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Old November 15th, 2005, 10:13 PM   #1
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Default Alternator Shield

I don't have much tech to post but this is one that works real well for me. Originally I got the idea from Det06roit from Michigan Jeepers. I'm not sure where he's at these days, maybe misfits. Either way, he made his shield out of rubber, I decided to make mine out of metal.

This was originally posted on .com until the big changeover to It can also be located over there but it is the same article except for a few updates on this version. See new notes at the bottom.

As an update, since I built this shield, I have yet to burn up an alternator. It's been multiple years.

Materials and Tools


* 12"x24" 26 gauge sheet steel (pretty thin, just like heat duct metal)
* 1/8" pop rivets
* Spray paint and primer (optional)


* Air cut-off wheel (electric grinder works better)
* Tin snips
* Hammer
* Rubber mallet
* Pop rivet gun
* Socket set
* Drill and bits
* Clamps
* 2 large boards (for making clean bends)


First thing I did was remove my alternator. Then I assessed the situation and decided the first thing I needed to do was find a mounting point for the shield. I choose the alternator mounting bolts (2).

The next step was to figure out how to get the steel up to the bolts and stil leave room for the alternator to breath and not overheat. Unfortunately I didn't get a picture of this so I will do my best to explain and the next pictures will help you understand.

The first bend was to fold the sheet in half longways like a hotdog bun. To do this, I placed the sheet in between the 2 boards and clamped them together on the center line. Then I carefully bent the sheet by hand until I could hit it with the rubber mallet into a 90 deg. bend. Take it out of the boards and finish the bend completely in half. Now you have to make a mark two inches from the folded edge down the whole length (longways again/hotdog bun) This is going to be your next bend line. Place it back in the clamp/board vice and bend one edge one way and the other edge the other way, using the rubber malet to make the corners crisp. Now it should look kind of like a "T" (although short).

Building the Shield

At this point you should have 4" wings(top of the "T" on either side of a 2" rise. With the alternator put in place, loosely place the "T" in the engine compartment to see where you'll need to make cuts for bending. I also forgot to measure these but it's really easily to visualize when the "T" is in the bay. I would say that there was that the first one was about 8" from the top, the next one was 5" from that and the the last one 8" from that, this allowed for about 3" at the bottom. Below is a photo of the shiled that might give you a better idea.

In that photo, you will notice the cuts that I had to make to be able to bend the "T" around the alternator. I used "V" shaped cuts to allow for easy bending and used the boards/clamps creatively to make the bends straight. After you've marked your spots for the cuts (don't use my guesstimates without first test fitting). I would take the chance to put in some pop rivets to hild the "T" in place. I choose to keep my rivets as close to the inside edge as possible (near the wings).

You'll see in this photo that I had to remove most of the center section. I left enough metal for the rivets to still be in place. Make sure that you leave room for the mounting holes (also visible in the photos).

Installing the Shield

There are a few other cuts that you will need to make at this point to clear things (A/C mounting bracket, fender, wiring, etc.). I won't get into much detail here because your options may be different than mine and your bends may be a bit different. I had to cut a space to clear the A/C mount (I do not have A/C). Here's a photo of that cut:

You can see the cut at the top of the photo. The tab that you see on top of the factory A/C bracket is going to get a bolt through it for more support. I also choose to fold over the last inch or so of the front to help a little more from the front and th reduce some clearance issues (not as sharp either).

In this photo you can see the bottom and final bend. I took the last 3" or so and bent them up towards the engine to help bottom splashes. I also attahced a strp to help suport the shield and to keep it from shaking while the engine is running:

I'm laying under the jeep with my head towards the front bumper. I also drill several weep holes in the bottom corner to allow water to drain. The strap attaches to a long bolt on my oil pan. I just sanwiched it between some washer and another nut. (Oil pan nut, washer, strap, washer, nut)

Final Touches

I rounded off sharp corners and smoothed out edges and then I primed and painted it white. Let it dry and then istalled it all The mounting holes on the shield should be sandwiched between the starter and the brackets on the fonr side of the alternator. Make sure that your new shield clears anyting important such belts and body panels to keep rattles away. Here's a couple photos of the shield installed.

The last photo is from the side of my jeep kind of at an angle. The left side is more like the top of the engine. I hope this gives you some ideas on how to protect your alternator from water and mud, and potentially leaving you stranded.

New Notes as of Nov. 2005
I've made several shields since then, almost cut my finger off doing it and basically have been really pleased with my first design. Keep in mind that the electrical components are in the rear of the alternator and the shield should really cover those up as much as possible. On 4 cyl models (at least in YJ's) the engine mount on the passenger side of the block really helps to block junk from getting splashed up. When I made my original shield, I took this into account. Since then, I've made a couple shields for 4.0's and they are slightly different. The engine mount does not provide the same kind of protection. To deal with this issue, the shield extends much further back on 6cyl. To do this I just made the rear "wing" of the T much longer and the front shorter. i found this design to work really well, unless you have factory air conditioning. Then you have to get creative on the back corner. I built one for Danford in the white lake area and his turned out very nice. Anyway, I hope you enjoy and if you have questions please feel free to pm me.

Article originally submitted by "sodapop" at
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Old November 17th, 2005, 06:27 AM   #2
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Thanks for the writeup SodaPop!

I purchased one from you about 2 years ago, and it worked perfect until I moved to the V-8...

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