Tex door mirrors - help!

[Horacetoo]

Is there a trick to keeping them on the car?

The shape of the plastic mounting plinth seems designed specifically for the grub screw 'fastener' to push it OFF - not secure it.

Twice now, when seeming solidly secured, the drivers door mirror has fallen off, once at 'speed' and once stationary on the garage forecourt when the mechanic shut - not slammed - the door.

What am I doing wrong? What's the knack?

[Bill_qaz]

Never had much luck with the grub screw clip on frame type on couple of different cars. So have drilled through the outer layer of the triangle near quarter light and fitted bolt on type.

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[geoberni]

Is there a trick to keeping them on the car?

The shape of the plastic mounting plinth seems designed specifically for the grub screw 'fastener' to push it OFF - not secure it.

Twice now, when seeming solidly secured, the drivers door mirror has fallen off, once at 'speed' and once stationary on the garage forecourt when the mechanic shut - not slammed - the door.

What am I doing wrong? What's the knack?

How old is the Mirror?
You mention the 'Plastic Mounting' which I see is a feature of the ones currently sold by ESM.
https://www.morrisminorspares.com/search/acc156
I brought a rectangular one 5 years ago from ESM and it didn't have plastic parts.
I brought it because the one that was fitted to the car (from when I got him), kept coming loose from worn screws.
.

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20260428_105217.jpg (1.07 MiB) Viewed 5040 times

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I did actually apply a small piece of black 'Gaffer Tape' under the metal plate that grub screws bear onto, just to protect the window frame, which it clearly the intent of the revised design....
But it was just a case of hold it all firmly together and tighten the grub screws really tight.
It's held there since 2021....

[Bill_qaz]

The later chinesium ones I tried have a plastic strip to protect the frame but before you can get the grub screws tight enough they just spread the mirrors channel section.
Like lots of the current repo the quality is poor.

[Horacetoo]

These are the type that need screw holes into the door, then a plastic fitting that pushes in, bridging the two holes so it's effectively a double rawlplug fitting. THEN, you add the mirror and tighten it up using a grub screw through the mirror base, parallel to the door. This supposedly tightens the mirror onto the plinth. In fact it does the opposite and pushes it off!