This is a follow-up/DIY fix to the problem described in the sticky-thread WARNING! All owners with lowering springs or modified suspension. ACTION REQUIRED if incorrectly installed!


First of all, the upper front mounts have lock-nuts with a deformed thread. The last two turns of the thread are oval, thus giving a locking function through higher friction. However, this type of thread locking is more or less for single use. The nuts on my car have been opened fully one time for mounting new springs and just loosened one time for the 4-wheel adjustment. And the nuts could, after loosing them 2-3 turns, now be turned by hand. Hence the locking function is not working any more. That's why we have seen cases of the mounts coming loose. However, as a mechanical engineer, I don't really trust this type of lock-nuts anyway. They might be good enough for a normal BMW 5-series and for normal driving, but not for the way most M5's are driven and the speeds you can achieve. I would recommend the use of a thread locking fluid as an extra precaution. I used Loctite 243. It has about 25 Nm of locking force, it's oil tolerant and can be removed with some extra effort with regular tools. I would not recommend any lower strength. If you use high strength fluid, you will need to use a hot air gun to dissolve the fluid. I would not recommend it, due to some delicate parts, such as the EDC cable.
If you do this properly, I see no reason to replace the nuts. But you should know what you are doing. If you feel unsure, after reading this step-by-step instruction, you should buy new BMW OEM nuts and have BMW/-representative installing them for you.
Before you start working, read the whole instruction and pay attention to note at the end of this instruction!

Follow these steps and you should not have any problems with the top mount nuts becoming loose:

1. Raise and secure the front end (one side at a time is OK), with a jack and stand, to relieve the mounts from any side-load. Make sure the car is securely lifted and supported.
2. Open the hood and locate the upper shock mounts. See image 1: Red marking shows the main location of the upper suspension mount. Blue marking is the electrical connector and feed-through for the EDC-system. Green markings are the screws for the plastic covering, that needs to be removed.
3. Remove the connector from it's snap-mount, by sliding it towards you. See image 2.
4. Remove the two plastic screws, marked with green in image 1.
5. The plastic cover is snapped onto the brace. Remove by lifting it, as shown in image 3.
6. The electrical wire for the EDC has very little slack under the feed-trough. Therefore the feed-through needs to go through the hole in plastic cover, as shown in image 4.
7. Now the cover can be moved to the side and you get access to the upper suspension mount, as seen in image 5.
8. Loosen one nut at a time (marked with red in image 5). Finish step 8 and 9 before removing the next nut! Clean the threads from any dirt and apply a good amount of Loctite 243 (or similar). The fluid should cover the clearance/gap in the thread, all the way from the first to the last turn.
9. Put the nut back and tighten it with a torque indicator wrench, set at 35 Nm. If you are a very experienced mechanic, you could probably do this without an indicator, but on the other hand you wouldn't be reading this then either.
10. Repeat step 8 and 9 for all three nuts and then do the opposite side, starting from step 1.
11. Lower the car again and wipe of any excess thread locking fluid and re-assemble the suspension mount covers (as step 1 to 6, but in reverse order).
12. Let the thread locking fluid harden for minimum 12 hrs before using the car.

Note! -Disclaimer: I take no responsibility what so ever for any damage, injury, or other faults caused by following my instructions!