After several no start situations this year (none last year after purchasing my '07 B), I decided to dig a little.
The main grounding bolt for your battery and wiring harness sits just above the starter motor. It is a short 6mm stud attached to a sleeve nut with a 13 mm head. With two ground terminals attached, this stud reaches only 7 mm (9/32") into an aluminum case. A great invitation to strip the threads. Put that 13 mm wrench on it and tighten it down real good!
Bin there!
The bore in the case is 18 mm deep. I ran a 6 mm x 1.0 tap to the bottom of the hole to clean the threads. Then I cut the head off a 30 mm long stainless bolt to make a stud and drove it all the way in with Locktite red stud and bearing mount. Now you have a good anchor.
Next I ran a 13/64" drill down the threaded hole in the sleeve nut (it clears the internal threads), till the bottom came out, dropping the short stud off the end. Now you need to run a 6 mm tap through it, and you now have an open ended sleeve nut.
The difference is that you now have 18 mm of secure anchoring, compared to 7 mm before.
You can now tighten the 13 mm nut down real good, and still mount your starter motor cover as before.
When I took it apart to investigate, the outer threads came out with the bolt. Hard to make a good ground connection that way, and it looks like the only one in the system, so it better be good.
The main grounding bolt for your battery and wiring harness sits just above the starter motor. It is a short 6mm stud attached to a sleeve nut with a 13 mm head. With two ground terminals attached, this stud reaches only 7 mm (9/32") into an aluminum case. A great invitation to strip the threads. Put that 13 mm wrench on it and tighten it down real good!
Bin there!
The bore in the case is 18 mm deep. I ran a 6 mm x 1.0 tap to the bottom of the hole to clean the threads. Then I cut the head off a 30 mm long stainless bolt to make a stud and drove it all the way in with Locktite red stud and bearing mount. Now you have a good anchor.
Next I ran a 13/64" drill down the threaded hole in the sleeve nut (it clears the internal threads), till the bottom came out, dropping the short stud off the end. Now you need to run a 6 mm tap through it, and you now have an open ended sleeve nut.
The difference is that you now have 18 mm of secure anchoring, compared to 7 mm before.
You can now tighten the 13 mm nut down real good, and still mount your starter motor cover as before.
When I took it apart to investigate, the outer threads came out with the bolt. Hard to make a good ground connection that way, and it looks like the only one in the system, so it better be good.