- First things first, always scribe a mark starting from the regulator plug-in to the fan on the alternator to mark it's position. They call this the "Clock" position. To figure out clock position you must have the Alt sitting on it's pulley with the Main Post facing you and the top post of the front housing (the portion where the Alt. number is stamped) facing directly away from you. Now, you want to look where the regulator plug in is. While your doing that picture a clock(Not a digital one!). Where ever the regulator is facing is the "Clock position". The 84/85 usually are 6:00 and the 86/87 usually are 4:30. There are 4 different clock positions these alternators can be positioned. the 84/85's can be: 12:00, 3:00, 6:00. and 9:00. The 86/87's can be 1:30, 4:30, 7:30, and 10:30.
- After we have it marked, remove the 4 5/16 socket size bolts that hold the Alt. together. Next, take a Hammer and LIGHTLY tap on the front housing ear to pull the alt apart. This usually isn't a problem but like anything It can take a while. set the front portion(pulley end) aside later for component rebuild. Now, as we look into the regulator portion on the alt, be sure to remove the two brush springs. They usually are scattered inside the alt from removal. Using your 11/32 socket, remove the three bolts holding the stator in place. Use a hammer to tap on the case while holding the stator to remove it from the case. Set the stator aside for now. Next, using your 1/4 socket remove the two bolts that hold the regulator and brush assembly into the case. Note: The bolt that goes through the brushes is NOT insulated. The one on the other side IS. Be careful, switching these bolts around WILL blow the regulator IMMEDIATELY!
- Set the regulator/brush assembly aside for later. Next, using the 7/16 socket, remove the main post from the rectifier bridge. This just slide right out. Make sure that the insulation piece also is removed from the back side also. Next, using compressed air blow out the rectifier bridge, Be careful, wear eye protection. The diodes/rectifier bridge do not have to be removed unless necessary. Place a paper towel/rag on your bench and set the alternator down on it. Using your ohms meter measure the resistance as follows: with the meter on the 1000k scale, take the negative and place it where the main post usually goes(the lower half of the rectifier bridge). Take your positive and place it on 1 of the 3 posts. Go through all three posts, one at a time and record the readings.Note: u may have to touch the copper portion blow the stud BUT be sure you are not contacting the 2 halfs of the bridge. The resistance should be between 400-800 omhs. Anything else is uncivilized:) Note: If you are replacing the diodes, be sure you get the screws in the right places.Check the stator now. You should have continuity though all three posts of the stator and NOTHING to ground. Now, if you are replacing the regulator, place the regulator in the vice. and clamp lightly. Using your soldering gun, unsolder the brush assembly and the metal clip. Hint: While soldering take a small screwdriver and pry up lightly the on the spade terminal. This will help you get them off faster:) Check the brushes, the should have more than 1/4 of total length.Remember those 2 spring we took off when we tore it apart?? Well, place those into the brush housing and then the brush. While holding the brush down into the holder, take your mechanics wire and run it though the small hole in the brush housing to hold BOTH brushes into place. Re-solder the metal clip on the regulator and the brush housing. Install the regulator/brush assembly in to the Alt, and be sure to get the insulated bolt by the metal clip and the not insulated on the brush housing. Tighten down the 5/16 socket size bolts. Next, install the Main Battery post and tighten down using your 7/16 socket. Note: Be sure that the insulation piece on the main post isn't cracked and is in place. Next, install the stator. Tighten down the 3 11/32 socket size bolts. Note: Be SURE that the stator wires ARE NOT contacting ANY other part of the rectifier assembly BUT the stud and copper pieces. Be really sure of this. Set the case aside.
- Now, since we don't know why we even started this project, pick up the pulley end of the Alt. now:) using your impact and your 15/16 socket, remove the nut. The pulley and fan SHOULD slide right off. Note:there are spacer washers between the fan and bearing(Smaller), fan and pulley(Larger). Be sure to get these in the CORRECT places. Other wise your fan might be sticking out a 1/4 of an inch more!:) Now, u *MAY* need a press to press the rotor off of the housing. Be sure to get the spacer off of the rotor shaft. If you don't have access to one a BRASS hammer will do. Once you have the rotor removed from the housing, using your 5/16 socket, remove the three retaining bolts that hold the retainer in. Now, using your Punch, punch the bearing out of the housing. Oil the new bearing and using a hammer tap it into the housing making sure it's flush. Install the retainer and tighten the three 5/16 socket size bolts. Next, using an ohms meter, make sure you have continuity through both slip rings(Where the brushes ride on)and NOTHING to ground.
- Place the rotor in a vice horizontally, using a punch, remove the small bearing on the shaft.(Yes, there is a special puller for this, but this works just fine! :) Next, place the rotor in a vice vertically. Using 80-120 emery cloth, sand the commentator(where the brushes ride on) Next, oil the shaft and install the bearing using s hammer. make sure it's flush with the end of the shaft. Next, install the spacer onto the rotor shaft and oil the shaft. Install the rotor into the housing and you *MAY* have to tap it into till it stops. Next, install the small spacer, fan, larger spacer, pulley, flat washer and then the nut. Tighten the nut with an impact. Place the pulley onto the vice and clamp LIGHTLY. Be sure to lube the bearing(Small) and place the case over the the rotor. Line up your scribe mark and using a hammer, tap on the housing till it stops. Install the 4 5/16 socket size bolts and tighten down. Finally, remove the mechanics wire that holds the brushes in. Well folks, That's it! We did it! It wasn't that bad now was it?
- The procedures for the 84/85 are similar. The Ohms readings are all the same. The only thing that is different is the regulator. It has three bolts that hold it down. Two are insulated and one isn't. It also has a diode trio. The diode trio powers up the regulator. Check it as follows: on the 1000k scale, place a rag under the trio. Take the negative and clip it on to the end with one terminal. While doing that, check and record the three terminals on the other side. Those too should be within 500-800 Ohms.
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| The Alt. used on the 84/85 is a 12SI. SI stands for Systems Integral. The was the first GM alt that was internally regulated. It debuted in 1972. (That was a 10SI) Of course, GM was the first to come up with an internally regulated system. This system was an excellent system. It is so easy to work with and is a good design. Well, in the 1980s with all of the computer controlled cars coming out, GM needed an alternator that could communicate with the ECM. In 1986 the CS series Alternators came about. CS stands for Charging Systems. The models, CS121, CS130, CS144 and now CS130D(this is another story!:) The number after the CS is the diameter of the stator in Millimeters. So, on the 86/87 TR it's 144 Millimeters wide. Most all of the CS series unit put out over 85 amps. The TR Alt. doesn't communicate with the ECM. Instead, the regulator monitors everything. It counts the AC counts so it knows how fast the alt is spinning. and can even cut the charge back if necessary. There are over 8 different regulators used in the CS series. They all look and plug in the same but they are different internally. I could go on about what each regulator does differently but that's another time:) The number is stamped on the regulator. On the 86/87 TR's it usually a 411. If you have any questions about your charging system please, feel free to e-mail me. GM by FAR has the best charging systems on the market today. |