Driveline "shunt".

Crispy · 09-16-2012, 04:01 PM

Has anyone else got a significant amount of backlash/shunt in their drivetrain?

There has always been a little but it appears to be getting significantly worse. Its noticeable when changing gear and when going on/off the gas, especially in top gear. The car has done less than 7k miles.

I've only driven one other M, a BMW track car, and that showed the same characteristic. No other signs of anything amiss.

Is this something that is evident on all M's and, if so, where is it coming from?
Wondered about the DM Flywheel or the diff but it could be the gearbox itself.

Or does mine need looking at?

flzrider · 09-16-2012, 04:36 PM

It's been discussed before. Seems to be fairly normal for these cars. Apparently caused by the M3 differential.

I find if you are a looking for smooth driving, go a little slower with the clutch and you shouldn't feel it.

More info: http://www.1addicts.com/forums/showthread.php?t=718087

Thibs · 09-16-2012, 09:20 PM

Mine seems to have gotten worse... I didn't notice this until around 7k either

1MOz · 09-16-2012, 09:51 PM

I believe this is normal, according to BMW on page 27 of the supplementary manual.
"Drive train
In your BMW 1-Series M Coupe, special
emphasis has been placed on the direct connection
between the engine and drive. The torsionally
rigid execution of the drive train results
in acoustic feedback of the torque, as is typical
in sports cars. Clacking sounds can arise during
load changes. They do not impair functionality
or shorten the lifespan of any component."

Crispy · 09-17-2012, 10:12 AM

Sorry for the repeat, did search titles but missed them.

Thanks for the various links. Like alot of the others that enquired I am OK with things like this once I know what they are.

Interestingly, I have noticed that it scarcely does it when cold. I guess the drag of the cold gearoil damps the effect.

09-16-2012, 04:01 PM	#1
Crispy Obtuse Member 0 Rep 19 Posts Drives: 1M Coupe & Mini GP2 Join Date: Dec 2010 Location: UK - Midlands iTrader: (0)	Driveline "shunt". Has anyone else got a significant amount of backlash/shunt in their drivetrain? There has always been a little but it appears to be getting significantly worse. Its noticeable when changing gear and when going on/off the gas, especially in top gear. The car has done less than 7k miles. I've only driven one other M, a BMW track car, and that showed the same characteristic. No other signs of anything amiss. Is this something that is evident on all M's and, if so, where is it coming from? Wondered about the DM Flywheel or the diff but it could be the gearbox itself. Or does mine need looking at?
	Appreciate 0 Tweet Quote

09-16-2012, 04:36 PM	#2
flzrider Captain 50 Rep 739 Posts Drives: AW 1M Join Date: Oct 2005 Location: Miami, FL iTrader: (1)	It's been discussed before. Seems to be fairly normal for these cars. Apparently caused by the M3 differential. I find if you are a looking for smooth driving, go a little slower with the clutch and you shouldn't feel it. More info: http://www.1addicts.com/forums/showthread.php?t=718087 __________________
	Appreciate 0 Quote

09-16-2012, 09:20 PM	#3
Thibs Private 55 Rep 93 Posts Drives: 2011 BMW 1M Join Date: May 2011 Location: Canada iTrader: (1)	Mine seems to have gotten worse... I didn't notice this until around 7k either
	Appreciate 0 Quote

09-16-2012, 09:51 PM	#4
1MOz Captain 193 Rep 707 Posts Drives: BMW 1M AW & F15X5 40d & M2C HS Join Date: Apr 2008 Location: Sydney, Australia iTrader: (0)	I believe this is normal, according to BMW on page 27 of the supplementary manual. "Drive train In your BMW 1-Series M Coupe, special emphasis has been placed on the direct connection between the engine and drive. The torsionally rigid execution of the drive train results in acoustic feedback of the torque, as is typical in sports cars. Clacking sounds can arise during load changes. They do not impair functionality or shorten the lifespan of any component."
	Appreciate 0 Quote

09-17-2012, 10:12 AM	#5
Crispy Obtuse Member 0 Rep 19 Posts Drives: 1M Coupe & Mini GP2 Join Date: Dec 2010 Location: UK - Midlands iTrader: (0)	Sorry for the repeat, did search titles but missed them. Thanks for the various links. Like alot of the others that enquired I am OK with things like this once I know what they are. Interestingly, I have noticed that it scarcely does it when cold. I guess the drag of the cold gearoil damps the effect.
	Appreciate 0 Quote