90 Amp Alternator upgrade / mod thread (1 Viewer)

[Randy88FJ62]

There is a 90 amp alternator (P/N 210-0177) that is reman by Denso I picked up for $75 shipped on eBay. I grabbed it knowing I could machine my 3FE mount to make it fit. I went to the local parts yard and grabbed an extra 91 FJ80 3FE bracket just in case which is the same bracket we have on 1988-89 FJ62's.

The stock alternator on the 3FE is 80 amps and the mounting ears on our bracket are 2.91" on the outside eye to eye mount (alternator sits on either side of this). The FJ80 RARE bracket that holds the 90 amp alternator is available for purchase from a few specialty cruiser supporting businesses but not worth what they are charging (in excess of $200). The RARE bracket is less than 2.685 in width and would be straddled by the 90 amp alternator.

Why would you want to play around with all this mess? The 90 amp alternators are cheap compared to the 3FE 80 amps if you want a denso/Toyota OEM reman. I don't want to pay $350 for a reman and the cheapo I bought at the local parts store is not putting out good voltage after 3 years and very little mileage on it.

I have scavenged 5 or so posts in the 60, 80, and 45/55 forums to gather this information. I then took some calipers at home and made a quick drawing for those wishing to understand the mod. The mod has failed on people who have ground the alernator aluminum casting. I plan on milling the steel forged casting by toyota rather than touch the alternator.

 

[Randy88FJ62]

 

[Randy88FJ62]

Interference shot

Stock 88-92 3FE alternator bracket next to the 90 amp alternator.

88-92 sand blasted bracket

 

[tmxmotorsports]

I have that rare bracket on my rare fj80 parts rig so what your saying is i can just bolt that rare bracket on my fj62 along with the fj80 alt the next time mine goes out...

 

[Randy88FJ62]

In short, yes. The rare bracket holds the internal fan 90 amp alternator without modification. I would be very careful and measure the ears first. The parts yard FJ80 whose bracket I grabbed had an internal fan alternator on the old bracket so I was very confused. I guess cheapo rebuilt alternators can have an internal fan but bolt to the 80 amp 3FE bracket.

 

[tmxmotorsports]

Hmm going to check it out and see what i have then post pic on your thread of year and month of the fj80 i have here.

 

[tmxmotorsports]

Mine is a 1991 fj80 it has the external fan on the alternator it was replaced cant tell what kind got a pic its not very good tho.

 

[Randy88FJ62]

external fan means you have the normal bracket like all of us.

 

[tmxmotorsports]

Well damn I'll modify that one when the time comes.

 

[SteveH]

Great photos and explanation - thanks. Two questions:

1. Is the wiring connector the same (can you directly plug your FJ62 alt. harness into the later-model FJ80 90a alternator?
   
2. Did this fix your (or at least my) low-voltage-at-idle problem? I suffer low voltage at stoplights with the headlights/fan turned on.

Thanks - Steve

 

[mattressking]

Nice job!

 

[Randy88FJ62]

@SteveH
Yes, the connector is the same. I do not know if this has any effect on the low voltage idle issues. I have not installed everything. I did all the research and I am sharing as I go. I stole pictures from multiple mud threads to show the before after etc. and then added my own CAD drawing to make it very clear as the dimensions were not listed in detail anywhere.

 

[Spook50]

Curious how this plays out. I have a 120 amp alternator but for some reasons alternators (even ones built with good Denso parts that I insist on) don't last more than a few years in my truck. Plus with the OEM 80 amp alt and the 120 amp alt both give me low voltage at idle. I suspect though that this could be alleviated by upgrading my factory charging wire. I had "upgraded" it years ago but removed that after I learned of "current hogging" in circuits that use more than one lead.

 

[Randy88FJ62]

This has been completed and successful. This is just my thread pulling all that info together. I was getting sick of looking at 5 different posts.

What is "current hogging" and how is it directly affecting or wagons if you upgraded the wire?

 

[red66toy]

Nice compilation!
If I have the wipers going, head lights (with upgraded harness) on and fan going my amp meter will go down to 12volts when sitting in traffic. On the highway it stays up at 14ish volts. This is of course all measured by the super accurate factory gauge.
Its a good swap and the price for the units makes it super attractive. I have had no issues with it for about a year.
I will say that the upper tension adjusting arm is also supposedly different between the 80 and 90amp, but the stock 80amp one works ok. Again, that bracket is also rare and hard to find but there are pics of it in the 80 series section.

 

[Spook50]

Current hogging is basically when there is more than one lead in a DC circuit, the lead (even if it's smaller) with the lowest resistance will carry the largest portion of current. This may or may not have been a contributor to my low voltage at idle, but I figured if the factory charging lead somehow had less resistance than the 1/0 cable I had put in it was still trying to carry most of the current, which for a 120A alternator would be no bueno when everything is running at the same time.

 

[SteveH]

I added a charging wire from the alternator to the battery and it made little or no difference in my idle charge voltage, FWIW.

 

[red66toy]

I added a charging wire from the alternator to the battery and it made little or no difference in my idle charge voltage, FWIW.

Yeah, same with me. Adding the wire helps with charging the battery but has nothing to do with the OEM wire harness. Making sure you have good grounds and clean connections will help with the idle charge voltage at the meter.

 

[Randy88FJ62]

So what are people upgrading as far as wires and sizes go? I have done the small added ground to the coil. I'm guessing people run larger wires from alternator to battery? Larger grounds? I have a cheapo hydraulic crimper so making my own cables isn't hard.

 

[red66toy]

So what are people upgrading as far as wires and sizes go? I have done the small added ground to the coil. I'm guessing people run larger wires from alternator to battery? Larger grounds? I have a cheapo hydraulic crimper so making my own cables isn't hard.

Yeah I ran a large cable from the B post on the alternator straight to the battery (fused as well). Should help with charging theoretically. I have also added extra grounds to the cruiser. So cleaned up the A pillar harness grounds and added a wire from those ground points to the battery as well.