richracing Posted March 31, 2011 Share Posted March 31, 2011 So the alternator in my '75 280z just took a crap on me, but luckily I have a spare alt from my '82 ZX. However, when I compare the two alternators, they look the same in size. According to the writeup in AtlanticZ, the ZX alt is supposed to be noticeably bigger. Another thing I noticed was that the label on the ZX alt says 12v 50A. Aren't ZX alternators supposed to be 60 AMP??? Going back to the blown unit that was in my s30, it is a reman and doesnt have a label, but does have a part number stampped on it (14118) which when looked up at the parts store, shows that it is a 60 AMP unit. Did the P.O. already do the ZX alt swap? The external voltage regulator is still in the engine bay and the wire harness looks to be untouched. So all I can think of is that the P.O. just bolted up a ZX alt without modifying any wires... Also, my s30 has a volt meter, which must have been swapped out since '75 cars came with an ammeter. Right??? Volt meter works fine btw. So, Why does my s130 alt say 50A on the label? And should I go ahead and follow the instructions on AtlanticZ to install my ZX alt, or should I just bolt it up and ride out??? Here are some pics of the alternators to compare... s30 alt on the LEFT, and s130 alt on the RIGHT The label on my s130 alt, sorry for the dark pic... Quote Link to comment Share on other sites More sharing options...
zeause Posted March 31, 2011 Share Posted March 31, 2011 I put a 82 zx reman unit from autozone in my 240z and it was the same size as my oem alternator. I cant help you on the amps tho. Sorry buddy. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 31, 2011 Share Posted March 31, 2011 1975 comes with a 60 amp alternator and an external voltage regulator. The main thing you get with the ZX alternator would be to save money on buying voltage regulators. I don't think that a ZX alternator would be 50 amps either. I think that Datsun went to 60 amps at the 260Z and stayed there for quite a while. You probably have an old external Z alternator. Are you sure it's the alt and not the reg? Quote Link to comment Share on other sites More sharing options...
richracing Posted March 31, 2011 Author Share Posted March 31, 2011 I pulled the alteranator from my ZX so im sure its internal regulated, plus it says "REG buit in" on the label. I had both tested at the local Autozone, the s30 was bad but the s130 alt passed. Im just going to hook up the ZX alt today and bypass the external reg Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 31, 2011 Share Posted March 31, 2011 (edited) Interesting. Some ZX's come with 50 amp alternators. I learned something. Watch out for the brake warning lamp check relay wire. 1976 has a wire to it that will leave it on all the time and slowly drain your battery after the AtlanticZ swap. 1975 might be the same. You'll know if you hear a click from under the passenger seat when you reconnect the battery, even though the key is Off. Edit - p.s. - Consider using jumpers at the plug instead of cutting the wires. You'll have the option of going back and it looks cleaner than cut wire ends hanging around. If you do cut wires, be aware that of the ones left over, one is hot always and one is switched so will be hot when running. Edited March 31, 2011 by NewZed Quote Link to comment Share on other sites More sharing options...
richracing Posted April 1, 2011 Author Share Posted April 1, 2011 ok so I wired it up and she is running good and charging good, keeping steady around 14V. The plug going to the VR only had 5 wires, not 6. So this is how I wired it up: at the VR plug, white/black "L" connected to green wire "12V switched" with a diode between "1N5402" from radioshack, and yellow "S" connected to white wire "12V constant". I did not wire into the charge lamp bulb since that wire was not present at the VR plug. Everything seems to be working great so far, except the factory tach seems to be a little bouncy now at idle, ehh I can live with that. Quote Link to comment Share on other sites More sharing options...
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