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A couple of welding / fabrication / petrol tank questions . . .


fisha

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In short i ideally would like to get a custom small petrol tank for the RRC. I want a tank that hangs between the 2 chassis rails of the RR, has roughly the same overall depth as the normal RR tank, but is only about 8 to 10" long from front to rear .

This is just really to be a back up tank should I run out of LPG. Having it that small will serve 2 purposes of keeping the rear chassis free from too much mud ( a particular problem of the RRC ) and also would give me a good 12"+ of space at the rear between the chassis rails. This in the future could possibly be utilised for a rear winch or something like that.

Now, what would be the best material to make a petrol tank from? mild steel, stainless steel or even Alu?

I have a gas / gasless MIG welder which to date has served me well - but i'm not sure of whether I would be able to:

a) make non pourous welds

B) even be able to weld SS with it?

So any recommendations on whether to attempt it myself or not. Or, does anyone have any recommendations on getting it done by someone else where it wouldn't cost an arm and a leg.

many thanks,

Donald

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You can Mig tanks up but porosity will be a major issue, fold the shape and fill the tank with argoshield and keep pumping it in, even then make sure you use dye penetrant to check for leaks.

Petrol is the last thing you want making an unplanned escape - unless you are confident in your skills in producing non-porous welds I would suggest paying someone to do it for you.

Personally I'd TIG it.

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I made my tank that sits behind the cage in the Hybrid, used 3mm plate as it was all I had...Nige would be proud :lol: ,

Still nothing short of a Nuclear strike will make a hole in it :P

Had no problem with leaks, so my welding must be good... :blink:

Used a 150Amp Mig with C02

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could you not use an ali kit car petrol tank? Or go down the scrappies and get seomthing small out of a metro or similar?

I am all for DIY so wouyld suggest using ali and making it yourself. I wonder if the lumiweld/technoweld stiff will work? The rods are quite £££ so in the end may work out chepaer to get something else.

Would a lwt underseat (10 gal) tank be too big?

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The Lumiweld stuff is not good, its ok for "splodge" solder type joints but having tried it it is hard to keep a nice neat finish. And its BL**dy expensive.

If I was doing it I would mig weld it out of some nice thick plate ("3mm ?) and then have it galvanised (hot dip, proper job) should see you out!

Geoff

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Prob with MIG is the pin holes, where as TIG will give a more solid and fuel tight weld....if you can.

AliSport is worth a call if your piggy bank can be caught and persuaded to cough enough up....

If you are really good (or lucky) with MIG and use a thicker steel you MIGHT get away with it....

Don't try SS with Mig, ...........you'll prob use argosheild plus steel wire .....so it would be woerse than steel as the SS is harder to heat up via Mig and the welds will rust and the SS won't - it will be a bit of a mess,

Ali welding is an art even with a MIG with ali wire and pure agron on anything, let alone huge welds for a fuel tight tank

Nige

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If you are getting pin holes there is something wrong with your set up Nige (no offense).

To weld alloy you need an AC MIG or pulsed TIG machine 1200 plus, you can do it with stick but the plate needs to be at least 3mm, no problem there then Les :D , and it takes quite a bit of pratice just to get a decent weld never mind the tricky bits.

Rule of thumb, if you can do a decent job with Ox/Acc then you have the skill to do a better job with TIG given the right equipment.

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If you are getting pin holes there is something wrong with your set up Nige (no offense).

To weld alloy you need an AC MIG or pulsed TIG machine 1200 plus, you can do it with stick but the plate needs to be at least 3mm, no problem there then Les :D , and it takes quite a bit of pratice just to get a decent weld never mind the tricky bits.

Rule of thumb, if you can do a decent job with Ox/Acc then you have the skill to do a better job with TIG given the right equipment.

I Know exactly what you mean re "something wrong"

My point was unless you have superbly clean metal and spend time and care welding, becuase you are looking at what is a large series of weld runs, the chances are you will start stop adjust at some point and thats when you can get a pin hole.

TIG welding is a completely differnet type of weld, slower and more siuted to something like a petraol tank, etc steel or ali.

Also my point was that try welding up a tank with a MIG welder loaded with ali wire and argon.......I don';t think so :lol:

Nige

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Ali welding is an art even with a MIG with ali wire and pure agron on anything, let alone huge welds for a fuel tight tank

Sorry Nige I know what you mean. :huh: to prevent me drifting way OT

What I was trying to do was, if not put Donald off getting either too technical or setting fire to his arse, direct his thoughts without actaully saying Oi! do this.

Perhaps I should have put it like this.

1. If you have plenty of time and materials to play with do it in mild steel of sligthly thicker gauge than the standard tank and use MIG but air test it afterwards. This is always going to be a higher risk, clagging panels together most of us can do but a panel falling off is unlikely to killl anybody.

2. Buy something suitable ready made as someone has already suggested, there are quite a few variations with kit cars and club racers around here is just oneCar Builder Solutions

3. Get a professional to make a one of to your requirements, it might not be as costly as you think.

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