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HV Battery to subframe bolts hanging loose

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The adrenaline is still pumping a bit.... 2 of my front hv battery mounting bolts were just hanging loose underneath the car (2015 85D), apparently the ones securing the front subframe to the hv pack. Probably 5mm of gap, I was able to finger tighten the drivers side one and retorque to 115Nm, but not the passenger side. I tried with a wrench and I can turn it but it has a lot of resistance so I'm nervous about turning it too hard. Presumably I've been driving around like this for a while but I'd prefer to fix it sooner than later. Anyone else run into this? I couldn't find anything on the forums about it. I'd like to know what exactly they're threaded into (welded on nuts, floating nuts, etc) so I know what I'm dealing with a bit more.

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Would you see it if you move the wheel well liner out of the way?
The battery is flush with the subframe, didn't appear to be anything unexpected but I couldn't see where the bolt went. I will dig into it a bit tomorrow though. It seems like there's a floating nut in there since the bolts are definitely threaded into something but they also moved around in the hole more than if they were going into a welded nut or tapped hole on the chassis. I'm also reading through the service manual for clues but haven't found anything useful yet except that the bolt seems like it's holding the battery in place but not the subframe itself.
 
Would you see it if you move the wheel well liner out of the way?
Pulled back the wheel well liner, behind was a hole with some of that butyl stuff covering it up. Inside is what I hoped, a floating nut which explains the large amount of play when it's loose.

I attempted cleaning up the threads a bit by going back and forth to work the bolt into the nut, with my torque wrench set to 115Nm even just the prevailing torque was over the wrench setting. A bit more back and forth dropped the prevailing torque below the setting just barely, but not much. I sprayed some liquid wrench all over the threads and will see if that helps after it's worked into everything.

I suspect that the car has been this way for some time...


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Reactions: henderrj
Probably a good idea, I have to pick up a set of sway bar links from the SC anyway, I'll add those to my list. Pretty cheap peace of mind. At least I feel a bit better about driving it now until I can do that, we'll see if this takes care of some of the clunking.

For reference, bolt is part 1009169-00 and the nut plate is 1014378-00 (the latter is supposedly a restricted part)
 
Interestingly, I had this noise back in 2021, and it went away on its own after i got an alignment, so i figured that maybe my alignment was so bad it was binding the rack or something.

Then just last week, I adjusted my toe to be more neutral (just 2 threads in on both sides) and the pops came back. It's only every so often, not on every turn, only at low speeds....

I recall checking these two bolts on my car after reading your thread last year and not seeing any space between the bolt and the subframe (and thus assumed it was tight), but I'll recheck them again when I have the wheels off this weekend.