Engine Vibration after manual swap.

[Pavlo]

Quick question, how are the BMW engines balanced from the factory? I have converted two of my BMWs from auto to manual, and Both developed a vibration! The flywheel is an Aasco aluminum and Sachs non-adjustable pressure plate that I bought used from members on this forum. My old E30 I ended up balancing it on car with a vibration analyzer, but it's a pita.
If anyone has any knowledge of how the auto and manuals are balanced at the factory, I will greatly appreiate the information.

[flyfishvt]

they are ballanced perfectly. That should be enough. You did a tranny swap on both and both developed a vibration right after. i would look at what was done during that swap. Damaged motor mounts? Damaged tranny mounts? is it vibrating at idle while the car is sitting still or when its moving? Vibration only when changing gears?

If you want to see how well ballanced they are look at this video. You can ballance a quarter on its side. That engine had 150,000 miles on it. the only thing I ever did was repalce the motor mounts.

http://youtu.be/nSTCBsuPr1I

I have had 2 M50 engines apart down to the block. I have never seen anything close to added weights or drilled out parts that would look like the engines were being ballanced artificially. Obviously the rotating mass is precision ballanced but I dont see anything else that is.

[Pavlo]

Cranks have drill spots, I have those too. Engine mounts are solid. That still doesn't answer my question on how they are balanced. I hope it's perfect lol, do they balance the manuals and the autos differently is the question.

[flyfishvt]

Yes cranks and cams and other rotating mass parts are ballanced. I said that. Atuo and manuals got the exact same engine. Decribe your vibration better and maybe we can help.

Motor mounts are NOT solid unless you replaced them with solid mounts. All OEM motor mounts are fluid filled. if you have solid mounts then you have to expect a bit more vibration.

Unless someone else knows differently I have never seen anything like extra weight or drill spots in the block or any other non-rotating part fo the engine.

[Pavlo]

I did mean the crank as far as drill marks for balancing, I must have misunderstood you. And I know about my mounts, I work at a BMW performance shop and install such parts for a living. That is all I needed to know.
Vibration starts at 2k then tapers down but still noticeable, I'll pull the clutch again and get it balanced as an assembly. Engine mounts don't cause vibration, they just make you feel the natural harmonics of the engine. AGAIN, I don't need help diagnosing my issue, I just need information on how the engines are balanced. Some manufacturers do what's called an external balancing, meaning the harmonic balancer and torque converter must be installed a certain way or the engine will vibrate.

[n3985]

You could have also tightened the tranny mounts too much, they only need 16 ft lbs. Any tighter and you transmit more vibration than let the mount absorb.

[marvinstockman]

Get yourself a 'mechanics ear', as you may have a mechanical 'short' someplace.

Listen on either side of all mounts. You should hear a large vibration drop when going from the engine/trans side to the chassis side.