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I'm in the process of building a bracket for a pass-through filter. I would like to attach it to the frame near the current filter. Rather than drill the frame, or use bands/clamps I would like to weld two small bolt brackets to the frame.
In the past I have cooked more than one Ignition Computer welding on vehicle body/frames. No doubt the Hummer has even more electronics that may be at risk. So...what do I need to disconnect before I do this?
Thanks in advance,
First, be very careful about welding or drilling the frame. You would be better advised to weld to a bracket or other attachment. The frame is specially-tempered steel and has a very thick anti-corrosion coating inside which will be damaged by welding. You may affect the strength properties of the frame by welding on it. DOT forbids welding on truck frames (big ones I'm sure, smaller ones I'm not) for that reason.
If you must weld on the frame, use "stitch welds"; do not weld across the entire face of the member, as that will leave a stress point for cracking, but rather use one or two short welds in the web, and do not weld at stress points (bends, joints) at all.
You might want to consider welding to the skid plates rather than the frame.
Second, there is a danger of frying the computer, and it's a good idea to disconnect both the trans computer and the heater control, but you can avoid a good deal of difficulty if you simply ground your welder as close to the welding site as possible. This makes the current path quite direct. My welder friend Tyler is often called upon to weld on pickups and other vehicles, including my hummer, without disconnecting the computer, and he hasn't fried any computers in a long while by using proper grounding techniques.
Disconnecting the battery power lead (+ terminal) should disconnect all electronics. If you are welding physically near any computers, you should shield them or remove them before welding. Removing is always safest, but not always practical.
Does anyone KNOW FOR SURE that it is safe to weld to the Hummer frame? Many truck frames are specially hardened metal, and welding will weaken the frame.
Check this out before you start.
Disconnect virtually everything, A/C controller (if electronic) radio, CD Player, Transmiision computer, DRA (if equipped) Speedometer (it's computerized, too), door lock controller (if equipped), and perhaps more!
Two suggestions, one is to drill and tap holes. That would weaken the frame less than welding, IMHO. Use the smallest, strongest fastners you can find, to keep the holes smaller.
Second is to gas weld, rather than arc. More difficult, I know! However, safer than arc welding for electronics.
In the AM General guide to OEMs and modifiers, AM General states specifically not to weld or drill the frame.
Everyone knows that you're NOT supposed to weld on automotive frames, but everyone does. (If you know what I mean)
If you're going to do it, make sure you disconnect the battery, keep your ground close to where you're welding and if it's a gas-drinking vehicle (LISTEN CAREFULLY HERE) fill your gas tank and top it off when you're ready to weld. THE FUMES ARE THE COMBUSTION PROBLEM, NOT THE LIQUID ITSELF. Put a water wet rag over the gas cap too. These are some of the safety steps that I have to follow whenever I am required to weld on a vehicle. Don't forget a fire extinguisher ! You never know !
If you don't know what you're doing, get someone who does !!!
Ron-----------The Yankee Fabricator