Hi guys,

When I got my car back together after doing the FMIC/intake manifold/electric waterpump/etc etc, I noticed the alternator ran a little low. It sits around 12.5-13 and drops lower and wants to stall if the thermo comes on while I have the headlights on, so driving at night is a no-no at the moment. I don't know if I've done something wrong or wired it back up the wrong way, or if the EWP is dragging it down, but I've bought a second hand RB30 alternator for it, as I've heard they bolt on. I just need some help with the wiring.

Here's a picture of the RB30 alternator on the left, and my current alternator in-position on the right. Sorry for the bad photo, but it's the best I could do, short of hiring someone from the circus to contort themselves enough to take a better one.
From what I can tell on my current alt (right of picture), I have wiring from my loom connected to B+ and another couple of wires bolted to the top right corner which I am assuming is ground/earth? Easy enough.

Here's where it gets different. My car has a single white wire with a red spade connector which connects to D+. On the RB30 alternator, the D+ terminal is being used by the capacitor, which the other end is bolted to D-. On my car, the capacitor is bolted to ground/earth, and the other end connects to B+.

The other difference is the black box (regulator?). On the RB30 alternator, it has wires coming off it (which have been cut off, just out of the picture). On my alternator, it's a standalone unit.

So my question is, can I re-wire the RB30 alt to match my current setup, i.e:
- Bolt the capacitor to earth/ground at one end, and B+ at the other, and;
- Remove the black box with wires coming out of it and replace it with the standalone one from my current alternator?

Any help is appreciated! Also, if anyone can see any problems with how my current alternator is wired that might solve the issue, that would be awesome because it would save me having to swap in this new one!

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build-threads.com

Not sure about the new alternator atm.
Do you have an ammeter in the car?
Or have you seen the charge light glow when the engine is running?
Assuming the alternator is wired correctly, the brushes for the rotor make be badly worn and therefore operating under reduced spring tension.
That causes a reduced current through the rotor and the alternator can not produce the required output for the electrical load.
If you don't know how old the brushes are, it is highly likely that they need replacing.
I'd check that out before we get to excited about replacing the thing

Here is the Charging System wiring diagram for the FJ20 as fitted to the S12 Slivia.
You should have something the same in your car: - I personally like to have an ammeter in the charging circuit, it can be VERY helpful.

_________________
Regards, Graeme
Just trying to help...
http://nissanman.shutterfly.com/
graemes@internode.on.net

The brush packs look very similar so they may even be interchangable.
They are only held in by two screws so remove and inspect them for wear/siezing first and then see if they will swap over.
Alternators are usually very reliable. The main thing that goes in them are the brushes and to a lesser degree the diodes but these are all housed in the same 'pack'.
The rest of the alt just has bearings and windings which are very robust and rarely fail...
P.s. the bosch brush pack you have currently fitted is very popular and comes out on many different makes of car and should be easily found at a pick-n-pull wrecker...

I don't have an ammeter, I only have a VDO volts gauge to go by. I'm thinking you might be right about the brushes and would rather go down that path than retrofitting the whole unit.

I just unscrewed and removed the brush pack on the RB30 alternator and the brushes have a nice semi circle shape to them, so I'd say they have some wear on them. I just took a better picture of the one in my car to get a part number from my brush pack, and I came up with "EE 14V3" and then underneath "9 190 067 005", a quick ebay search brings this up...

http://www.ebay.com.au.au.au.au.au/itm/ ... 2327c07238

Edit: found a cheaper one http://www.ebay.com.au.au.au/itm/005-Bo ... 256cea8363

Looks like it might be a good idea to try that before playing around with fitting the RB30 one (which will need me to swap the pulleys, too).

Nick, would I be able to swap them over, even though the one on my car doesn't have a plug on it, but the RB30 one does? Wouldn't mind testing it out before buying the new one.

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I was just saying that because both Bosch alt bodies look very similar it might be possible the brush packs have the same bolt pattern and will fit both alternators. You have to change the wiring to suit of course.
The ebay ones seem a good price but if i were you, id try and grab another one or two used brush packs from the wreckers to suit your current alt. But im a cheap ass...
Also, just because the brush surface is round it doesnt mean its worn. They are meant to be curved like in the ebay pic to match the curvature of the slips rings.
Worn brushes are usually short in length, they will eventually reach a point where they dont have enough travel to make contact.
Also look for brushes that have alot of carbon build up around them and are sticky when depressed as these will jam and also not make good contact...

Does this thread help your wiring questions?
http://ozdat.com/forum/viewtopic.php?f= ... 9&start=15

Hey anth, im glad you brought this up. Does the RB30 unit bolt straight up?

Can you measure the distance between voltage reg mount holes on the FJ unit for me? Is it 65mm?

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1600 with FJ20 & Simmons. something different.

Also, does your alternator have an exciter circuit? Bosch alternators generally require a 3-4 watt globe to excite the unit. This may help your previous charge problem?

I have two ewp's and the thermos in my car, your alternator should run the thermo and ewp no worries.

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1600 with FJ20 & Simmons. something different.

It looks like they have the same bolt pattern, it's just the changing of wiring that I'm not sure about. I'm thinking that the 30 odd bucks for a new brush unit delivered to my door would be money well spent compared to trawling around a wreckers to find a second hand one which would potentially be just as worn Good point about the brushes already having that curved shape, I actually noticed that the pictures of the new ones on eBay.
Hmm not really. The image at the bottom of page two confirms the differences, where the capacitor goes from D- to D+, whereas my current one goes from ground to B+. But from what I've read the capacitors are apparently just to reduce radio interference.
From what I've heard they bolt straight up except for the pulley, you have to swap it over with the FJ unit because the belts are different. Then I've also heard you might need to use a small washer to get the belt alignment right. I'll measure it up for you
I have no idea about the exciter circuit, how would I check for that? Yeah I've heard the EWPs take stuff-all power to run, so somethings up.

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build-threads.com

I dunno mate, wiring is certainly not my forte. Does your car have the standard FJ20 wiring loom installed? Do a quick google search on alternator exciter circuit and you'll understand what it does. Probably something for an auto sparky to install if it doesn't have it.

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1600 with FJ20 & Simmons. something different.

I can confirm an R31 alt bolts up with a pulley change.
With wiring, you'll only need the wire that goes to the dash. The exciter wire can just have an eyelet on it and run it to the battery post. On the bottom of the reg you'll notice an S and an L, S is signal or exciter and L goes to the light.
I'll grab you a couple of photos tonight.

Not sure about my loom, engine was already installed in the car and running when I bought it. The more I think about it, the more a new brush pack should be my first call to action as it's the easiest thing to do. Just wish I did it before buying the second hand R31 alternator!

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Just found this...

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build-threads.com

And here's a pic of someone else with a Bosch alt that has their capacitor set up like mine...



I'm thinking the thin white wire with red spade that connects to D+ on my current alternator is the exciter wire, just can't remember if I have a dash light, will have to check tonight.

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build-threads.com

The capacitor is only necessary for suppression of RF into your radio/HI-FI system, nothing more.
Usually fitted between the +12V terminal [B+] and Ground [D-].
No radio?
No capacitor!

_________________
Regards, Graeme
Just trying to help...
http://nissanman.shutterfly.com/
graemes@internode.on.net