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I had one of my masters re-sleeved, due to pitting in the bore. Works great with new seals and been trouble free for over 4 years. I'd rather rebuild and refurbish original components if they can be, newer parts don't seem as well made. Thanks for checking your clamps, I'll go with what was on the Green 5/70 BAT 240Z as it was low mileage and relatively untouched.

Go to the summit racing website and order a new champion replacement.

It might be fun to run with the ECU cover off. When you kick the case all of the components feel it. With the cover off you can pick the one you want to test. Hit it with a hammer, wiggle it, whatever. It is odd though that two ECU's would have identical failure characteristics. Might be worth the tme to do a pin drag test on the active pins in the connector that CO shows in his diagram. Maybe you have a loose one.

Well, certainly if you see something pop up for brake master guts, I'm all ears. There's one guy on ebay who has them, but I'm struggling with the price. I'm not sure if the master I have here would work even if the guts were new. I'm not digging the idea of spending over $100 as a gamble just to see if it works. And I wish I could help you with the wire clamp details, I've got original clamps here, but they are all aged to the point that it's quite doubtful I could tell what color they were when new.

The input filters could certainly become intermittent if vibration has taken it's toll. You could put meter across the visible wire coming off one side of the input choke coil and it's corresponding ECU connector pin. Should be pretty easy to figure out which pins they are filtering. Many of them are dead shorted, but the few (three?) that have the coil installed should be easy to determine. Looking at the approximate positions of the filters on the board and the pin functions of the ECU I/O connector, I'd guess that the filters are on pins 7, 27, and 13. Those would be inputs to the ECU that would be susceptible to noise. Those pins are 7) the AFM slider, 27) the air temp input, and 13) the water temp input signals respectively. But of course, that's a guess from across the interwebs. Here's a crude sketch I whipped up bunch of years ago. I know this info is available in other forms, but this form made sense to my brain: So about the failure mode for the Darlington outputs... No, they would probably not fail in the mode you are seeing. HOWEVER, the solder joints TO those transistors could fail with the symptoms you are describing. Any solder joint on the board could potentially go intermittent over time, but it would be unlikely for most of them. Vibration, stress, and temperature would be the risk factors. So about those risk factors... The reason those output transistors are so big and bolted firm to the chassis is that they get hot. There's your heat risk factor. And the I/O connector gets mechanically stressed every time you move the wiring harness or attach/detach the harness to the ECU. There's your stress factor there. Bottom line... If I were looking for a failing solder joint, I would start at the I/O connector and the output transistors. However, all that said, if I'm placing a bet at window #3, I'm betting the root problem is not inside the ECU case.

The ignition system is stock other than the wires and plugs. I did replace the coil many years ago, and maybe the ignition module a few years ago. I say "maybe" because I can't remember if I kept the original (which tested out perfectly) or swapped it back in and put the new one back in my parts bin. The problem that go-around was simply the car battery. Fun fact for anyone playing the stay at home version: It is possible for your battery to have plenty of juice to turn over your car and still be low enough on voltage so that your injectors won't fire. That was a fun one to diagnose. I can say for certain that the tach is spinning as normal and at least the tapping is not imaginary. I can make it stumble/stall 100% if I upgrade the tap to a "knock". However, it is entirely possible that more than one thing is going on and the stalling without tapping or opening/closing of the door could be something else entirely. Problem 'B' doesn't care one lick if you are already dealing with Problem 'A'. Alas. It looks like my order finally got out the door but it won't arrive until next week. We'll soon see what the future holds. Now taking bets at Window #3.

What ignition system are you using? The ECU uses the coil voltage pulse to trigger injection. Maybe the problem is actually in the ignition module. The coincidence with the tapping on the ECU might be imaginary. No offense, the human brain can rationalize itself in to knots. I had thought of this earlier - if the problem is repeatable and you can make it happen while you're in gear and moving, the tachometer should still show RPM if it's the ECU crapping out. If it's spark related the tach will drop like a rock.

Just a gut feeling, but based on the how-and-where-and-how-hard I tap on the ECU/connector, it seems like there might be a break in one of these coils...I think this only because they can rattle around a tiny bit in their respective tubes and would likely still "settle" with some sort of contact again because of the confines and 45+ years of work-hardening through vibration might do them in. I'll try and have a peek down the tubes with some sort of magification and see what I can. Alternatively, based on your comment about the darlington transistors, is this any sort of failure mode that makes sense for them? Where rattling or knocking with make them fail temporarily? The very temporary nature of the problem is what is most baffling to me.

Haha. Indeed. This is me, all day every day. No matter which way this goes, I will be using at least one of my ECUs as a learning/traning tool to do a refurb from the ground-up and truly learn every last function, and to really play with tuning. This is why I already had: A spare ECU, a spare AFM, the FSM, the FI Bible, Bosch Fuel Injection & Engine Management, an Ignition 1-2-3 distributor, and an oscilloscope...as well as a host of articles and posts from around the Internet. But I had planned to do this on my own schedule. It seems my Z has other ideas... In related news, last night I discovered that rebuilt ECUs are actually a dime a dozen; I just failed to Internet properly. I've fallen into some sort of pavlovian response mechanism where I assume everything is unobtainium and start scouring ebay and specialty z-parts shops. But if you look at AutoZone, O'Reilly, RockAuto, NapaAuto, etc. a rebuilt unit can be had for as little as $200, or $175 if you are willing to return a core. I've now re-added the standard parts-jobbers for future needs. It looks like they still have some bits and bobs. If it is useless I can return it no problem, so I figured: why not? When it gets here I'll do some compare-and-contrast. More news at six. Film at eleven.

Ball joint failure is a real thing. It usually causes major damage and loss of control. So the calculation is about how close a person wants to get to that catastrophe. Which also endangers other people on the road. But in this case, Nissan has given an inspection procedure. If it meets spec. why replace? What's odd is that they say that the ball joint cannot be disassembled, when, obviously, it can be.

This is a spread sheet of what I had couple of years ago when I tried to sell on Facebook. Not many left the building…..

I have an embarrassment of riches when it comes to standard A11 600 000 ECU’s for 280’s. Can’t ever see using them all locally, so anyone interested in picking up a “Few” in the USA where you can distribute them from there to those that need? Asking $50 each. Ask me for volume discounts….. There are a few ZX turbo, both 280 and 300 if that suites your fancy. I can try to build a list. Similar situation with AFM’s…..

Sometimes I take a best guess, no matter what the depth of my knowledge on a subject, and just try something. Then hope my brain will take the results and come up with something better. In retrospect, I doubt that the transistor(s) was/were the cause of the problem. I imagine that almost any open circuit or short inside the ECU could cause it to malfunction. Your situation is unusual in that it seems so repeatable that it's almost controllable and is the same for two different ECU's. Maybe you're just losing a connection at one of the pins. Probably one of the multi-vibrator functions! 🥴

@Captain Obvious I'm always on the lookout for NOS OEM parts, sometimes they have the right part number but are not in Nissan boxes...you just have to know where to look. I have a spreadsheet with all the period correct cross reference numbers and keep a look out for those on a regular basis. It seems the Nissan part suppliers of the day back in the early 1970s had no qualms about selling the same part to Lazorlite/WorldParts/BeckArnley. I wont try and reproduce the coating, too many other parts to restore at the moment but will keep it in mind for the future. I will use the master cylinders with the cast in letters on my 8/70 and 10/70 240Z, the engraved one will go on the 5/70 for period correctness. The fun anomaly I have discovered in the wire clamps. Some people say they should be all clear zinc, other say gold zinc...what's correct. Again referring back to the Green BAT 5/70 240Z, it has gold zinc wire with clear zinc screws...go figure that one out as it's totally original. However the large ones on the radiator hose are clear zinc.

Wow. I wish I could nap a set of pistons/seals/springs/washers for $85. If you see another one of those, please send me a quick note to let me know? Nobody will see the pistons after they are installed, so it's not like you're going to be judged on whether that coating exists or not. And I understand about polishing it off... The decision which is better...Keep some of the original failed coating, or just remove it all. Totally understand. If you do decide to look into it, there is probably nothing very special about that coating, It's a black oxide coating on steel. It's a controlled rusting kind of coating. Similar to "gun blue". Any coating shop should be able to reproduce it, but cost prohibitive for a single piece. As for the changeover point between the stamped lettering and the cast-in lettering? In that other thread it appears that point is between 7/70 and 12/70 when they changed the markings from stamped-in to cast-in. I got the chance to mess with a 9/70 car and it had the cast in lettering. So with a sample size of one, I could narrow the date window down to between 7/70 and 9/70. However: 1) It's a sample size of one. 2) I don't know if it was the original brake master on the 9/70 car, and... 3) The 9/70 car was an automatic, and some of the stuff on the autos is different than the manuals from the same month (valve cover for example). All that said, I think your MAY car should have the stamped lettering.

The large cans bolted to the outside of the chassis.... Labeled NEC D411A... Those are discrete transistors, but are a unique pair in the design. Those are the final output transistors that drive the injectors. There are only two of them, and they are known as "Darlington Transistors" because of the internal construction. The discrete transistors I was talking about are the much smaller black plastic bodied things with three legs. I whipped this up labeling some of the components: And you had asked about the copper tower and blue things near the connector... The copper towers are coils (aka inductors or chokes) and the blue Chicklet things are capacitors. Those two components in conjunction act as a filter on the incoming signals to the ECU in an attempt to eliminate high frequency noise. They originally designed the ECU with provisions to put those filters on many of the signals going to/from the main connector, but it appears they decided somewhere along the way that they are not all necessary. So they only populated a couple of them by the time they got to the end of the run. Most of them are just shorted across with a piece of wire. Hope that helps.

It's just the law overhere... i can't help it..

@Captain Obvious I've been buying them up from Ebay, they pop up every now and then. Last kit was in Feb this year, I got the pistons/seals/springs/washers for $85! Yes the piston did have the black coating, it was already coming off when I stripped the cylinder down. I hit them with the brass wire wheel to clean them up. I'm not sure the original coating from 50 years ago is still available so I'll keep them as it is. Hopefully nobody faults me for this. Nothing wrong with pedantic, you guys have been doing this longer than me and are more knowledgeable. Thanks for pointing it out. I have a rebuilt cylinder with the early engraving, I'll make sure I use that now I know it's the correct one. I have two of the cast type so I'll keep those for the later August 1970 and October 1970 240Z I have. Anyone know the exact changeover date? I'm using the Green May 1970 240Z that went for $310k on BAT as my reference along with @Zspert for his intimate knowledge with the cars. Again appreciate you correcting me and guiding me to the correct parts for my restoration.

Seiko Watch CorporationThe Datsun 240Z and Prospex Speedtimer: New collaboration...

I'm just learning what's what. I have near-zero electrictronics background but I am handy with a soldering iron and recently bought an oscilloscope to learn on (Tektronix TDS 1012) I can see that the WMIC labled parts are all metalized polymer capacitors and the resistors I recognize are pretty common...but the ICs? Are those the silver 14(?) pin guys with the heat sinks? And what the heck are those copper-coil towers with blue things next to the plug? I need a magnifying glass. I can't read 'em. Nothing looks like a discrete transistor that I recognize, but the round caps on the side say NEC...so I guess that would be those? When I was running the car previously I've grabbed the harness connector and given it a good hearty wiggle with no change but today when I did the second "tap" it was on the plug and not the unit itself, and it went off like a switch. Mostly though, when I tap it with my foot it is on the lower metal bracket. Tomorrow I will be sure to try and move/wiggle each bit of the harness from the connector up on into the dash and see if that makes any changes.

Most of the components in the ECU would be available generically. Caps, resistors, discrete transistors... No problem. The integrated circuits, however... Nada. You should be able to get pretty much anything but the ICs at Arrow and Mouser. But before you condemn the ECU, I would suggest try to isolate the problem. Even if it's an electro-mechanical issue, it would be important to know if the problem is in the wiring or connector to the ECU, or inside the ECU itself. So, the first thing I would try, would be to slowly and gently wiggle the wiring harness to the ECU and see what happens.

Roo, Nice work on the brake stuff. I have a couple comments / questions about the master cylinder: First, where did you find the rubber seals you used to rebuild the master? Second, the pistons originally had a black oxide coating presumably for friction reduction and/or corrosion protection. It looks like you hit the pistons with a wire wheel and burnished that coating off? Any thoughts about having them recoated? And last, a little pedantic, but I'm thinking that is not quite the correct master cylinder for a 5/70 car. I'm no expert on the early cars, but I think you should have the one with the ground and stamped "F" and "R", not the cast-in markings. The correct one I believe would look like this: There was some discussion about such matters here >> https://www.classiczcars.com/forums/topic/65579-brake-master-cylinder-46010-e4602-up-to-91971/?&page=3

Hey All, I hope someone can help me out, this is a rehash from another Z forum, but I'm spreading it in the hope of finding a solution. I'm in the early stages of restoring a 71 240z and thought a chassis jog would make life easier. As of now, step one is creating headaches, as described below. As of now i have built a chassis jig/frame and am in the process of bolting up my bent 240z to it. And here is the rub. I spent countless hours pouring over the only chassis dimensions document out there. That being the BF-3 204z dimensions PDF. As described previously I was thinking that the dimensions are wrong, or my car is very, very bent. With what I describe below, I don't think the car can possibly be 'that' bent. Some framing of the problem, with a crap pun: I have used four mounting points (described from rear to front): (1) Rear diff mount (not mustachio bar), (4 lateral bolts) (2) Front mount to the rear lower control arm, (4 lateral bolts) (3) Transmission mount, and then (two lateral bolts) (4) Front Strut Tower Top ("A" point). The dimensions (that don't work): (1) Reference point. (2) 465mm from ref. (1). this one is 15mm to short. (closer to 480mm) (3) 1427.5mm from ref. (1). This one lines up. (4) 2381.3mm from ref. (1). This one is 20mm to short. (closer to 2401.3mm) To my point......what the heck is going on here??!! Between point ref 1 and 2 my car is 480mm. In the BF-3 document, there is no reference to a 480mm dimension.... The car cannot be warped by 15mm, it's all structural mounting points. So, what am I missing? Moving on to the dimension between 1 and 4. Again, too short by 15 to 20mm... So, what is the actual dimension? All of the lateral dimensions are correct. I scratch my head. It's great though as it gives me something to talk with my wife about over dinner. Thank you in advance!

I'd love to have quick jacks, but I've used a set of standard plastic ramps for a couple of decades.