1977 280z: 80Amp Alternator

[ckurtz2]

Hey guys,

          My old alternator failed, so I decided to upgrade the alternator to an 80amp alternator from zcardepot: https://zcardepot.com/products/alternator-high-amp-80-240z-260z-280z . I did some research on how to rewire some of the components to accept the new alternator, and this is all I could come across. He used the same alternator I got for his 240z.

Is there anything specific differences between the 240z and 280z that I need to watch out for regarding alternator wiring? I am not sure how I should setup the wiring, besides what I found from that forum post. I figured I would just copy what he did, but any advice would be wonderful so I don't fry something:)

Here are some photos in case they help.

 

[SteveJ]

6 hours ago, ckurtz2 said:

Hey guys,

          My old alternator failed, so I decided to upgrade the alternator to an 80amp alternator from zcardepot: https://zcardepot.com/products/alternator-high-amp-80-240z-260z-280z . I did some research on how to rewire some of the components to accept the new alternator, and this is all I could come across. He used the same alternator I got for his 240z.

Is there anything specific differences between the 240z and 280z that I need to watch out for regarding alternator wiring? I am not sure how I should setup the wiring, besides what I found from that forum post. I figured I would just copy what he did, but any advice would be wonderful so I don't fry something:)

Here are some photos in case they help.

 

Look through Blue's tech tips. The link is in my signature. (Make sure you read this on a computer rather than a phone so you can see the signature.) He has documented what to do for the 75-77.

[S30Driver]

I installed that same alternator in a friends 75 280z last year.  Had no issues getting it working correctly.

Unplug or remove the external voltage regulator, and use the connector pictured below wired correctly to the T connector in your 1st picture to excite the new alternator.   Only thing I did not like about it, was the location of the main 12v output post compared to the stock position.  On the side as opposed to the rear.

 

Edited April 25, 2021 by S30Driver
addition

[Zed Head]

On my 76 I found that the brake lamp check warning relay was powered all the time after using Blue's Tech tips wiring.  It drained the battery over a day or two.  I ended up using the fuel pump power line to power the relay and disconnected it from the constant power wire.

Might not be the same on 77.  Seems like Nissan changed things around every year.  Something to be aware of.  I think that Blue's tech tips are specific to 77 so should work.

Here's the link from SteveJ's sig link. (The AtlanticZ page is so tiny now...).

https://www.atlanticz.ca/zclub/techtips/alternatorswap/index.html

[ckurtz2]

9 hours ago, S30Driver said:

I installed that same alternator in a friends 75 280z last year.  Had no issues getting it working correctly.

Unplug or remove the external voltage regulator, and use the connector pictured below wired correctly to the T connector in your 1st picture to excite the new alternator.   Only thing I did not like about it, was the location of the main 12v output post compared to the stock position.  On the side as opposed to the rear.

 

So you did not have to rewire anything like what was in Blue's tech tips, besides putting on that new t-connector and removing the external regulator? In addition, by chance does your friend have a part number for that connector. Zcardepot stopped selling them:(

[ckurtz2]

Thx! @SteveJ @Zed Head

         I read through the whole post and it actually seems pretty straight forward! I know that post is for a zx alternator, does that still mean I need to do that for this alternator that isn't a zx? What would happen if I just removed the external regulator, put on a new T to plug in and bolted everything up? Without splicing those wires near the fuseable links. As you can tell electronics aren't my forte, but they do make me curious.

[Pooky]

Zed Head, the 77 source power comes from the voltage and fuel gauge. Specifically the alt warning light per the 77 wiring schematic. I also know this because I have been having a problem with my upgraded alternator, a 60 amp zx. I believe my problem lies in the fact that I installed LEDs in my dash and the current draw of the LED isn't enough to trigger the regulator in the alternator. Question for you is: Where did you hook up a link to the fuel pump? Under the hood somewhere or did you run a line from the back of the car? I really don't want to pull my dash again!

[S30Driver]

Here is the correct harness plug for the alternator...

https://www.amazon.com/gp/product/B07ZMN2B59/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

On the 75 Z car, I did not have to do anything with the harness plug side from the old regulator.  The 78 and newer internally regulated Hitachi alternators that Nissan used are what Blue has referenced in his tips.  Also needed a diode to prevent discharge thru windings when car was off.  

 

[Zed Head]

I tapped in to the fuel pump power at the plug next to the passenger seat.  It's under the carpet.

 

 

[Zed Head]

2 hours ago, ckurtz2 said:

Thx! @SteveJ @Zed Head

         I read through the whole post and it actually seems pretty straight forward! I know that post is for a zx alternator, does that still mean I need to do that for this alternator that isn't a zx? What would happen if I just removed the external regulator, put on a new T to plug in and bolted everything up? Without splicing those wires near the fuseable links. As you can tell electronics aren't my forte, but they do make me curious.

The internally regulated alternators are all the same, two wires, one Sense, one Lamp.

I don't think that the guy who wrote those instructions or made the diagram knows what he's talking about.  It's wrong, if you want the Charge light to work.  One prong is the L wire, the other goes to any positive point on the power supply circuit.  Better to have it close to the loads.

What he's describing the "one-wire" setup, which can lead to lower output since it's measuring voltage right at the alternator, not out where the loads are.  Basically he's dumbed the system down to no Charge light and poor voltage regulation.  He threw away about 20 years of development.

New direct replacement high amp alternator for Datsun 240Z, 260Z, 280Z and 280ZX, 1970-83. This alternator is rated at 80 amps and bolts up in the same location as the original. Internally regulated. Datsun Z cars 1970-77 have an external regulator so the external regulator will no longer be used. Alternator uses standard flat male/female connectors or you can purchase the optional connector.

*Optional connector plugs right into alternator. Yellow wire connects to switched 12V and green wire connects to the positive post on the alternator

[ckurtz2]

Makes sense, thanks. So I am starting to work on this now. On the old alternator connector where it has the S and L port. Is the S one the connection that switches? And then the L wire is what I connect to a constant 12V force? 

This may be a stupid question, but I want to make sure. On my car the L wire is striped white and black, while the S connection seems to be solid yellow. 

[SteveJ]

S - Sense (connects to the battery)

L - Lamp (switched)

https://auto.howstuffworks.com/alternator2.htm