Welding alternator bracket - big oops!

How about looking at alternators at the wrecking yard and figuring out how you can modify one to mount on your BMW.

If you are going to have to disassemble the alternator to rebuild it, I would do that before I did any welding.

Dan

Alas... '94 325is

Well, here's how I see it.

You got little to lose. You are NOT welding for NASA.

Therefore...

Use pretty much whatever filler you have on hand. I'd use 1100 first if I had some.

Keep your weld times short to avoid a lot of heat build up in the case. Nothing says that you cannot bury the part in a bucket of water and leave just the bit you are welding sticking out. It'll dry after and be just fine.

Less hammer, more brain! :-)

Good luck!

Cheers Trevor Jones

What year is it, I have a 87 325 that will be going to the wreckers soon.

stan

I typically use 4043 fill rod to fix cast aluminum with little or no problem. I have fixed a transmission housing out of a Subaru. I would disassemble the alternator first and then v groove grind the area where the break occured. TIG weld it with 4043 rod after cleaning the area with first a _clean_ wire brush and then some acetone. It should weld up just fine.

Let me know how it goes, James Walsh Jr. Jigsaw Custom Fabricating

I meant to say, that I've successfully fixed a transmission housing out of a Subaru using 4043. It wets in nicely and will fill in the cracks fairly easily.

Sorry about the re-edit, I should re-read my own writing.

Thanks James Walsh Jr. Jigsaw Custom Fabricating

Try adapting a an older GM alternator, the kind with one wire to charge battery and plug with two wires. I've seen them used in many applications from lawn tractors to hot rods. These are readily available at salvage yards and auto parts stores. This is the least expensive solution I can think of. Hope this helps.

Before you try welding that tab back on you will have to disassemble it and work on the bare housing casting, or the welding current will induce voltage in the coils and fry the internal voltage regulator and/or diodes in the rectifier. Or induced currents can go through the ball bearings and wreck them. And you need to jig it together properly - if the tab is off center even by a fraction, the fan belt will run cockeyed and can give you grief. Multi-rib belts will not tolerate misaligned pulleys at ALL, they'll toss or break, or both.

Before you go through all that, check the local auto electric rebuilders in your area. They might have a rebuilt unit all ready to go, or one with a good case and toasted internals they can use as core parts to fix yours. The internals of an alternator are simple - the wear items that should be replaced are the slip-ring brushes and the bearings. The rotor and stator coils, regulator and diode bridge each either test good as a unit, or get tossed and replaced as a unit.

Or as has been brought up, plop it on their counter and see what other alternators they have that will fit in your car. BMW probably doesn't make their own alternators, they get them from Bosch, or Motorola, or Nippondenso, or Delphi (GM/Delco). With a good rebuilt alternator and the proper pulley swapped from your old one, and maybe a custom wiring harness adapter, they more than likely can make you up a unit that fits and works, and not too expensive.

Heck, you might even get more amps out of the new one, so you can go crazy and install that big 2KW stereo you always wanted. When a "Boom Car" pulls up at a stoplight pumping Gangsta Rap, you crank down the windows and shoot back with the Telarc "1812 Overture", or Don Dorsey's Beethoven "Rage Over A Lost Penny". Or worse, Opera...

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The chances are, that another make of German car uses the same alternator! Take the old one to an auto wreckers, and see if they have a match for it.

Steve R.

That's why I like my Chevy small block v8, rebuilt alternator costs me $40., performance brake pads $40, rear shoes Wagner $30, 92 Camaro 177K miles, paid 22k new.

As it happens, I spent a portion of my day in a wrecking yard looking for an alternator for my Jetta. I got one that looks like it will do, out of a (drumroll.....) BMW! (vintage unkown, but probably late 80's)

The pulley is different, but the case offsets are all the same. It has one less bolt hole than the one in the Jetta, but all else looks good.

So, try a VW dealer. After you go to a couple wreckers looking at VW's. Remember that the mounts are the thing to look at. Pulleys can be changed. The electrical connections are all pretty much the same from any given manufaturer (Bosch, in this case) even if the back of the alternator does not ook quite the same.

Worth a try, anyways.

Cheers Trevor Jones

Thanks for all the great suggestions guys - Bruce's post was very detailed - I may have found it in a U-pick junk yard - if that's there I'll go that route otherwize.... tig & tap tap tap - repeate as necessary.

Thanks

Surftom

I might have made a mistake in reading this thread wrong. But, It reads like you are concerned with welding a broken mounting ear back on a nonfunctioning BMW alternator. I'd suggest that the mounting ear could be gas welded. What the heck! It doesnt work anyway. I've been in the alternator repair business for 35 years and have seen alot of mounting ear repairs. It is not a simple task I am sure you are aware that there are electronics within the alternator. What chance do you think you'd have of *not* frying the electronics with the HF of the TIG?

Have you thought of taking the nonfunctioning/broken BMW alternator to an Auto Electric shop where they specialize in repair alternators? Disassembly and repair of most alternators is usually easy after you learn some of the "tricks".

Jerry

Clean stainless steel brush.

How about a 4th option? Try buy

It aint worth the potential hassle of a weld breaking. Although it isn't the same, here's my story:

Alternator goes bad in Fairfield CA. Replaced by reputable dealer (I thought).

Anyway, those brackets are made from the crappiest metal and subject to high levels of fatigue. Is the chance that the weld will break or the parent metal breaking due to heating changes worth it or is just getting a replacement bracket a safer bet?

Ten cents of formed "L" reinforcing ended up costing me several days work as well as the repair costs in the middle of nowhere. Some things just aren't worth scabbing back together.

Koz (who also extolls the virtues of GOOD batteries due to similar experiences)