E90 M3 6MT Drivetrain play / noises

[marc_f]

Hi,

I am new to this forum and while I have been reading for some time now, it’s time for a first question related to some issues I am currently experiencing.

Since about 20 years, I have owned multiple E21, E30, E36, E46 and E9X BMW 3-series and still own a few of them today. A few months ago, I finally purchased a 2008 E90 M3 in Silverstone II with 6MT transmission. The car had 128.000 km when I bought it and I now just passed 130.000km with it.

The car was fully serviced at BMW dealerships until now and it is generally in a very good condition. Immediately after buying the car, I replaced the rod bearings (which I would have done on any M3, regardless of mileage, maintenance history etc) and needless to say that the old shells were pretty worn (down to the copper on the upper shells of cyl. 4/5/6/8), but there was no visible damage on the crank. I replaced them with ACL bearings and everything has been fine since the change. I also replaced engine mounts and both serpentine belts with all pulleys while I was in there.

Now I have noticed a few other issues which I would like to address this winter, in order to fully enjoy the car next summer, and I would appreciate your advice to point me in the right direction:

• The drivetrain has quite significant play and makes some unusual noises. When test driving the car before buying it, I only noticed a diff clunk maybe 2 times while driving. This is a noise which I am quite familiar with from my E46 330i and while I believe that it is not fully normal in the sense that it was probably not present when the car was brand new, I believe that it is quite common at this mileage and quite well manageable by properly using the clutch. While my E46 does not have an LSD, it seems that on the E9X M3s the noise is supposedly coming from worn clutch packs creating play in the differential. Is this theory correct and what is the recommended approach? Repair it (how?) or learn to live with it?

• Further to the diff noise, I have another noise in the drivetrain, which I believe is coming from the clutch area. The noises appear at different occasions:
  1) When taking off in 1st gear a clunking/rattling/whirring sound comes from the clutch area when engaging the clutch
  2) The same sound also appears quite often in 2->3 gear changes (under partial load). I am an experienced MT driver since 20 years, so I can exclude that it is coming from improper use of the clutch. I can often avoid it when very carefully engaging the clutch, but this is definitely not what the M3 was built for.
  3) At idle, mainly on a hot engine, a subtle knocking sound is coming from underneath the car, at a frequency of about 2-3 knocks/thumps per second. This might be unrelated and actually be an exhaust leak, but I thought I would mention it because it might be related after all.
  4) In Neutral with the clutch engaged (released pedal), I hear a grinding noise, which could be normal flywheel chatter on the transmission input shaft bearing (my E30 M3 with the dogleg Getrag gearbox does exactly the same)
  5) Another symptom I have is that when taking off in 1st and second gear, I sometimes feel some slight hesitation in bringing the power to the rear wheels (pulsing power development).
  
  All in all, I am quite sure that all these symptoms must be related to the flywheel / clutch assembly (broken springs in the dual mass flywheel?), so my idea currently is to replace both by new parts (and use the occasion to install new gearbox mounts, guibo, driveshaft centre support bearing, pilot bearing while I’m in there). I would appreciate your input on whether my diagnosis sounds correct.
  
  Now regarding the parts to be used, I had foreseen to use LUK parts, which seem to be the OEM supplier and a lot cheaper than the OEM parts. However, I am unsure on whether I am finding the correct part numbers.
  - Realoem gives me the following OEM numbers for clutch kit 21212284034 and flywheel 21212283499. The flywheel has however been superseded by the number 21212283820. Realoem indicates a clutch diameter of 215mm. The price for both parts is around 2000€ here in Europe.
  - Now when I check for equivalent LUK part numbers using these BMW numbers, I find LUK 622315700 for the clutch and LUK 415 0453 10 for the flywheel. The price for both parts is around 700€, but the indicated clutch diameter is 220mm, so it doesn’t seem to be the same as the original parts?
  According to this thread https://www.m3post.com/forums/showthread.php?t=1343867 (thanks to Theodore and all other who have provided their input there, this thread is a great help for identifying after-market parts which are identical to OEM), the LUK clutch kit to be used is 03-102 (also sold as 622330800) and the flywheel is LUK DMF148. The LUK (Schaeffler) online catalogue however only lists the numbers 622315700 / 415 0453 10. Also, the other numbers from Theodore’s thread do not seem to be available for sale anywhere, at least not in Europe.
  Upon further research I found that the M3s up to 2008 had a different clutch (220mm?) compared to the later model years (215mm?) and that BMW only sells the later model anymore?
  Can somebody enlighten me on what the correct LUK parts to be used are, because as you can see I am lost ?

• The last issue I’m having is related to the vacuum compressor of the brake booster. Upon first pressing the brake pedal after a cold start, the compressor starts running. Until there, this seems to be normal behavior for E9X M3s according to my research, but on some occasions, I was able to get the compressor to run a few times by simply releasing and pressing the brake pedal a few times. Is this normal behavior of this system or does the vacuum pressure sensor need to be replaced or might this be another issue? I didn’t find any fault codes related to this system.

Sorry for the long post, but I really would like to solve all these issues during the winter, so that I can fully enjoy the car during the next season.

Thanks a lot in advance for your help.

Marc

[Etansinsta]

start by changing the centre support bearing, then diff bushings, and guibo

the knocking at idle is the flywheel - nothing you can really do to get rid of it as they all do it. push the clutch in an if the noise goes away then you know what it is

[Richneerd]

Since you have the same year as mine, I too found out that they discontinued the flywheel and clutch assembly.

You'll have to contact your local dealer and provide them your vin.

They can then try to source parts for you.

GL

[endur0]

#3, #4 knocking sounds at idle are typical. It's a 'baby' version of LWFW clatter sound. Clunking/rattling/whirring #1 is also typical, not certain what it is but I imagine it's throwout bearing related. I like it. Racecar sounds. Mine has been doing it for at least the 30k miles I've driven it. People complained and 09+ got saddled with a heavier flywheel. Mine's still going strong but is getting a single mass 12lb flywheel in the near future, which will produce the same noises, but 3x as loud.

If it occurs while slipping during engagement, pulsing power delivery could indicate some glazing.

[marc_f]

Thank you for your replies.

It makes sense that these noises are particular to the M3s up to 2008 and that later BMW changed to a different setup to stop the complaints :-)

Knowing now that these noises are normal for a 2008 car makes me feel better, but the pulsing power delivery and the strong rattle during clutch engegement are probably nevertheless signs that the clutch is starting to go out. Therefore my plan is to replace the clutch and flywheel, and to use the opportunity to replace pilot bearing, centre support bearing, guibo, transmission mounts and diff mounts while I’m in there, to give the car a general refresh in this area. I’ve read that the rear main seal should not be touched on this engine as long as there’s no leakage - is this the gerneral consensus?

Can somebody comment on the LUK part numbers for clutch and flywheel? I’m not really willing to pay BMW prices on these parts. My assumption is that the LUK numbers I found, which are the only ones listed in the LUK catalogue for all E9X M3s, are probably identical to the upgraded post ’08 ones from BMW. However, as Theodore’s post (and several other posts here) is making reference to another number, I’d rather be sure before buying the part.

Thank you!
Marc