'75 Cracked Headlight Housing

[Patricia Brown]

Hello,

While starting a rebuild of the headlight units off a '75, I discovered one of the housings has a crack. I understand the material is die cast aluminum. Is there a good way to fix this, or am I stuck finding a replacement?

Can die cast alum. be welded? Can I use an epoxy repair glue? This crack is just below the large pivot bolt and the area is hidden under the headlight bezel.

Thank you for any advice! These housings are about $250 each, new, so I'd sure like to fix mine if possible.

Patricia

[Terry F.]

Re: '75 Cracked Headlight Housing

A large hardware store or welding supply store will sell a special rod the can be used with a propane torch and aluminum. V-out the crack and make sure it is super clean. Use a stainless steel brush to clean the area after it is V'd out. Make sure it is totally void of paint or oxidation in and around the area. Heat the area with the propane torch and keep touching it with the special rod to the heated surface. Take the rod out of the flame if the surface is not hot enough to melt the rod. The secret is to melt the rod with the metal surface, don't melt the rod with the flame. Result is as good as new and as strong if done right. Terry

[Terry F.]

Re: '75 Cracked Headlight Housing

You can also call around in the phone book to machine shops. Ask them who can weld aluminum. They will know who to recommend. An aluminum weld may not cost much at all. Prep is the worst part. Clean the area up real well so all they have to do to it is hit it with the welder. Saves time and money. Perfect results usually and you can grind down the weld later if you like and pretty it up. Personally, if not seen, leave the weld alone. Terry

[Joe L.]

Re: '75 Cracked Headlight Housing

Patricia and Terry-----

I'm pretty sure that the non-cover portions of the housings are zinc diecast material and not aluminum. However, in any event, either can be repaired with the low temperature welding rod you mentioned. I've never seen this in hardware stores, but it is available from the Cecil Muggy Company of Torrance, CA. I believe their website may be www.muggyweld.com. This rod is a special low temperature, aluminum alloy rod that was originally invented for the refrigeration industry. It's the hobbyist's dream-come-true, though. You can repair just about any metallic substrate material with it. It's not for structural repairs where very high strength is required, but for most everything else, it's perfect.

If you don't want to do the repair yourself, there are many radiator shops that are expert in the use of this special rod. The Cecil Muggy Co. should be able to direct you to one in your area.

[Patricia Brown]

Re: '75 Cracked Headlight Housing

Terry-thank you for the description on how to fix the crack. And, Joe, thank you for clarificaton on the type of metal the housing is made of. Such exotic materials! I appreciate the link for the welding rod. I'm pleased to hear it can be fixed; they're expensive little buggers!

Patricia

[Patricia Brown]

Re: '75 Cracked Headlight Housing

Terry and Joe-

I checked out the Muggy Weld company (thank you for the link). I'm wondering if you could tell me exactly which rod I would need. It *appears* I would use the Super Alloy 1 kit?

Patricia

[Joe L.]

Re: '75 Cracked Headlight Housing

Patricia------

I think that the Super Alloy 1 would be your best bet for this repair. If you're going to do this repair yourself, you want to practice with the rod before you try to repair the housing. Just find a piece of silmilar material and practice with it.

Also, the zinc diecast material is not really what one would call an "exotic material". Zinc diecast is the true name for the metal that's commonly called "pot metal". I think that term comes out of the fact that it used to be used a lot to make cooking pots and pans. It's VERY common on automobiles and is used for a wide variety of things. It's also easy to break, so learning how to repair it with the Muggy Weld can be very beneficial if you do a significant amount of restoration work or other repair work. Until Muggy Weld came around (quite a few years ago, now), zinc diecast or pot metal was a very difficult-to-repair sort of thing. Very often, broken or damaged pot metal pieces were considered scrap. While Muggy Weld is not really something that you want to use for a high strength application (regardless of what they say), it's perfect for pot metal which is never used in a high strength application, anyway. The Muggy Weld is going to be as strong or stronger than the parent metal.

[Patricia Brown]

Re: '75 Cracked Headlight Housing

Joe,

I had no idea "pot metal" is really zink die cast. Yes, "pot metal" sounds far less exotic! I was removing all the springs and screws and such from the headlight housing today and looked carefully at the piece; I can't detect any evidence the top plate is seperate and bonded in any way to the understructure, but that's not to say it isn't.

Thank you for help confirming Super Alloy 1 is the stuff to use. It's a bit pricey at $50 to get started, but, like you say, it can be used for other pot metal applications. So this process would actually be closer to soldering than welding, wouldn't it? And, just to clarify, this Muggy Weld Super Alloy 1 would also work ok on straight aluminum, not just pot metal, correct? They offered a Super Alloy 5, but it sounded like it required higher temperature.

Here's another Q I'll run by you: While removing the various screws from the housing I noticed some were the original machine-screw-thread while some were a sheet metal screw, which I am under the impression is a replacement. (?) I just got wondering what in the world would I do if the threads were screwed up in the housing, being such soft material. Could I install some sort of thread insert? I have never worked with thread inserts, but I'm wondering if having a good steel insert to replace some of the holes where sheet metal screws were used would be a good idea?

Thanks,
Patricia

[Joe L.]

Re: '75 Cracked Headlight Housing

Patricia-----

I am virtually certain that the cover of the headlamp housing (the part that is visible with the housing in the down position) is a piece that is somehow fastened or bonded to the "frame" of the housing. I have not looked at one of these closely in a long time, but I don't see any way that it could be manufactured as a single piece. I suppose that such a monolithic housing could be made using CNC machining, but that didn't exist when these things were made and such a manufacturing process, even today, would be FAR too expensive for making a piece like this.

Yes, the Muggy Weld is really more like soldering than welding. However, it produces a bond which is far stronger than any solder bond. Not as strong as steel or aluminum welding, but far stronger than solder. It can be used to "weld" just about any metal. That's one of the "beauties" of it; you don't even have to identify the metal prior to using this method. It will work just as well with aluminum as with pot metal. Or, most other metals, too.

On the housing, it's my recollection that there may be a few sheet metal screws used. I think that the side attachment points of the bezel may be sheet metal screws which thread into j-nuts somehow attached to the housing. The bezel screws from the front, thread directly into tapped holes in the housing and are machine screws. You can repair these tappings directly into the housing with inserts such as a Heli-Coil. You can also repair them with other types of inserts. And, you could use a repair like filling the tapping with an epoxy like JB Weld and redrilling and tapping. MOST of these are definitely NOT high strength applications, so this will work fine. Another approach would be "welding" with the Muggy Weld and redrilling/tapping. There are all sorts of repair methodologies that will work for something like this.

[Patricia Brown]

Re: '75 Cracked Headlight Housing

Joe,

Thank you for your help. I'm going to look at Heli coils at my local hardware store, if they carry them. If not, perhaps JB Weld will come to the rescue. I agree these are not high-strength areas and either method ought to work.

Patricia