Thanks for the answer!
The mirror "leg" that is attached to the door, is not loose however. The mirror is attached to it and is moving a few millimetres on the leg. Any ideas?

 

I don't know how the RX mirror is made. I have only taken my IS mirrors apart. The only thing I can suggest is to pop the mirror out of the housing and look.in there.

 

Does anyone know what size the starlock (internal toothed) washer is for the IS250? My gf is in NC and I'm planning to see her this weekend and fix her loose mirrors. I'm assuming since it's a yota/lex it's metric. The reason everyone in this thread says they pop off after following the YouTube vids is because these are one-time use washers.

Rant - Either the Lexus design engineers didn't choose the right size for the mirror post/shaf, they went with a standard size instead of a special/custom size for these one-offs so as to keep the standard part cost down which might not engage/lock onto the shaft properly, or the manufacturing techs aren't using a calibrated tool when setting/installing the starlock washers in the first place.

Either way, don't reuse the existing, deformed washers. Discard them and put new ones on. Same thing for replacing aluminum bolts, etc.

If anyone has a pair of calipers laying around or a link to the parts like realoem does for my bimmer that would be great. The shaft/post diameter at the constant radius and the outer washer diameter should be enough to allow me to find the right spec washer. Also something to be aware of for those using other hardware like shaft collars, clamps, and bolts...use similar materials if you don't want to accelerate galvanic corrosion.

 

As I previously posted, both of my mirrors came apart. I looked at the mark the star washer left on the post and drilled a hole through the tube just above that mark. I re-assembled the mirror using the original star washer and then installed a cotter pin through the holes I drilled in the post. It's going to be a long, long time before that mirror comes apart.

You don't need to re-engineer the thing.

 

Hey, thanks for the help...I'm pretty sure drilling a hole and buying a cotter pin is the definition of "re-engineering" and retrofitting. I'm just trying to replace the starlock washer with a new one (the original design). So thanks for nothing lol.