SteveJ

Not fast enough. The alternator is spinning better this morning than it did yesterday. Perhaps with no load, it was the field providing the resistance to movement. Anyway, I'll move to some in situ experiments and check the P terminal on the 240Z's alternator.

So I turned the alternator with a drill and probably spun it faster than it should go. The bearings are shot. All in the name of science! I would see peaks around 6VAC on the P terminal, so it is definitely unrectified. The FPR signal for the brake warning lamp check relay is probably the way to go.

I thought it might be unrectified. The first test is to see if it registers DC voltage on a voltmeter. I was also going to test it with a SPDT relay. If it pulls in the coil and holds, it works. I might even play with using a diode to make it a pulsed signal if it is sinusoidal. I could even do a test rig in my 240Z to see if it holds up for some trips. I could rig the contacts for the relay to a taillight socket with an LED bulb to see if it stays bright. A dim LED would indicate the contacts are cycling. Anyway, I've put a DC coil in an AC circuit before. The sound isn't pretty. Good point on the FPR. That sounds like the preferred solution if the P terminal doesn't pan out. The only advantage of the P terminal is that it you wouldn't have to do much outside of back the pin for the yellow wire out of the the T connector and put it in a single pin connecter.

Here's how the brake warning light circuit works in the 76: The green wire (ignition on) goes to the brake warning light in the speedometer. It comes out as green/yellow. There are 3 branches for the green/yellow wire. One branch goes to the brake pressure differential switch. The switch grounds the circuit when there is a problem. The second goes to the parking brake. The wire is grounded if the parking brake handle is lifted. The third branch goes to the brake warning lamp check relay where it goes through a normally closed contact that connects the wire to ground. The relay coil is energized by the neutral from the alternator, opening the contact when the engine is turning the alternator fast enough. The benefit is that it does light up if the engine stops turning when the key is on, as @Captain Obviouspointed out. This wouldn't be a plug-and-play solution, but here is one idea: Connect the yellow wire to the switched source. At the brake warning lamp check relay re-wire the circuit so that the yellow wire goes to the 85 and 87 contacts of a time on delay relay. The 86 contact would be grounded, and the 30 contact would go to the same pin on the brake warning lamp check relay that the yellow wire formerly connected to. The warning light would come on for a few seconds when starting the car and go out. The downside is that it would not respond to engine dying. Solution 2: Connect the yellow wire to the switched source. Replace the oil pressure sending unit with a 78 style. Run the normally open contact at the sending unit to the brake lamp warning check relay and put it on the ground for the coil. (If the relay is grounded on the chassis, the relay would need to be replaced with a modern SPDT relay.) The green/yellow and ground wires would stay on the normally closed contacts. At least the old functionality would be maintained. Solution 3?: (I'd have to do some testing.) ZX alternator only Connect the yellow wire to the P terminal. Done. I'll see if I can't bench test #3. I have a spare internally regulated alternator handy. I'll need to give it the lamp and sense signals and spin the alternator with a drill to see if I can get good voltage out the P terminal.

I didn't service the u-joints when I should have. It tore up the yoke, so I just replaced it with a 280Z driveshaft.

I've used a 280Z driveshaft in my 260Z for almost 6 years. I guess you can't believe the BS you read on the internet.

I think you're right, Bruce. So, it would take more modification, like using a 78 oil pressure sender to get a signal that the engine died.

I looked at the brake warning light circuit. The relay is energized by the neutral. I'm not sure why it is important to have the brake light illuminated on only while the alternator is turning. Do you know? According to the wiring diagram, there is a white wire that goes to the alternator. That should be the source for the sense wire. There is also the green wire near the VR that goes to a condenser. That should be the source for the lamp wire. That could also be connected back to the yellow wire for the brake light relay. It wouldn't be quite as simple as cutting some wires and splicing, but it could be made to work with the ZX alternator or Frontier alternator. Unplug the old voltage regulator to prevent problems, and you're done.

14 AWG will be fine.

The connection to the blower will need this connector: http://www.vintageconnections.com/Products/Detail/79

Thanks, I don't recall seeing that issue discussed.

One of the tangents that I travelled down when I was cleaning up was researching the company that made the VR, Furuhashi. I actually found someone selling a new Furuhashi 260Z VR online.

Thanks for the suggestion @Zed Head& @Dave WM, I'll try that soon. I think I played with putting the lights on, but with LEDs everywhere, that isn't much of a draw. I'll have to turn on the wipers, blower motor and stereo to add some load. Stay tuned.

If the brake check warning lamp works with the ZX alternator, I don't see why it wouldn't work for the Frontier alternator. I should note that I did not have any backfeeding issues with the Frontier alternator like the 240Z has with the ZX swap. Since I didn't experiment with swapping a ZX alternator in first, I would have to study the wiring diagrams in more detail to see if the black/white wire in the 260Z that I used for the switched source is wired differently than how the similar wire is in the 240Z.

Do we ever? 😉

Are you thinking it's documented wrong in the parts manual and FSMs?

At least it's not as challenging to change as when it's under the dash.

This is from AC-59 in the 77 FSM. You can see the U shaped hose connecting on the opposite pipe from where you have it. The U shaped hose is part number 16 in the image in my previous post.

I looked at the 77 FSM and the parts manual. http://www.carpartsmanual.com/datsun/Z-1969-1978/electrical/car-heater/from-aug-73 I think you have it backwards. This is from the parts manual with my enhancements in red.

Yeah, I had the same issue when I looked at the thread on my phone, too.

I just like the flat sides on the ones I found on Amazon. I'll have a set in a couple of days.

So, @Zed Head, it appears as though it's not that difficult to do this swap, despite what we've seen in other threads. It's mostly having the knowledge about what should connect to what. It only took me 20+ years to be fully comfortable in that realm.

Okay, so it's these tabs holding it in. The one on our top right is the clearest. You'll need to push out the sides a little to separate the tabs. Have you tried some long-nosed pliers pushing against the sides on top, pushing on the other side to get the connector past the tabs? I tried to take a photo of that, but it doesn't look like it would work well. You may be able to use the pliers to squeeze one tab at a time and push past it. Or a tool like this may be able to facilitate my first idea: https://www.amazon.com/SPEEDWOX-Installing-Gearshift-Automobile-Transmission/dp/B07QWTB149

That looks like a 73 wiring harness.