what to do before welding?!

on the to-do list for the next days is the welding of the rear sub-frame mounting point, have done some welding in the past but never on the car so my question is:
besides Battery what should I disconnect before welding? Starter? Alternator? ECU?

thanks

guessing mig. some disagree about the battery. just make sure you clamp it electrically close to where you work.

arc welding

Disconnect the battery, and as Trax says place the return lead clamp close to your work area.

thanks, hope I can fix the creaking noises

buy a disco

on a more serious note, as has been said,
disconnect the battery
clamp the weld return as near as possible to where your working
attempt to find some good metal to weld to

Serious? This is landyzone.

And no don't buy a disco, silly. You'll still have to weld it, just in different places

the_wolf said:

Serious? This is landyzone.

And no don't buy a disco, silly. You'll still have to weld it, just in different places

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have I missed this!!! having no decent www access at home sucks

Clean the area to be welded, disconnect the battery, alternator and starter, flap disc the area to be welded, wire brush the welder return, clamp the return onto the pristinely cleaned bolt/bit of chassis, weld it up, flap disc the weld after chipping the slag off, paint with zinc oxide or Galvafroid, paint with bitumen or greasy oil ... Job done!

What you're welding needs to be squeaky clean. You can't weld rust!

just weld it

I never disconect anything. I even welded exhausts with the engine running....you know the hole is fixed then.

Ive never had a problem.

Pull all inflammable material out of the way; carpets, plastics etc, protect any nearby fuel and brake lines, the same with wiring looms. I've even seen experienced people welding the floor underneath a vehicle while the carpets inside are quite merrily burning away!

Keep a fire extinguisher within easy reach.

brian47 said:

Pull all inflammable material out of the way; carpets, plastics etc, protect any nearby fuel and brake lines, the same with wiring looms. I've even seen experienced people welding the floor underneath a vehicle while the carpets inside are quite merrily burning away!

Keep a fire extinguisher within easy reach.

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do you mean flammable? inflammable does not burn But then there is nothing that is inflammable

Thor1950 said:

do you mean flammable? inflammable does not burn But then there is nothing that is inflammable

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The difference between British English and US English!

In the past I have spent time disconnecting batteries and alternators and even ECU's to weld vehicles.

A close friend who is a mechanic, said not to bother, as he never does and has not had a problem.

I have recently done welding to my 90 and also my mitsi EVO 6 (jap import no under seal) and they were both fine.

As said above, keep earth clamp close, mind out for fires warping through too much heat, and weld spatter getting on body windows or carpets.

Arc welding rusty metal is really hard going, try to mig if you can. It's easier to fill the holes ;-)

You might get away with not disconnecting ECU's but I would unplug them, that way you know there should be no problem. Apart from that, what everyone else has said, make sure you have properly clean sound metal to weld to, have an extinguisher handy etc.

Oldseadog said:

Clean the area to be welded, disconnect the battery, alternator and starter, flap disc the area to be welded, wire brush the welder return, clamp the return onto the pristinely cleaned bolt/bit of chassis, weld it up

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really no need to disconnect the starter + alternator. the earth does not need to be on a " pristinely" cleaned bit of metal, just no rust...
you don't need to flap disc the area either, just a go with a wire wheel. the OP is only stick welding :hysterically_laughi


also I have never disconnected the battery whilst welding on a vehicle.and have never had problems.

Thor1950 said:

do you mean flammable? inflammable does not burn But then there is nothing that is inflammable

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inflammable is the same as flammable; in UK English too...

fergus123 said:

really no need to disconnect the starter + alternator. the earth does not need to be on a " pristinely" cleaned bit of metal, just no rust...
you don't need to flap disc the area either, just a go with a wire wheel. the OP is only stick welding :hysterically_laughi


also I have never disconnected the battery whilst welding on a vehicle.and have never had problems.

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had issues with batteries not holding charge after welding being carried out, to many and too much of a coincidence, so I now disconnect them.

all contact points should be down to clean bare steel.
I use a grinder rather than a wire wheel.
that's after a good dose of the needle gun to find out how much rot I need to cut out.
stick welding is an art, but can be done.

other precautions are good advise, shift anything important that burns, and I keep a 2 litre pop bottle on hand full of water with a 1/4 hole in the cap!