Expert: Dan Roberts - 9/14/2006

Question
Hello,

For whatever reason, when I come to a complete stop, I hear a pop sound coming from my trunk.  I recently changed by battery so I though it was that, it wasn’t.  My reject mechanic tells me to change the back breaks, I took off the back tire and there is plenty of meat left on it.  One day I decided to cost in natural, came to a complete stop and didn’t hear that pop.  Could it be my tranny?  Could it be my differential? Suspension? Any advice would be greatly appreciated.  

Answer
John,
This is unfortunately normal. There is an old service bulleting at the BMW dealer about the output flange on the transmission. There is an updated flange and nut. Maybe have a service advisor at your local dealer check that bulletin and see if it applies to your car and if it does have the flange changed and if you are anywhere near 100k miles change the guibo that connects the driveshaft to the transmission. This may be kind of pricey since the exhaust has to comm all the way off. Most people just ignore the clunk since they all do it.