Question to all 7A flywheel users

[A80Avant]

I know about the trembling when engaging and disangaging the pedal..

any of you have a metallic/ sound that comes aroun 1500rpm as if the engine is coordinating(wrong word) with something loose? Is there any sound flywheel related coming on that rpm?
esp when you have higher gear and starting from low revs?

[JP]

The trembling is something new to me did you reface the flywheel before using it? Otherwise it may still have impurities embedded in the face of it causing slippage.

As for the noise no there isn't any either. Box issues would cause a noise like that or a failed release bearing. Did you replace the spigot bearing on the flywheel that support the nose of the input shaft? These are all things that can lead to unusual sounds.

[A80Avant]

the flywheel bearing is new, yes as well as the fact that we refaced and leveled the face of it. Clutch kit was new.

this sound is as if normal engine vibration that occurs when you try to pull of on a higher gear than 2nd, on low revs. For example on 2nd gear, it doesnt do it

[A80Avant]

By trembling i mean on reverse gear for example with the lack of the dual mass, if you keep the pedal midway to allow for small movement, the car trembles a bit, thats all. I expect that, now only having single mass

[JP]

Have to say at a loss on that one, can't say I ever drive below 2200-2500rpm as it doesn't do an engine any good as it puts a lot wear on the bearings.
Only noise I can think of is a metallic rattling noise that you would get from the pistons slapping around the bores from detonation as you load her up quickly at too low an rpm in too high a gear.

[A80Avant]

no, this is definitelly not piston/engine related. I initially thought it was the downpipe, but although with the new one, some rattling has gone, part of it is still there.

my timing is quite low on those revs anyway for any chance of knock!

[JP]

Downpipe hitting the heatshield on the chassis leg? or exhaust system hitting heat shield in transmission tunnel? Sorry can't be of more help

[A80Avant]

yes that is something i need to look at really....

just wondering if it is flywheel related as well, since i had read somewhere of new noises...

[JP]

Keeping in mind that the I5 engines are externally balanced and the dual mass flywheel acts like a secondary harmonic dampener. If you were to just swap the flywheels without balancing the whole rotating assembly you can run into issues. Very much luck of the draw, an engine can be surprisingly far out of balance before the average person notices it. It's not until you've driven a perfectly balanced engine in comparison where you notice the difference in the smoothness.
So yes there will be the occasional person that is unlucky and is too far out of what are considered to be acceptable tolerances on a flywheel swap.

[A80Avant]

yes but would an unbalanced flywheel only cause issues on low specific revs? or would an unbalanced rotating mass create increasing imbalance as revs get higher? for example i have no vibration or issues whatsoever with the car.Its only the sound that is annoying. Any engine that tries to be reved from low rpm with a higher gear will vibrate to some extent.

By the way, i used a normal 7A flywheel, without any shaving, so we didnt balance it to zero assuming that it has it's factory balancing.

[goodall]

Keeping in mind that the I5 engines are externally balanced and the dual mass flywheel acts like a secondary harmonic dampener. If you were to just swap the flywheels without balancing the whole rotating assembly you can run into issues. Very much luck of the draw, an engine can be surprisingly far out of balance before the average person notices it. It's not until you've driven a perfectly balanced engine in comparison where you notice the difference in the smoothness.
So yes there will be the occasional person that is unlucky and is too far out of what are considered to be acceptable tolerances on a flywheel swap.

Sorry for off topic question but how does a crankshaft balancing machine would, I understand you drill metal off to lighten it, but how do actually test for imbalance?

[Jamo]

I had that sound for a while, went after 5000 miles, can only assume it took the time for the clutch to bed

[A80Avant]

i see!, so it could be clutch disc related as well. thanks

[JP]

Sorry for off topic question but how does a crankshaft balancing machine would, I understand you drill metal off to lighten it, but how do actually test for imbalance?

It measures vibration dynamically much like a wheel/tire balancing machine.

[JP]

yes but would an unbalanced flywheel only cause issues on low specific revs? or would an unbalanced rotating mass create increasing imbalance as revs get higher? for example i have no vibration or issues whatsoever with the car.Its only the sound that is annoying. Any engine that tries to be reved from low rpm with a higher gear will vibrate to some extent.

By the way, i used a normal 7A flywheel, without any shaving, so we didnt balance it to zero assuming that it has it's factory balancing.

Yes balanced from factory to a specific crank and rod assembly. It's not like a 4pot where the flywheel is zero balanced to itself. As for vibrations they can happen harmonically at any rpm. It's like having an unbalanced wheel that starts vibrating on the motorway at say 60mph but you can pull through it if you do 80+mph.