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A A A A Author Topic: How to fix crack in CX500 plastic rear fender?  (Read 110 times)

Krisby

How to fix crack in CX500 plastic rear fender?
« Started on: 05-Dec-18, 15:32 »
Allo, I've just noticed a crack in the plastic rear fender of my CX500, where it mounts to the frame.  There are two holes for the securing bolts, and one has an obvious crack, and the other hole is just starting to develop a crack.  Any ideas how to remedy these fractures?  It would help if I knew exactly what kind of plastic these fenders are made from, so that I can search for some compatible glue.  Has this ever happened to anyone else?  Please see photos below:

 

CX PHREAK

Re: How to fix crack in CX500 plastic rear fender?
« Reply #1 on: 05-Dec-18, 16:39 »
If you can find a source for the parent material {spare fender liner etc.} this stuff can be welded with a soldering iron.

i have modified one for a bike I'm currently building this way.

82 Turbo & 2000 Valkyrie

Re: How to fix crack in CX500 plastic rear fender?
« Reply #2 on: 05-Dec-18, 20:52 »
see this link - how I did my blinker lens

https://www.australiancx.asn.au/forum/index.php?topic=12363.msg154332#msg154332

it's not really difficult and if you want to strengthen the area - just get some similar material from an old fender and weld it in place


Mins Man

Re: How to fix crack in CX500 plastic rear fender?
« Reply #3 on: 06-Dec-18, 10:20 »
I haven't got a clue what type of plastic they are, but I found cable ties worked pretty good for repairing the dash pieces on my turbo.

CX PHREAK

Re: How to fix crack in CX500 plastic rear fender?
« Reply #4 on: 06-Dec-18, 11:54 »
There's cable ties and there's cable ties. I guess not all are the same plastic. But this is where I started with the guard above and it didn't work for me. The bond was weak and the material inflexible after trying to bond it.

 I ended up cutting strips of the parent material with an angle grinder to use as filler rods.

 

Joolstacho

Re: How to fix crack in CX500 plastic rear fender?
« Reply #5 on: 06-Dec-18, 12:15 »
I believe the only way to do a PERMANENT repair on a job like this is to laminate both sides with a wide strip of Epoxy resin impregnated glasscloth.
Plastic welding is a temp solution at best, it'll always fail at the edge of the weld if there's any tension or vibration.

CX PHREAK

Re: How to fix crack in CX500 plastic rear fender?
« Reply #6 on: 06-Dec-18, 12:28 »
Maybe .... but I actually did try to tear the fender liner above apart.

Krisby

Re: How to fix crack in CX500 plastic rear fender?
« Reply #7 on: 06-Dec-18, 13:05 »
Hmm, plastic welding seems the way to go, as long as the appropriate filler material can be sourced.  From what I've seen online, preparation of the surface is important, and not unlike that of metal welding.  If the crack is sufficiently "V"ed, and the plastic rod filler is of the right stuff, then the strength of the repair should be as good as was the original condition.

Joolstacho:  When you mention "Epoxy Resin", is that the same as "Styrene",  which is the resin usually used with fibre-glass cloth?  If so, will it really bond with the subject plastic fender (assuming the surface is roughed up in preparation)?  I believe Styrene is also used in plastic body filler compounds.

Well, it looks like I'll have to do some experimentation...............

CX PHREAK

Re: How to fix crack in CX500 plastic rear fender?
« Reply #8 on: 06-Dec-18, 13:21 »
Polyester is generally used for fibreglassing {it may also be called styrene, I don't know} Alternatively epoxy can be used. It is stronger but more expensive.

 Polyester generally won't bond to waxy plastics like the fender liner but epoxy may.

 But I've always found welding with the parent material best.

Joolstacho

Re: How to fix crack in CX500 plastic rear fender?
« Reply #9 on: 07-Dec-18, 08:47 »
No, forget Polyester resin if you want good adhesion. Epoxy resin is the only way to go. And roughing up surface prep is all-important.
Ships Chandlers often stock West Systems Epoxy resin, that's the stuff.

VC3

Re: How to fix crack in CX500 plastic rear fender?
« Reply #10 on: 07-Dec-18, 10:04 »
Why not just buy a good used inner fender and be done with it?


ps - make sure you have the fender plate, #9 in this schematic:

https://www.partzilla.com/catalog/honda/motorcycle/1978/cx500-a/rear-fender-i

 


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