fiberglass tanks

radiofun · Oct 16, 2011

I'm looking at buying a 72 Interstate with a fiberglass tank. would it be better to replace this with a steel tank....or can the inside be coated so that the use of modern gas is not an issue?

swooshdave · Oct 16, 2011

Steel.

rvich · Oct 16, 2011

This is an ongoing conversation that will probably only cease once there are no viable fiberglass tanks left. There have been a few here who have split their tanks open and coated them, but "many" would agree that the slosh method is pretty well doomed to failure. Steel or alloy is really a better way to go. I would factor in the price of a new tank if I were making an offer on a bike with a fiberglass tank.

Russ

radiofun · Oct 16, 2011

steel it is.

travelerjerry · Oct 16, 2011

radiofun said:
I'm looking at buying a 72 Interstate with a fiberglass tank. would it be better to replace this with a steel tank....or can the inside be coated so that the use of modern gas is not an issue?

Try lining the tank with a ethanol resistant coating and use alcohol-free gasoline if available.

DogT · Oct 16, 2011

If you can use avgas only or non corn fuel, you'll be good with the F/G. Otherwise make plans.

Dave
69S

rvich · Oct 16, 2011

It should be remembered that despite the fact that most riders buy a bike planning to never crash it, that the reason fiberglass tanks became obsolete originally was due to the fact that they split open on impact and spew gasoline. I ride, therefore I am not particularly a safety freak. But you should go into ownership of a fiberglass tank knowing this detail. If for no other reason to buy the bike at the most reasonable price you can.

Russ

platinumsmith · Oct 16, 2011

What about the aluminum tanks? Are those user friendly?

platinumsmith · Oct 16, 2011

& do they need to be lined? The Aluminum ones, I mean.

Jeandr · Oct 16, 2011

platinumsmith said:
& do they need to be lined? The Aluminum ones, I mean.

I wouldn't line any metal (steel or aluminum) tankl, the chance of the liner not adhering well is greater than the possible benefit.

Jean

Torontonian · Oct 16, 2011

Jean is right ,steel or aluminum, Shell Premium too.

radiofun · Oct 16, 2011

I prefer to fix something once and for all. I'll spend the extra $$ to get a worry-free stell tank rather than dick around with some inferior solution.

Carbonfibre · Oct 17, 2011

If a GRP tank is sectioned and a proper chemical resistance layer installed by a professional, then it will be problem free. Epoxy slosh coatings are unlikely to work long term due to problems with adhesion, and cracking due to the cured "sealer" being very brittle, and GRP tanks being subject to vibration. New GRP tanks made with the appropriate materials and production methods, with Efuel usage in mind, will be problem free, but as unit production costs are a little higher and GRP tanks are now regarded by most people as not fit for purpose, nothing along these lines is being produced currently.

GRM 450 · Oct 17, 2011

What is the correct way to repair a glass tank so it will last? I'm in the process of spitting the seams (where the bottom joins the top) so I can grind the inside before I line it with a light weight cloth chop strand and vinyl ester. All advice happily accepted. And no, it's not a Norton tank. Graeme

JimC · Oct 17, 2011

Its aluminum for me. I read that some have had good results by cutting out the bottom of the tank, but I just couldn't handle riding around with a tank that the bottom has been cut out and then patched up.

Jeandr · Oct 17, 2011

GRM 450 said:
What is the correct way to repair a glass tank so it will last? I'm in the process of spitting the seams (where the bottom joins the top) so I can grind the inside before I line it with a light weight cloth chop strand and vinyl ester. All advice happily accepted. And no, it's not a Norton tank. Graeme

Take a look at cafe-commando-build-thread-t8372-60.html and fixing-fiberglass-tank-t6227.html?hilit=%20fiberglass While some will say it will fail, I have done three tanks so far and not a bubble has appeared. I try to stay away from ethanol by filling up with either Shell, Esso or Ultramar who all have answered by e-mail they don't put ethanol in hi test.

Jean

Skyguyz · Oct 17, 2011

If you are from "goofy newfy" then maybe this on the tank?

*Just saying.

Carbonfibre · Oct 17, 2011

GRM 450 said:
What is the correct way to repair a glass tank so it will last? I'm in the process of spitting the seams (where the bottom joins the top) so I can grind the inside before I line it with a light weight cloth chop strand and vinyl ester. All advice happily accepted. And no, it's not a Norton tank. Graeme[/quote

You will need novalac vinyl ester resin, which is denoted for use with ethanol in manufacturers chemical resistance data sheets. When the tank has been sectioned, the interior surfaces should then be blast cleaned to remove all traces of oxidised fuel, to ensure a good secondary bond.

After the interior surfaces have been scoured with acetone, and have been left a couple of days to ensure they are completely dry, you can apply a chemical resistance layer, using synthetic veil (or tissue) and the novalac ve resin. Two layers of veil should be sufficient, but these must be laminated perfectly with no voids or air bubbles present at all.

Finally the 2 parts of the tank must be bonded back together using a bonding paste made using the novalac ve, and something like aerosil silica thickening agent. Before the bonding paste has fully hardened, introduce a small quantity of novalac ve into the tank, and ensure that this runs all along the bonded seams, so that any pinholes or defects can be sealed.

If there is any possibility of post curing at an elevated temperature, then this is always a good idea and will increase the final chemical resistance levels of any high cross link resin.

Not a great idea to use any product which does not have proper chemical resistance data provided by the manufacturer, and in many cases while some "sealing" resins may be quite able to resist the ethanol, they are very brittle and not suitable for use inside GRP fuel tanks, which vibrate and cause brittle materials to crack and fall off in many cases.

GRM 450 · Oct 17, 2011

Thanks CF, is "novalac" a brand name or type of VE resin?
Is "synthetic veil" or tissue a very fine light chop strand? like the tissue chop strand used as the first coat when making a seat etc from a mold?

The things you recomend may be refered to by different names here?

graeme

rpatton · Oct 18, 2011

rvich said:
It should be remembered that despite the fact that most riders buy a bike planning to never crash it, that the reason fiberglass tanks became obsolete originally was due to the fact that they split open on impact and spew gasoline. I ride, therefore I am not particularly a safety freak. But you should go into ownership of a fiberglass tank knowing this detail. If for no other reason to buy the bike at the most reasonable price you can.

Russ

There have been a lot of old beat up steel tanks on ebay. Some of them get filled with a half a pound of bondo and painted over. But you never see a used FG tank for sale with a single dent in it. Assuming they get in as many crashes as steel ones... I wouldn't cut out the bottom of one and try to fix it. I'd cut out the top and fill it with potting soil.

fiberglass tanks

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