One of my Givi hard cases, I think it was called E38,
has developed cracks around the mounting lugs. If they
continue to grow, the case will become unusable.

Does anybody have experience with problems like this,
and better yet, know of an adhesive that sticks well
enough to provide meaningful strength in a repair?

I could drill a bunch of holes and bolt a reinforcement
plate in, as the area is mostly flat, but that's going
to provide a covey of new stress failure points.

I've written to Givi USA, but expect them to say
"replace the case". At current prices, I'd rather
fix it, even if only temporarily.

Thanks for reading,

bob prohaska

bob prohaska <bp@www.zefox.net> wrote in news:umhosi$h9a$2@dont-email.me:

> One of my Givi hard cases, I think it was called E38,
> has developed cracks around the mounting lugs. If they
> continue to grow, the case will become unusable.
>
> Does anybody have experience with problems like this,
> and better yet, know of an adhesive that sticks well
> enough to provide meaningful strength in a repair?
>
> I could drill a bunch of holes and bolt a reinforcement
> plate in, as the area is mostly flat, but that's going
> to provide a covey of new stress failure points.
>
> I've written to Givi USA, but expect them to say
> "replace the case". At current prices, I'd rather
> fix it, even if only temporarily.
>
> Thanks for reading,
>
> bob prohaska
>
>

I would replace it as an E38 must be ancient. I have an E33 & an E45 both
bought over 25 years ago. The E33 is now my map store and lives under a
bed. The E45 is my topbox so does not get the stress on mounting lugs like
on a side case.

As for a repair, you could use some fibreglass matting and epoxy resin
which is what I used to stop a fairing panel cracking any further. That
crack wasn't bearing any load, though.

bob prohaska <bp@www.zefox.net> wrote:
> One of my Givi hard cases, I think it was called E38,
> has developed cracks around the mounting lugs. If they
> continue to grow, the case will become unusable.
>
> Does anybody have experience with problems like this,
> and better yet, know of an adhesive that sticks well
> enough to provide meaningful strength in a repair?
>
> I could drill a bunch of holes and bolt a reinforcement
> plate in, as the area is mostly flat, but that's going
> to provide a covey of new stress failure points.
>
> I've written to Givi USA, but expect them to say
> "replace the case". At current prices, I'd rather
> fix it, even if only temporarily.

> Thanks for reading,

> bob prohaska

Find where the far ends of the cracks are, and drill small ‘crack stopper’
holes there. Then use fibreglass matting and a suitable adhesive inside the
case to reinforce the cracked area.

Car body repair kits should provide the necessary materials.

--
Spike

Spike <aero.spike@mail.com> wrote:
>
> Find where the far ends of the cracks are, and drill small ?crack stopper?
> holes there. Then use fibreglass matting and a suitable adhesive inside the
> case to reinforce the cracked area.

The notion of "suitable adhesive" is what's stopping me. I don't know what
Givi cases were made of ~20 years ago, but they are injection molded and
most moldable platics are tricky to glue. ABS and PVC are glue-able, but
need different glues. Polypropylene and polyethylene (polythene on your
side of the pond) are close to un-glueable AFAIK.
>
> Car body repair kits should provide the necessary materials.

I didn't think of auto body repair kits, that's worth checking.

Thanks for writing!

bob prohaska

On 28/12/2023 20:07, bob prohaska wrote:
>Spike <aero.spike@mail.com> wrote:
>>
>> Find where the far ends of the cracks are, and drill small ?crack stopper?
>> holes there. Then use fibreglass matting and a suitable adhesive inside the
>> case to reinforce the cracked area.
>
>The notion of "suitable adhesive" is what's stopping me. I don't know what
>Givi cases were made of ~20 years ago, but they are injection molded and
>most moldable platics are tricky to glue. ABS and PVC are glue-able, but
>need different glues. Polypropylene and polyethylene (polythene on your
>side of the pond) are close to un-glueable AFAIK.
>>
>> Car body repair kits should provide the necessary materials.
>
>I didn't think of auto body repair kits, that's worth checking.
>
I think at the end of the day, things usually crack or break at the
weakest/most stressed point and a glued joint is usually weaker than the
original. At best the glue will provide a mechanical bond, not a chemical
one on moulded plastic so some kind of patch is essential, maybe some thin
aluminium on both sides with pop rivets?

--
Geoff
NTV 650

geoffC <me@home.nl> wrote:
> On 28/12/2023 20:07, bob prohaska wrote:
>>Spike <aero.spike@mail.com> wrote:
>>>
>>> Find where the far ends of the cracks are, and drill small ?crack stopper?
>>> holes there. Then use fibreglass matting and a suitable adhesive inside the
>>> case to reinforce the cracked area.
>>
>>The notion of "suitable adhesive" is what's stopping me. I don't know what
>>Givi cases were made of ~20 years ago, but they are injection molded and
>>most moldable platics are tricky to glue. ABS and PVC are glue-able, but
>>need different glues. Polypropylene and polyethylene (polythene on your
>>side of the pond) are close to un-glueable AFAIK.
>>>
>>> Car body repair kits should provide the necessary materials.
>>
>>I didn't think of auto body repair kits, that's worth checking.
>>
> I think at the end of the day, things usually crack or break at the
> weakest/most stressed point and a glued joint is usually weaker than the
> original. At best the glue will provide a mechanical bond, not a chemical
> one on moulded plastic so some kind of patch is essential, maybe some thin
> aluminium on both sides with pop rivets?

It would help a lot to know what the plastic is. I've written to
GiviUSA but probably won't get an answer till well into the new
year, if then. Somewhere I got the idea that Givi cases were made
of ABS, which can be glued very well using solvents. If that's
true, a sheet of ABS affixed with solvent cement might be a
fairly good repair. I posted in large part hoping somebody
on these lists might know. So far, nobody's offered a clue.

Thanks for writing,

bob prohaska

bob prohaska <bp@www.zefox.net> wrote in
news:umntmr$119vf$1@dont-email.me:

> It would help a lot to know what the plastic is. I've written to
> GiviUSA but probably won't get an answer till well into the new
> year, if then. Somewhere I got the idea that Givi cases were made
> of ABS, which can be glued very well using solvents. If that's
> true, a sheet of ABS affixed with solvent cement might be a
> fairly good repair. I posted in large part hoping somebody
> on these lists might know. So far, nobody's offered a clue.
>

I looked on my Givi E21 box but could not see a mark

Just dug out the E33 map storage box. Had to remove the maps but it is
clearly marked as recycle code 7 ABS in a roundel in the middle of the
base. The case was bought when I had my first VFR750 in 1993/94

bob prohaska wrote:

> It would help a lot to know what the plastic is [...] so far,
> nobody's offered a clue.
Flames can give clues ...

<https://www.boedeker.com/Technical-Resources/Technical-Library/Plastic-Identification>

Andy Burns <usenet@andyburns.uk> wrote in
news:kva857Fndg1U2@mid.individual.net:

>
> bob prohaska wrote:
>
>> It would help a lot to know what the plastic is [...] so far,
>> nobody's offered a clue.
> Flames can give clues ...
>
> <https://www.boedeker.com/Technical-Resources/Technical-Library/Plastic
> -Identification>
>

excellent idea - burn it and buy another one

On 30/12/2023 10:02, Andy Burns wrote:
>
> bob prohaska wrote:
>
>> It would help a lot to know what the plastic is [...] so far,
>> nobody's offered a clue.
> Flames can give clues ...
>
> <https://www.boedeker.com/Technical-Resources/Technical-Library/Plastic-Identification>

That is so UKRM!
:-)

Chris
--
The Deuchars BBB#40 COFF#14
Yamaha XV750SE & Suzuki GS550t
http://www.Deuchars.org.uk

In uk.rec.motorcycles Andy Burns <usenet@andyburns.uk> wrote:
>
> bob prohaska wrote:
>
>> It would help a lot to know what the plastic is [...] so far,
>> nobody's offered a clue.
> Flames can give clues ...
>
> <https://www.boedeker.com/Technical-Resources/Technical-Library/Plastic-Identification>

I was going to suggest putting a flame to it as a possible means
of identification.

Nominative determinism to the rescue!

(Rt Hon J. Cleverly notwithstanding)

--
FJR1300A, GL1000, KLR650A6F, EX250J9A, DR200SE, Vespa Ciao

In uk.rec.motorcycles wessie <willnotwork@tesco.net> wrote:
>
> Just dug out the E33 map storage box. Had to remove the maps but it is
> clearly marked as recycle code 7 ABS in a roundel in the middle of the
> base. The case was bought when I had my first VFR750 in 1993/94

Sure enough. With enough light the same shows up in the bottom
of my case. ABS glue is readily available for pipe, if I can soak
some fiberglass cloth with it there's hope.

Thank you very much for the needed investigative inspiration!

bob prohaska

bob prohaska <bp@www.zefox.net> wrote in news:umsru5$1seq9$1@dont-email.me:

> In uk.rec.motorcycles wessie <willnotwork@tesco.net> wrote:
>>
>> Just dug out the E33 map storage box. Had to remove the maps but it is
>> clearly marked as recycle code 7 ABS in a roundel in the middle of the
>> base. The case was bought when I had my first VFR750 in 1993/94
>
> Sure enough. With enough light the same shows up in the bottom
> of my case. ABS glue is readily available for pipe, if I can soak
> some fiberglass cloth with it there's hope.
>
> Thank you very much for the needed investigative inspiration!
>
> bob prohaska
>
>

it's weird that the E21 cases bought in 2015 just have a date code in the
same roundel. No evidence of a recycling code or material ID.

In rec.motorcycles.tech wessie <willnotwork@tesco.net> wrote:
>
> it's weird that the E21 cases bought in 2015 just have a date
> code in the
> same roundel. No evidence of a recycling code or material ID.

Perhaps it's tacit acknowledgement that plastics are seldom
actually recycled. The main target of the markings was packaging
for merchandise, mostly food and beverage products. Marking
end products so they can be recycled is noble but futile.

At least here in the USA. We neither repair nor recycle 8-(

On a brighter note, it looks like I can buy a small swatch
of fiberglass cloth and a few ounces of ABS pipe cement for
less than $15. If it works, great. If it fails, it was cheap.
It turns out both of my E38 cases are cracking at the mount
lugs, so a workable fix has considerable benefit.
Thanks very much for your help!

bob prohaska

On 1/1/2024 5:59 AM, bob prohaska wrote:
>
> At least here in the USA. We neither repair nor recycle 8-(
>

Speak for your own locale. (A red state, I assume.)

Here in SoCal, we have 3 bins - black for trash, green for organic waste
(including weeds and food stuff,) and blue bins for recyclables. That
includes plastic containers and styrofoam, along with metal, glass, and
paper. The only thing we don't recycle but should are plastic bags,
because China canceled the contract.

--
The erstwhile Thomas
FJR1300, R1200GS & ST1100 (in memoriam)

On 01/01/2024 13:59, bob prohaska wrote:

>
>On a brighter note, it looks like I can buy a small swatch
>of fiberglass cloth and a few ounces of ABS pipe cement for
>less than $15. If it works, great. If it fails, it was cheap.
>It turns out both of my E38 cases are cracking at the mount
>lugs, so a workable fix has considerable benefit.
>
>Thanks very much for your help!
>
>bob prohaska
>

You can get rolls of woven fibreglass, with edges that are nicely seamed,
5-10cm wide normally used for stitch and tape boat building. Normally it
would be soaked in epoxy resin which would adhere to the glass and the
wood. I think the cement you are planning to use melts the plastic and
welds the two surfaces together. If it sticks to the glass as well you
should be looking at a very strong join. Here's hoping :-).

--
Geoff
NTV 650

On 01/01/2024 22:16, geoffC wrote:
> On 01/01/2024 13:59, bob prohaska wrote:
>
>>
>> On a brighter note, it looks like I can buy a small swatch
>> of fiberglass cloth and a few ounces of ABS pipe cement for
>> less than $15. If it works, great. If it fails, it was cheap.
>> It turns out both of my E38 cases are cracking at the mount lugs, so a
>> workable fix has considerable benefit.
>>
>> Thanks very much for your help!
>>
>> bob prohaska
>>
>
> You can get rolls of woven fibreglass, with edges that are nicely seamed,
> 5-10cm wide normally used for stitch and tape boat building. Normally it
> would be soaked in epoxy resin which would adhere to the glass and the
> wood. I think the cement you are planning to use melts the plastic and
> welds the two surfaces together. If it sticks to the glass as well you
> should be looking at a very strong join. Here's hoping :-).
>

I prefer to use carbon fibre tow and epoxy, often melting some holes
each side of the crack/break and lacing it before applying epoxy, it can
also be reinforced by tape as you describe but carbon fibre. This tends
to work on plastics that the epoxy won't adhere well to.

This video

https://youtu.be/mnNeqSvPQKk

shows a new method by adding staples heated by electrical resistance, a
bit too expensive for me but I shall try a DIY one with nichrome wire
when the opportunity presents itself.

ajh wrote:

> This video
>
> https://youtu.be/mnNeqSvPQKk
>
> shows a new method by adding staples heated by electrical resistance

That was what I mentioned after my first "is it melty" question ...

Andy Burns wrote:

> That was what I mentioned after my first "is it melty" question ...

Oh ... that message sent on the 28th seems to have disappeared into the void

Andy Burns <usenet@andyburns.uk> wrote in
news:kvj7qbF8sf8U10@mid.individual.net:

> Andy Burns wrote:
>
>> That was what I mentioned after my first "is it melty" question ...
>
> Oh ... that message sent on the 28th seems to have disappeared into
> the void
>

yes, one I sent around the same time about the brand of kit[1] I used on my
fairing panel also disappeared

can't find the kit availalbe now - it was in the 1990s on a VFR750

Other Plastic Padding products are still available

[1] just a pack with some fibreglass mat and 2 part epoxy resin sold as
"motorcycle repair kit"

On 02/01/2024 19:46, Andy Burns wrote:
> ajh wrote:
>
>> This video
>>
>> https://youtu.be/mnNeqSvPQKk
>>
>> shows a new method by adding staples heated by electrical resistance
>
> That was what I mentioned after my first "is it melty" question ...
>

Your reply to mine is the first post of yours in the thread that I can
see, I wasn't trying to steal your thunder.

Price wise stitching with carbon fibre then sdding epoxy and tape is
worthwhile.

Spike <aero.spike@mail.com> wrote:
>
> Find where the far ends of the cracks are, and drill small ?crack stopper?
> holes there. Then use fibreglass matting and a suitable adhesive inside the
> case to reinforce the cracked area.

I managed to get some 4" wide fiberglass ribbon and a small can of
cement for ABS pipe. The cement is basically ABS resin dissolved in
acetone. It seems to stick quite well to the case and soaks nicely
into the glass cloth, so that part of the project looks promising.

On close inspection the cracks are much longer than I realized,
extending from the bottom front of the case where the cleats screw
on forward and upward a couple inches toward the corners.
That seems rather bad.

Does anybody have suggestions for a reasonable stop drill size?
My first guess would be no smaller than the case thickness, up
to maybe five or ten times thickness, say somewhere between
one and six millimeters. Does anybody have a better-substantiated
approach to the sizing a stop drill hole?

Thanks to all for writing!

bob prohaska

ajh wrote:

> Your reply to mine is the first post of yours in the thread that I can
> see, I wasn't trying to steal your thunder.

No that's fine, I hadn't realised my reply didn't show up here (or on
google)

> Price wise stitching with carbon fibre then sdding epoxy and tape is
> worthwhile.

bob prohaska <bp@www.zefox.net> wrote:
> Spike <aero.spike@mail.com> wrote:
>>
>> Find where the far ends of the cracks are, and drill small ?crack stopper?
>> holes there. Then use fibreglass matting and a suitable adhesive inside the
>> case to reinforce the cracked area.
>
> I managed to get some 4" wide fiberglass ribbon and a small can of
> cement for ABS pipe. The cement is basically ABS resin dissolved in
> acetone. It seems to stick quite well to the case and soaks nicely
> into the glass cloth, so that part of the project looks promising.
>
> On close inspection the cracks are much longer than I realized,
> extending from the bottom front of the case where the cleats screw
> on forward and upward a couple inches toward the corners.
> That seems rather bad.
>
> Does anybody have suggestions for a reasonable stop drill size?
> My first guess would be no smaller than the case thickness, up
> to maybe five or ten times thickness, say somewhere between
> one and six millimeters. Does anybody have a better-substantiated
> approach to the sizing a stop drill hole?
>
> Thanks to all for writing!

> bob prohaska

For a crack stopper, I’d suggest a 2mm drill, and a problem you might have
is that the through-thickness crack front might not be square across the
thickness. You’ll need to examine each crack to ascertain where the ends of
each crack is both inside and outside, and then drill along the crack
front, which might not be square to the local surfaces. This is to avoid
drilling larger holes than needed.

Another thing you might consider is to epoxy short pieces of steel across
the ends of each crack, before applying the glass-fibre matting, whether or
not you drill crack-stopper holes. If doing this, clean the steel strip
with alcohol before applying the epoxy and avoid handling the bonding
surface. Apply pressure until the epoxy sets.

HTH

--
Spike

In uk.rec.motorcycles Spike <aero.spike@mail.com> wrote:
> For a crack stopper, I?d suggest a 2mm drill, and a problem you might have
> is that the through-thickness crack front might not be square across the
> thickness. You?ll need to examine each crack to ascertain where the ends of
> each crack is both inside and outside, and then drill along the crack
> front, which might not be square to the local surfaces. This is to avoid
> drilling larger holes than needed.
>

There's enough material for 5-10 mm holes, but I'll look more carefully
to see if the crack inclination can be discerned.

> Another thing you might consider is to epoxy short pieces of steel across
> the ends of each crack, before applying the glass-fibre matting, whether or
> not you drill crack-stopper holes. If doing this, clean the steel strip
> with alcohol before applying the epoxy and avoid handling the bonding
> surface. Apply pressure until the epoxy sets.

I wonder if using a small screw, washers and nut clamping the ends of
the cracks flat might have a similar effect. That's easier to do,
looks aren't a huge issue. Flatness near the crack ends might be
as the cracks follow the curve from the bottom of the case to the
corners. The end area might not be entirely flat.

Thanks for writing!

bob prohaska