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Stephen03
08-08-2005, 03:27 PM
Recently I posted a thread talking about a noise i hear on my 2001 M3. The noise only occurs when I am in 1st or 2nd gear or reverse and to produce the noise, I have to lift up the clutch about half way while Im in gear, and then press it down and thats when i hear the noise. I was told that its the dual mass flywheels but I looked into it further and it turns out that its the synchros on the tranny. Has anyone else had this problem before? and what can I do to stop the noise?

dawgbone
08-09-2005, 08:25 AM
Recently I posted a thread talking about a noise i hear on my 2001 M3. The noise only occurs when I am in 1st or 2nd gear or reverse and to produce the noise, I have to lift up the clutch about half way while Im in gear, and then press it down and thats when i hear the noise. I was told that its the dual mass flywheels but I looked into it further and it turns out that its the synchros on the tranny. Has anyone else had this problem before? and what can I do to stop the noise?

Apart from rebuilding the tranny...you could use a thicker tranny oil...but you will notice a slight degrade in performance...in which may make it hard to get into first at a stop sign or get into reverse after rolling forward...
I'm not convinced that you have a problem at all and that you may be describing a characteristic of a 6spd...in which is probably due to the dual mass flywheel...Mine makes noices as well(clack, clack, clack) when I push in the clutch, like when I'm parking and in first...But I can also not make it do it by simply pushing in the clutch a bit slower, instead of stomping it down to the floor....

Sab
08-09-2005, 01:36 PM
I agree with Dawgbone, I have a 2001 M3 and it makes the same sound. I especially notice it in my garage because of the echo. If I depress the clutch with a bit more care it doesn't make the sound. The faster I press down the louder the clack. I already had the dealer look at it and of course they say its normal. It is annoying.

Stephen03
08-09-2005, 02:36 PM
You guys, Dawgbone and Sab, seem to have the same problem as me. You are both right, when i do push the clutch lighter, i can elminate the noise as well. It probably isnt a problem but it is annoying because in some instances, you cant baby the clutch, you have to push it down fast and the noise occurs. Have either one of you guys tried switching to a heavier tranny oil? Is it worth it?

dawgbone
08-09-2005, 03:04 PM
You guys, Dawgbone and Sab, seem to have the same problem as me. You are both right, when i do push the clutch lighter, i can elminate the noise as well. It probably isnt a problem but it is annoying because in some instances, you cant baby the clutch, you have to push it down fast and the noise occurs. Have either one of you guys tried switching to a heavier tranny oil? Is it worth it?

No..the tranny oil suggestion was just for if, in fact, it was the synchros...But it sounds like the all too familiar "characteristic" of the e46 6spd...in which is probably from the dual mass flywheel...There is nothing wrong with it, and apart from nearby people hearing it and thinking your BMW is a piece of rattling crap, it won't hurt anything..I try as much as possible to not make the noise...but like you said, there are some times that it's just not possible...
You can actually learn to drive it, without the noise..I learned to push the clutch in, not only a little slower, but a little later..like around 800-900 rpms..you can also push in the clutch just before letting off the gas, to help not make the noise...either way works..

My car also makes a horrible noise when I drive over the little lip of my garage unevenly..like the axles of the rear diff are moving in/out and clunking against the diff...IMO for the price of these cars, you'd figure it ,not sound like a tractor...But then again 333hp is alot for a 6spd tranny to deal with...So it has to be somewhat of a brute..

Pinecone
08-09-2005, 05:21 PM
Sorry, but synchros ONLY do something when going into gear. Once in gear, they are fully mated.

Synchros are like little metal to metal clutches that speed up or slow down one gear set to match teh speeds when engaging the gear. They can't make noise, once you are gear.

Worn synchros cause the gears to grind WHILE shifting.

dawgbone
08-10-2005, 09:22 AM
Sorry, but synchros ONLY do something when going into gear. Once in gear, they are fully mated.

Synchros are like little metal to metal clutches that speed up or slow down one gear set to match teh speeds when engaging the gear. They can't make noise, once you are gear.

Worn synchros cause the gears to grind WHILE shifting.

But they still spin in gear...Obviously, you have never had a synchro problem with any car/truck you've driven...although worn synchros will make tons of noticeable noise when sticking a gear...they will also produce noise when driving..especially in slower gears..unless you are having problems sticking a gear, you can usually silence the noise and squeeze a little more life out of you tranny by changing tranny oil..

oh...synchros usually don't clunk...they wine

Pinecone
08-10-2005, 06:09 PM
They spin, but they are locked together with the gears, so they don't move against each other.

As you engage a gear, the synchro gets smashed against another friction surface to bring the two gears to the same speed (like slipping the clutch) but unlike the clutch, since the gears engage teeth, the synchros can't slip in gear.

And yes I have had worn synchros. And changed them.

Noises in gear, especially in all gears except the 1:1 gear (5th in these cars) is more likely lay shaft bearings. BT, DT, too.