M3 F80 manual gearbox clatter/clunk

[Joe Nav]

Need help in Diagnosing:

BMW M3 F80 (2015 ). Manual Transmission. Odometer reading. 6000 kms (3,728 mi)
No modifications.

Excessive clatter/clunk on driveline when vehicle cruising and suddenly depressing clutch pedal to shift at any forward gears ( except in neutral to 1st gear) Most noticeable and replicable at low speed, low rpm.

Also notice the stick shift vibrating and vehicle body jolting during clunking sound.

Transmission mount, driveshaft flex disc (guibo), front & rear differential carrier bushings, all okay upon inspection.

Currently under service dealership for inspection.

Any inputs appreciated. Thank you.

Reference Video clips as follows.

[1000hp]

How did you check the mounts? There isn't much down there to keep the transmission from moving around, other than the transmission and engine mounts. For the shifter to move all around like that when the driveline is loaded, the mounts can't be too solid.

Does your car still have the original carbon fiber driveshaft?

[Joe Nav]

Engine and tranny mounts were checked through visual inspection, and by using wrench, and prybar. Bolts tight, no signs of rubber tear or crack nor unusual sound and irregular movement.

Yes. Driveline still has the original CF Driveshaft

We also checked noise level on Gearbox Vs Rear Differential using stethoscope while car is on lift engine running, gears engaged. Noise is heard on differential side but definitely louder in Gearbox. Most likely, the sound is transmitted to the rear.

Other infos:

Shift engagement = Smooth No problem, No grinding.

Unusual rapid sound (klak-klak-klak) is heard and felt in vehicle body sometimes with driveline jolt, when Clutch is suddenly depressed (+/- .60 second) to shift at any given forward gear most noticeable at 1st to 2nd to 3rd gear at slow speed, low rpm (5Mph-10Mph) or even at high speed.

But when clutch is consciously and gradually depressed (+/- 1.5 seconds), noise can be restrained.

When Releasing clutch either fast or slow, doesn’t create any unusual sound.

Roadtest results while using “improvised chassis ear” connected under gearbox and differential confirms Clatter and bearing whining is loud in the gearbox side.

I’m thinking it’s either in the ff:

DMF
Clutch Disc or Pressure Plate
Pilot bearing or release bearing
Gearbox bearings (input shaft/output shaft/counter shaft)

Other possible parts to consider and reevaluate:
Driveshaft and Differential

Current status: DMF/Clutch Assembly/ Gearbox to be unmounted for inspection.

[1000hp]

What about the shifter carrier? Is rear carrier mount bushing shot? Front carrier bushings shot?

That would explain the shifter movement, and the noise could be the carrier clacking against the trans tunnel if torn bushings allow it to move all over the place.

Not sure why that would happen only when the clutch is rapidly depressed, though.

Edit: just read the part about the gear whine. Interesting. Keep us posted when you figure it out

[Joe Nav]

Shifter carrier bushings all good. Looks like vibration is transmitted only to the shifter coming from the Gearbox assembly. Would definitely feel it in the shift lever if its coming from trans tunnel due torn worn carrier bushing. Clacking is more in the driveline, like inside the gearbox, DMF and clutch, or the driveshaft. But complicated due to the additional bearing whining noise. More like a loose clatter from input shaft against the pilot bearing or input shaft main bearing. Could be separate issues. Will check it again and update. Thanks for the inputs and comments, sir.

[1000hp]

Originally Posted by Joe Nav

Shifter carrier bushings all good. Looks like vibration is transmitted only to the shifter coming from the Gearbox assembly. Would definitely feel it in the shift lever if its coming from trans tunnel due torn worn carrier bushing. Clacking is more in the driveline, like inside the gearbox, DMF and clutch, or the driveshaft. But complicated due to the additional bearing whining noise. More like a loose clatter from input shaft against the pilot bearing or input shaft main bearing. Could be separate issues. Will check it again and update. Thanks for the inputs and comments, sir.

No problem. Good luck.

[swagon]

I think I've got similar noises coming out of the drivetrain. 6MT 2016 45k miles. Been like this since day one (14k miles) and I basically had to learn how to shift well in this car; it just is specific and different and from other BMWs I've driven.

Thunks when I shift from neutral to 1st immediately after pushing in the clutch. Does not make any noise when I push the clutch in and wait a second before I put it in gear.

Very loud thunk and a bit of a jolt when driving AND turning at the same time at low speeds and shifting from 1st to 2nd (under 2k rpm), e.g., at a junction. Sort of feel it in the whole car how the car engages into 2nd gear and it goes through to the rear diff. Can feel it with your feet in the passenger foot well. Learnt to be more smooth with the clutch pedal and to shift higher up the rpm range.

Does buckle and jolt when I slowly let off and go back on the throttle at city speeds especially, can hear and feel it coming from the rear. Also happens when I set cruise control to, e.g., 30 mph and I'm going slightly downhill - going between coasting to decelerate and using gas to accelerate. Solved by pushing the gas pedal more quickly.

Flex disc and diff bushing look good. Diff and gearbox fluid all fresh.

I've not driven other M3s, so I take all this as a quirk of this car also as yours is very low-mileage to the point it'd have been quite difficult to fuck it all up in four thousand miles. Or maybe our cars are fucked. I don't really know.

[Joe Nav]

Originally Posted by swagon

I think I've got similar noises coming out of the drivetrain. 6MT 2016 45k miles. Been like this since day one (14k miles) and I basically had to learn how to shift well in this car; it just is specific and different and from other BMWs I've driven.

Thunks when I shift from neutral to 1st immediately after pushing in the clutch. Does not make any noise when I push the clutch in and wait a second before I put it in gear.

Very loud thunk and a bit of a jolt when driving AND turning at the same time at low speeds and shifting from 1st to 2nd (under 2k rpm), e.g., at a junction. Sort of feel it in the whole car how the car engages into 2nd gear and it goes through to the rear diff. Can feel it with your feet in the passenger foot well. Learnt to be more smooth with the clutch pedal and to shift higher up the rpm range.

Does buckle and jolt when I slowly let off and go back on the throttle at city speeds especially, can hear and feel it coming from the rear. Also happens when I set cruise control to, e.g., 30 mph and I'm going slightly downhill - going between coasting to decelerate and using gas to accelerate. Solved by pushing the gas pedal more quickly.

Flex disc and diff bushing look good. Diff and gearbox fluid all fresh.

I've not driven other M3s, so I take all this as a quirk of this car also as yours is very low-mileage to the point it'd have been quite difficult to fuck it all up in four thousand miles. Or maybe our cars are fucked. I don't really know.

Thanks for sharing. Car is now 7,000 kms on the odometer. Clatter clunk noise still heard rearwards in the drivetrain and or differential. No more, no less.

[hC1001]

Yea, this aint normal...

Normal things to look at would be driveshafdt CV joint, the tranny and engine mounts. Are you sure the nuts are tightened on the top of the tranny mounts? If you didnt have the CF driveshaft i would suspect the driveshaft center support bearing isnt tightened and knocking/vibrating because its loose but you dont have that... Maybe the driveshaft nut connecting to the rear diff came loose? Was the driveshaft recall ever done on this car?

Maybe a strap/finger on the the pressure plate is bad?

Pilot bearing would be a constant noise. Bad throwout bearing would be apparent when holding down the clutch even when the car isnt moving.
Let the dealer take care of it. They will probably throw new parts at it until the noise is gone...

[thock09]

Originally Posted by swagon

I think I've got similar noises coming out of the drivetrain. 6MT 2016 45k miles. Been like this since day one (14k miles) and I basically had to learn how to shift well in this car; it just is specific and different and from other BMWs I've driven.

Thunks when I shift from neutral to 1st immediately after pushing in the clutch. Does not make any noise when I push the clutch in and wait a second before I put it in gear.

Very loud thunk and a bit of a jolt when driving AND turning at the same time at low speeds and shifting from 1st to 2nd (under 2k rpm), e.g., at a junction. Sort of feel it in the whole car how the car engages into 2nd gear and it goes through to the rear diff. Can feel it with your feet in the passenger foot well. Learnt to be more smooth with the clutch pedal and to shift higher up the rpm range.

Does buckle and jolt when I slowly let off and go back on the throttle at city speeds especially, can hear and feel it coming from the rear. Also happens when I set cruise control to, e.g., 30 mph and I'm going slightly downhill - going between coasting to decelerate and using gas to accelerate. Solved by pushing the gas pedal more quickly.

Flex disc and diff bushing look good. Diff and gearbox fluid all fresh.

I've not driven other M3s, so I take all this as a quirk of this car also as yours is very low-mileage to the point it'd have been quite difficult to fuck it all up in four thousand miles. Or maybe our cars are fucked. I don't really know.

Reading this makes me feel so relieved lol. Just got a 2018 F80 6MT, still trying to figure out what work has been done because at the very least it's flash tuned Stage2. But yeah, I live in a city and all the behaviors you mentioned above I've been noticing.

Thunks when I shift from neutral to 1st immediately after pushing in the clutch. Does not make any noise when I push the clutch in and wait a second before I put it in gear.

Noticed this to a T. Also happens with second for me, and into second usually is just a bit louder.

Does buckle and jolt when I slowly let off and go back on the throttle at city speeds especially, can hear and feel it coming from the rear.

Yep, jolts even slowly letting off gas. Also jolts if I go farely quickly to 4.5k rpm and quickly engage the clutch. Rattles a bit too, but I think mine but have a bad bracket or loose somthing that I need to get checked out soon.

[uncle ben]

If you remove the starter or if there is an inspection window, and can look inside bell housing of the transmission, where the clutch and flywheel are. If there is grease marks splattered inside the bell housing of the transmission, then I would say that the dual mass flywheel may be the problem. Sometimes they fail and puke out all the grease, and effectively leave you with a rattly flywheel.