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General Category => Modifications => Topic started by: 2big on June 20, 2020, 02:36:37 PM

Title: Bodywork repairs and repaint
Post by: 2big on June 20, 2020, 02:36:37 PM
Been taking apart the FJ and dry building new wheels and brakes today
Virtually every panel, fairing and the tank has at least one small scratch crack or small chip on it

Only to be expected with a 30 yr old 10 owner bike....

The belly pan is cracked and repaired on the inside with epoxy kit but not on the outside with cracks visible

The fairing is cracked on the right side where I suspect the bloke I bought it from dropped it on gravel drive whilst parked up for sale...an FJ owners club sticker hastily applied to cover it up, it's split at the bottom on the return by the frame mounting boss, the air box scoop on same side has fresh vertical scratches that won't T cut out....

Seems a shame to have to re do such a great factory paint finish - but smart repair would cost a fortune

What plastic are FJ fairings moulded in? Ive seen online videos with welding using zip ties but that's surely a different type of plastic to the bikes panels

While I'm at it tempted to cut down the fairing to make it smaller and lose / infill the air box scoops. Opportunity for some 3D printing and splicing in new bits in ABS

Anyone got any suggestions?
Title: Re: Bodywork repairs and repaint
Post by: FJmonkey on June 20, 2020, 03:42:12 PM
ABS welding/repair. All the FJ plastic is ABS and can be fixed/rebuilt.

Plastifix

ABS hot air welding

Acetone/ABS putty

and on ...
Title: Re: Bodywork repairs and repaint
Post by: Charlie-brm on June 20, 2020, 05:48:16 PM
Original parts are definitely ABS. My 84 is getting fragile now. I seem to be patching up in a few places every year now. Some are from me being a putz and some from material fatigue.

I also have a 3D printer and this was one of my objectives, to make replacement bits. I'm not entirely getting the hang of 3D design so many times by the time I'd get a 3D design correct just to print one little piece, I'm better reverting to making ABS goo.

A few of my experiences:
- For 3D printing, pure traditional ABS filament is preferred. I selected an enhanced ABS with more strength, better layer adhesion, next to no warping etc. BUT what ever is in that modified ABS, it absolutely refuses to break down with solvents. I can leave it in Acetone/MEK for days and it doesn't change anything about it.

- To breakdown standard ABS, I buy black ABS plumbing couplers and chew them into pieces with large drill bits or metal snips, small enough to soak in a sandwich sized "tupperware" food container with Oatey brand "Premium Grade Yellow ABS Cement" because it breaks it down faster and with smoother blending than straight Acetone. It's got Acetone, MEK and adhesives. You end up with a really nice mixture.

- For a few square inches or more of uniform material, I would pour that goo on a flat bed of plastic cut from a windshield washer jug. I'm pretty sure it's polypropylene. ABS will pop right off. Do it in thin layers built up (days if necessary) until you have mini sheets at the desired thickness, peel them off then cut and form.

- Moulding - the washer jug plastic is good as a "skin" on the exterior of fairings, spray glue or tape it on the outside, curve it with a heat gun, then build up the goo in layers from the back. For small curvy bits like mounting tabs, kid's modelling clay is good if you can shape it or push it over a good example if you have a spare.

I don't care if it takes more than a day for the ABS to set up because these results are strong. I've done a bit of heat welding dragging a soldering iron in a zig zag through the seam, but I end up applying goo anyway as a smoothing filler.
Zip ties were originally made of nylon but I think everyone you'll source now at retail is polypropylene.
Title: Re: Bodywork repairs and repaint
Post by: 2big on June 20, 2020, 05:56:04 PM
Excellent thank you
There's no markings on the inside of the mouldings Just date clocks oct/nov/dec/jan 90-91. surprising that abs lasts that long in the sunshine!

Good opportunities to modify and fabricate, could use some 3D printing too

Is there any 'work' people have done to modify and reduce the shape of the fairings etc?
Is it a crime to mess with the design of the bike?
Title: Re: Bodywork repairs and repaint
Post by: Millietant on June 22, 2020, 05:59:45 PM
I've used Plastifix to good effect on various bits of my bodywork - holding together cracked panels, making new/stronger mounting tabs. It solved issues with both my belly pan and side panel, as well as giving me more solid fastenings for the air scoops and firming up the instrument cluster surround.

Many years ago I dropped my instrument cluster and the surround panel and smashed the cluster and damaged the surround, luckily I had a spare FJ in the garage that was being converted into a race bike, so I took the instruments off that bike, put them on my daily rider (took 30k miles off the bike  :sarcastic: :sarcastic:) and repaired the surround with Plastifix.
Title: Re: Bodywork repairs and repaint
Post by: giantkiller on June 22, 2020, 11:30:17 PM
Plastex is pretty much the same as plastifix. Only has reusable rubber moulding bars. And various accessories, and sizes. Have used it extensively and so far no failures. About the simplest/easiest way to make repairs.
Title: Re: Bodywork repairs and repaint
Post by: 2big on June 23, 2020, 09:06:08 AM
Have to say a massive thank you to you all gentlemen
You make the most daunting tasks simple

Great advice. Much appreciated
Im off to the workshop to make a 1/72 scale replica of the Sydney opera house out of FJ fairing panels...

Cheers Jan