I have this hum noise I can not identify where it's exactly coming from. I spent all day changing a bearing that looked fine when I took it out. I can't 100% tell if it's coming from the front, middle or the rear. I keep thinking its coming from the rear, but now I am not sure.

When I hit somewhere past 3000 RPMS, maybe sometimes as low as 2500 RPMS, I hear this steady hum/whine sound (not the typical low transmission fluid sound I've heard in the past) . It goes up with the RPMS, and if I hold it steady sometimes it can get loud. as soon as I take my foot off the gas it goes away immediately. when I barely touch the gas I hear it again. It does not matter how fast the car is going (can happen at any MPH). It does not do it in park or neutral only in gear.

I did an experiment where I drove the car at 3000 RPMS and held it steady on the road so I could hear the hum, I put the car into neutral while trying to still hold it at 3000 rpms (lighten my foot at the same time I put it into neutral) while the car is still moving, and the sound went away immediately. Still holding it at 3000 RPms and coasting, I put it back into gear and the hum came right back.

I was thinking maybe a bearing in the differential. (didn't sound like a rear wheel bearing). so today I just replaced the smaller bearing right behind I think it's called the Yoke, where the drive shaft connected to, so I pulled out the seal and replaced that bearing. I haven't taken the back cover off tho. and the fluid level is fine. Transmission fluid level is find also..

So I don't have a clue. unless I start pulling more stuff off.

So its a hum (can get louder , can go up in pitch or stay steady and can resonate), when I am in gear and the engine's RPMs are at least above 2500. doesn't matter how fast the car is moving or coasting.

It still idles high, can be 1500 rpms , warmed up and in gear. and I haven't figured that out yet, but I don't know if that contribute or not.

any ideas, or a common problem someone else has fixed, please let me know. I appreciate it a lot

I have a 1992 Camaro RS 305 V8 thanks!

 

First Guess: Differential (Ring 'n' pinion) gear noise from improper adjustment or damaged gear teeth.

Noise with load, silence on coast can be a common symptom of differential set-up problems.

 

. but it bothers me too that you said replaced the bearing behind the yoke. because once you loosen that nut you have to replace the crush sleeve in there as well and check to make sure you have 25 in/lb of running torque on those bearings for the yoke. so...... you might be in need of a new differential soon if you didnt do all that.