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2G Alternator Recommendation

Clawless

Proven Member
79
13
Jun 20, 2018
Astoria, New_York
Hey guys,

I've recently been noticing issues with my alternator and its undercharging. I would get my OEM one rebuilt but don't have the time right now. My car is the 4g64 Spyder for reference. Are there any recommendations for an aftermarket alternator?

I was thinking of buying one from NAPA or Rockauto. Also is there any difference between the 75amp and 90amp or do they both fit the same. Thanks in advance!
 

ec17pse

Freelancer
5,082
2,332
Nov 1, 2008
London, UK, Europe
The 90amp with just help with more power and if you got things like amps and subs in will help those added power suckers to. Seems to keep headlights from dipping dull as much which is what i noticed on my car but might not be the same for every car of course.

Its no harm in going 90A really. Its there if you need it and might aswel install it now then think later you should of done it. It will only weight a small amount more vs 75amp and maybe a fraction more cost for the unit itself.
 

Blinkyblinx9

Proven Member
44
11
Jan 22, 2019
Clinton, Iowa
90 amp alternators came on automatics as the TCU and transmission solenoids together require about 10 to 15 additional amps. There shouldn't be a difference between the design. Make sure it's for the 4g64/3 and not a 420a. Websites like rock auto have a really bad habit of mislabelling parts.
 

motomattx

Proven Member
3,309
1,207
Dec 9, 2010
wampum, Pennsylvania
You likely wont be happy ultimately with a re-manned alternator, I have never seen one that worked right yet, the use junk Chinese regulators in them and you end up with voltages at idle that fluctuate wildly and belt squeal from voltages that ramp up instantly rather than gradually like the factory regulator would. You would be WAY better off with a good used factory non rebuilt unit or a new Mitsubishi unit, trust me.
 

Clawless

Proven Member
79
13
Jun 20, 2018
Astoria, New_York
You likely wont be happy ultimately with a re-manned alternator, I have never seen one that worked right yet, the use junk Chinese regulators in them and you end up with voltages at idle that fluctuate wildly and belt squeal from voltages that ramp up instantly rather than gradually like the factory regulator would. You would be WAY better off with a good used factory non rebuilt unit or a new Mitsubishi unit, trust me.
What about a Reman Denso?
 

motomattx

Proven Member
3,309
1,207
Dec 9, 2010
wampum, Pennsylvania
Who is doing the reman? thats the real question, if it was Denso themselves then I might trust it but even then if it doesn't use the factory regulator I would say no way. They dont test the regulators at most reman companies, instead they just assume they are bad and toss them, most of the time the regulator is fine, so they throw them out and install a $5 Chinese regulator in place of a $100 regulator that had a lot of engineering behind it with the cheap one that is basically just an on off switch.

In an emergency I guess any alternator that puts out is better than a bad one, but long term you would likely regret it.

https://www.mitsubishipartsonsale.com/alternators
 
Last edited by a moderator:

Clawless

Proven Member
79
13
Jun 20, 2018
Astoria, New_York
Who is doing the reman? thats the real question, if it was Denso themselves then I might trust it but even then if it doesn't use the factory regulator I would say no way. They dont test the regulators at most reman companies, instead they just assume they are bad and toss them, most of the time the regulator is fine, so they throw them out and install a $5 Chinese regulator in place of a $100 regulator that had a lot of engineering behind it with the cheap one that is basically just an on off switch.
DENSO says they do the reman themselves. Here's the link from RockAuto:
https://www.rockauto.com/en/moreinfo.php?pk=870658&cc=1205839&jsn=388&jsn=388&jsn=388
 

motomattx

Proven Member
3,309
1,207
Dec 9, 2010
wampum, Pennsylvania

pottersgst

Proven Member
77
10
Oct 15, 2006
franklinville, New_Jersey
So out of pure curiosity last year I bought a 90 amp alt for my gsx last year as mine died. I looked at rock auto and found one by Wai global there for about 125. Turned out I had a grounding issue, burnt that one, but got a replacement through rock under warranty. Have had it in for just over a year now and I actually just checked voltage when I finished motor swap the other week, and she is still putting out 14.5 volt consistently. Free replacement warranty, 90 amp for 125 and is a direct bolt in. Just food for thought

https://www.rockauto.com/en/catalog...433929,electrical,alternator+/+generator,2412
 

motomattx

Proven Member
3,309
1,207
Dec 9, 2010
wampum, Pennsylvania
14.5v is a little too high for me, 13.5v is where you would want to be, who cares about a warranty? who wants to be broken down at 2am in 20 degree weather like I have been with a junk reman alternator? heck I just replaced a Bosch reman alternator on my car a few weeks ago, I went against my own advice and bought a Bosch reman alternator, it lasted about a year and a half, the lights flickered at idle (go figure), the idle surged with the flickering lights as usual with jumping voltage, and it did that from day ONE that I bolted it on, if it wasn't such a bad job I would have pulled it off and returned it under warranty, several times when I was hundreds of miles from home on vacation the battery light came on at long periods of idle in traffic, thats fun huh? long story short, on my way to work a few weeks ago it finally let go, freezing cold out of course, but I did JUST make it into the parking lot when it died, worked all day, got to look forward to calling a tow truck to tow me home right after work, also needed to have someone come get me because with the current situation you cant ride in the truck with the driver, even more fun.

I dont have a place to work on the car thats not outside, and in 6 inches of snow and temps in the 20's an 11 hour alternator job was going to be fun! thankfully a buddy came and got me and took me to my house (where I had another stock used alternator waiting for this one to fail) in the meantime I had the car towed to his unheated but dry garage which the two were in complete opposite directions, got from my house back to his garage around 7-8 pm, started on the car and got finished around daylight the next morning. And there is my point, who CARES about a warranty when the biggest problem is the trouble that a broken alternator causes. Its no fun laying on your back for 10-11 hours on a cold cement floor in 20-30 degree weather to replace something that should have never been a problem.
 

pottersgst

Proven Member
77
10
Oct 15, 2006
franklinville, New_Jersey
Well first, the 1 I suggested is not a reman it is a new unit. Also my high is 14.5, generally around 14.1 but I also replaced every wire in engine bay to do with the alt circuit, and am pushing 15 extra volts compared to stock alt so I expect mine a touch higher then stock. I also run hid's, never dim , and can have all my lights on heater blasting turn signals on and still have windows that go up and down like it was 1999.

And if it takes 7-8 hours to change a alt...that's a different story. I'm not even sure how many union breaks that could contain...maybe 2 hours for removal and install tops with about 2 wrenchs and a jack...

And yea who cares about a warranty that's insane talk...
You want to make a valid point of a off name unit, sure, you got me.. and if I cared more I'd get a gm Saturn alt honestly,, but only issue Ive had was user error due to not changing crappy alt wires with the first unit ...should have known better then trust 25 year old wiring. But mine hasn't let me down since even thru the ice storms we had recently here. Sure I have a red top but that alt is keeping up even with no heat shields on a t28 pushing 16 lbs heat soaking the poor thing... but while some people are too good for it , my 2g is out in snow in jersey eatting instead if being towed. Just sayin
Op asked for recommendation and I just wanted to lend a honest opinion on a rock auto item that some people may be skeptical of. I just am fortunate enough at my age that I don't mind breaking down its a risk every time I take her out quite honestly. i have a daily truck. . I wouldn't be in a dsm if i had to rely on it to be truly reliable daily
Op good luck with your search
 
Last edited:

Clawless

Proven Member
79
13
Jun 20, 2018
Astoria, New_York
Thanks everyone for all the advice. I understand the skepticism towards reman parts but not all are complete garbage. I wouldn't mind buying a genuine or even the saturn alt but I'm trying to get the most affordable option right now. @pottersgst Thank you for your experience with the WAI alt, I'm considering it now especially since its a new/nonreman part. I'm also taking a guess on my alt being toast, it could also be the crusty wiring like you mentioned. I just haven't had time to check with all the snowfall thats been happening. I appreciate a good warranty in a product and know RockAuto stands by it always. I'm hopeful this job is for sure 2 hours tops, maybe even 3 if you're being meticulous. Anyways, I'm leaning towards either the DENSO reman or the WAI new unit. I'll make sure to test the wiring first before anything. Thanks all again for the insight!
 

ec17pse

Freelancer
5,082
2,332
Nov 1, 2008
London, UK, Europe
You likely wont be happy ultimately with a re-manned alternator, I have never seen one that worked right yet, the use junk Chinese regulators in them and you end up with voltages at idle that fluctuate wildly and belt squeal from voltages that ramp up instantly rather than gradually like the factory regulator would. You would be WAY better off with a good used factory non rebuilt unit or a new Mitsubishi unit, trust me.
Mitsu ones are also reman, my oem one blew in just over a year. So i went aftermarket and its been great ever since, just got to get a good one

My auto has or had a 75 amp alternator stock. Canada cars got 90amps stock.

No need to rewire andything as if you get the right alternator its a dirrect swap/fitment.
 

The616darkknight

Probationary Member
7
0
Apr 7, 2021
Wyoming, Michigan
I know this is an old thread but I can't find the answer to my question anywhere. Would the 98 galant alternator fit the bottom bracket for my 98 Spyder GS A/T or is it going to be too narrow to fit over it? I've been looking forever and I can't seem to find a solid answer. My alternator just went out and I'm looking to upgrade to power the system I'm going to put in.
 

The616darkknight

Probationary Member
7
0
Apr 7, 2021
Wyoming, Michigan
Yeah I think I figured it out after a couple hours of searching and comparing. I went with the 13585 which according to rock auto can replace the one that comes stock. We'll find out in a couple days. From what I gather It might also be a good idea to run a thicker wire with inline fuse 100a to the battery? If that's true do I then run another ground as well or just run a thicker one instead?
 

MattHDSM

Proven Member
60
26
Oct 20, 2018
Ottawa, ON_Canada
So out of pure curiosity last year I bought a 90 amp alt for my gsx last year as mine died. I looked at rock auto and found one by Wai global there for about 125. Turned out I had a grounding issue, burnt that one, but got a replacement through rock under warranty. Have had it in for just over a year now and I actually just checked voltage when I finished motor swap the other week, and she is still putting out 14.5 volt consistently. Free replacement warranty, 90 amp for 125 and is a direct bolt in. Just food for thought

https://www.rockauto.com/en/catalog...433929,electrical,alternator+/+generator,2412
I recently just upgraded my 75A to the 90A Wai Global alternator. It's only been on for 100km or so, but my voltage is more consistent and having that extra overhead for current is nice as well.

For anybody else curious about fitment, the 90A (WAI GLOBAL 13585N) alternator body had the exact same dimensions as my 75A model with the exception being the pulley diameter. The 90A had a 63mm pulley and my old 75A had a 60mm pulley.

If anybody is curious on how fast the alternator spins (using math, not a tachometer) here are some values using different dampers:
Factory Damper - 154.940mmRatioRPM @ Idle (750rpm)RPM @ Redline (7500rpm)
75A - 60mm2.5823:11937rpm19368rpm
90A - 63mm2.4594:11844rpm18445rpm

Fluidampr - 161.925mmRatioRPM @ Idle (750rpm)RPM @ Redline (7500rpm)
75A - 60mm2.69875:12024rpm20240rpm
90A - 63mm2.57:11927rpm19270rpm

A good alternator should come with a spec sheet that has a performance curve showing the current output at a given rpm. Using my values above and comparing that to the spec sheet I received, my alternator should be outputting ~70A at idle. Having information like that can be great for understanding stuff like dimming headlights or low voltage.
 
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