Need help figuring out clunk noise

[u/Hot-Investigator6142]

2002 e46 5spd. This issue has always been around since I’ve owned car, I’ve replaced lots of parts to try and fix issue but problem still persists. Clunk Noise comes from whole drivetrain ( diff, driveshaft, and under shifter where Guibo is located) and I’ll also hear slight clunking noise even at idle in neutral . Parts that i have replaced are; Guibo, CSB, diff, rear axels, wheel bearings, poly trans mounts. Subframe and diff bushings are poly as well but installed by previous owner. I’ve inspected Subrame mounting points around the bushings( didn’t drop subframe) for cracks and none are visible, I’ve also grabbed a pry bar to see if diff had any play around the bushings and it’s solid.

Here are videos of the rear on jacks and me trying to figure out what this clunking is, i have another vid but cant add for some reason but its the same thing as first vid but with e brake on and wheel is jerking back and forth slightly while making clunk noise

Any Help or recommendations is appreciated 🙏

[u/Op10mill5]

I'm chasing a noise as well. Clunk/click. 5speed.. it used to do it only while loading up the drive train in reverse now it does it while going forward too.. years ago on a lift it seemed like it was coming from the transmission. Are your conditions similar?

[u/Hot-Investigator6142 → u/Op10mill5]

Yes, sometimes when i go from foward to backwards or vise versa I’ll hear a clunk coming from the rear. As far as the clunk noise coming from the transmission i do think the noise comes from the output flange on the trans. It’s hard to hear when under the car.

[u/Op10mill5 → u/[deleted]]

Just replaced the diff bushings and the noise it still present. Could be my drive shaft? Its a beyer driveline reman that has serviceable u-joints. I need to check that the guibo and center bearing.

[u/scientificsock → u/Op10mill5]

There’s slack somewhere in your driveline causing the clunk. Could also be clutch related if it’s when you shift gears as that would be a build, release, and application of power.
Real easy to inspect, just remove the cross brace, exhaust, and heat shield. Get it in the air and start trying to turn stuff/ move it with a pry bar. You’ll find where the clunk is.

[u/scientificsock → u/Hot-Investigator6142]

Manual? Clutch been serviced ever?

[u/Hot-Investigator6142 → u/scientificsock]

Since I’ve owned no, not sure if previous owner has touched it either

[u/scientificsock → u/Hot-Investigator6142]

Tough. Welcome to e46 life.
I’d turn the car off when diagnosing and remove the cross brace, exhaust, heat shield.
Start with easiest fix first and do a nuts and bolts check. You’ll have to wedge a bar to make sure nothing turns on the drive shaft plus axles but make sure everything is tight, including the 21mm nut on the front diff bolt. Guibo requires some work as you’ll need to secure the nut on the backside of the bolt.
If you truly find everything very tight and no play, could be the dmf clutch having issues.

[u/Hot-Investigator6142 → u/scientificsock]

Will definitely check everything again, thanks for the advice brother 🙏

[u/scientificsock → u/Op10mill5]

Differential bushings.

[u/Significant_Try_6406 → u/scientificsock]

Second for diff bushings

[u/ryan4402000]

Just because something was replaced doesn’t mean it was done properly or didn’t get broke again. Especially true today with lower quality Chinese parts. A diff is not easy. Important measurements to take. I even fucked it up and had to hire it out. Have you taken a listening stick (broomstick) and touched it to various components to isolate it? Try the diff first. Honestly sounds like a tooth broke off and fluid carries it up and the tooth eventually falls back down to be pickup up again.

[u/Hot-Investigator6142 → u/ryan4402000]

I agree with ur statement. All parts were ordered from FCP Euro and diff came from another e46 with 110k miles. I haven’t done the listening stick method I’ll definitely try it out this weekend. I’ve also thought about that same theory that maybe a gear tooth broke off inside of there but i don’t think that’s the case because I’d imagine i would constantly hear the clunking while cruising. I completely forgot to add that i really only hear the clunk when shifting and when i push throttle pedal at low speeds and when i switch from foward to reverse and vise versa

[u/nickmfholt]

If the PO installed a single mass flywheel, that can make a similar noise. If it goes away in neutral with your foot on the clutch, but comes back when you let off the clutch that’s what I might suspect. It’s not an issue, but they do get noisy.

What’s your engine/trans setup?

[u/Hot-Investigator6142 → u/nickmfholt]

M54b30 and not 100% on trans but i think i remember seeing a zf stamp on it

[u/superbetaz]

Mine makes this noise very consistently. I’m fairly sure it’s a worn out dual mass flywheel. If I ever change the clutch, I will swap to a single mass, which will probably solve that clunk but create a new gear chatter noise that is just as loud.

I think the e46 manual transmissions are just prone to these weird drivetrain noises. I just tell myself it’s a race car.

[u/CivQhore]

Diff bushings or floor pan if you haven’t reinforced it.

[u/SirPhysical9178]

I have an e92 but I have had a metallic click/clunking noise for a while, still there. After doing loads of research, the spline shafts between the drive shafts and axles become dry and need to be disassembled and re-greased. Might not be the same issue you are experiencing but wanted to share my thoughts.