Anyone using a lightweight alternator?
#22
Does anyone know if the alternator Leafy mentioned could be wired to run on a NB2?
My fourth alternator has been acting funny. I have had 3 failed autozone/oreilly/pepboys alternators, I found a used stock one and it has been good for about a year or so, but now it's giving me a battery light over 5000 RPM, not that I go there very often(street car), but still annoying.
My fourth alternator has been acting funny. I have had 3 failed autozone/oreilly/pepboys alternators, I found a used stock one and it has been good for about a year or so, but now it's giving me a battery light over 5000 RPM, not that I go there very often(street car), but still annoying.
#23
Does anyone know if the alternator Leafy mentioned could be wired to run on a NB2?
My fourth alternator has been acting funny. I have had 3 failed autozone/oreilly/pepboys alternators, I found a used stock one and it has been good for about a year or so, but now it's giving me a battery light over 5000 RPM, not that I go there very often(street car), but still annoying.
My fourth alternator has been acting funny. I have had 3 failed autozone/oreilly/pepboys alternators, I found a used stock one and it has been good for about a year or so, but now it's giving me a battery light over 5000 RPM, not that I go there very often(street car), but still annoying.
#26
I rewired mine on an NA. I can't remember exactly how right now. Stock Miata alternator is powered all the time through one of the little wires. The 60amp Swift one is not and uses a keyed power source for that otherwise I can confirm it drains the battery very slowly when the car is off. I spliced in some wires near the fuse box with male and female spade connectors and it is setup so I can quickly switch how it’s wired ether keyed or not keyed just by changing how I have the spade connectors plugged. The stock Miata one can be wired like the swift one with a keyed power and it works fine as well I think but I haven’t tried it to see if it will run the battery down without constant power. I am not an electrical guy. It’s all compressed smoke to me.
#29
Somehow the stock Miata electronics in the stock internal regulator switch something when the alternator is not spinning to keep the coils from slowly sucking the battery down. I think it needs a constant 12V on one of the two small wires to perform this function but I’m not sure.
The internal regulator on the Swift one I’m using the power on the IG termanal needs to be a switched voltage with the ignition switch otherwise it runs the battery down slowly when the car is not running. I found a wiring diagram for the swift to see how it was wired to figure this out.
I also tried the aftermarket style jumper wire 1 wire alternators which supposedly turn the alternator on only as it reaches a certain RPM. They also ran the battery down slowly with the car off no matter how I hooked them up unless you disconnected the battery entirely. If you let it sit for a week in-between events you had a dead battery.
I don’t have a clear understanding of how any of this works but that is what I have found.
#30
Might give slightly more insight. From the sound of this, yes the ING for certain needs to get power for the alternator to charge. I'll probably grab mine off the switched power I had to use for the ABS pump.
#31
So I pulled a chevy tracker alternator, didnt look right, too new. Then I saw the geo tracker that was all crunched up. After freezing my *** off my scale says its 8.5lbs and a stock 1.8 alt is 11.5. So not quite as light as advertised, maybe the 3 rib belt ones are lighter. This alt does use only 2 wires and its a smaller shaft diameter than the miata alt. So maybe the 3 rib early prizm one is even lighter and this pulley will work on it. The two wires it uses are the ING and L terminals.
So it doesnt quite fit directly. You need to drill two different holes out and tap one of them. You need to drill the tab with a steel sleeve out to 7/16s, 13/32 if you have one on hand would be better. The other tab thats in line with that hole you just drilled needs to be tapped to M10x1.25, no drilling required its already the right size. Then the remaining tab was already tapped, this needs to be drilled out with a 5/16th drill bit. Then it just drops right in and the pulley lines up. You end up putting the tensioner bracket in front of the tab rather than behind like the miata one. You also have to loosen the bolt on the block for the tensioner bracket and swing it down a bit. And from now on you will have to loosen this bolt in order to make any large tension changes since the alternator does not swing in the same arc as stock. I'd also recommend getting a shorter belt, it works fine with the stock one, but when I replace this belt it will be with a shorter one. Now that the tensioner is on the front of the alternator tab, replacing it with something lighter gets easier.
So it doesnt quite fit directly. You need to drill two different holes out and tap one of them. You need to drill the tab with a steel sleeve out to 7/16s, 13/32 if you have one on hand would be better. The other tab thats in line with that hole you just drilled needs to be tapped to M10x1.25, no drilling required its already the right size. Then the remaining tab was already tapped, this needs to be drilled out with a 5/16th drill bit. Then it just drops right in and the pulley lines up. You end up putting the tensioner bracket in front of the tab rather than behind like the miata one. You also have to loosen the bolt on the block for the tensioner bracket and swing it down a bit. And from now on you will have to loosen this bolt in order to make any large tension changes since the alternator does not swing in the same arc as stock. I'd also recommend getting a shorter belt, it works fine with the stock one, but when I replace this belt it will be with a shorter one. Now that the tensioner is on the front of the alternator tab, replacing it with something lighter gets easier.
Last edited by Leafy; 01-10-2015 at 04:43 PM.
#32
So I pulled a chevy tracker alternator, didnt look right, too new. Then I saw the geo tracker that was all crunched up. After freezing my *** off my scale says its 8.5lbs and a stock 1.8 alt is 11.5. So not quite as light as advertised, maybe the 3 rib belt ones are lighter. This alt does use only 2 wires and its a smaller shaft diameter than the miata alt. So maybe the 3 rib early prizm one is even lighter and this pulley will work on it. The two wires it uses are the ING and L terminals.
So it doesnt quite fit directly. You need to drill two different holes out and tap one of them. You need to drill the tab with a steel sleeve out to 7/16s, 13/32 if you have one on hand would be better. The other tab thats in line with that hole you just drilled needs to be tapped to M10x1.25, no drilling required its already the right size. Then the remaining tab was already tapped, this needs to be drilled out with a 5/16th drill bit. Then it just drops right in and the pulley lines up. You end up putting the tensioner bracket in front of the tab rather than behind like the miata one. You also have to loosen the bolt on the block for the tensioner bracket and swing it down a bit. And from now on you will have to loosen this bolt in order to make any large tension changes since the alternator does not swing in the same arc as stock. I'd also recommend getting a shorter belt, it works fine with the stock one, but when I replace this belt it will be with a shorter one. Now that the tensioner is on the front of the alternator tab, replacing it with something lighter gets easier.
So it doesnt quite fit directly. You need to drill two different holes out and tap one of them. You need to drill the tab with a steel sleeve out to 7/16s, 13/32 if you have one on hand would be better. The other tab thats in line with that hole you just drilled needs to be tapped to M10x1.25, no drilling required its already the right size. Then the remaining tab was already tapped, this needs to be drilled out with a 5/16th drill bit. Then it just drops right in and the pulley lines up. You end up putting the tensioner bracket in front of the tab rather than behind like the miata one. You also have to loosen the bolt on the block for the tensioner bracket and swing it down a bit. And from now on you will have to loosen this bolt in order to make any large tension changes since the alternator does not swing in the same arc as stock. I'd also recommend getting a shorter belt, it works fine with the stock one, but when I replace this belt it will be with a shorter one. Now that the tensioner is on the front of the alternator tab, replacing it with something lighter gets easier.
#35
Some of the early 1.6l alternators used smaller shafts as well. I have run for years with just putting electrical tape around the shaft to center the pulley before tightening it down without issue before. Currently though I have an Unorthodox Alternator pulley that I found on EBay for $50. Its lightweight aluminum has the correct small shaft diameter hole to fit the Suzuki alternataor and correct Miata compatible multi rib pulley and offset. I think the pulley that worked best was for a Mitsubishi eclipse.
#36
I've been running a Suzuki alternator for a season now. I picked it up for $30 from a wrecker and it already had a 4 rib pulley that was slightly larger which helps slow down the spin rate a bit.
I moved the alternator to the exhaust side of the engine so that I have more room to access the oil filter and underneath of the intake manifold. It's mounted by a small waterjet cut bracket that is mounted off the block.
This verson has a T plug for ignition trigger and doesn't seem to draw down the battery.
I made a billet tension bracket... but accidently made it flipped. Still works though but just looks wrong. It mounts off my EWP water pump delete plate.
I moved the alternator to the exhaust side of the engine so that I have more room to access the oil filter and underneath of the intake manifold. It's mounted by a small waterjet cut bracket that is mounted off the block.
This verson has a T plug for ignition trigger and doesn't seem to draw down the battery.
I made a billet tension bracket... but accidently made it flipped. Still works though but just looks wrong. It mounts off my EWP water pump delete plate.
#37
Nice bracket!
My experience with a couple of alternators is similar to Bob's. A true "1 wire" creates dark current; the battery will drain.
All of my dead battery problems were solved when I took a closer look at the wiring diagram and realized there are a couple of diodes and resistors inside of the gauge cluster, between the +12v power supply, the alternator/charge/battery warning light, and the white/black wire that goes to the alternator. I've since gone back to stock.
My experience with a couple of alternators is similar to Bob's. A true "1 wire" creates dark current; the battery will drain.
All of my dead battery problems were solved when I took a closer look at the wiring diagram and realized there are a couple of diodes and resistors inside of the gauge cluster, between the +12v power supply, the alternator/charge/battery warning light, and the white/black wire that goes to the alternator. I've since gone back to stock.
#38
Back from the dead. Thanks to one of out mazda sedan based cousins I found the secret sauce. 5.7lb alternator that bolts right in and just needs a simple re-wire of a plug avalaible on ebay. 95-97 geo metro 3 cylinder or 89-97 geo tracker 1.6. You want the denso one not the mitsu one because the mitsu one sucks. Stock its 55 amp, there's a company that sells them rebuilt to 75amps though. The 89-94 metro 3 cylinder alternator uses a 3 rib pulley so it wont work. Oh yeah the electrical connector. And the wiring diagram.
I did see where Leafy stated on M.net in June of 2015 (5 months after his last input on the topic here) that his Geo alternator was working quite well.
https://forum.miata.net/vb/showpost.php?p=7532566&postcount=11