Whining when shifting into third on a 915

[Triplethree11]

On my 1980 911sc, I have recently noticed that when shifting into third, it gives off a whining (or high frequency grinding??) noise, and an apparent "feel" of vibration through the shifter. At first it started out as a whine if I pushed the shifter too far towards the dash, but now, any resistance in and around third seems to give off this noise. Only while shifting of course. I replaced the transmission oil twice now in the last week, with no improvement. On the drain plug magnet there appeared to be a negligible amount of metal filings, but I'm no expert as to how much "should" be there, or what normal is. This car has 150000+ miles (odometer stopped at 142k) and as far as I know, nothing has been touched in the last ten years, referring to the transmission. This noise only occurs while the car is in motion, and changes pitch depending on the speed. Any ideas or help would be greatly appreciated!

[Danny_Ocean]

My trans makes so much noise in 3rd, I can't keep it there. Have to shift to 4th.

Syncros?

[Bob Kontak]

He is saying while shifting into third - not while in third.

I had the same noise. Trans re-build last year. Mayo did it.

[john walker's workshop]

a whizzing sound when shifting is often caused by a loose guide fork. that's the pivot point for the main shift lever which is mounted on the removable square plate on the bottom of the center housing of the trans. put the trans in neutral and remove the 4 nuts and pop off the plate to check. you could drain the oil first or just let it run out when the plate comes off.

[Bob Kontak]

Noise is when shifting and not when in gear. I had my synchros replaced and noise went away. However, there was plenty else wrong with the transmission like the nut torque on the array of stuff on the input shaft was 15 pounds - not 160.

I sent you a private message with my phone - call me if you would like to discuss.

[Bob Kontak]

What John Walker says is exactly what I wanted to talk to you about over the phone. I pulled my trans - THEN - found out about the guide fork. Pulled my guide fork out before I shipped the trans and sure enough, it was loose - not much but loose. I am not sure that was the problem but man, I wish I would have known before I pulled the trans. Once out - I just got the thing done - it was tired.

[Bob Kontak]

Here is the guide fork and the side of the trans. Note loose nut - blurry pic but you can still see it.

[kwikt 911]

Make sure you locktite the mounting studs and nuts when assembling. My fork almost completely vibrated off.

[Bob Kontak]

With Red Loctite, correct?

[Triplethree11]

Wow!! Thanks for the call Bob, and everyone else for the input! Wasn't expecting so much detailed info in such a short time. You guys must love your 911's as much as I love mine. I will get down to business and check out that guide fork. Thanks everyone!