Stripped Thread on Rear Light Housing > How to fix?

[Garbo]

One of the threaded holes in my series 3 rear light housing is stripped. It one of the holes where a screw fixes the lens to the housing.

How can I get this back to the correct size (if I drill and tap it I'll need a larger screw in the rear lens, which I don't want).
Could a heli coil or something similar be used? It's only going to fix the light lens so not going to be under a great strain.

If there's something that could be done while the light housing is still in situ, that would be great. I've just had it painted and don't want to risk it getting scratched on a bench etc.

Any ideas would be most welcome!

[HxPaul]

Drill out the thread and aroldite(dont know if thats the right spelling) a nut with the correct thread to the back of the housing.Fit the lense and the screw until the glue is hard.

[MK Monty]

My only suggestion could be classed as a bodge but has worked on small screws like light switches.. May be a bit harder with it painted but worth a try. Screw in and Gentley tap the boss against the screw so it grips the screw, a bit of stud lock and it should hold fine. Used this on things like choke threads on carbs all depends if you can get at the area with a small hammer or even a punch

[steve t]

A helicoil would be fine I had same problem with mine the kits are available from eBay etc they are simple to use and do a good job imo

[al pushpak]

You could drill out the stripped thread & fit a rivnut & secure it using araldite or chemical metal, it should be strong enough & as you stated it only has to hold the lens on. hope you get sorted . al

[gaz_powell]

I would use a rivnut and epoxy resin it in.
Done it on a painted headset for the rim screws.
You can buy the correct size off ebay for coppers.
Plenty of meat on a S3 housing so ideal

Gaz

[Garbo]

Thanks for the replies, much appreciated. Everyone is a good solution.
I had a look on youtube regarding rivnuts and can see how they will work good.
My only question is with the rivets having a 'crumple zone' if they were fitted with the unit in situ, I'm guessing I may need longer screws to reach the threaded part of the rivnut or do I fit them from the backside of the light housing?

BTW the original series 3 lens screws are M3 aren't they?

Cheers!

[gaz_powell]

Dave
Screws are m3
I've used rivnuts very successfully but not in this circumstance so I can't say how it would fit or work out exactly nut yes you may need a longer screw.

gaz

[Garbo]

Thanks Gaz, I'll get a couple of the m3 rivets and take it from there!

Cheers!

[Warkton Tornado No.1]

There is, as ever, yet another way.

Obtain M3.5 (x 0.6) tap & a couple of stainless screws. These are commonly used for domestic electrical sockets on household walls.

(If you are careful & use plenty of lube(!) you can get away with an M3.5 thread 'chaser' as it seems to 'form' the thread rather than cut it. Formed threads are usuallly much stronger & the equivalent of a rolled thread on a stud, say, if they exist in aluminium....)

Put the threaded end of the screw into a pillar drill & carefully using a file, Dremel or die grinder (etc) reduce the head size to match what you have with your M3 screws. This process is like a poor man's lathe.

Tap/chase out the housing to M3.5. The correct tap drill is Ø 2.9 mm, but you''ll get away with it as the tap will start off following the M3 hole pitch which is 0.5.

It does work as several of these have been done over the years in this area.

[EddieStone]

I've used these for stripped threads. Drill out the hole and either fit them in from the back if possible or epoxy them in
http://www.ebay.co.uk/itm/181799619948? ... EBIDX%3AIT

[Garbo]

HI guys, update...
I got some M3 rivnuts from ebay and when I've tried the lense screw into the rivnut thread, it does not fit, the screw is too big.

The screw is too big. I've since reread Warkton Tornado's post and also read this thread :- viewtopic.php?f=10&t=4414

Am I right in thinking that the rear lens screws are M3.5 not M3? That will explain why the M3 rivnuts are too small for the screws.

Cheers!

[Scooter Paul]

Rear light screws are 3.5mm.

[carlos fandango]

I found a use for an old jetex jet ...drill out to m5, loctite in, then re drill and tap