Knocking in rear when in gear

[Sevorith]

I've had a consistent problem I would like to fix, and could use some help figuring out what it is.

When I'm in gear, there will be a knocking sound coming from the rear, it sounds like it could be the driver side but it might just be because of where I sit. I can be coasting in 3rd, hear it, pop it into neutral, and it'll go away. It sounds like it's matched to the rpm of the engine and not the wheel itself. Any ideas? Maybe the guibo?

[tomstin]

"pop it into neutral, and it'll go away" Everything in the drive train is still turning but no longer under load. Any more prevalent on the drive or coast side (load, unload)? Right turns or left turns? Any particular gear other than third? I'm guessing U-joint, but we'll need a little more diagnosis.

[LowR3V'in]

hey are you SUUUUURE its the rear?
i had a knocking like that that turned out to be a blown tranny.

https://youtu.be/8mcS0zwVBA0

https://youtu.be/yN3yP2LNObw

[Sevorith]

It's not specific to a gear or turning, it'll do it if I'm going straight. I just said third as an example.

The sound is smiliar to what's on the video except it's a little louder and deeper. It also seems to happen after the car warms up a little. Did yours do that as well? Also does it do it in every gear?

[LowR3V'in]

ya, every gear and started when it warmed up.
then it did it just at idle.

only stopped when i put in the clutch.
was the loudest in 3rd.

just put it on stands and you'll know if the flex disc is blow or if it's the support bearing.
probably one of those two.

[estoguy]

^^^^^

What he said... sounds a lot like a blown flex disc and/or support bearing. My car still had the original support, and part of the ring had rusted away, letting the driveshaft move around and ruin the disc.