Fibreglass fuel tanks - road legal?

[jonbuoy]

Searched but couldn't find anything on GRP fuel tanks here. Are they road legal? I've seen some nice custom ones in the USA and OZ but will I get a warrant with a GRP instead of metal fuel tank? The problem seems to be they will crack not dent in an accident.

[JimO]

the old PE250 suzukis had plastic tanks back last century and most of them was road legal

[Motu]

There is no wording about construction of fuel tanks,they can be made out of steel,aluminium,fibreglass or an approved plastic.Fibreglass tanks used to common when it was the new wonder material,I've had a couple of bikes with glass tanks - the one in my avatar had all fibreglass bodywork,and there is nothing stopping it being on the road today....if I could afford to buy it back.If it was OE fitted there would be no problem,but if you fitted a glass tank to a bike that came out with a steel tank then that is a modification (changing the structure of a component) and will need a LVV.

[pete376403]

Ducati 750 SS (the old roundcase ones) has glassfibre tanks, also Norton Commando Fastbacks. I doubt if there would be a problem with either of these.

Anyway, how could they tell? If (as I believe) wof testers are not allowed to use magnets to detect non-steel body repairs now are they going to find out what a tank is made of?

[jonbuoy]

Ok Thanks - good advice as ever. I will have to get bike re-registered so I might own up to having changed the tank.

[Motu]

Anyway, how could they tell?

Because it's made out of fibreglass?

[jade]

If its painted they wouldnt be able to tell...
It would be a fair bit of work to make one but a good project none the less,
As someone who works with carbon fibre and fibreglass everyday let me tell you though ..in the event of the tank getting an impact, id virtually guarantee it will crack and leak, if its carbon fibre and it recieved a big impact it would almost certainly explode (the carbon) and splinter like you wouldnt believe...
If it was my choice to modify a tank - id leave it made of metal, strip it back - have clearcoat carbon graphics and paint the rest...
In saying that - the fuel tanks we make for our boats are carbon fibre, lightweight - match the boat - you have to use the right resin as well - cant remember if its epoxy or vinylester

[Motu]

If its painted they wouldnt be able to tell...

Do you think us WoF testers are stupid or something? Bring your bike down and we'll see how many things I can fail you on.The Yanks are the best fibreglass constructors in the world,take a look at a Corvette,panels are gell coated on both sides and would be pretty hard to tell apart from thickness.But most tanks are only gell coated on the outsideand it's pretty easy to see the fibreglass.The Rickman Metisse was a motocrosser and was 10 years old when I had it - it had taken some pretty big knocks over the years and was still sound,although there were some gell coat cracks....never any leaks.

[imdying]

Do you think us WoF testers are stupid or something?

Not stupid, but I'd be surprised if the average WOF tester would even think twice about a sportsbike with a composite cover, given that a number of tanks are merely covers over the airbox and 'sub' tank.

[Motu]

Depends if the WoF inspector is an Indian at a testing station whose ''trade experiance'' is pumping gas for Mobil....or a mechanic who has spent his life working on cars.Most of the guys I've worked with over 37 years would pick up a fibreglass tank - whether they would question it or even comment on it is debatable.Personaly I wouldn't worry about it,unless it was some obvious replacement that stood out like dog balls.

[redr1]

If its painted they wouldnt be able to tell...
It would be a fair bit of work to make one but a good project none the less,
As someone who works with carbon fibre and fibreglass everyday let me tell you though ..in the event of the tank getting an impact, id virtually guarantee it will crack and leak, if its carbon fibre and it recieved a big impact it would almost certainly explode (the carbon) and splinter like you wouldnt believe...
If it was my choice to modify a tank - id leave it made of metal, strip it back - have clearcoat carbon graphics and paint the rest...
In saying that - the fuel tanks we make for our boats are carbon fibre, lightweight - match the boat - you have to use the right resin as well - cant remember if its epoxy or vinylester

My understanding is vinylesters are more chemical resistant and have greater heat resistance. I made a f/g tank for a VFR400 many years ago and it worked well, weighing in at around 800g, although I wouldn't try that again. Imagine having a lowside, the tank bursts and sprays fuel all over the rider, and a spark from metal against road sets everything alight! Not nice.

[Motu]

I was on a bike going down the road on it's side for sometime - and when I looked at the tank later it was blue,and I pushed a screwdriver through the tank it was so thin....damn close to going up I'd say.I've also sent a fibreglass tanked bike down the road a couple of times with out a scratch on the tank.

[imdying]

It seems like an unnecessary risk given the weight saved. However, if I'd paired back the weight from everywhere else, I'd give it a go.

[Hellraiser]

Ok so why not fit it with a bladder like the race cars have?

[F5 Dave]

ok its not often I'd find something to call you on but:

. . .The Yanks are the best fibreglass constructors in the world,take a look at a Corvette,panels are gell coated on both sides and would be pretty hard to tell apart from thickness. ..

How is that good fibre glassing? They make them the same way they make boats, spray it on with a chopper gun. This makes for real heavy fibreglass which is only strong when thick. I was well under impressed when I saw a friends 'Ray how thick it was. Modern glass cars like another mates Lotus 111R Elise (or something like that) actually impressed me, but they are vacuum formed & he said the bodywork is made in Netherlands (early ones were hand laid in UK). Whole car is supposed to be 800kg.
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[edit]
About this point I have to say I haven't seen a modern Vet (I don't really follow cars& only think of the Stingray when I hear Corvette) so you can shitcan me by saying that is what you meant If they are Gel coated both sides they are vacuum formed & the old Vet was chunky underneath. Oh dear, oh well I had my speel.