it with the oil way too low and I guess the R&P wore at the same time. With 66,000 mi you may have wear if in the past there was too little oil. Just my guess.

[RSBob]

My R&P on the 914-6 sings when under load (accelerating or steady cruising) but is silent when off throttle. It's extremely loud and annoying which makes driving less than fun. This spring it will be fixed.

As the other responders have said, the fix isn't cheap, and that's why I have put it off. Good luck on your fix.

[Porsche2217]

Mine sound all the time as long as is in gear

[Jase77]

I had exactly this issue a few months ago. The noise would be loudest in 2nd but was also there in 3rd too. I had a look and the breather was also pointing to the rear of the car and was very efficiently dumping most of the transmission oil all over the rear and underneath of the motor.
I drained the fluid, repositioned the breather, refilled and it's been quiet and dry ever since!
I hope this also works for you too?