Wednesday, March 20, 2013


Last night I had a few minutes to try something new: rebuilding a CS-130 alternator. I've rebuilt GM's SI alternators before, but never a CS alternator. Due to an excess of reading internet forums where guys say that "the CS alternator can't be rebuilt unless you like welding," I almost didn't do it. Is it as easy as an SI alternator? No. Is it that hard? I guess I'll find out if it works when I install it, but it sure didn't seem overly difficult.

The reason for the rebuild: the alternator wouldn't charge when the engine rpm dropped to idle. It would charge as soon as the engine rose to 1,000 rpm or so. Also, the bearings were a bit gritty, and I don't know of anyone who likes gritty bearings.

The reason to not just go purchase a rebuilt alternator: who knows what gets replaced in a rebuilt alternator? When it comes to any rebuilt parts--alternators, compressors, water pumps, etc.--I have seen plenty of examples where only the pieces that are "out of spec" get replaced, and nothing else is touched. That may be good for the rebuilder's bottom line, but that's not much better than a used alternator with a warranty. When you rebuild yourself, you can replace all of the replaceable parts, and you will know what you're getting.

The task of rebuilding the CS is similar to rebuilding an SI, but the main difference is that the SI alternator is entirely screwed together, whereas the CS alternator has five connections that have to be soldered.

One solder joint is where the brush holder (the white part that holds the brushes) connects to the regulator (the black part).

The second is where the regulator connects to the rectifier (the metal part with the cooling fins).

The other three joints are where the stator (the wound up wires that ride inside the case--not to be confused with the armature, that's the part that spins) connects to the rectifier.

None of these seemed particularly difficult to solder. There's plenty of room to work inside the case, and the soldering the stator to the rectifier is pretty easy because you're simply filling the crimped connections with solder. If I can do it--and I really don't like to solder--I would think it to be a pretty doable task.