RX450h 3rd Gen Rear View Mirror Screw

[NeilJordan]

Does anyone know the size/spec for this - ours is missing at the moment and can't get anything from a dealer at the moment?

Thanks

[Herbie]

Do you mean the ball? Can you take a photo of where it should be or perhaps find a photo online, because I'm not sure exactly what you mean?

[NeilJordan]

It is the screw that would normally fix to the bracket on the windscreen.  Photo attached as best I could.

 

[Herbie]

This is the only thing I could find:

[NeilJordan]

Thanks. Yes I have found the same now, but still no real joy.

An M4 hex bolt is too small and an M5 too big. I am not even sure you can get an M4.5.

I asked the dealer and they suggest they can't get the bolt separately, so only choice is to buy the full assembly - around £1k or so...

The only thing I can think of is to keep looking on eBay for anyone selling a mirror with the bolt, buy it, then sell the mirror again.

[Herbie]

I must confess that even though I posted those two pages from the workshop manual, I've not actually looked at it in the car and so I'm still not sure what part this screw plays. What does it actually do? Does it simply hold the cover on?

What I'm getting at is, could you not just forget the screw and use a bit of glue to hold the cover on instead, if that's the job of the screw?

Alternatively, could it be a different thread, such as BA or something else other than metric?

The text below is taken from http://www.wheels-alive.co.uk/need-to-know-series-no-4-threads-spanners-and-things/

Conceived as the age of electricity dawned to fulfil a need for small to sub-miniature nuts and bolts, BA fastener sizes are designated by a number, allocated on the basis of ‘the smaller the diameter, the higher the number.’ The series starts with 0BA – the biggest bolt diameter, at 0.236 inches (approx. 6mm). Standard diameters down to 12BA are still easily available, and the series is specified down to 25BA (0.25mm). Sizes smaller than 16BA (0.79mm) and odd numbers like 3BA, 5BA etc are rare.

Extensively used in electrical and electronic equipment and fittings, over the years BA fasteners have found wide application in instrumentation and similar equipment built in Britain. Use was also widespread over many years in British motor vehicles, with BA nuts and bolts found in minor part attachments around the vehicle, and in externally sourced ancillary equipment, including fuel pumps, wiper and heater motors, dashboard instruments, and sundry auto-electrical equipment.

BA nuts and bolts have their own unique spanner sizes, which, though today quite expensive, remain available. It’s also possible to obtain so called “nut spinners” (similar to a screwdriver but with a miniature socket on the end) in BA (and small metric) sizes, useful when dealing with small nuts and bolts in confined spaces. A set covering 0BA, 2BA, 4BA and 6BA should cover most classic automotive work.

Since the 1970s, BA threaded components have been replaced by small metric-style fasteners, in sizes such as M2, M3, M3.5 and M4, bringing a delicious irony to what was one of the great survivors from the age of independent British engineering. The BA series dared to be dimensionally unique, but shared a 47½ degree thread angle with the small metric thread set dreamed up in 1878 by Professor Michael Thury of Geneva University and known as Systématique des vis Horlogères. The BA thread design has roots in both Joseph Whitworth’s ideas and British simplification of Thury’s complex metric thread dimensions, and survived well into the 1970s – but the Professor’s design fell by the wayside when common thread standards for metric fasteners were agreed in 1898.

[NeilJordan]

On this version, the mirror kind of slots into the metal plate on the windscreen, but basically wobbles all over the place without the bolt.  The bolt goes through the base of the mirror which is threaded with the end pushing against the plate.  Basically it is the only thing that really fixes it to the screen - it is pretty intrinsic to the fixing of the mirror.

Glue might be possible, but it isn't a direct fitting between the two sections as they have to be slid together - it would probably cause a bit of a mess and there might not be much glue left in contact.

It seems pretty odd that they wouldn't have just gone for a standard metric bolt.

I keep trying sellers who are breaking or those selling the mirrors themselves on eBay, but have had little joy in finding someone who hasn't discarded the bolt. I have one option at the moment which looks like the right thing but a long delivery time for some reason. From a 2010 model so I hope that wouldn't have changed...

[Herbie]

Only other thing I can think of then is to maybe drill and/or re-tap to a different size.

[PeterI]

McMaster do a M4.5 bolt https://www.mcmaster.com/bolts/thread-size~m4-5/ so they do exist only question is if it's the right one and who sells them in the UK.

[Illogan]

M4.5 bolts on amazon UK - - may be worth a tickle:  https://www.amazon.co.uk/DealMux-Metal-Machine-Screw-Silver/dp/B072KN17Y6