Was on the way back from my folks and whilst on the long 270 degree sliproad to join the dual-carriage way, I noticed the light change to my right in my peripheral view. The wing mirror had dropped slightly and was wobbling. Stopping on the sliproad I thought I could pop it back in, thinking I'd knocked it when filling up with petrol minutes before. But as I pulled it back up a load of rust fell out of the bottom and the thing was loose in my hand. Only the wires for the mirror adjustmnt and demister holding it on. Had no tools so had to leave it dangling. Paintwork! I thought. Tied a t shirt from my bag around it but that lasted to 50mph or 200m. I thought the first aid kit was just for humans, but used a burn compress and surgical tape to create something soft between the mirror casing and the door.
I was slightly horrified at 2nd hand prices thinking that one may turn up also partly corroded. And for another 50 quid I could get a new one from ebay. Still 175 quid for a wingmirror and the base would need painting. So I thought I'd fix it.
It's basically the steel collet that has corroded. This holds the spring that allows the mirror to be rigid but flick back or forth when enough force is applied. They are machine assembled so cannot be replaced AFAIK.
I bought 1 stainless steel M12 x 70mm Allan bolt 2 SS washers and a SS Nylock nut. (Dunno where pound sign is)
#1.83 at my local Chandlery.If you have the facility you could drill out the centre of the bolt to allow the wires along the same path as the collet allowed. For me my engineering friend is 100 miles away and the Mrs was moaning about struggling to parallel park and joining a carriage way a nightmare. So I had to improvise. I drilled out the remains of the rusted collet with a 12mm bit. I think the alloy casing is 14mm but the chandlery chap said 14mm is an odd metric size.
As you can see from the photos I can hopefully add in a minute, the fix fits in all the casings, allows the base rubber to be reseated without hindrance. The only thing I did was to drill and elongate 2 holes into each other to allow a new path for the wires. The metal is quite thick here 4-5mm so will not be structurally weakened by the hole. I chose the position by assuming the position of the mirror if knocked out of position and so that the flange does not slice the wires. The outside of the mirror would have to touch the window. Possible but unlikely. You can adjust the tightness obviously to eliminate vibration and take out any slack.
So a fix for any other head in hands people who didn't realise how much a secondhand or new one is. I believe they are 260 quid from BMW, again only supplied primed.
Apologies if I can't get the photos up straight away. Never done it before.
( Maybe it has) 
