Since my BMW i3-REx is in the shop for a 'broken driver side motor mount bolt', I have some questions:
When I got the BMW i3-REx to Huntsville, the 'motor mount bolt' action was performed. So now I'm wondering what would have been done?alohart wrote: . . .
Our 2014 i3 hasn't had its defective motor mount bolt replaced, so I can't offer any personal experience with the updated software. However, what apparently causes the motor mount bolt to crack or break is when the rotation of one drive wheel suddenly accelerates rapidly when the drive wheel briefly loses contact with the road (e.g., when driving over a curb, speed bump, etc.). When that rapidly spinning drive wheel hits the road again, the shock of its rotation suddenly decelerating can crack or break the motor mount bolt. Others have stated that the software fix adjusts traction control to prevent the sudden acceleration of a drive wheel. I'm not sure that any of us knows for sure the details of the fix, but it apparently hasn't changed the i3's performance, so you might not have very strong grounds for suing BMW.
Would all of the bolt(s) have been replaced or just inspected and the software patch applied?
During the recent failure, the technician reported he was disconnecting the HV in the motor compartment and saw the broken bolt:
This suggests he would have been looking at the top of the body side of the transmission/motor mount to see one or more broken bolts.
These images suggest there are five bolts holding the transmission/motor assembly to the frame:
The top two should be visible but the lower three may be hard to see.
There is one additional support attached to the anti-sway bar:
In a good design, the bolts are 'mechanical fuses' that fail before damage to the frame or transmission/motor housing. But given the nature of this failure, I would like to know all bolts including the anti-sway bar ones have been replaced. For good measure, inspect the transmission/motor housing and body attachment points to make sure there is no damage.
As for the broken bolt, I've had to deal with them in the past and it is a b*tch! There are specialty tools used to back out the broken bolt part but it isn't fun. It certainly is not something I would want to do with the transmission/motor still in the car.
Looking at this YouTube, the strain, the motion inside the compartment, is impressive:
After the car is repaired, I may look at ways to monitor/record the transmission/motor displacement.