Will any glue stick bike plastics?

Hi All,

I tidying up my little CB250 ShiteHawk (the Daughter may well move
onto it after her test) and there is some crack damage to the lhs
panel and the little one that joins the two side panels over the
taillight that I like to sort pre re-painting (a mate will do that for
me for nowt).

Ages ago I drilled the crack on the side panel and cable tied it
together at the open end of the crack (it nearly went across the whole
panel) and it hasn't got any worse over the last couple of years.

I have now taken plastics off, cleaned them thoroughly and super glued
the cracks together, just to keep them aligned for the next step.

So, working on the theory that outside of a proper 'plastic welded
repair' (assuming that might be expensive?) I was thinking of screwing
some small ally plates across the back of the cracks using small
countersunk screws from the outside (than could be filled over) maybe
with the plates bedded in some Epoxy or summat (after keying up the
panel)?

Is there a better (cost effective) d-i-y way please?

All the best ..

T i m

 

I used some fibreglass webbing and a 2 pack resin to fix it in place for a
panel on a VFR. You can buy it in a kit but you can probably get the items
individually from hobby shops or motor factors.

Lozzo's the man for this sort of stuff.

 

Cracked side panel is a POP to do yersel with a hot air gun and filler
rod. I've used a soldering iron to good effect, but it's stinky and
messy. Pre plastic welding, another method I used successfully on panels
was a couple of layers of fibreglass on the rear/inside.
--
Dave
GS850x2 XS650 SE6a

"A scone and tea at half past three
Makes the day a little brighter
Keep your cakes and fancy tarts
And stick them up your shiter."

 

Thanks for that. I'm fairy handy with fiberglass and probably have
enough stuff here to do something anyway, what I really wasn't sure
about is the bond and reaction parts. A cracked side panel being less
obvious than a dissolved / melted one etc :-(

Ok, I'll look forward to his input .. ;-)

All the best ..

T i m

 

You will need a nozzle to concentrate the air flow, to make a smaller,
hotter area. You could easily make one, or adapt the wide one.

--

 

That's what I thought and the idea of the ally strips, to make a
mechanical support before I did any aesthetic stuff (the super glue
was simply to keep the bits in-line till I supported them better). Say
50mm long, 20mm wide and 3 mm thick, two small countersunk machine
screws either side of the crack in a few key places (and bedded in
epoxy to help it all stay together)?

Understood.

All the best ..

T i m

 

For a quick but reasonably strong bodge, I use Isopon plastic bumper
fill reinforced with plates of plastic on the inside across the crack. I
retained the lad's cast off KX65 front mudguard for supplying such
patches. Not cheap at 8 quid for 100ml, but once hard seems very strong
and any fill showing on the outside sands down to a nice finish.

The repair I did recently to the tank 'fairing' on the Nordie stood up
to Champ's treatment at Prescott OK.


--
+----------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+----------------------------------------------------------------+

 

I did a bit of Googling on that before I asked here and it looked like
the 'basic kit' for plastic welding (inc some sample plastics) was
gonna cost me 100 notes (for what looked like an everyday hot air
gun?) and £300+ for something that looked like it would focus the heat
more specifically (and with a rod feed tube etc). I'm not saying that
the fist set wouldn't work, but as a fairly long term solderer and
metal welder I imagined the plastic getting too hot generally and all
folding up (like welding thin ally)? :-(

I even asked about to see if I could put a decent kit to some extra
use, to help it pay for itself at least but it was suggested I would
probably have to do the painting as well and I'm not up for that, not
right now anyway?

I had also considered that, at least just peening / stitching (?) the
joint together from the back so it's got some continuation to the
plastic at least. So is the basic idea to build up a plastic weld
'bead' over the crack to carry the load round the crack? Or to 'weld'
some extra material over the crack (sorta the same thing but using
'bits' of the same sort of plastic rather than filler rod as such)?

Well, I guess I could do that as well Dave? So, I clean the inner
surface back to the native plastic (it looks a sort of yellow?) and
just layup some glass mat (I've got some woven cloth / carbon cloth
and tissue as well) over the broken area (a few inches either side
etc).

All the best ..

T i m

 

..

That's what I saw and was thinking Steve but there must be more to it
than that.

The more pro systems seem to have a fairly fine air nozzle with a
temperature controlled hot air gun. Better systems seem to look more
like a fat soldering iron that uses air, either from an external
compressor or one built into the 'air iron'.

I can see how a *very* fine stream of suitably hot air could be used
on plastic, just as an oxy / acetylene welder might on some sheet
steel but even with steel you get stuff distorting ..?

All the best ..

T i m

 

And is that it Joe (assuming some matching material to act as filler
rod etc)? Is temperature control essential (especially for a novice)?

Is it then just a matter of building up some material behind the
crack?

All the best ..

T i m

 

Ah, thanks and I guess it's specifically designed for such
traditionally 'non-stick' plastics?

Well I have a spare rear panel I could cut up and use in a similar
way.

Ok and I like the idea of being able to d-i-y it quickly and easily
etc. I wonder if it would be as strong or stronger and stick better
than the fiberglass solution?

That sounds like it took some knocks (not knowing Champ or Prescott
sri). ;-)

Thanks and all the best Pete ..

T i m

 

I know someone who used to remodel body panels for custom bikes using it
(or a similar goo called bumper repair IIRC).

The main thing is to bridge the gap. The patch doesn't need to be very
thick. In fact if you have room to smother the patch with the filler as
well as stick it on that is good. Needless to say you need to roughen up
the surface of the inside of the panel and the patch well and make sure
they are really clean (I gouge them with a sharp screw driver and clean
using brake cleaner spray). I've also used it successfully to repair
broken mounting points on seats (with the aid of a plastic bobbin for
extra strength). In fact I need to do just that on GFR#2, and the job I
did on GFR#1 has lasted since 1998.

Well I dare say he was giving the panels a fair squeeze under braking.
--
+----------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+----------------------------------------------------------------+

 

So it's quite versatile then.

Ok. In the case of this side panel (it's long thin and goes from the
back of the tank to the end of the taillight) I believe it was broken
by someone pulling it off at the front carelessly (before I got it
honest). The break is very clean and there is no material missing. It
goes about 3/4 the way across the maybe 4" wide lightly 'U' section
plastic, under where the pillion leg might rest. I'm pretty sure there
isn't anything under there when it's in place so I have quite a bit of
room for 'bracing' etc. If it were fiberglass I would simply glass
over some small softwood 'bridges' after putting a layer of glass over
the general area first.

Yup, pretty sure there is plenty of space (but would check before
doing so).

Good stuff then! ;-)
All the best ..

T i m

 

Weld it, it's far easier and makes for a more permanent repair. I've
been using the soldering iron and filler rod approach so far, but I'm
about to start experimenting with hot air gun useage. my filler rod is
an old GPZ500 fairing chopped into strips afterremoving the paint.
Paint contaminates the weld and makes it brittle as well as making it
harder to get a good paint finish. Ideally you need as much of the
original plastic as possible, don't go cutting V grooves cos you'll
only need more filler rod and it will take longer.

When I'm repairing a crack or welding back in a broken part I start on
the back of the panel and tack it into place. I'll turn it over and
check it's all in line before finishing the weld on the back side. Then
I'll repeat for the front after removing the paint from 5 to 10mm each
side of the line I want to weld. To start with I just get the bits
stuck together, then I'll go back over it with filler rod building it
up until it's proud of the panel. When it's done I flatten it back
until it's just a little proud and give it to my painter to finish off
with a DA sander or whatever he wants to use.

If you're being really flash you can make the inside weld as invisible
as the outer one, which is handy on some bikes that have fairing panels
visible from both sides, like my Thunderace mirror mount was.

I'll let you know how I get on with the hot air gun tomorrow. There's
an SV top fairing in the garage I can experiment on

 

SWMBO has an example of the very same bike. On her 92 model the side
panels come off all in one unit. I must admit I had to have a good look
at the handbook to discover how to do it. I can understand someone
breaking it if they didn't RTFM.

It works for me. Lozzo's method is far more elegant and probably
ultimately stronger. I must experiment with it on the old Nordwest
panels I have lying around. I will confess that the bodge on the Nordie
was a mega-bodge in that I didn't even remove the panel. I was in a
hurry to get the bike ready and then dropped on to the corner of a tool
box (6 inches to the right and i would have got away with it) whilst
checking the oil (yes Pip I lack balance and strength).

Also the break was in a position that feared that the crack would
'travel' as the tension was removed on undoing the fastener near the
break. So I did the patch with the panel in situ. The break left a gap
the size of a 50p piece without any surviving fragments left worth
using. The bumper fill built up on the patch brought the surface up to
match nicely.

--
+----------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+----------------------------------------------------------------+

 

Ok, I've got a cheapo temperature controlled one so I guess hot enough
to melt but not so hot as it bubbles and burns etc?

Got it, good description. ;-)

Understood, I do have a complete spare lhs panel I picked up from ebay
and although it's not broken it does have a lug missing (I didn't spot
that till after I'd bought it but it was cheap enough so ...). I also
have a spare back fairing panel so I might be able to cut some
de-pained strips from that to use as a filler rod.

Understood .. ;-)

All the best and thanks Jim.

T i m

 

Yup, that's the beast. 2 x 10mm bolts and the whole lot comes off easy
enough though.

Indeed. It would make more sense if it was the rhs panel as that's
where the battery lives?

I might be letting you all know tomorrow!

I did similar when I got this bike with the nearly_cracked_in_two
panel. Drilled the hole at the end of the crack and two either side on
the edge to run a cable tie through. It hardly noticed but you just
had to be careful when taking it off. I had considered doing some
cable tie 'stitching' (like I'd seen done elsewhere) but as I wanted
to get it painted as well it seemed a shame not to try to get it as
tidy as possible.

Oooowwwwaa.! Dontcha just hate it when that happens? Like when you are
using the wrong tool because you are in a hurry and think "if this
slips I could hurt my ... ah .. " :-(

Sounds like it served you proud. ;-)

All the best ..

T i m

 

Yeah, I'm going to get some of that as well as it sounds pretty handy
(thanks).

All the best ..

T i m

 

Ok, well I like the idea of that on both counts. ;-)

Ah, well, good luck with that then? What hot air gun do you have?

Is it generally considered ok to use *any* bike fairing plastic or
should you try to stick with similar model bits?

Do you sand that off or is it a Nitromors job (wasn't sure what that
would do to the plastic)?

Ok, noted. Luckily nothing is missing from this job (basic crack) but
I understand if there was a hole etc.

Ok, so that's the same as my super glue stage then (mind you that's
gonna stink when it get's hot eh..) :-(

Ok ..

Ok, so on mine you probably wouldn't even know there was any damage at
that point (the crack is pretty clean and tight) but you would still
also process it from the front side to provide the strength?

(rasp / glass - emery- paper / wet_n_dry)?

That will be me again. So just sand it flat with whatever works ..

Understood. In this case it's a straight one_sided affair. ;-)

And me with the iron. Any advice re the shape of the tip please Lozzo,
what are we trying to do here? I imagine a chisel tip would allow
penetration whilst allowing you to move the plastic about a bit?

Luckily I don't have anything as yet .. <touching wood>.

All the best, good luck tomorrow and thanks for the info.

T i m

 

And modest, don't forget modest.
--
Dave
GS850x2 XS650 SE6a

"A scone and tea at half past three
Makes the day a little brighter
Keep your cakes and fancy tarts
And stick them up your shiter."