Alternator Brush Replacement
Original brushes in 2003 Civic alternator, 170k miles, 2016

Brushes from eBay

Brushes from local shop, sans
springs and terminals

My 1991 Civic needed a new alternator after eight years and 106k miles. I decided to be preemptive with my 2003 Civic and replace its alternator brushes before the alternator showed any symptoms of failure. From my reading, usually the cause of failure is worn brushes. 

A lot of night driving will tend to lead to brush failure sooner, due to the demands the lights place on the alternator. Also I have read that, if the old brushes are less than half the original length, then the brushes should be replaced. The Honda Civic service manual states that a brush length of less than 5 mm justifies brush replacement.

Preparation
1. What are part numbers that might help me locate brushes for my 2001-2005 Civic?
-- The OEM alternator is Mitsubishi model AHGA50, Mitsubishi p/n A5TA7091ZC. The Honda p/n is 31100-PLM-A02. The ACDelco aftermarket alternator is p/n 334-1427A.

-- The OEM voltage regulator (which includes the brushes) is Mitsubishi
A866X48782. The ACDelco aftermarket voltage regulator is E657C. One more p/n for the voltage regulator that I ran across is bwd r2103. Notice that the voltage regulator by itself costs more than a remanufactured OEM alternator.

--  brush set part numbers
Mitsubishi p/n A647X50170, from http://www.shoforum.com/showthread.php?p=1347825
Honda OEM p/n is 31140-P64-902  (also known as 31140P64902).
Carquest p/n 20-1628
140817 from another site
ABR5515 from another site
38-83002 from http://www.metroautoinc.com/PDF%20File/38%20&%2039-Brush%20Holder%20&%20Parts%20List.pdf .
38-8307 from
http://www.aspwholesale.com/index.php?act=viewProd&productId=6550. The latter site gives dimensions of 5mm T x 8mm W x 23mm L x 30mm lead length. The 23 mm length refers to the longest edge. The shorter edge is about 21.5 mm long.

I recommend paying the extra money for brushes that already have the springs and terminals attached. See below for more discussion of this.

2. Where do I buy new brushes?

-- Online Honda stores. You will pay over $20 for a pair of brushes.
-- Google for {alternator rebuild [your zip code]}. Call and see if they have a pair. The first shop I called where I live had them. Because the brushes are so inexpensive, and the shop does not usually deal with DIY-ers, it had a minimum charge of $5. The springs and terminals were not included for these locally purchased brushes. Below I reused the old springs and terminals. The front desk person at the shop cautioned me not to drip solder into the region where the springs are, or the springs will likely get soldered and not work per design.
-- I think a better option is to buy brushes with the springs and terminals already attached from eBay or Amazon.  Search using the various part numbers and/or dimensions. For example, in May 2014 this international Ebay seller wanted $7 for four brushes:
http://www.ebay.com/itm/BRUSH-SET-FOR-MITSUBISHI-ALTERNATORS-SECOND-BRUSH-SET-FREE-ABR5515-140817-/221199584729#shpCntId. I think avoiding the trouble of detaching the old springs and terminals from the old brushes, and then attaching these to the new brushes, is worth the additional cost.
 
3. What special skills are needed here?
You need to know how to solder. For the job below, I used an inexpensive Archer 30-watt soldering iron. I bought new soldering iron tips for $3 from Sears first.


Replacement of the Brushes on a 2003 Civic
I downsized and no longer have a garage. Also I am older and not moving as fast. I decided to spread this project over a few days. I bought a second-hand 2001-2005 alternator from my local salvage yard, gave it a good cleaning, changed its brushes, and then installed this in my 2003 Civic. The second-hand alternator cost me about $37 in 2016. As another option, one can buy a rebuilt OEM alternator on eBay for $42. 

Both honda-tech.com and civicforums.com have DIY guides for removing the alternator. Use this excellent youtube video to disassemble the alternator and replace the brushes: http://www.youtube.com/watch?v=qOo0iSnmwP4. What follows are some highlights from what I did and the youtube video. (Many thanks to WestronicsIrl for posting this video. Please visit his store at http://stores.ebay.ie/goldlion-autoelectrics.)

To introduce you to the main parts of the alternator, become familiar with the schematic below:
Parts that may be necessary for a full rebuild are the voltage regulator (#13 above); brushes (#9 above); and the bearing (#5 above). Rebuild kits are available online.

Remove the four bolts below with an 8 mm socket:

With a hammer tap as shown:
Rotate one side of the alternator housing and tap all the way around the circumference. The green arrow below points to a gap that should open up as you tap:
Pull apart the housing: 
Identify the half of the housing that holds the brushes. This is the half that has the stator attached to it.The stator is the copper windings exposed as you separate the two halves of the housing. Both the photo above and the photo below show the stator. 

The purple arrow below is pointing to a brush that is in pretty good shape. The red arrow is pointing to the second brush. The second brush is well worn and needs replacement. After 170k miles and 13 years, my 2003 Civic's brushes had a similar wear pattern: The inboard brush had worn significantly more than the outboard brush.
Take a large phillips head screw driver, insert it into each of the two phillips head screws above (green arrows), tap the end of the screwdriver a few times with a hammer, and unfasten the screws. They are a little tight, so make sure your screwdriver fits the heads well and does not strip the head.

One more phillips head screw needs to be removed. The green arrow below points to this screw. To access this screw, carefully lift the stator a tiny bit and move it out of the way. Note how the copper stator (part #3 in the diagram above) has several leads that are welded to the voltage regulator-brush assembly.
Flip the housing over to expose the B terminal nut. Remove the nut and the plastic insulator beneath it:
(Note that the plastic insulator fits only one way.) Separate the housing from the stator and brush holder assembly. Note the plastic cap that the technician below is pointing to:
Gently pry off the cap. It should come off readily. This will expose the terminals of the alternator brushes. The green arrows below point to the blobs of solder that ensure a good electrical connection between the alternator and the terminals:
With your soldering iron, heat each blob while pushing the alternator brush from the inboard end. Once the old solder melts, the springs will help push the brush terminal out of position. A little prying on the terminal, using needle-nose pliers and a small screwdriver, will help.

If you have new brushes without the springs and terminals:
The ends of the old braided copper wire leads appear to be glued to the terminals. As needed, detach each terminal from the old copper lead by scraping off the copper lead's end. Slide each old spring over each new brush's copper lead. Attach the new braided copper lead of the new brush to the old terminal by compressing the spring, setting the length to that of the old brush's lead length, and wrapping the end of the new copper lead around the tab jutting out of the terminal. Apply two-part epoxy or similar to glue the copper lead to the terminal. I used this epoxy from Harbor Freight (costing $2):
Wait 15 minutes for the epoxy to set, then check for continuity with a digital multimeter, from the far end of the carbon brush to the metal of the terminal.

Insert the new brushes into the brush holder. Check that you have your new brushes oriented correctly using the holes in the brushes and the hole in the brush holder. Not this way:
But this way:
Solder the new brushes into place. Check for continuity with your digital multimeter. Re-solder as needed.

If you assembled your new brushes to the old springs and terminals, then the brown lines below show the wrappings after the brushes have been re-installed. Snip off the excess copper lead:

Put the alternator back together in reverse order as above, with one extra step: Remember that the brushes ride on the rotor's commutator, held in place by the springs. You have to get the brushes out of the way while you put the two halves of the housing together. This is where aligning the holes (see above) comes in. Push the brushes in to line up the holes, and insert either a needle, thin wire, or thin screwdriver through the hole shown below to hold the brushes in place while you put the two housing halves together:
Here is an old brush (top) compared to a new brush ( bottom):
New alternator brushes often have a "wear line" etched on the side of them. When the brush wears to this line, only 5 mm of brush remain.The OEM factory service manual states this is the end of the brush's useful life. Here are the brushes I removed from my 2003 Civic's alternator after 13 years and 170k miles (and not much night driving):
If you look closely at the photo above, you can see the "wear line" on the left side of each brush. The brush on the right had lost about 14 mm of length over 170k miles. This suggests a wear rate of about 1 mm every 12k miles. I estimate I had about 24k miles more before this brush would have worn to the line. Hence I might have been able to take my 2003 Civic to 194k miles before I saw the alternator warning light on the instrument panel come on, indicating the alternator was close to failing.


1991 Honda Civic Alternator Brush Replacement
The following describes how to access a 1991 Civic LX's alternator brush assembly.
 
Drive your car onto approved ramps, or lift and support the front using approved jackstands. Block the rear wheels. Raise the hood. Disconnect the cable going to the negative battery post.
 
From the driver's side of the car, leaning over the engine compartment, remove bolt A in the photo below. Move the cable aside as needed. Gently lift the black rubber hood covering terminal B, and remove the nut underneath it with a 10 mm box wrench. Move terminal B's cable aside as well. This will expose another nut. Use a 10 mm socket to remove this, and then lift off terminal B's insulator. Now look at the alternator connector at C. It is green and has a tab on its aft, inboard side.
alttopbef.jpg
Before, Top View
Take various 8 mm sockets and associated ratchets and crawl beneath your car. Look up at the alternator. Push the green, alternator connector's tab towards the centerline of the connector to release a lock, and gently pull the connector in an inboard direction. (My Civic's lock tab has actually been broken for some time.) Your alternator is now electrically disconnected. See the photo below for guidance.
altbotbef.jpg
Before, Bottom View
Remove the 8 mm nut holding the bracket near the bottom of the alternator, pull the bracket off, and move the cable aside. Remove a second 8 mm nut under the first one. Remove the two other 8 mm nuts shown in the photo. (So a total of four 8 mm nuts must come off.) Now gently pry on the end cover. It should come off easily. The alternator without the end cover appears below.
altbotaft.jpg
After, Bottom View
Photos here of the bottom of the alternator were taken by positioning the camera a little higher than one's head can go while under the car. Lying beneath the car, an axle will tend to obstruct a person's view.
 
The arrow above points to the brush holder insulator. Two, horizontally oriented Phillips head screws attach the brush holder to the alternator. Now look at the photo below. It shows a new brush assembly (brushes, springs, and holder). This should help you locate the screws. Tegger on the Honda newsgroups recommends a short stubby, Phillips screwdriver, preferably new, for removing the possibly somewhat rusted-in-place screws. In the alternative, for my Civic sedan at least, it might be necessary to remove the whole alternator. Click on the photo to go to a site that sells brush assemblies.
brshassy.jpg
From our friends at MaximumAutoParts.com
My 1991 Honda Civic's brushes are size JX-116, 5 mm T x 7 mm W x 15 mm L x 49 mm LL.


Other notes from the Usenet Honda newsgroups:
Sand all electrical connections bright before rejoining. Do not overtighten the several small bolts and screws.
 
At least one report at the newsgroup indicates that for some Civic Hatchbacks, space is so tight that the alternator really should be removed to get to the brush assembly. By contrast, an Acura Integra owner says he has done the job with the alternator in place. An Accord owner reports that he expects the same.
 
When re-installing the brush assembly, use a tiny flat-blade screwdriver to help the brushes over the edge of the slip rings.