Plastics use on Kbikes

jjefferies · 1 Plastics use on Kbikes Sat Feb 20, 2021 9:55 pm

jjefferies

Life time member

Number of posts : 551

Hello all, anyone know for sure what the side panels on a K100/K75 are made of? This is a dark plastic. I've been attempting to repair a side panel, the one covering the fuses and next to the battery. The bit which holds the metal clip broke. I've tried repairing it with JB Weld metal epoxy. That worked for a while but finally failed as the JBWeld didn't bond to the plastic side panel. I'm removing the old JBWeld but need an idea how to make the bond solid on the repair.

As always thanks for the info./opinions.

robmack · 2 Re: Plastics use on Kbikes Sat Feb 20, 2021 11:11 pm

robmack

Life time member

Number of posts : 2326

Very detailed description of the fibreglass used by BMW is here: https://forums.bmwmoa.org/showthread.php?38950-What-type-of-plastic-is-the-K75S-bodywork-made-of&p=493002&viewfull=1#post493002

Point-Seven-five · 3 Re: Plastics use on Kbikes Sat Feb 20, 2021 11:26 pm

Point-Seven-five

Life time member

Number of posts : 4172

I could be wrong, but I think those parts(battery covers) were injection molded using ABS(acrylamide-butadeine-styrene). This resin is very popular in the automotive industry for body panels. I would try making the repair with Super Glue. ABS and Super Glue should be pretty compatible because they are both acrylic based.

An alternative would be to solvent weld the repair using the cement made for ABS pipe fittings.

Whichever way you go, it's important to clean the surfaces to be bonded with alcohol and use some of the primer made for ABS pipe if you choose to use the ABS cement. Don't use the primer with Super Glue.

To make sure the repair lasts as long as the rest of the bike, I would reinforce the repair with some wire. After you glue up the parts drill a couple holes through the joint and Super Glue some pieces of .030" brass or steel wire into the holes.

Last edited by Point-Seven-five on Sat Feb 20, 2021 11:43 pm; edited 1 time in total

Point-Seven-five · 4 Re: Plastics use on Kbikes Sat Feb 20, 2021 11:38 pm

Point-Seven-five

Life time member

Number of posts : 4172

robmack wrote:Very detailed description of the fibreglass used by BMW is here: https://forums.bmwmoa.org/showthread.php?38950-What-type-of-plastic-is-the-K75S-bodywork-made-of&p=493002&viewfull=1#post493002

The resin described in the link is known as bulk molding compound, or BMC. It was used in the main fairing headlight surrounds, lower fairing side panels, radiator grilles, and the tail cowl. It was also used in the K75S and K100RS belly pans.

This material wasn't used in in parts like the battery covers, radiator side panels, and mirror pods and requires different repair methods.

jjefferies · 5 Re: Plastics use on Kbikes Sun Feb 21, 2021 12:43 am

jjefferies

Life time member

Number of posts : 551

Point-Seven-five wrote:

robmack wrote:Very detailed description of the fibreglass used by BMW is here: https://forums.bmwmoa.org/showthread.php?38950-What-type-of-plastic-is-the-K75S-bodywork-made-of&p=493002&viewfull=1#post493002

The resin described in the link is known as bulk molding compound, or BMC. It was used in the main fairing headlight surrounds, lower fairing side panels, radiator grilles, and the tail cowl. It was also used in the K75S and K100RS belly pans.

This material wasn't used in in parts like the battery covers, radiator side panels, and mirror pods and requires different repair methods.

Thank you for the links. I followed those and then continued my search for ABS. What I believe I've learned is that the main fairings, tail section, headlight cowling are made of the "Fibron" BMW's name for their proprietary Fiberglass. The smaller pieces like the side panels are apparently made of some version of ABS. Following this:

How can I easily identify a plastic?
Frequently Asked Questions

One of the simplest ways to carry out a flame test is by cutting a sample from the plastic and igniting it in a fume cupboard. The colour of flame, scent and characteristics of burning can give an indication of the type of plastic:

    Polyethylene (PE) - Drips, smells like candlewax
    Polypropylene (PP) - Drips, smells mostly of dirty engine oil and undertones of candlewax
    Polymethylmethacrylate (PMMA, "Perspex") - Bubbles, crackles, sweet aromatic smell
    Polyvinylchloride (PVC-U, Unplasticised) - Self extinguishing flame
    Polyvinylchloride (PVC, Plasticised) - Green tinge to flame and white acrid fume
    Polyamide or "Nylon" (PA) - Sooty flame, smells of marigolds
    Acrylonitrilebutadienestyrene (ABS) - Not transparent, sooty flame, smells of marigolds
                Observe the color of the flame when the plastic is in the fire. If it is ABS, it will
              have a yellow flame while others may produce a green, blue, or orange flame.
                Looking for blue edges around the yellow flame, indicating it's ABS plastic.
            Notice a pungent smell if is ABS.Feb 13, 2020
   Polycarbonate (PC) - No drips, phenolic smell
    Polyurethane foam (PU) - Yellow flame, acrid smell, plastic crumbles
    Polyethylene foam (PE) - Drips, smells of candlewax

I took a small piece of the side panel and heated it with a butane torch. It burned yellow with blue edges non-transparent, somewhat sooty, bubbled up and I can't say what it smells like as my sniffer isn't up to snuff. But I think it probably is some variant of ABS. I also tested the material with acetone but while it cleaned off and left a slight dark stain behind on the acetone soaked cotton Q-tip the material didn't soften up like I expected of ABS.

For the moment I'm going to go with the assumption the panels are made of ABS and see if that works.

Thanks for the info/links etc.

Also I'm working on an '86 K100 and the radiator cowling appears to be the "Fibron" but my K75's all seem to be made of the"ABS??" plastic. Probably a manufacturing change.

Point-Seven-five · 6 Re: Plastics use on Kbikes Sun Feb 21, 2021 1:07 am

Point-Seven-five

Life time member

Number of posts : 4172

If you really want a treat for your nose do the flame test on a sample of Acetel resin(Delrin or Celcon). Smells just like tear gas.

If your flame test doesn't exactly produce the results typical of ABS, it could be that the material was a resin marketed in the 80's to the automotive industry under the trade name Pulse. It was an alloy of ABS and polycarbonate that was supposed to have the flexibility of the ABS and the impact resistance of polycarbonate. Unfortunately, it had the bad properties of the two base resins and was a bitch to process so I don't think too many parts were made with it, but I wouldn't be surprised if BMW used it.

Dai · 7 Re: Plastics use on Kbikes Sun Feb 21, 2021 8:15 am

Dai

Life time member

Number of posts : 5383

If the repair doesn't have to be visually externally perfect, I've made up L-shaped stainless brackets the same height as the original and used a 3mm buttonhead to screw it to the sidepanel. Add a dab of the correct colour paint and it's almost invisible unless (a) you're aware it's there and (b) you look straight at it. It's also very strong.

jjefferies · 8 Re: Plastics use on Kbikes Sun Feb 21, 2021 4:37 pm

jjefferies

Life time member

Number of posts : 551

Dai wrote:If the repair doesn't have to be visually externally perfect, I've made up L-shaped stainless brackets the same height as the original and used a 3mm buttonhead to screw it to the sidepanel. Add a dab of the correct colour paint and it's almost invisible unless (a) you're aware it's there and (b) you look straight at it. It's also very strong.

Ok, we're talking K75 or later model K100 side panels with a flat spring attached to the lower part of the panel which hooks over a 1/8" diameter steel stanchion/rod which is welded onto the frame. There is a rubber piece which goes onto the 1/8" stanchion/rod on which the flat spring rides. Now the L-shaped stainless bracket you are describing, does it hold the flat spring in place or does it replace the flat spring?

Up til now my efforts have been to repair or replace the ABS plastic extrusion which holds the flat spring. Hence my questions about the types of plastic. After several different attempts to repair the ABS plastic extrusion I'm now attempting to replace it. But the several efforts have left the plastic side panel substantially weakened and I'm open to other approaches to mounting the panel.

Thanks

Point-Seven-five · 9 Re: Plastics use on Kbikes Sun Feb 21, 2021 5:03 pm

Point-Seven-five

Life time member

Number of posts : 4172

It would be great if you could post some photos.

jjefferies · 10 Re: Plastics use on Kbikes Sun Feb 21, 2021 6:16 pm

jjefferies

Life time member

Number of posts : 551

Point-Seven-five wrote:It would be great if you could post some photos.

I agree. And I've tried several times with accounts on various hosting platforms. Spent a bit of time trying to. So far the only photo I've managed to upload is the one of my Red K75. This despite assurances it was so easy even a dumb southerner could do it. NADA.

TacKler · 11 Re: Plastics use on Kbikes Sun Feb 21, 2021 7:12 pm

TacKler

Life time member

Number of posts : 1283

jjefferies wrote:

Point-Seven-five wrote:It would be great if you could post some photos.

I agree. And I've tried several times with accounts on various hosting platforms. Spent a bit of time trying to. So far the only photo I've managed to upload is the one of my Red K75. This despite assurances it was so easy even a dumb southerner could do it. NADA.

Do you have Snipping Tool on your computer menu? It is one of the best and most basic copying tools I have come across. It literally is just cut & paste. No need to have a host server to store your photo as you are cutting out a copy and pasting it on the page you write. A digital version of what you did in kindergarten.

Nerdy bit: From memory it does not come complete with the meta data if hosted elsewhere and I don't think it will come up on a tineye or other search. Computer geeks will clarify this info which is incidentally irrelevant for what you are trying to achieve.

An example below from this Post a reply window:

Plastics use on Kbikes P9zp3QX0mxrbgAAAABJRU5ErkJggg==

Plastics use on Kbikes P9zp3QX0mxrbgAAAABJRU5ErkJggg==

jjefferies · 12 Re: Plastics use on Kbikes Sun Feb 21, 2021 11:59 pm

jjefferies

Life time member

Number of posts : 551

TacKler wrote:
Do you have Snipping Tool on your computer menu?

Unfortunately in some senses the snipping tool is a Windows thingie and I run linux. There's always a downside to all good things. There are other ways I'm sure to achieve the same effect such as taking a screen shot. Something else I can play with once I have solved the problems ahead of it.

Thanks for the heads up and I'll give it a try later as a workaround to being able to upload pictures.

Laitch · 13 Re: Plastics use on Kbikes Mon Feb 22, 2021 1:16 am

Laitch

Life time member

Number of posts : 3136

jjefferies wrote:This despite assurances it was so easy even a dumb southerner could do it. NADA.

You're probably too smart for it, J. Dumb yourself down for 15 minutes and you'll figure it out.

stanthomas · 14 Re: Plastics use on Kbikes Mon Feb 22, 2021 8:25 pm

stanthomas

Silver member

Number of posts : 107

Point-Seven-five wrote:

robmack wrote:Very detailed description of the fibreglass used by BMW is here: https://forums.bmwmoa.org/showthread.php?38950-What-type-of-plastic-is-the-K75S-bodywork-made-of&p=493002&viewfull=1#post493002

The resin described in the link is known as bulk molding compound, or BMC. It was used in the main fairing headlight surrounds, lower fairing side panels, radiator grilles, and the tail cowl. It was also used in the K75S and K100RS belly pans.

The belly pan / spoiler on my 16V doesn't seem to be the same material as the fairing. While the fairing is solid and stiff (ooh, err, missus), the spoiler is flexible and has splits that seem inconsistent with a fibre reinforced part. In fact the bumper/fender plastic on cars seems a closer match. Need to repair it and I'm going to try plumbing ABS solvent together with melting in some steel reinforcing pins.

jjefferies wrote:

TacKler wrote:
Do you have Snipping Tool on your computer menu?

Unfortunately in some senses the snipping tool is a Windows thingie and I run linux. There's always a downside to all good things. There are other ways I'm sure to achieve the same effect such as taking a screen shot. Something else I can play with once I have solved the problems ahead of it.

On my system (MATE 1.22), in the Applications menu under tools, there's "Take Screenshot". It's a GNOME tool I think. Also in the GIMP you can do File / Create / Screenshot. Unfortunately, this is the biggest image I could get away with directly pasting into my reply so it's unlikely you'll be able to add any useful photos by this route.

Plastics use on Kbikes 4LcXkdSaAQ2T0AAAAASUVORK5CYII=

Plastics use on Kbikes 4LcXkdSaAQ2T0AAAAASUVORK5CYII=

Point-Seven-five · 15 Re: Plastics use on Kbikes Mon Feb 22, 2021 9:30 pm

Point-Seven-five

Life time member

Number of posts : 4172

K1100RS belly pans were made with some sort of thermoplastic rubber. I would guess polyurethane so an ABS cement probably wouldn't work. I would search on the internet for information on repairing flexible bumper skins.

brickrider2 · 16 Re: Plastics use on Kbikes Tue Feb 23, 2021 12:25 am

brickrider2

Life time member

Number of posts : 729

Plastex has been marketing repair kits for plastic for decades. Have you considered something like this?
https://www.walmart.com/ip/Plastex-Plastic-Repair-Kit-Standard-Size-Kit/577314724?wmlspartner=wmtlabs&adid=22222222222342816728&wmlspartner=wmtlabs&wl0=e&wl1=s&wl2=c&wl3=74973075949182&wl4=pla-4578572612226860&wl5=&wl6=&wl7=&%20wl10=Walmart&wl12=577314724_10001034659&wl14=plastex%20repair%20kit&veh=sem&msclkid=e7567ca99c1212a16c8c1c9d1edc75d2

jjefferies · 17 Re: Plastics use on Kbikes Tue Feb 23, 2021 1:24 am

jjefferies

Life time member

Number of posts : 551

brickrider2 wrote:Plastex has been marketing repair kits for plastic for decades. Have you considered something like this?
https://www.walmart.com/ip/Plastex-Plastic-Repair-Kit-Standard-Size-Kit/577314724?wmlspartner=wmtlabs&adid=22222222222342816728&wmlspartner=wmtlabs&wl0=e&wl1=s&wl2=c&wl3=74973075949182&wl4=pla-4578572612226860&wl5=&wl6=&wl7=&%20wl10=Walmart&wl12=577314724_10001034659&wl14=plastex%20repair%20kit&veh=sem&msclkid=e7567ca99c1212a16c8c1c9d1edc75d2

I'm looking at the tradeoffs. Plastex as a repair method is $40. ($30 for the kit and $10 for shipping) I found a pair of 2nd hand panels the other day for $20. Not broken just the wrong color. The reason for repairing the old panel is that it's already painted the correct color. I'm going to give the repair a chance as I found ABS glue was $4.00. If abs glue works then the repaired panel is the way to go. Otherwise I'll get a spray can of paint made up in the preferred red color which will be an additional cost and shoot the panels.

Dai · 18 Re: Plastics use on Kbikes Tue Feb 23, 2021 4:13 am

Dai

Life time member

Number of posts : 5383

Oops. Wrong bike. Both of mine are the early type where the lower bracket slides over a spike on the frame. Sorry...

Point-Seven-five · 19 Re: Plastics use on Kbikes Tue Feb 23, 2021 9:58 am

Point-Seven-five

Life time member

Number of posts : 4172

Whatever way you make the repair, take the time to reinforce the joint with wire. If the clip lets go, the battery cover is off the bike in seconds. If your luck is like mine, it will fall off 25 feet in front of a fully loaded cement truck.

I really wish you were able to post some good closeups of the break.

stanthomas · 20 Re: Plastics use on Kbikes Tue Feb 23, 2021 12:53 pm

stanthomas

Silver member

Number of posts : 107

It occurred to me that the nose cone on a Mk1 MX-5 (Miata) feels very, very similar to the belly pan/spoiler. And MX-5 forums are recommending "plastic welding epoxy", with Permatex being one suggestion. Anybody used this?

{Edit}
Alternatively, this gadget is the technique my local body repair shop told me about:
https://www.ebay.co.uk/itm/Handheld-Plastic-Welder-Garage-Staple-PVC-Machine-Car-Bumper-Repairing-Repair-UK/193857146233

As far as I can see, it just melts metal clips into the plastic. No adhesive or solvent.

Laitch · 21 Re: Plastics use on Kbikes Tue Feb 23, 2021 2:08 pm

Laitch

Life time member

Number of posts : 3136

Point-Seven-five wrote: I really wish you were able to post some good closeups of the break.

jjeffries wrote:So far the only photo I've managed to upload is the one of my Red K75. This despite assurances it was so easy even a dumb southerner could do it. NADA.

Clearly, Servimg hasn't taken into account Bay Area citizens' intellectual paradox when developing ease of use. Laughing

92KK 84WW Olaf · 22 Re: Plastics use on Kbikes Tue Feb 23, 2021 3:13 pm

92KK 84WW Olaf

Life time member

Number of posts : 7899

Dai wrote:Oops. Wrong bike. Both of mine are the early type where the lower bracket slides over a spike on the frame. Sorry...

I have those on my RS.....and the tabs are intact. Does that make them valuable??

Dai · 23 Re: Plastics use on Kbikes Wed Feb 24, 2021 4:33 am

Dai

Life time member

Number of posts : 5383

It makes them ready to break Laughing

tgolden · 24 Re: Plastics use on Kbikes Thu Mar 18, 2021 8:24 pm

tgolden

Silver member

Number of posts : 112

robmack wrote:Very detailed description of the fibreglass used by BMW is here: https://forums.bmwmoa.org/showthread.php?38950-What-type-of-plastic-is-the-K75S-bodywork-made-of&p=493002&viewfull=1#post493002

That MOA forum post claims "FIBRON" is a BMW proprietary Fiberglass. I've never been able to confirm that information. I think FIBRON was a German manufacturer that produced BMW motorcycle body parts. You can see "FIBRON" and what appears to be a part number on the attached pic of the lower tail part.

My research indicates the material is probably SMC or BMC. Depending on the severity of the damage, it can be repaired with fiberglass mat (epoxy CSM) and epoxy resin, and finished with epoxy bondo. Polyester resin won't adhere to SMC or BMC, because a mold release agent is part of the matrix.

tgolden · 25 Re: Plastics use on Kbikes Thu Mar 18, 2021 9:10 pm

tgolden

Silver member

Number of posts : 112

The side panels on the K100/75 might have a plastic material code molded on the inside. I don't think the side panels are ABS. I think they are polypropylene or similar thermoplastic polymer which is tough and flexible. The radiator trim panel is not as flexible. The radiator trim panel may be ABS. The side panels on the early K100s were a different type of plastic than the radiator trim panel.

Automotive Plastic ID Guide

https://www.semproducts.com/blog/automotive-plastic-id-guide

92KK 84WW Olaf · 26 Re: Plastics use on Kbikes Thu Mar 18, 2021 9:57 pm

92KK 84WW Olaf

Life time member

Number of posts : 7899

Dai wrote:If the repair doesn't have to be visually externally perfect, I've made up L-shaped stainless brackets the same height as the original and used a 3mm buttonhead to screw it to the sidepanel. Add a dab of the correct colour paint and it's almost invisible unless (a) you're aware it's there and (b) you look straight at it. It's also very strong.

This is my choice repair too.

I have an 83 RS...the belly pan is flimsy flexible like the side panels so it's not made of the same material as the fairing and seat cowl of the RT LT and RS.

Sponsored content

1 Plastics use on Kbikes Sat Feb 20, 2021 9:55 pm

jjefferies

2 Re: Plastics use on Kbikes Sat Feb 20, 2021 11:11 pm

robmack

3 Re: Plastics use on Kbikes Sat Feb 20, 2021 11:26 pm

Point-Seven-five

4 Re: Plastics use on Kbikes Sat Feb 20, 2021 11:38 pm

Point-Seven-five

5 Re: Plastics use on Kbikes Sun Feb 21, 2021 12:43 am

jjefferies

6 Re: Plastics use on Kbikes Sun Feb 21, 2021 1:07 am

Point-Seven-five

7 Re: Plastics use on Kbikes Sun Feb 21, 2021 8:15 am

Dai

8 Re: Plastics use on Kbikes Sun Feb 21, 2021 4:37 pm

jjefferies

9 Re: Plastics use on Kbikes Sun Feb 21, 2021 5:03 pm

Point-Seven-five

10 Re: Plastics use on Kbikes Sun Feb 21, 2021 6:16 pm

jjefferies

11 Re: Plastics use on Kbikes Sun Feb 21, 2021 7:12 pm

TacKler

12 Re: Plastics use on Kbikes Sun Feb 21, 2021 11:59 pm

jjefferies

13 Re: Plastics use on Kbikes Mon Feb 22, 2021 1:16 am

Laitch

14 Re: Plastics use on Kbikes Mon Feb 22, 2021 8:25 pm

stanthomas

15 Re: Plastics use on Kbikes Mon Feb 22, 2021 9:30 pm

Point-Seven-five

16 Re: Plastics use on Kbikes Tue Feb 23, 2021 12:25 am

brickrider2

17 Re: Plastics use on Kbikes Tue Feb 23, 2021 1:24 am

jjefferies

18 Re: Plastics use on Kbikes Tue Feb 23, 2021 4:13 am

Dai

19 Re: Plastics use on Kbikes Tue Feb 23, 2021 9:58 am

Point-Seven-five

20 Re: Plastics use on Kbikes Tue Feb 23, 2021 12:53 pm

stanthomas

21 Re: Plastics use on Kbikes Tue Feb 23, 2021 2:08 pm

Laitch

22 Re: Plastics use on Kbikes Tue Feb 23, 2021 3:13 pm

92KK 84WW Olaf

23 Re: Plastics use on Kbikes Wed Feb 24, 2021 4:33 am

Dai

24 Re: Plastics use on Kbikes Thu Mar 18, 2021 8:24 pm

tgolden

25 Re: Plastics use on Kbikes Thu Mar 18, 2021 9:10 pm

tgolden

26 Re: Plastics use on Kbikes Thu Mar 18, 2021 9:57 pm

92KK 84WW Olaf

27 Re: Plastics use on Kbikes

Sponsored content