Zed Head

The blue wire will still be connected to the tach. It just won't be connected to the old ignition module which seems to be interfering with the new ignition module's purpose. The wire branches in to two after it leaves the coil, one branch to the tach, one branch to the old ignition module.

I'd just keep it to scare my friends. Rev, rev...Beees!

Those puck style discs don't have the marcels, or cushioning plates, between the friction material surfaces. They are prone to chatter. https://www.maximummotorsports.com/Clutch-Disk-Tech-C294.aspx#:~:text=Marcels - A clutch disk with,the flywheel and pressure plate. http://thecartech.com/subjects/auto_eng/Auto_Clutch.htm

The blue wire is actually the coil "control" wire. The ignition module in the footwell makes and breaks the electrical circuit to the coil. That is its main purpose, not tach sense. You can just unscrew all of the wires at the module. Some of them (two of them?, the blue one for sure) are hot with the key on, can't remember which. So don't bundle the ends together, keep them separate and tape them up. Or check the wiring diagram and isolate the hot ones.

I screwed up. I thought you were talking about connecting a wire from the Crane module. Wild guess - the old ignition module is still connected, by the fuse box. When you say "connect the blue tach sense wire" you're talking about connecting the wire at the coil? That also branches off to the old module. You have two modules connected when you connect the blue wire at the coil. You can disconnect all of the wires at the old module and tape them off. The blue tach wire branches off before it gets there.

Usually they put a sticker on that says "flywheel side". I don't see it on yours so it's probably right. And the hub usually pokes in to the hole in the pressure plate which yours does. Looks correct. But, I think that problem might just be related to the fact that you're using one of those high performance clutches. They're not made for comfort. They're made for grabbing and going. Found some stuff - https://www.google.com/search?rlz=1C1SQJL_enUS862US862&q=6+puck+clutch+disc+noise&sa=X&ved=2ahUKEwja17zGup_5AhUXIjQIHVdNDnAQ7xYoAHoECAEQMw&biw=1345&bih=620&dpr=1.19

p.s. it's not clear from your sound bite that the vehicle is completely stationary, like foot on the brake stopped. Might be a clue. Plus, it seemed like I heard some gear grind when you put it in gear. Definitely an odd noise. Everyone should listen to it.

So, if the vehicle is stopped, transmission in gear, clutch is slightly engaged (but vehicle is still not moving), what happens? The pressure plate, disc, and flywheel are pressed together, the main shaft and the gear that is engaged are loaded with force but still not moving. The only parts that are spinning are the flywheel, pressure plate, and throwout bearing. The disc is still static, rotationally, because it is splined to the mainshaft which is engaged with whatever gear is selected, but the disc is still subjected to the spinning flywheel. According to your description in the sound bite the noise happens when the disc is slightly loaded. One part that might buzz is the spring(s) in the disc. What did you buy? Maybe it's some sort of weird resonance that only happens in 1st and 2nd. Are you sure you can't make it happen in 3rd, 4th, or R? Edit - also, the disc could be rattling on the main shaft as the pressure plate spins against it. That might give a spinny buzzy noise. Loose splines.

I deviated from CO's point about nothing moving if the gears are engaged and the vehicle is not moving. My post above doesn't really fit the "vehicle not moving" scenario.

That does sound a like a spinny noise. Too bad you spread your threads around I'm pretty sure I saw one about the pilot bushing. How did the pilot bushing fit? Did you put a dab of grease on it? The noise kind of sounds like what I would imagine a dry and/or loose pilot bushing to sound like. It has a certain wobble to it. But throwout bearing seems possible too. You didn't record third and fourth so I assume that they don't make the noise. Or, maybe the needle bearings around 1 and 2. 1 and 2 also share the same coupling sleeve. The guys that have rebuilt theirs would know more about that possibility.

A couple came up today. A 78 in the 20's. A 72 still climbing. https://bringatrailer.com/listing/1978-datsun-280z-128/ No reserve - https://bringatrailer.com/listing/1972-datsun-240z-232/

Here's an actual example.

Like this?

Looks like your question now is "what brand"? Looks like the Exedy's only come with a bearing but no sleeve. So you'll want to measure and try to hit 92mm stack height. Or measure the old setup and match it. It would be interesting to see how close it is to 92mm.

Considering all of the potential problems, if I was buying a clutch kit I would just make sure that it came with a throwout bearing sleeve/collar. That's where people run in to problems, a mismatch between the sleeve and the pressure plate. Are you buying a flywheel too or having yours turned? 225mm flywheels are hard to find. You might find that you'll have to go 240mm (but it should already be 240 like you said) unless you get a Fidanza flywheel. The transmission that you use doesn't matter as long as it's a 71B type. That goes all the way through 1983. But, if you decide to change the differential to match the gears of a later model 5 speed you'll find that the 1975 year has an oddball pinion flange pattern on the diff.

Your promotion would have more impact if you picked an item of misinformation and corrected it. Also not sure that the author can define his own work as definitive.

If it only happens in 1st and 2nd but not 3rd or 4th then it seems likely to be a transmission issue. The clutch operation is the same for all gears. Any chance it's actually a vibration coming through the shift lever? That's a common thing for 1st and 2nd. Both on the left side of the pattern. I wouldn't worry too much about it. Keep track of it, if starts getting worse you can take action.

What transmission did you end up putting in the car?

73 shows similar but they actually show a connection between the ground circuits. Seems like there would be a sliding contact like for the turn signals, to ensure a ground circuit. Just offering another possibility. There might something buried under the mechanism. I had mine apart long ago but can't remember what was underneath. Whatever it is would not pass much current. Just enough to trip the relay.

The 76 wiring diagram shows the ground through the combination switch.

Zero to plus or zero to minus. Might be that you have a short or an open circuit somewhere.

Check your points and the coil. Might be that the various problems are related. Check coil resistance of the primary and secondary circuits, verify supply voltage, reset the points gap, or, ideally, set the dwell. Verify a good ground for the points. Spark strength is all about current through the coil. Check the advance mechanisms in the distributor. Verify proper ignition timing. Retarded timing can kill engine performance. Once you know that spark and timing are good, you can focus on carburetion.

I edited right after I posted. Was hoping I'd beat you to it. Sent the person an email about the year and title. See what happens.