Jump to content
CBR1100XX.org Forum

Plastic repair for dummies.


Zero Knievel

Recommended Posts

There is a crack in my front fender.  My last attempt to fix it didn’t hold, and the crack came back.  I have a spare fender which I can swap out…leaving me plenty of time to fix the cracked one.  I was debating sending it off to someone who repairs and paints motorcycle plastics, but I wonder if it’s that hard to DIY with the right tools.

 

Any recommendations for resources (web pages or videos) that show how to do it in detail, step-by-step, and with what tools to get it done?

Link to comment
Share on other sites

Do you need 2 fenders or just simply want 2 fenders. Seems a little lavish to have a back up fender. How often does one crack a fender? Rode for 30 years - never cracked a fender. Must be nice to have all this spare stuff when it’s truly not needed. 
 

Life must be really good. 

Link to comment
Share on other sites

7 minutes ago, Zero Knievel said:

There is a crack in my front fender.  My last attempt to fix it didn’t hold, and the crack came back.  I have a spare fender which I can swap out…leaving me plenty of time to fix the cracked one.  I was debating sending it off to someone who repairs and paints motorcycle plastics, but I wonder if it’s that hard to DIY with the right tools.

 

Any recommendations for resources (web pages or videos) that show how to do it in detail, step-by-step, and with what tools to get it done?

Post a picture of the fender.

Link to comment
Share on other sites

50 minutes ago, DBLXX said:

Do you need 2 fenders or just simply want 2 fenders. Seems a little lavish to have a back up fender. How often does one crack a fender? Rode for 30 years - never cracked a fender. Must be nice to have all this spare stuff when it’s truly not needed. 
 

Life must be really good. 


Okay.  I had that coming.  😂

 

I have a spare because insurance replaced the one I originally had, so I have the original part and the replacement one.

Link to comment
Share on other sites

57 minutes ago, XXBirdSlapper said:

Post a picture of the fender.


I fixed this before with plastic weld and a strip of fiberglass (on the inside).  I noticed the crack returning this year and added a strip of electrical tape to ensure it doesn’t get worse.  Taking the photos now, while the crack seems to remain separated, the fender does not flex too much…indicating that the fiberglass/plastic weld on the back is holding strong.  If my past research is right, I might have to drill a hole where the crack terminates then carve out enough plastic to widen the crack so plastic weld can get in and bind the two edges together…then sand and paint.

 

AAE4E9FA-7B8B-40C2-81BD-0DDFCDA4EBEE.thumb.jpeg.9893f96d007792b05cec132ff5a4bba2.jpeg

 

5A3E5EBF-982D-4ACE-B57C-D60CA4AA04BC.thumb.jpeg.cb650ef00effa1c0dccbaaaedfb20b46.jpeg

Link to comment
Share on other sites

You can use a soldering iron to melt the back of it and "weld" it together.  Some soldering kits also include specific paddle bits to do this.  And this is very effective if you just want to glue it.  @superhawk996 used it on his Talon, maybe he can comment on how it has held up.

 

https://www.loctiteproducts.com/en/products/fix/super-glue/loctite_plasticsbondingsystem.html

Link to comment
Share on other sites

4 hours ago, SwampNut said:

 @superhawk996 used it on his Talon, maybe he can comment on how it has held up.

Not at all.  Something in my mind says that I didn't use it right but I don't remember for sure.  I've used it on other stuff and it did well.

Link to comment
Share on other sites

JBweld will cure that fender, as long as whatever you used before gets removed or covered past where it ends so that the JB isn't relying on what already failed.

Link to comment
Share on other sites

Jb weld will eventually fail,something about different rate of temperature expansion vs. plastic. Been there, done that. So weld it. 

 

Now, if you have to pay someone else to repaint it- better to buy new piece from BMW. 

Link to comment
Share on other sites

12 hours ago, Zero Knievel said:

I might have to drill a hole where the crack terminates then carve out enough plastic to widen

Always drill the crack assuming you can essentially zero relieve, or even negative relieve the drill lips and also know you can control the drill as the center penetrates the off side. You probably have no choice but a lower or zero helix angle will be better.

  Fiberglass mesh can be effective but more critical is the glue/bond strength and equally glue stiffness IMHO.

Edited by XXBirdSlapper
Link to comment
Share on other sites

5 hours ago, XXBirdSlapper said:

Fiberglass mesh can be effective but more critical is the glue/bond strength and equally glue stiffness IMHO.


With what I now see, it appears my repair held very well but I didn’t get the crack to bond because there was no space for the glue to get in between the pieces.

Link to comment
Share on other sites

cheap harbor freight plastic welder comes with stainless steel screen.  melt that into the back side of that crack.

 

here's a clip that illustrates but, you don't really need the extra plastic, just use the welder to push the screen into the plastic surrounding the crack.

 

 

  • Upvote 2
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

Terms of Use