Hey everyone, new member here and hoping to be one for awhile. I had an E39 wagon ages ago, finally picked one up as the new daily this weekend. One of the issues I noticed with my new purchase is that the volume knob wiggled and could be pushed in and out. I took out the radio and realized the knob switch was missing the nut that goes behind the knob, allowing the whole switch to move about. Does anyone have a part number for that, or willing to take theirs off to measure the thread pitch and nut height?

 

Use calipers to find out the nut size. Thread pitch should be easy enough to guess,

 

Yea except i’m missing the nut, hence why i’m posting -_- Luckily someone over on bimmerforums was able to send me a spare, turns out it’s a very weird nut. I think it’s a M7x1.25, my hardware store only had a M7x1.0 test stud and the nut could only get a quarter turn before binding. It’s about 6mm thick, and it fits an 11mm socket. Here’s some pics in case someone has to recreate it with washers or something:

 

I clearly understood you did not have the nut. Using calipers, one can ascertain any nut size by measuring the diameter of whatever it screws onto.