Conversion finally complete! The hardest part of the conversion was removing the old factory alternator mount and installing the Trail Gears one. With a little massaging it went together with little difficulty.

The CS130 is a very adaptable alternator. It's really only a 3 wire alternator (main batt, sense, and dash light) with a few wiring options. I did not cut the factory wiring harness and taped up the factory batt wire. The wiring in my case was slightly different since I'm running a battery isolator. With this option you have to provide a switched 12V to the isolator in order to get the alternator to excite.

Overall I'm very pleased with the bracket and how the easy the alternator mounted up. The only problem I have (had it with the old alternator as well) is that since I'm running a LC underdrive pulley the alternator doesn't spin fast enough at idle to provide a good charge. I can either go back to the factory one or find a smaller alternator pulley. I'll mull around on the net and see which idea will win out.

The alternator itself is a junkyard special. The only requirements I had was that it was a 105 amp unit and has the 12 to 6 mounting ears. The only mod I had to do was clock it so the main connector was facing the drivers side. These alternators are very simple and come apart relatively easy. In order to rebuild them you have to cut the 3 leads on the stator that connect up to the rectifier. I sourced 2 CS130's for 25 dollars. One came off of a 90 Olds Cutlass V-6 and the other came off of a 93 Pontiac with a 4 banger. Both tested good at the auto parts store. The one I'm using I pulled apart to check the condition of the brushes and all checked out good.

So why the conversion? Well the main reason is the increased amperage. From 40 to 105 is a big improvement. Second reason is availablility. It's much easier to source one of these GM powerhouses than it is the old Denso 40 amper. Third reason is that you can now remove the factory voltage regulator and clean up some wiring if you desire. So far I've left everything in place, but time will tell if I end up getting rid of what I don't need.

 

How did you wire it up? I've got the ToolBox guy version. It's sitting in a box and I just need an alternator. I think I could afford a junkyard alt.

 

The GM plug has letters on it P L F S. You will use the S sire (which is the bigger of the wires) and the L wire. U

can ignore the other 2 if your plug comes with them. Think of S meaning sense and L meaning light. The sense wire

can either be monuted to the main battery terminal on the alternator or to a point in the system where most the

load can be monitored. I put a distro block off of a Chevy on mine and routed all the positive leads there,

including the lead that goes to the main fuse center next to the battery. This way the alternator monitors voltage

in a place where all loads are being drawn.


There are several ways to test which lead on your original alternator plug is the light one. The port you are

looking for is the one that has switched 12V. I believe the other ones have constant power. You can use a test

light to test which one is switched or you can ground out the suspect port and the light on the dash should light

up. That's it! The hardest part is replacing the bracket.



I'd source a CS130 with the 12 to 6 o'clock mounting. You can find em on early nighties GM cars. If space is very

limited you can always grab a CS120 as well. Same mounting distance, but 10mm smaller in diameter. At my local

wrecker these alternators are about 20 bucks. Reman from the auto store they are about 100 plus core. I gambled on

2 and both worked just fine.