Thread: Welding a D3

Usual precautions
Disconnect battery, keep earth clamp as close as practicable to the area being welded. Make sure earth clamp has good connection. Keep welding cables well away from electrical bits of car.

The problem can be twofold.

First the current in welding can induce voltage in any cables running by the metal being welded between the weld and the earth clamp. Also the welding leads can induce voltage in any other cables they run close to. I remove my watch when welding as the current can magnetize the internals or induce currents to damage the electronic bits. When welding with high current you can see metal filings jump onto the welding leads due to the current induced magnetisim. Same thing will cause damage to electronics.

Second the arc in welding is effectively a spark gap transmitter like they used way back when. Broad frequency transmitting basically. This can interfere with the sensors and confuse the computers. The electronic computer chips do have protection on their pins to help avoid static and other possible damage. Generally this will be enough. Risk is if the circuit is powered on and a spike causes part of the chip to turn on it can end up destroying itself. Safer when turned off.

I fix electronics for a living and weld at home so have seen both ends of the issue.

James

Thanks James, have done a lot of welding on cars but not one with this much electronics. Only a small repair to weld a new nut to the rear pillar that holds the gas strut to the body. Ball joint undid itself enough to allow the nut to be worked back and forward and finally broke the nut away. Will have to insert a new nut and MIG it into position. Properly be a good idea for everyone to check the tightness of these balls so it wont happen to them.
Cheers Tinman

Another precaution is to earth the lead that goes to the battery positive, once it is removed from the battery of course. This attempts to provide a path of least resistance to earth for any stray currents generated in the wires, rather than via electronic components which all have an internal resistance.

Hi All, When I built the custom ally rockslides for the D3, all components were tacked together in situ on the vehicle. Following exactly the procedure mentioned by others, there were no adverse effects on the vehicle. Safe to say any small welding job will require far less amp/volts than required for 10mm ally ;-).
Now James whilst I unconditionally yield to you knowledge on electronics, I can assure you that your watch is safe to wear whilst welding with the exception of spatter burns on the glass that is:-). I've worn the same watch for 8 yrs doing both wet n dry welding and apart from the burns on the glass it's working fine!
Happy Burning tinman!!

What sort of watch do you have?
My current one is Seiko kinetic with metal band and when using high current it comes off was engagement present and married 12 years now. Actually so does the wedding ring. (I also got a tractor for engagement present, beat that) I used to get burnt so now have proban jacket, skull cap, spats and nice auto mask and appropriate gloves. Prefer TIG over other welds.
James

Originally Posted by Graeme

Another precaution is to earth the lead that goes to the battery positive, once it is removed from the battery of course. This attempts to provide a path of least resistance to earth for any stray currents generated in the wires, rather than via electronic components which all have an internal resistance.

Just make sure there is no voltage on the positive cable from a 2nd battery. My El Cheapo battery isolator has FET's in it and they will back feed due to the diodes in them. I can be working on the D2a with the radio on for music, remove the main battery and still have the radio working. Then I think Oh crap, gotta pull the fuse ion the 2nd battery.

Regards Gordo

We used to disconnect the computer and battery just to be sure when any welding was to be carried out.
Cheers
steve

Completed my welding job all went fine. D3 up and going
Cheers Tinman