if you have the same vibration the rest of us do, motor mounts are not going to fix it. i replaced them on mine and it made no difference.

last weekend i replaced the vibration damper, i think it made a bit of an improvement but the shake is still there. so now we know it is not the motor mounts, tranny mounts, exhaust mounts, vibration damper, flywheel, clutch, or anything belt driven. what does that leave? crankshaft, oil pump, something in the top end, or is it just a resonance at that rpm that s62's have?

 

nightkrawler, now that the noise from the Oil Filter housing has been resolved, I can agree with you that there defenitely is a vibration as well. I feel it most at highway speeds. I am also ruling out Flywheel, and Flex Disk (guibo) since I just had mine replaced with the clutch.

 

You may be right, but it couldn't hurt. The mounts are toast anyway. At the very least, it will put me on the same page as you guys.

BTW, I had a 135i loaner and that car was freaking smooth (and fast). First time driving a 1 and loved it. That may be my next car.

 

When I deleted my clutched fan (for a zionsville) my motor did smooth out some....perhaps my fan clutch was going?

 

i made a discovery the other day. i checked for the shake with the front end up in the air and to my suprise, it was all but gone. lowered the car back down, it came back. someone else want to try this and confirm? put a jack under the front left and right lift block. jack it up so the front wheels are about 10in off the ground. rev it up in neutral and see if it has an effect on the shake.

i also just found out that at work we have a kent more eva2 vibration analyzer. im gonna try it and see if i can get a frequency.

 

Very interesting... this could indicate the vibes are being transferred through the wheel supports to the body? Did you try just lightening the front end? I mean if the vibes came back as soon as the wheels touch the ground or the shocks and springs get some force into them.

 

well i've determined with the vibration analyzer that frequency of the shake im chasing is 22hz. i've been doing a lot of research on vibration troubleshooting. supposedly to find out the frequency of an engines crankshaft at a give rpm you divide the rpm by 60. ie the shake can be felt at it worst at say 2800 rpm, so divide that by 60 and we get about 47hz. so if my reasoning is correct it isnt the crank which is causing the vibration. there are two ways to fix this. fix the cause of the vibration, or eliminate the route of transmission of the vibration to the cabin.

 

Where did you measure this 22 Hz? Against what engine rpm are we comparing this number to?

We attached a vibration analyzer today also and to my surpise we couldn't get any significant results from the seat rails, body, shifter knob whatsoever. The engine was too hot to attach the sensor we had this time. We will be trying again later on as soon as we get the engine rpm out from the crank sensor and into the device. Where did you attach your sensor?

 

I brought my M5 into the dealer as well. To me, it felt like the clutch was starting to go (46k on the clock) and was just going to go with an OEM clutch since this is primarily a daily driver. I took a tech out, he confirmed that he felt the vibration I was talking about and left the car. I threw out some options but really wanted him to investigate and come back with what he felt it could be. Fan clutch, motor/trans mounts, exhaust, etc.

Again, my car has a Britalman exhaust and is Shark Injected. Those are the only mods.

The next day they came back and said they traced it back to the front exhaust hangers (which I already replaced). We went back and forth a few times on this, and they moved some of the bands on the exhaust and allowed more room inbetween the exhaust and the exhaust support bar that runs behind the transmission.

"Guys, that's not it. That might be aiding in transferring the vibration to the cabin, but that's not the source of the vibration."

"No, we think we got it. Took it out for a test drive and can't feel any vibration. Also, we tried to make your clutch slip but could not, so I wouldn't touch the clutch yet. Also, the fan clutch and motor/trans mounts look fine."

I picked it up last night and, as I suspected, the vibration is felt far less in the cabin, but it's still there. That attitude of "we found something broken so that must be the cause of all the problems, next car please" really annoys me.

However, with the fact that the vibration did decrease in the cabin, could it be a resonance in the post-cat exhaust? Something with the length of these Britalman tubes? Not even sure if that is possible.

Oh, and my diff is leaking at the drive shaft. $600 to repair that. I'm hoping that's something I can do here.

 

i attached it to the top of the drivers seat rail. idk what equipment you are using, i have a kent moore eva2 vibration analyzer. you just input what rpm you feel the vibration at it strongest and the machine spits out the hertz rating, order of the vibe, and the g's. you dont want to put the sensor on the engine itself. you want to put it where you feel the shake. ie seat frame, console, door frame etc.

what i really dont understand is how the shake is being transmitted to the seat. the engine is isolated from the body by liquid filled mounts. also dont know why it goes away when the front end is off the ground.

 

Now this vibration seems to be the one that I'm familiar with (not the "wah" sound), at a frequency of roughly half crank speed. I still think that whatever the source is, at least on my car it seems to be the exhaust that's amplifying the vibration and making the rest of the car shake a bit.

For the front wheels of ground phenomenon, here's a perhaps slightly far-fetched idea: what if the wheels in the air are acting kind of as a stabilizer; since they are not fixed with the rest of the car, their inertia will counteract the vibration to some degree?

 

the front end dosent have to be off the ground much, just enough for the wheels to hang. even with only one side jacked a bit the shake is reduced significantly.

 

The vibration is persistent, even when the engine is not under load?

 

dont really feel it under load, only free rev in neutral.

 

I thought this was when you were cruising between 2400 and 3k?

 

no.

 

That's weird. I get the vibration under load, at a static RPM, or through deaccel (in gear, foot off the gas) mode. Under load, it's pretty quick but the engine feels a little off. At a static rpm or under deaccel, there's a vibration through the cabin at around the 3k mark.

To back up Apeman's statement, the vibration transmitted to the cabin went down GREATLY after the dealer moved around my under-cabin exhaust rubber mounts.

 

Hi guys,any news on the problem?Have the same vibrations.Changed tranny mounts,flywheel,clutch,guibo,exhaust mounts,relocated oilfilterlines,...Starts to drive me crazy!

 

i've been meaning to update this thread for a while. a couple weeks ago i did a seafoam treatment to the engine. afterwards i checked for the hell of it to see if it had any impact on the vibration. i was really suprised to find that the shudder between 2500-3000 was not as bad. i've done a couple more, waiting about a week between treatments. with each one it seems to get progressively better. i cant really explain why it is working as it is, though i have a theory. i noticed the first time i had the intake runners off that if you open the throttles you can get a good look at the valves. 2 and 3 cyl, and 6 and 7 cyl valves were pretty much spotless. but 1 and 4 cyl, 5 and 8 cyl valves had carbon build up on the tops. so im thinking now prehaps its due to some carbon build up.

 

how are you introducing the seafoam into the engine. I assume your theory on the vibration has to do with the series of cyl that have more carbon than the others, but why do you think only some have the carbon and it's not even across all cyl's.

 

Sounds interesting!Drove mine today empty and filled racing fuel(not V-Power,real racing stuff) in.Result was smooth idling and less vibrations in the significant rpm range.also better response to throttle.Any thoughts?If it is carbon built up in the combustion chamber,would also explain nightcrawler´s sea foam treatment and my high octane experiance...

 

Maybe the layout of the funnels in the airbox could result the clogging of a few and not all cylinders

 

im not saying this is defintely the problem, its a theory. the cylinders that have carbon are the first one and the last one on each bank. im thinking this is due to the runners sucking up oil which runs through the intake from the oil seperators. i can introduce the seafoam directly into the throttle bodies, from the hose that leads to the idle valve, or the brake booster hose.

 

Are the runners for the corresponding cyl's the ones that face forward in the plenum?

 

the front two face backward, but end right over the ridge in the plenum which channels oil to the back drains. last two point inward and also end over an oil pathway.

 

+1

Here is a picture of the intake runner inside the intake plenum.

Regardz,

J Irwan

 

Opened my airbox yesterday again after using Liqui-Moly´s valve cleaner and the carbon built up was less after the treatment(gas filling before i added their injectioncleaner).with both treatments,the car now has smoother idle and like nightkrawler after his seafoam i also experianced less vibrations.

I think I´ll use these products now regulary(every 5000km or so).

But anyway,vibration still there,but lesshmmm


Regards from Finland,

VantaaM5

 

i may be onto something here. im about relatively sure now that this is not a mechanical problem. i want a couple of you guys to try the following and report back. get the car up to operating temp, shut it off and then unplug the DME. leave it unplugged for at least 10min or so. plug it back in and start her up, check and see is vibration is still there. if you're going to do this make sure after you shut the car off you wait about a minute before you unplug the DME, this is so the main realy drops out. you want it to be powered down before you unplug it.

 

For anybody who currently has this resonance/vibration..
Have you had any rod bearing or main bearing failures or knocking?

Somebody suggested that this may be the onset of worn bearings, but I'm having doubts about this.

 

Have new rod bearings and still 3k vibrations...

 

its not a "mechanical" problem, meaning crankshaft, rod bearings etc. please do what im asking you guys to do. get the car up to temp. shut it off and wait a minute or two, then unplug the dme from the wiring harness. wait about 15min then plug it back in and immediately check and see if the vibration is still there. try this please, it is easy to do. dme is under the right microfilter housing. remove the filter housing, then loosen the screws on the ebox and you can lift off the cover.

 

Will try!Did you also disconnect the battery?

 

no, no need to. just make sure you wait at least a minute or two after you shut off the ignition before you unplug them dme. you want to do this so the dme main relay drops out. you dont really want to unplug it while it is still powered up. more likley than not even if you did it would be ok but its just the proper procedure. in actuality the main relay drops out in about 20 seconds but the rule of thumb is wait 2min.