Captain Obvious

I've never messed around with converting to the CV axles, so I'm all kinds of confused. With that in mind... You cut length off the end of the stub axle. And now (with just the washer and nut) on the threaded portion of the stub, the end of the axle is below the surface of the nut? How does it look with everything assembled in-situ? The reason I ask is that when installed "as used" the nut will not thread on as far as you have in your pics and you will have even less thread engagement. I'm not really worried that you'll have enough threads, but I am a little concerned that there won't be any place to put your anti-vibration peen. In other words... When you put everything together, it's the bearings and spacer tube (distance piece) that establish where that nut will get tight. Not where the washer bottoms out on the splines like you have in your photo. The nut will become tight before it's as far on as you have it in your pics. Another question is how do the new CV adapter flanges attach to the original rectangular flanges? I've never messed with them, so I have no idea. Do you drill holes for bolts, or do you weld them on or what? And lastly. it should be a relatively simple matter of machining the original wheel mounting flange to accommodate some sort of hub-centric ring. I haven't done it, but seems like you could turn down the original center hub to a smaller diameter and fit a special made centering ring over it. Press it on with no welding required? What is the diameter of the original hub ring, and what diameter are you trying to achieve?

They fit just fine. Fuel profile is different (no surprise), but mechanically they mount identically.

It's a 3-screw round top. 1972 only.

Well if you've been working with new ITB's, they probably have ball bearings and viton vacuum seals on the shafts. They probably are a lot smoother and tighter than the old SU stuff. If you aren't worn through the chrome, then I'd assume you're fine. As for the needles, my notes say that the N-54's were the factory needle for the 72 year. Manual trans I believe. They should be OK for what you're doing. My assumption is over the years, they leaned things out a little bit for emissions. So the 72 needles are a little leaner than the previous years. I've got a pair of brand new aftermarket "N-54s" here that are complete trash. The profile is so far off that it's not suitable for any Z. I think it was a screw-up by the company that sold the rebuild kit (or their supplier). The numbers for yours look much better than what I have here.

I meant stick a short piece of wire between the two shorting them together. They are already supposed to be connected hard together inside the wiring harness. One of the working theories is that connection inside the harness has become questionable. If you're not comfortable just trusting some guy on the internet who says "Naaah. It'll be fine. Just short that junk together." I totally get it. Next time the problem comes up, just start by taking the voltage measurements from each of those wires to the alternator case. We'll go from there. Actually, the first thing you should do the next time the problem starts is to wiggle that "T" connector around on the back of the alternator and see if wiggling does anything. Then take the two voltage readings of the two W/R to case.

Thanks for the post haircut pic. Much better. So as for the test... Yes, the "T" connector is involved. When the problem is occurring and the alternator voltage is too high, try sticking a wire in the back of the "T" connector at the W/R wire and connect the other end of that wire to the other W/R at the BATT connection. Here's a pic of the back of my alternator. Jumepr the two W/R red wires together like this:

I'm pretty much positive the needles that come in the generic rebuild kits are the wrong profile. According to some of the documentation, they claim to be suitable for the 72 carbs, but I think that's incorrect as well. The needles that are supposed to be in the 4-screw SU's are N-27's. I can see the "N" in one of your pics, but can't read the rest of it. Can you read it? Many people change over to "SM" needles, but I'm not a fan. If you want original profile needles and can't find them commercially, let me know. As for sealing up the shafts, yes... One side is pretty simple. Just cap over the whole thing. Other side where the linkage connects is a little more complicated, but putting an O-ring in there would certainly help. How sloppy are they? Is the shaft worn through the chrome plating into the brass?

Great work on the heater core stuff. Excellent camera work. I like the AN bulkhead feedhrough.

Excellent. I bet that thing feels a lot better on the road than when you started!

Oh, and it looks like your PO was into the harness. Always suspect when that happens. The W/R that goes into the twp position connector... What direction does that wire head? Does it turn the curve and head into the harness? Can't tell on the pic because the tape flap is in the way.

Good. Those colors match the 78 wiring diagram I'm working from. That page EE-15 from the 78 manual is all kinds of messed up. Bottom line is you should have the same voltage on both the W/R wires at all times. So if you're taking voltage readings, it would be good to get one with the car off, and another one when the problem is occurring. One lead to the alternator body, and other lead to the W/R wires. And the idea that Zedhead suggested would be a good test... When the problem is occurring, if you jumper between the two W/R wires, does the problem go away? You don't have to run a fresh wire all the way from the battery to run the test, just run a wire between the two W/R right on the back of the alternator and see what happens.

I agree. There are no mis-statements anywhere, but kinda deception through omission. There were a couple feedbacks that highlighted that situation. Some people were surprised and disappointed that the parts they got were 3-D printed. The seller is very responsive to problems and does his best to make it right, but I think some of those misunderstandings could have been prevented at the get-go if it was more clear what the parts are.

Yeah, I'm no ebay jockey and was wondering about that. So it sounds like ebay asks you if the part is new or not and as soon as you say your part is "new", they fill all that in for you. I did browse through some of the feedback and it's clear that the guy is credible and trying to make things work. I just think it should be called out specifically somewhere that the parts are 3D printed repros.

I doubt the needles in the replacement kit were the correct profile.

Uh-Oh. Now I'm worried that we're getting caught up with potential mistakes in the documentation and discrepancies in wire colors. When I was saying there are two W/R going to the back of the alternator, I was operating from this: And that's clearly different than the pic from the 78 manual posted above. So @chaseincats, what color wires do you have going to the two position spade connector on the back of your alternator? Here's a pic showing the connection layout:

I would think the highest amount of info would come from two readings... 1) With the engine off, and 2) While the problem is occurring and the engine is running. And just to be able to keep the analysis simple... I'd measure it to the alternator body (ground on the body itself).

My thoughts on the matter are in the form of a complaint... I don't like the condition description of the parts. I find it deceptive. There is no mention that the part is 3D-printed, and in fact, I find it easily misconstrued as an original part. For example: "New: A brand-new, unused, unopened, undamaged item in its original packaging (where packaging is applicable). Packaging should be the same as what is found in a retail store, unless the item was packaged by the manufacturer in non-retail packaging, such as an unprinted box or plastic bag. See the seller's listing for full details." Of course it's new. Of course it's in it's original packaging (because since he made it, "original packaging" would be whatever packaging this guy puts it in). And of course it's the same as what's found in a retail store unless it isn't. Maybe it's just me, but I find it deceptive. I think the condition should be "New aftermarket 3D printed reproduction part.".

First Q - Depends on your definition of "needed". I've seen junk in those filters, so I consider them cheap insurance as a "last chance" filter. Would catch anything that comes off the inside of your fuel pump or the rubber hoses between the main filter and the bowl. As mentioned above, they are still available (for the round tops) and they're not that expensive. I'd run 'em. Second Q - No. And I doubt the real issue is the bushing. I bet the problem is more the shaft than the bushing. Once you wear through the hard chrome into the soft brass underbelly, it wears pretty easily. You comfortable with precision stuff on your lathe yet? Third Q - My (non-expert) method is to use a thin layer of rubber sheet (1 mm thick rubber gasket sheeting) on the jaws of your bench vice. The rubber provides a little stickier surface to grip the needle along with some cushion and compliance to spread the force. Grip up high, slight twist and pull. Don't chew your needles up with pliers.

Yeah, I probably should have prefaced my post with "In my limited, ancient experience...." Haha! So hope the parts work out and whether they are good enough or not, I find the fact that the people here are willing to jump up and try to help out by making parts i fantastic. One of the reasons this is the best forum!

Exactly. That will take care of it. Failures like this are really intriguing. When the "impossible" happens. I will have to look at the gear train and flow of power, but I wouldn't have thought that portion of the gear train was even under stress when that failure happened. He was in 1st gear, right? And the wheels locked up and skidded to a stop after the "bang"?

Starting in 77 they included a groove along the top of the stainless window trim to accept a piece of rubber stripping. I don't have any pics handy, but can snap one if you want to see it. Just another reason that the 77s are better.

Sorry. Not intending to imply that you didn't... Just highlighting the details in the design to save you the potential trouble that I went through once. I once had a leaking slave cylinder that needed attention. Since the rubber hose looked fine, my plan was to unbolt the slave cylinder off the bell housing and unscrew it from the hose and then simply screw the new slave on in it's place. The thought was that while the rubber hose looked great, the mounting tab fitting welded to the body was a little rusty crusty and I didn't want to mess with potentially breaking it off the body. Simple plan, right? So the main portion of the plan worked great. Got the cylinder off the bell housing no problem and the new one went on fine, but the problem was that it was now pointing just about 180 degrees in the wrong direction. The hose screws into the slave and stops where it stops it when it's tight. And if that happens to be in the wrong direction, so be it, You either MUST deal with the rusty crusty other end, or mount it up the way you PO did it. I'm thinking they decided that twisting the hose was better than cracking the other end free. All that said, if you're replacing the hose, you'll have both ends loose so it shouldn't be an issue. Just don't save the cylinder mounting for the very end. Save the double flare fitting for the very end.

My experience with connector shells is that there are very tight dimensional tolerances and very thin walls. I would be surprised if connector shells like that could be successfully printed. Not to mention the brittleness vs. flexibility of the printed materials. Hope I'm just being pessimistic and it works!!

Thinking about it a little mire... I've not been inside a Z transmission, but here's some thoughts: I'm not so sure welding the washer and nut together is a good idea. My read on the way it was designed is that locating feature on the washer (whether it's a ball or a pin like the later design) is that feature exists exactly to isolate the nut from any rotational forces from the gear on the other side. In other words... You've got this gear spinning on one side and a nut that could potentially be loosened (or tightened) on the other side. They wanted something in addition to the peen on the nut to prevent that nut position from ever changing. So they used that locating feature to keep the washer from ever spinning with respect to the nut. If you weld the nut to the washer and completely skip the locating feature, you will allow whatever rotational forces are ever generated to be directly translated to the nut. You would be counting solely and completely on the peen to prevent the nut from changing position and I'm thinking that's not a good idea. In fact, I'm thinking you've got a chicken and the egg thing going on with the failure... Did the nut loosen up and allow the ball to slip out of place? Or did the gear transmit too much torque to the washer somehow (lack of oil, burrs on the surface, debris between the two, something) and start to spin the washer. And then when that washer spun, it ripped the ball out of the hole and started to rotate the nut. So I'm wondering what happened first, did the washer (and ball) slip first which loosened the nut, or did the nut loosen which allowed the washer (and ball) to slip?

Yikes! That's not good! Glad it didn't shatter anything and send chunks between gears!