AlB

My car shifts so much better now!!!

Ok, I took my car in for the squeaky clutch issue so many of these manuals are known for. It was explained to me that a neoprene pin either wears out or dries out which causes the squeaking sound. The Service manager said he has replaced several of these which fixes the squeaking problem. The pin is located somewhere in the clutch assembly so to replace the pin, the tranny must be unbolted. This was a fix they were ready and willing to do under warranty, even tho the labor was a bit high for such a simple replacement part.

When I dropped the car off, I also mentioned that I had some minor clutch judder, when slowly pulling into my garage (which is uphill and very tight maneuvering). I asked him to check the clutch to make sure all was fine. As it turns out, I had a bad dual mass flywheel wherein (as described to me) there was excessive play in the flywheel (clutch side) allowing it to travel farther than it was supposed to. He told me that BMW had realized this to be an issue and were providing a different (improved) dual mass flywheel when replacement was necessary. While they were in there, in addition to a new flywheel, they also replaced the pressure plate, friction disc, release bearing, and ball pivot. The final verdict, no more squeak.

I consider myself to be an accomplished manual shifter and seemed to do quite well before the replacement...but, I gotta tell you, after the clutch/ flywheel replacement, this car shifts like a dream now. Very smooth, very crisp, no play, no judder, no notchy first to second shifts. I guess I didn't realize how bad it was, but now, it is awesome. Also, the clutch pedal resistance seems lighter now, easier to stroke. My wife will prolly like that.

Al

1esquire

Thanks for the update. Great to hear. The feeling you describe with the pedal resistance and ease of shifting was the same feeling I experienced after they replaced my clutch. Definitely an improvement on that side of things. I will have to call my dealer about the neoprene pin thing. Thanks again,

AlB

Some information that helped me understand the DMF and how mine failed.


Dual Mass Flywheel (DMF)
The OEM flywheel found in most modern manual transmissions (as well as semi-automatic transmissions like the Audi/VW DSG and BMW SMG) is classified as a dual-mass flywheel (DMF). The DMF is designed to eliminate engine vibrations before they are transferred to the drivetrain.

A DMF is tuned by the manufacturer to match engine torque and horsepower curves, engine harmonics, and vehicle load dynamics, based on transmission gear ratios as well as overall rolling diameter of the rims and tires. It is constructed by splitting the standard single mass flywheel in half. The primary section bolts to the engine crankshaft and the second section is where the clutch assembly is installed. Contained within the two sections is a complex system of varying rate springs, axle and radial bearings, and lubrication. The two halves are rubber-sealed. The aforementioned series of components is referred to as the friction pack. The main purpose of the friction pack is to absorb vibration, allowing for smooth, comfortable shifting, low speed driveability, and reduced drivetrain noise.

When increasing the horsepower of a vehicle, the DMF can be the weakest link. It is designed with an over-torque friction release. As engine torque is increased, the flywheel has the potential to overload. To protect itself, the flywheel will slip, causing a reduction in torque, protecting the internal springs.

Pros: Reduced noise, smoother shifting, increased fuel economy, longer engine life.
Cons: High replacement cost ($799-$1599), can prematurely fail if horsepower and torque are increased, can slip under increased load, 8-11 degrees of movement before clutch engagement.