Cautions when welding

wtm442 · #1 (**permalink**) 08-08-2007, 10:52 AM

I'm having a friend weld up the support brackets on the side pipes over the weekend. They broke half way down the length between the side pipe and the rubber body mount. He owns a welding shop and said he would decide what type of welding to do once he crawls under the car. I told him they were ceramic coated.

What cautions should I do for the Cobra?

Just disconnect the negative ground cable at the battery?

What about the stock Ford Duraspark ignition module?

Clois Harlan · #2 (**permalink**) 08-08-2007, 11:07 AM

That should do it but I usually disconnect both cables to be sure. Keep a fire extenguisher handy just in case.

Clois

cobrarkc · #3 (**permalink**) 08-08-2007, 02:13 PM

You might want to consider taking them off just in case there is an OOPPPSSS!!!! You'll be kicking yourself later.

RedBarchetta · #4 (**permalink**) 08-08-2007, 03:01 PM

Warren, I had this done a couple years back when I re-did my mufflers. Took it to the same guy and we did it on the car. He disconnected the battery and I helped him hold in place a splatter shield to protect the car/paint. He used a wire feed MIG welder and no problems. You just have to take your time to do it right. Good luck!

-Dean

Excaliber · #5 (**permalink**) 08-08-2007, 03:02 PM

I recall something about the path of current possibly traveling through a 'bearing' (wheel, trans, etc.) from the postive welding lead to the ground lead (or vice/versa). Concern would be damaging the bearing(s). I'd make sure whatever 'ground' point was selected is a short and direct path back to the point being welded. Can you weld over/through a ceramic finish? Sounds like it would be tough getting a decent ground/arc established.

jams · #6 (**permalink**) 08-08-2007, 03:05 PM

Better safe than sorry.

As long as the grounded welding lead is close to the spot being welded you should have no issues.

Problems come when the grounded welding lead (wire) is a far distance from the spot being welded. This make you frame or other metal part a giant wire carrying a whole lot of amps.

Electricity takes the path of least resistance, so when the spot being welded is close to the ground wire everything works for the best.

Excaliber · #7 (**permalink**) 08-08-2007, 03:13 PM

The ground wire on my ERA got to loose sometime back and the lights and stuff got 'wierd' on me. Then one day I lost my clutch slave cylinder hydraulic line. A plastic line wrapped with a metal spring like protective covering. Well THAT spring like protective covering BECAME my electrical system ground! Eventually it actually heated the spring enough to melt a hole in the plastic hydraulic line! The starter always worked good because it was direct ground to the battery. All other loads had to travel through the clutch slave cylinder line! Frame ground may be not be good enough as the exhaust pipes could be isolated from the frame via the rubber motor mounts! In addition, what kind of frame back to body back to battery does the car have? Big enough to 'weld' with?

Rick Parker · #8 (**permalink**) 08-08-2007, 04:24 PM

Unplug the ignition box from the distributor. Disconnect switched 12 volt source leading to the box and disconnect both the ground and Hot lead to the box. High frequency arc can kill some electronics.

CHANMADD · #9 (**permalink**) 08-08-2007, 04:35 PM

In response to Excaliber, Our cars have fibreglass bodies and you cannot put enough grounds. Seperate grounds for the front lights, back lights and engine and ground the transmission as well.

Excaliber · #10 (**permalink**) 08-08-2007, 04:42 PM

Indeed, in my case I had several 'different' grounds, but they all went to the same single location fixed with a single screw. Perhaps a number of different grounds, bolts/screws and contact points (which is what I have now) is the best way.

CHANMADD · #11 (**permalink**) 08-08-2007, 04:54 PM

Front lights etc are all grounded to the chassis at the closest possible point. The ground cable from my battery goes to the engine and then another from the engine to the frame.

Lowell W · #12 (**permalink**) 08-09-2007, 07:12 AM

Warren,

I haven't done as much welding as a lot of guys here, but I did weld on nuclear submarines for a little while and also did a fair amount of maintenance welding years ago. I have gas, MIG, TIG and stick welders and a plasma cutter for my own projects and wouldn't hesitate to make the repair you describe.

The prep work here is as important as the actual welding, IMO. What I would do is "V" the two pieces to give about a 45° angle, all the way to the bottom, then grind the ceramic coating off for about 1/4" back from every place you'll be welding. I'd put the wide part of the "V" facing down so it doesn't show. Take just a LITTLE weight off the back of the pipe by placing some kind of support under it. Bolt the broken end of the bracket into the rubber frame mount, then align it with the end still on the pipe and clamp everything in place with a couple of C clamps and a piece of 1/4" or so thick scrap steel. If both pieces don't line up perfectly, see below. DON'T use the C clamps and scrap steel to pull the pieces into alignment! Now remove the pipe and take it to your friend at the welding shop and he can take it from there. Just be sure he clamps the ground on the bracket and insulates the pipe from the welding bench.

The rubber cushions on my first set of rubber sidepipe mounts cracked the first season I had the car. When I replaced the mounts, I found that the holes in the brackets and the frame were about half a hole off, which placed a lot of strain on the rubber cushions. I "ovaled" the holes in the brackets so they would bolt up without any misalignment and these ones have lasted almost 4 years.

I think there's an article on SCOF or CC regarding reinforcing the sidepipe brackets but I'm not convinced that's necessary. If you think that's what you want to do, however, now would be the time to do it.

There are a lot of ways to get the skin off the cat. The above is just my opinion but that's the way I'd do it. Since you asked...

Good luck,

Lowell

imagine2frolic · #13 (**permalink**) 08-09-2007, 02:15 PM

Get everything down to clean metal, tack it with a splatter shield, and take it off the car. It takes more time, but it is worry free. Plus you can get a lot more weld on the parts.

I am wondering how the exhaust is mounted? On some very firm brackets? I have mentioned this a few times here. There are some tongue, and groove brackets that allow the system to slide back, and forth a bit. They keep the system from going up, and down though.

By the video you shared it appears you need a forgiving bracket that will allow some movement. If you want this failure to stop, you may need to go to a different bracket. If you want I will bring out the camera, and take some pics of these type of brackets. Any muffler shop can get them for you. They come in many different configurations. Good luck with the project.

imagine2frolic · #14 (**permalink**) 08-10-2007, 10:31 AM

This bracket type comes in many different configurations. Almost all muffler shops have hardware books to look through. There are even some applications for XJ6 axle pipes that might work. They are a pin through a hole.

Tinker51 · #15 (**permalink**) 08-10-2007, 09:39 PM

I had the same problem with my pipes.
I took them off the car to weld them up.
It was about ten minutes work per side to R & R.

wtm442 · #16 (**permalink**) 08-24-2007, 09:45 AM

My friend welded up the support brackets a couple of weeks ago. I just jacked up the car, and disconnected the neg battery lead. He made sure the ground of the MIG welder was about 6 inches away from where he was welding. He beveled both ends of the piece to be welded like this /\.

I had used a piece of flat metal about 3 inches long with a couple of metal hose clamps around the bracket so it did not squeek after it broke. He also welded that piece to the support. Looks great and so far so good. Now I just need to clean the area and paint it to keep the rust away!

Thanks for all the comments.