Torn OEM Crank Pulley / Vibration Damper due to SC pulley?
 

I just found out that my OEM crank pulley is torn right where the vibration damper is. It is torn halfway around the rubber portion of the pulley. The only reason I could think this would happened is because it couldn't handle the torque required to turn my 19% SC pulley. Has anyone with 19% SC pulleys experienced this problem?

I was thinking of replacing it with an Alta lightweight pulley or something similar due to the fact the these pulleys are made of pure steel/aluminum with out the rubber portion. But I don't want to get any additional vibrations or other side effects of a lightweight pulley. What have ou guys experienced with lightweight pulleys and what do you guys suggest?

John

Read this,

taken from innerauto.com
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The harmonic balancer, or vibration damper, is a device connected to the crankshaft to lessen the torsional vibration. When the cylinders fire, power gets transmitted through the crankshaft. The front of the crankshaft takes the brunt of this power, so it often moves before the rear of the crankshaft. This causes a twisting motion. Then, when the power is removed from the front, the halfway twisted shaft unwinds and snaps back in the opposite direction. Although this unwinding process is quite small, it causes "torsional vibration." To prevent this vibration, a harmonic balancer is attached to the front part of the crankshaft that's causing all the trouble. The balancer is made of two pieces connected by rubber plugs, spring loaded friction discs, or both. When the power from the cylinder hits the front of the crankshaft, it tries to twist the heavy part of the damper, but ends up twisting the rubber or discs connecting the two parts of the damper. The front of the crank can't speed up as much with the damper attached; the force is used to twist the rubber and speed up the damper wheel. This keeps the crankshaft operation calm.
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These forces left unchecked by the balancer would destroy the engine in the long run if not sooner. So getting a lightened crank pulley is not a good idea unless you plan to race and have the budget for a few more engines. Go with a lightened flywheel instead, its only downsides are gear chatter and difficulty when starting on hills.

Thanks for the advice. Actually, amy main reason for considering the lightweight crank pulley is it's durability over the OEM rubber damped pulley. And as I've read in here, it seems a lot OEM vibration dampers have failed. Are the newer OEM crank pulleys better than the older generation pulley? Mine MCS is an '02 build, so maybe upgrading to the '05 crank pulley is the way to go.

John

vibration / harmonic balancer (damper)
 

nabeshin,
I might add that with a solid crankshaft pulley the torsional vibration will be transferred to the belt and supercharger/water. Failure of the belt may destroy the crankshaft pulley without a tensioner stop. Using a solid crankshaft pulley will have a negative impact on the supercharger/water pumps life cycle.



johnD,
This just proves the point that torsional vibrations do exist in this engine.

I don't care what the Vendors say that sell these things.

The older version of the vibration damper is prone to failure. Please do a search and you will find photos of torn dampers. Mine began to vibrate and make noise; I replaced it with the later OEM model and all is well. As a bonus it’s lighter also; BTW, (although it has nothing to do with causing failures) 30,000 miles with a 19% and the later model crankshaft pulley.

As K-huevo, my car started making a chatter noise at full throttle, diagnosed as faulty harmonic damper (it was torn, same as yours). Replaced with newest version and fine since. I think the service guy said it was the third revision of this part?
Nothing to do with the charger pulley (that'll reduce the life of other bits, lol)!

I had the samething happen to me and mine is an '02 as well, i ended up replacing the pulley tensioner and belt, and also upgraded to an '05 crank pulley.

it's lighter and better . i plan on it as soon as i tare down .

Remembering now they did the tensioner assembly at the same time when mine went in too. I think it is that slapping about which makes the noise when the harmonic damper gives up - ie it is the manifestation of that vibration the harmonic damper removes from the belt train?

Ok, I'm sold.....:lol: . I'm getting the newer model vibration damper. Thanks guys!! I was a click away from finishing my order on the lighweight pulley.:eek:

John

Good choice johnD!
 

I'm going with a new model vibration damper on my 03 soon.

The vibration damper split into two pieces on my 06/02 build MCS. It actually busted off so badly that it wedged itself into my passenger side axle shaft. I just replaced it with the 06 vibration damper which is a bit lighter than the older ones plus its better. All is well now.

I would like to run a poll on how many people have aftermarket/light weight crank pullies who have and have not blown their engine. As a matter of fact, who has blown their crank due soley to an aftermarket crank pulley?

I understand what Rusty means about crank pullies flying off...I knew of one vendor who had a bad batch where the tolerances weren't correct. That particular vender did do a recall on that batch and offered a replacement for the affected pullies.

Here's somthing to think about too...why does the regular mini not have a big damper? I don't know but would it be possible to take the pulley from a cooper and put it on an MCS? I'm not sure if it's the same size or not.

http://www.realoem.com/bmw/showparts...89&hg=11&fg=18

Do you guys have a price of the newer version OEM vibration damper? Thanks!

John

I have been thinking about going with the 05 crank pulley on my 02 MCS.

is vib damper the same thing as "Crank Pulley"? I'm a little confused.

Same, same

bringing back an old post, but i have the same problem right now and need to replace the same parts. Does anyone remember where they got their parts and how much they were. and the install?

I got mine from the dealer as I was in a rush. :roll: IIRC, Chad at Detroit Tuned had PM'd me right after I purchased mine letting me know that he had some 05-06 Dampers and they were cheaper than at the dealer. Give them a call. :thumbsup:

Here's a thought - are the MCS and MC crank pulleys the same diameter? Maybe there is a newer, lighter, larger version - though I doubt we would be that lucky.

Yes

yeah i went with a one-piece from alta (2%). I like the throttle response alot better too. Im happy but it was kind of a ***** to install. luckily i had some help from my friends at bootandbonnet motorsports.
p.s.
If you dont have a upgraded sc pulley this would be the tome to install becuase it will all be apart then.

I have a 2002 MCS with just over 100K kms on it. Had the supercharger pulley replaced with an Alta 15 % reduced pulley a few weeks back. While removing the OEM supercharger pulley my trusted mechanic found that the tensioner assembly needed replacing: the piston was empty of oil and the thin metal plate running inside the spring had broken. So off it went and on went a new OEM one.

Got home yesterday after work and pulled into the garage with the windows down. I could hear a slight and irregular ticking sound. Popped the hood and determined it was coming from the superchrager / tensioner pulley area. The radiator fan came on and the the ticking speed increased slightly. Called my guy and he wants to see the car tomorrow.

I took the car out at lunch and popped the hood again. Sure enough, there was that tcking sound again. Can't hear it while driving. Can hear it if I'm coasting with the windows down and sound is being reflected back to the car by nearby objects. Ticking speed increases when light throttle is applied and seems to persist (not sure) under light load. Can't hear it at all under heavy load as the ALTA CAI drowns everything else out:D

I did notice however that the ticking would (almost) stop when I pressed down on the tensioner assembly, as if the slight extra pressure lessened the clicking / ticking sound.

I'm wondering if there's anything loose on the new tensioner assembly or
that replacing the busted tensioner with the new one has revealed another problem (possible defective vibration damper)

Too bad I didn't come across this thread before I had the supercharger pulley replaced. I would have replaced the vibreation damper / crank pulley at the same time :sad:

What do you guys think?