rodney25

Ok this is a strange one. Have a 1975 4 speed all stock. When the temperature drops to 40 and below first start there is a rattle noise coming from the transmission. The colder it is The louder The noise is. The noise stops when you step on the clutch pedal. When the car warms up the noise goes away. Shifting is perfect and crisp. This does not happen at all in the summer. Was told it's the gear oil in the transmission, if it's cold out gear oil is very thick and it needs to warm up to lubricate correctly. Does anyone know what this is? Driving me crazy.

HeadsU.P.

Who knows how old the tranny lube is? If there is not a drainplug you could buy a cheap siphon pump off EBay and change the fluid just for peace of mind. Whatever lube is in there should be designed to work well below zero, just like from the factory.
I suspect a clutch throwout bearing that has gone south. Maybe dry, rusty, but a lot more work to exchange.

rodney25

To my knowledge it is all original. I got the car about 7+ years ago and I never changed it. I don't think the prior owners did either. The very strange thing it's only when the temperature outside is cold. When the temperature was 20 degrees it was so loud you heard it a good distance away. After a 10 minute drive the noise is gone. Yesterday the temp was 49 and practically nothing at all with no warm-up time. If the temperature gets to 59 degrees nothing at all all is perfect.

rodney25

Ok, your not going to believe this, the problem was the gear oil. I couldn't take it anymore and brought 2 quarts of gear oil. There was maybe half a cup of gear oil in the transmission. No mental on the drain plug. Filled it up and quiet as a mouse at cold start. Shifting is smoother and quiet. I think the little oil that was in there had to get warm to completely lubricate. Wow simple oil was the issue. Thank you all, I learned a lot from your experiences!!!!

Big2Bird

Good. Now drain it all out and put in new. That old oil is now crude, and you probably have it all loosened up now.