Zed Head

I think that internally regulated alternators can be damaged if they get more than ~3 volts on the L wire. The L wire is the wire that goes to the lamp in your voltmeter. You can check it at the T plug before you connect the alternator by turning on the key and measuring. If you get battery voltage, you need to rewire to the voltmeter lamp or put a resistor in line. The other wire is the S wire and should measure battery voltage.

I ran 50 pennies, using 24 lb paper, and 5 staples. Battery voltage was 9.33 to start (colder in the garage). I got 0.68 volts out or 7.3%. Close to yours but with the heavier paper and more staples, should have been a lower output. It would be nice to see what a "bad" one reads. I sent mine to MSA for the core.

In Post #26 hogie said 1 3/4" pressure plate height. But I think that is the new one. Maybe. He said he had ordered one from NAPA. hogie, right now your only point of reference is your old collar and your old pressure plate. If you measure those, you'll know your starting point for comparison. So far, I don't think that you have told what the old parts actually measured, beyond the picture of the collar and the tape measure. It would be great if you could measure the old stuff, so that there would at least be confirmation of something that didn't work OR maybe it would point at the slave cylinder and rod. Then compare it to the new stuff. My two examples above, Post #27, give a range of 3 3/8 to 3 13/16" for the height from the bottom of the pressure plate to the top of the ears on the collar, combined. That would be everything that fits between the fork and the pressure plate fingers. These two measurements both worked, one 1 3/4" and one 2" pressure plate, same collar. This comes up all the time but rarely are any measurements reported. Overwhelmed yet?

I hope we don't get banned for what's going on here... FW, if you could run the 28 quarters, we could see if an 82 AFM has the same spring tension as a 78 AFM. Or at least the equivalent weight in pennies. It appears that you have a balance of some kind. It looks like the AFM is designed to simply split the input voltage in half, then scale it to full potential on one side of the potentiometer and zero on the other as the vane travels from closed to full open. The ECU uses one of those voltages for its injector time calculations. Also, you can see from your chart how you lose the leverage as the vane drops past perpendicular. Each new penny has less effect. Were you tilting the AFM to avoid the rubbing or not?

Howdy hogie. It does look different than old factory stock but the necessary bearing surfaces are there. The tops of the ears and the bearing and the spring clip are the only contact points. If you look at Carl's pictures in Post#31, you can probably figure out where to measure from to see what you have. They sent you the collar/sleeve with no bearing, so you'll have to measure from the top of the ears to where the top of the bearing would be. It does look like a short one though. Maybe a 240Z collar/sleeve. If so, it certainly won't jam your clutch partially open, but may not disengage it fully either. You might need an adjustable slave rod. Edit - actually it looks like it might be designed to handle two different bearings. I would guess that your bearing will only press up onn the narrow section, so it is probably taller than it looks in use. If you have a bearing, you could guesstimate where it will end up once pressed on take a measurement there. I looked back at your pictures but can't read the tape on your measurements. How does the new one measure out compared to the old one?

Here is a single mid-vane data point if anyone ever has the urge to see where their AFM falls in comparison. 1978 AFM 9.62 volts across pins 9 and 6 Output measured at pins 7 and 8 AFM bore pointed down and leveled Mid-vane measurement taken with a taped roll of 28 quarters hanging by a thread from the edge of the vane. Vane Closed 4.74 volts (49 % of input) Vane Open 0.12 volts (1.2 % of input) 28 quarters 0.488 volts (5.1 % of input) The first two measurements tell about the potentiometer and the last one tells about the spring tension. The vane was only partially open with 28 quarters hanging from it. I tried 20 quarters but the thread rubbed on the housing and I could not get a consistent number. I have attached a picture so that you can see how far open the vane is with only 5.1 % of the input voltage going to the ECU. This might seem like some nonsense but it's pretty interesting. If you consider that the ECU is also using small resistance readings fromthe various temperature sensors also, it's easy to see how things can go wrong. Note that this AFM ran well on a parked car, and had normal (100 and 180) resistance readings but I have not actually used it under load. Except for starting the car in gear on jack stands and applying the parking brake while the wheels were turning, to test it. It sounded good. Fun, fun, fun...

A flow bench would be the best way, considering the application. I wonder how the rebuild guys do it. There is leakage past the vane, plus the offset from the air idle circuit. I found that my rebuilt AFM had enough air going through without moving the vane that, after advancing my timing, I had to adjust the fuel pump cutoff switch to only work when the vane was just barely open. The engine almost had enough air through the idle circuit and leakage to run without any vane contribution. The idle air circuit will change the liftoff point of the vane, I used it to keep my fuel pump switch from cutting off for a little while. I had to lean the idle air back out for Oregon emissions though (eventually I just bent the fuel cutoff switch arm to make it work). I already tried a few things with a roll of quarters on top of the vane but the only way to be reproducible, in my opinion, is to hang a thread from the edge of the vane, so that the lever arm length is consistent. Basically, I ended up where atlanticz did. But I think that one measurement, with the vane perpendicular or midway, is all you would need since you can't change the spring constant (edit - actually, maybe you can, with the other screws inside the AFM, I haven't been that deep) and you can only change the preload by rotating the wheel. I would say that using atlanticz's method of attaching the weight, but using a known reproducible weight (rather than pop cans and water), hanging that weight and measuring the voltage ratio, volts in at 6 and 9 vs. volts across 7 and 8, would give you the best calibration number to try and match. (second edit - the main purpose of this exercise is to compare AFMs, voltages to the ECU, I think, known good ones vs. others). I'll go hang a known number of quarters from the vane and measure the voltages. That's really the best it will get without a flow bench, I think.

I'll see if I can come up with at least a one or two point calibration number using a 9 volt battery. Maybe a fishing weight or similar hanging on the vane. My beer comes in bottles. The hard part in these situations is coming up with something reproducible. Using common coins as weights might work.

Running rich will make quite a stink. My 76 with EFI stank bad until I fixed the fuel pressure regulator. Maybe you just need a little more tuning at the idle and low rpm end.

You could also put it in high gear and roll it by grabbing a tire and turning it. An alternative if it's a manual.

Black/white is switched power from the ignition switch. Black is the intended ground wire and should be opposite the bump on the plugs. Maybe someone de-pinned your connector to clean it or put a new plug on and screwed up when they put it back together. FastWoman may have the right idea, get out the volt/ohm meter and see where those harness wires go. You'll need to know anyway even for an alternator swap.

I overlooked the part about Pin 2 being the black wire on the harness plug. I just looked at both FSMs, 76 and 77, and they both show Pin 4 as black/ground. Pin 2 should be power from the alternator, a white wire. I have attached a drawing from the 1977 FSM (Page BE-22) of the regulator side of the plug, just to confirm the wire colors, plus it shows where they come from. A for Alt, L for Lamp, E for Earth, Ig for switched power. I thnk that F and N come from the T plug on the Alt. It is upside down compared to Steve's Post #2 drawing. You can see that it matches the 1976 wiring diagram.. L signifies a blue wire in the drawing, so you can see that they don't match wire colors across the plug for every wire. Blue in the harness goes to W/R on the regulator for example. There is definitely something odd if your car's harness has a black wire at the Pin 2 position. Any chance you could take a picture of this odd connector? If you decide to go with the internally regulated alternator, be aware that the yellow wire also powers the brake light warning switch circuit. Your battery will slowly drain if you don't cut it, and wire it to a switched source. Edit - Forgot to say that I already converted to an IR alternator so can't compare plugs.

E represents Earth or Ground. If you have a voltmeter, you could see if Pin 4 on the harness connector has power when you turn on the key or is grounded, key off. According to the diagrams, it should be a ground wire. What you've described so far is as if the wire to pin 4 from the harness has power to it when the key is turned on. It's possible that someone had a short in the past and the wires melted together in the harness, or that insulation has frayed away over time inside the bundle. If you connect your voltmeter positive to Pin 4 from the harness, and the voltmeter negative to ground, then get power when the key is turned on, there is a short somewhere along the Pin 4 circuit. It might be burned at the other end also. My 76 has some wires stuck together in the main harness from a short sometimes in it's past (before I got it). The ground wires run right alongside the power wires in the harness. The ground wire got hot and almost took the whole harness out. Edit - my clairvoyance is acting up again...

I almost hate to get involved in the fusible link discussion but it seems to me that the "red = 50 amp link" data that is on the Atlanticz site is incorrect. Everything that I have seen in the FSM (the wire gauge information, from smallest to thickest), the labels on the actual fusible link holder in the car (Br matches Br in the FSM), and on the Nissan representative's own web site (Courtesy Nissan) suggest that "red = ~30 amps." I have not seen the atlanticz page data verified anywhere else. Edit - I also just noticed, on the atlanticz page, that it calls out red as 0.69 mm^2. This might well be a 50 amp link. But it's not the red that Courtesy sells, and it's not the Br that the FSM calls out. Also on the page, it is suggested that Br (Brown, page BE-2) is actually BR (black with red stripe). More confusion. "Pink" is called out as 30 amp. From the Courtesy Nissan web page - Black = 1.25 mm^2 Green = 0.5 mm^2 Red = 0.3 mm^2 The attached image is from the 1976 FSM showing that the numbers are the same as the FSM but what was Brown is now red. Also attached is a picture from the fusible link holder on my 1976 car. B (black) for accessory, Br (brown) one for ignition and one for headlights, and G (green) for ignition. The Courtesy Nissan page for reference - http://www.courtesyparts.com/kb_search_result.php?chassis_id=59&keywords=link&Submit_Button=Go&cat=1 So, on the atlanticz page, either green is not 40 or red is not 50. Or Courtesy Nissan is selling the wrong gauge fusible link wire. Thanks for listening. I know that this has been beat to death over time, but these logic errors just bug me.

I listen to my fuel pump to tell the state of my charging system. It even tells me when my blinkers are on.

Page EE-30 in the FSM has a pretty good drawing. It has been suggested in other threads that you try cooling the module down when the problem occurs. If cooling it allows you to restart faster than waiting, that's a pretty good indicator that the module is bad.

Thanks for the information Carl. I wil be saving this thread for future reference. I wonder if hogie had a 240 mm (2+2) pressure plate with a 28 mm sleeve similar to ktm's situation in the other thread, but somehow the PO got it bolted together? hogie, if you want to be sure that your slave cylinder is not bottomed out, holding some pressure on your pressure plate fingers, note that on my car, I can pull the slave cylinder rod back and remove it from its spot on the fork without unbolting anything. There is enough unused travel in the slave cylinder to do that. If your slave cylinder was bottomed mechanically, you won't be able to do that.

Is that the typical place to measure the sleeve/collar? The 1 13/16" collars I mentioned, also measure out to 28mm (~ 1 1/8") using Carl's measurement points. One more data point. It looks like hogie has all of the parts for a 280Z coupe clutch. What are the measurements on the original parts that didn't work?

The pictures that Carl posted in the link that Dizeazd gave are very useful in showing that there are at least four collars out there. But there are no measurements associated. Here are some measurements from parts that I know, for reference (I still have these parts for some reason) - The dimensions for my 1976 4 speed 2 seater (225 mm clutch aka 8 inch) is 1 13/16 inches from the bearing surface (where the clutch fingers touch) to the tops of the ears (where the fork rides). This collar was used with a pressure plate that measured 2" from mounting surface to the tops of the fingers. I drove this around for quite a while before I replaced the clutch when I replaced the transmission with the 5 speed. I have the collar and pressure plate from the 1978 280Z that apparently drove fine when it was parked. The transmission had all the signs of never having been removed. It too had a 1 13/16" collar, but the pressure plate measured 1 3/4". The 4 speed 1976 transmission is the FS5W71A which has the identical bell housing to the 1978 5 speed FS5W71B. So there is a 1 13/16" collar dimension used with both a 1 3/4" and 2" pressure plates heights, on an L28 with either and FS5W71A or ...B transmission. I would guess that your new pressure plate is the latest 280Z style. If you have the later 5 speed, the 1 13/16" collar should work for sure, maybe with any transmission. Thanks for giving me a reason to go dig through my old parts. I did not even realize that my pressure plates were of different height. I had just bought the clutch set for a 78 280Z when I did the trans swap, put it all in and apparently got lucky.

Thanks for the reply. Maybe they stopped putting the collar in because of all of the returns for "wrong part." Edit - I wrote a bunch but most of it is covered in Dizeazd's link... One last thought, your throwout bearing and collar looks very gummed up. It has to slide back on the transmission main shaft front cover cylindrical portion to release the pressure on the clutch. I wonder if yours was jamming on the cover. Make sure the collar slides freely back and forth. I am interested because I don't want to get stuck in this situation! Still looking for the definitive measurements to ensure everything will work together. Last, last edit - Removing comments. I'm just adding to the confusion...

Do they include the bearing? I thought that a new bearing could be pressed in to the old collar. The wear on the collar "tabs" is usually pretty minimal isn't it?

I agree!. I guess my sense of humor didn't come across. It's not the first time.

"My girlfriend convinced me to head up to the pick and pull" - what an odd statement...

How much for a t-shirt? Maybe I'll buy one - sort of...

Looks like venus is drumming up awareness of his/her Z Island t-shirts, hats and coins, and the plan has gone awry. She/he has now indirectly insulted Ferrari people also. It's a slippery slope, trying to defend a poor decision.