Welding Precautions Disco2

**LandyAndy** · 19th September 2005, 07:49 PM

Hi Guys
What precautions do you need to follow when using a welder on a Disco 2??????
On a "normal" vehicle I normally disconnect the 2 battery terminals.
Im concerned about all the electronics and dont want to do any expensive damage.
I will need to tack weld bits and pieces whilst making my sliders.
Andrew

**Slunnie** · 19th September 2005, 08:00 PM

I asked the same question recently on a Disco2 forum. The suggestion in a nut shell was:

Disconnect battery leads and earth them. Connect the earth lead to the work piece, not the chassis, start the weld on the job, not the chassis.

**LandyAndy** · 19th September 2005, 08:09 PM

Thanks Slunnie
Thats the line I normally follow anyway.
A mate once had a custom exhaust fitted to a falcon powered Nissan ute,luckilly for him he came back early to collect it and caught them welding up the exhaust with the battery connected and the earth clamp on the tailshaft!!!!! He went beserk at them telling them they should know better,he was really ****ed the next day when he found they had fried the voltage regulator/seperator(it still had the 24volt system) and 2 days later the uni joint let go.They sent a mechanic down from Perth to fix it at their expense.
Andrew

**uninformed** · 21st September 2005, 07:21 PM

this may sound a bit red neck but i thought that electricity took the path of least resistance. when i did some welding on my chassis (def 110) i clamped the earth to the peice i was attaching and did not disconect any thing, i have a engine immobilizer and dual battery set up, no dramas to date

serg

**disconut** · 22nd September 2005, 06:50 PM

I read somewhere to disconnect both battery leads and then bolt them together. Not too sure about this. I thought it would allow a current flow through the electrical components.:?:

Taking the battery negative off and earthing it should do the job.

Trev.

**discowhite** · 22nd September 2005, 06:57 PM

ive welded a lot of things on a lot of cars and have never disconnected
anything. all is fine as long as you keep the earth as close as possible
to the job.
ide be more worried about fuel lines and smoldering sound deadening
than anything else.

<div class='quotetop'>QUOTE</div><div class='quotemain'> the earth clamp on the tailshaft!!!!![/b][/quote]

and this is just asking for trouble!

phil.

**PhilipA** · 22nd September 2005, 07:10 PM

Just had a new quieter back muffler put on to please the manager last Saturday and the guy who I trust to be knowledgable just linked the MIG earth on to the exhaust pipe and away.
I have 2 alternators and injection and no probs.
Must say I was surprised but know that the guy does it every day for a living.
Regards Philip A

**abaddonxi** · 22nd September 2005, 08:17 PM

I thought that the issue is the cpu/electrics being fried rather than anything else.

Though I guess if that was logical you would be disconnecting the cpu as well and I haven't heard of that.

Cheers

Simon.

**LandyAndy** · 23rd September 2005, 09:27 PM

Hi Guys
Checked up on the Rave CD
It seems pretty easy,disconnect battery terminals,negative first.Disconnect alternator wiring.
Sounds easy enough.
Andrew

**disconut** · 24th September 2005, 05:18 AM

I think its all about creating "earth loops" and and preventing current from passing throught electrical components by "looping" back to earth at different points.
Some components may be more prone to this.
As has been said before, earth clamp on the piece to be welded, then the current will take the path of least resistance and not travel via vehicle components and earth cables.

As an aside to this, some years back on a construction site, the boiler makers were welding a lobsterback in a 36" duct. ( a large 90 degree bend made of sections). They had connected their earth cable on the building at the base of an RSJ column, and began to weld the job on the 3rd floor. The ducting exited a large 36" automated spade valve, (sliding steel gate), the rest is history. Two days later on completion of the duct, the valve was sucessfully welded closed!!. All of the welding curent had been passing through this valve to get to the lobsterback ducting being welded. They had clamped onto the base of the building because they only wanted to drag one welding cable up to the third floor. The valve was worth around $150,000.

A second amusing job was the welding of "grouser plates" to build up the worn bits, (these are the tank track thingy's on a D9 Dozer). It was in the workshop for around 2 weeks. Again the earth was connected to a common chassis point. Two weeks on, all of the bearings, and the track pins, were successfully welded. The D9 and its powerful engine could not move it. The tracks were required to be cut off and all of the bearings and chains on both sides replaced.
There seems to be a lack of knowledge about the current flow when welding, and as an Instrument Technician of some 30 years, I have many stories about the gear I have been required to replace.

Trev.

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