repairing plastic side cover

[steven c]

 On my 77 Lemans the bottom tab where the grommet fits to hold it on the bike broke in half and I lost the broken part. Would epoxy work to make up the other half? Not sure if it would bond to the plastic side cover.

[fotoguzzi]

FYI, new side cover unpainted and reasonable price,

http://www.mgcycle.com/index.php?main_page=product_info&cPath=288&products_id=542

[JACoH]

You can buy plastic repair kits, similar to fibreglass repair, at auto parts shops. I have used before and are stronger than the original piece.  Then you have to sand and paint, but easy to do. I don't remember specific brands, but they make them for all the sport bikes to repair fairings, also.

[Stephen Hill]

The same thing happened on my 1976 LeMans right hand side cover.  Here is how I fixed it.
I believe the side cover is made of ABS plastic.  I used a piece of solid ABS black plumbing pipe and cut thin disks off of it.  Straightened out, this became my welding filler material. 
I then sliced another piece of pipe, heated it with a heat gun, and made flat material out of it.  This was used to replace the missing material on the broken tab.

Now for the tricky part.  You need to learn how to plastic weld.  You can buy specialized plastic welding guns of various sizes and shapes.  I use an electric wood burning pencil, which is a whole lot like small soldering iron.
I run the pencil through an electronic variable rheostat that allows me to control the heat.  Depending on the heat of the pencil/soldering iron you have, you may not need one.

Before you repair the part, practice on pieces of scrap.  Essentially you are making a butt weld, so you need to V the material out, just as if you were welding metal.  You then melt and paddle the filler rod into the V, bridging the two pieces.  Then flip the piece over, repeat the V, and weld the back side.  Play with the practice pieces until you get a good weld.  A good weld can be filed and sanded flush on the surface.  You can add extra reinforcement on the back side.  And it should be as strong as the original material.  If you google "welding plastic soldering iron" you will find some useful examples.  Tricky at first, but dead simple once you get the knack.

Stephen Hill

[steven c]

 Thanks!

[Antietam Classic Cycle]

Have a read here, down towards the bottom of Jim's post:
http://wildguzzi.com/forum/index.php?topic=89764.msg1481273#msg1481273

[John A]

you can also make your own plastic glue by taking some similar plastic and putting it in a glass bottle with MEK overnight. if it dissolves or at least starts to, it'll work. some experimentation is needed to get the consistency to your liking. If you can get it to dissolve it will be very strong, the key is to get a solvent that attacks the plastic. sometimes I use that with plastic welding. sometimes you can make a patch with aluminum pieces bolted to the back of the cover. in all of it some skill is needed to make it invisible or at least look good if you cant hide it.

[LowRyter]

My body guy uses a two part 3M product.  I can't remember the name of it specifically but I am sure I've posted here before. if you aren't a DIY type you might take it to a professional based on research here.  Actually the labor costs weren't bad when considering the cost of the product.

[guzzisteve]

I was using Loctite 404 to make my own orings and it worked on sidecovers, then the guy at the bearing house told me about Loctite 495 and it works great.

[Bluerobotz]

you can also make your own plastic glue by taking some similar plastic and putting it in a glass bottle with MEK overnight. if it dissolves or at least starts to, it'll work. some experimentation is needed to get the consistency to your liking. If you can get it to dissolve it will be very strong, the key is to get a solvent that attacks the plastic. sometimes I use that with plastic welding. sometimes you can make a patch with aluminum pieces bolted to the back of the cover. in all of it some skill is needed to make it invisible or at least look good if you cant hide it.

I use solid copper wire to join parts, strengthen the area around grommet holes etc. Make sure it is flat, and shape it so it won't pull out - bend the ends into hook shapes. Melt it into the material from the back side - easy with the copper as it conducts heat from the iron well. Just be careful that you don't push it though the surface of the "good" side. Don't push hard on the copper as this may deform it, let the heat do the work and the copper will sink into the material. Once this is done, continue with filling with plastic & then finish with filler.