Paging the stripped thread recovery experts - Plastic so helicoil not an option.

So the new M4x70 screws I sourced for the CEV rear light unit are
exactly right, except that now I remember why one was missing - the
thread in the mounting has stripped. This is the thread in a plastic
moulded 'tube' that forms part of the light reflector base. I have a
spare from the Strada I am breaking, but surprise, surprise that lens
was also held on by electrical tape and both the threads are stripped.

No chance of a helicoil or similar and as the lens obviously needs to
come off to change a bulb occasionally a simple adhesive solution isn't
practical.

All I can think of doing is filling the tube completely with bumper
repair (the two part black stuff which is v. good for repairing well
bumpers and other plastic parts) and then screwing in a screw liberally
coated with copper grease. Wait for the goo to have nearly set and
carefully take out the screw to leave a new 'plastic' thread to harden.

Is this likely to work, or am I going to end up with a permanently
bonded screw and tube?
--
+-------------------------------------------------------------------+
| Pete Fisher at Home: |
| Aprilia Shiver Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+

 

Probably the more elegant solution. Which reminds me that I didn't get
to Lidl for that cheap set of taps and dies. I'm not sure if I have an
M4 tap, though I think I have an ancient pikey compendium somewhere. Got
a set of three (1st cut, 2nd cut and plug) good quality ones for M8, but
not much else.

I already have tubes of Bumper Repair and copper grease though.
Spoiling the ship for a 'happorth of tar perhaps.


--

+-----------------------------------------------------------------+
| Pete Fisher at Home: |
| Visit my *NEW* Home Page : http://www.flarefox.com/Joomla |
| "Do not adjust your mind - there is a fault in the reality" |
+-----------------------------------------------------------------+

 

Agree 100%.

 

In communiqué <1js7w07.b4k00rc0zfl2N%>,

<googles>

--
+-------------------------------------------------------------------+
| Pete Fisher at Home: |
| Aprilia Shiver Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+

 

Fill it and re-tap it properly. If I haven't got an M4 tap I can drop
in the post to you I'll abuse my power and order a set.

Why can't you use a helicoil? The only reason I can think of is if
it's too badly fucked and if that's the case then you'll be better
trying to plastic weld it with a bit of similar plastic and a
soldering iron before tapping it rather than using a chemical filler.

 

I ought to be properly equipped as I now have more time to fettle SO
bikes but the offer is appreciated. Off to Lidl tomorrow and will also
get a drill stand if there are any left.

The plastic tubes that stick out from the rest of the back of the light
unit are very thin walled (one is also coming loose from the rest of the
assembly and needs strengthening with JBweld or similar anyway). I can't
see that there is enough meat for a helicoil. Otherwise I might have got
brutal and just drilled and tapped them out to M5 and worried how to
enlarge the hole in the lens without cracking it later. As someone
suggested when I couldn't find long screws, I could use lengths of all
thread right through to the back of the unit with nuts on that end and
dome nuts to hold the lens on. Or just even longer screws and nuts. TBH
that's probably the easiest fix of all if I could find M4 x 80 screws.



--
+-------------------------------------------------------------------+
| Pete Fisher at Home: |
| Aprilia Shiver Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Pete Fisher

I have. Chuck me an address and I'll pop it in the post. You can send it
back when you're done.

 

Very kind, but see reply to Andy. If I can't find my ancient pikey tap
and die set I will get one from Lidl tomorrow. I'm bound to need them
more in the future. Once the 2C/375 is complete (and it very nearly is)
I am turning my attention to the SO YZ250 and the spare Morini 350
engines. Bound to hit some dodgy threads on those. Mind you, I'm upping
the prioritisation of the not required Morini bits Togging out on Ebay.
Two plastic knobs with a bit of M5 thread sticking out for securing the
dual seat on a 350. Already up to £6.50 with 9 days to go. TOG is right,
it's many a mickle that macks a muckle.

--
+-------------------------------------------------------------------+
| Pete Fisher at Home: |
| Aprilia Shiver Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Pete Fisher

Saw that later, fair enough. Let me know if you get stuck, and the
WUNderland machine shop is always at your disposal.

 

I've used epoxy for building boats and it is indeed wonderful stuff. It sets
rockhard so that self-tappers will not work, you have to drill and tap.
It will stick to virtually anything except PVC and if you accidentally
manage to glue a screw tight you just have to heat the screw with a
soldering iron and it will melt the epoxy just enough to free the screw.

 

+1

 

Whilst nodding to JBWeld as the very dab for many things, for a light
unit I'd squeeze some clear silicone sealant into the tube, wind the
screw in and tape it up until the sealant goes off. That'll hold the
lens perfectly well and it'll undo when you need it to.

 

Glue gun - YKIMS

--
Frooty

GSX1300RX - The FAST AS FECK wan
TT250R - The wee dirty wan
Lifan LF50QGY - The wee monkey wan
Down to just three toys :-[

 

What about using some threaded rod bonded in to the reflector posts and a
dome nut with a spring washer underneath to hold the lens on?

 

That would be fine for:

1) A fitting that didn't need to be opened (in this case to change the
bulb - unless Pete was to fit an LED bulb, 'cos they last for ever)

2) A fitting not subject to vibration as hot glue is brittle and the
tail end of bikes rattles around like a Rabbit with Duracells in and
something to prove.

 

Now that sounds my kind of bod\b\b\b ingenuity.
--
+-------------------------------------------------------------------+
| Pete Fisher at Home: |
| Aprilia Shiver Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+

 

Quick, dirty(ish), so cheap as to be effectively free, reasonably
effective and removable. Gingenuity, innit.

 

IMO, no.

Fot this application I've used hot-melt glue with complete success. You
need to squirty-squirtily fill the hole, lightly coat the thread of the
sscrew with a HMP grease, heat the screw and whack it in quickly.

Greasing the thread (*LIGHTLY*!) is most important...

 

Sticky rays!

 

Wrong gluestick then.

The sticks I use remain almost plastic.