Captain Obvious

Sweet. Looking forward to it. So, the gauge I have works fine, and I know that because I used it for a while in my car until I swapped out my entire dash for one with "fewer" cracks. Now all I have to do is keep my mitts off it until you get here. Problem is you've got me all curious now!! So to quell my curiosity, I did a few minutes of armchair research and I believe the bi-metallic strip with the contacts (not the one that moves the needle, but the other one) is a temperature compensation device in addition to a voltage regulator. It pulse width modulates the current through the other strip in response to changes in ambient temperature and system voltage. http://home.roadrunner.com/~john.strenk/Gauge%20web%20page/WebPageGauges1.htm Remember though, I still haven't been inside one myself. And I promise to TRY to keep it that way until you get here!

Don't get me wrong. I'm not saying my 77 doesn't have the rollers... I'm just saying that I don't remember seeing them. I had my driver's side door panel off a little while ago and I just put it back on. I wasn't in there for window stuff so I wasn't specifically looking into it. I'm gonna pull the pass side next, and I'll definitely pay a little more attention while I'm in there on that side.

And another suggestion... I've got a spare 77 gauge that works fine, and you're welcome to have it if you want. Don't know if it's the same as what you're working on, but if it would help, just let me know!

The small hoses are 1/4 and 5/16. Between those two sizes you'll have all of the small stuff covered. The bigger stuff (the braided stuff) is more difficult. The hose on the top going to the valve cover is straight enough that you can easily find a replacement at the parts store. The problem is the braided stuff from the air cleaner to the carbs and between the two carbs. Of those, the one between the two carbs is the highest priority since it's at the highest vacuum and will such the most air if it has a leak. I'm thinking that you should visit that guy who knows the SU's.

I've never looked inside the gauges, so I'm shooting from the hip... Put a small capacitor across the arcing contacts to act as a snubber to prevent future arcing and use some gold leaf from the craft store burnished onto the contacts to provide a better contact?

You can add round top carb swap to your list of updates/replacements. A previous owner removed the original flat-top carbs in favor of the older round tops, swapped the original EGR balance tube for one from a previous year, and replaced all the carb linkages accordingly.

Are the 77/78 doors supposed to have that roller? I don't think I've got one (in my 77).

Mine was giving me trouble, so I carefully opened it up to clean it out and adjust. Then I drilled and tapped the casing for three small screws to hold the clamshell back together. Now I can disassemble and reassemble at will. Not supposed to come apart? Mine is! :laugh: Sorry for the crappy pics, but I didn't take it off the car just for a photo shoot. Two screws on top: And one on the bottom:

I wouldn't worry much about some oil in the valve cover hose. It's part of the PCV system and it's gonna happen. However, with that in mind, you should add checking/replacing your PCV valve to the maintenance suggestions provided earlier. Speaking of which... How much have you done with the car? Looked into any of the stuff mentioned earlier?

Yeah, I'm with E. I figure they felt they didn't need to show the tenths since the trip-O includes that. Just seemed funny to me that it was in there at all! Go through all that effort just to cover it up? The tenths digit does increment the 1's digit, and the assy (as designed) would not work without the tenths. Makes me think there were other vehicles that used the same assy that did show it. Something without a trip-O maybe? When I opened that thing up and saw six digits, my first thought was that there was a hidden 100K digit in there. And that would have been more than trivia. That would have been big news!! No more guessing how many times it rolled over! You know... With some modifications to the mounting tabs to make them a little wider, I bet I could add a 100K's digit to that thing... :bulb:

Not sure if this is common knowledge or not, but I learned something neat about the odometer today. You see five digits when you look at the odometer, but there are actually six digits available. There is a "tenths" digit on the odometer that is screened by the hole in the speedo face. Here's the front. There are five digits: And here's the guts. There are six digits, and the extra one is tenths: Who knew!?!

It looks great, and again... Thanks so much! As for the revision indicator, I think you misunderstood what I was suggesting. I was not suggesting a list of the changes that have occurred since inception. I was simply suggesting some indicator on the page as to what it's current revision is. Could be something as simple as "Revision H - Created 9/25/2012" in the legend area somewhere. Just so you can tell by looking at the picture itself when it was created or last modified. Just a time or date stamp, not history. Haha! I'd be happy to do what I can.

And... I just checked this, and the private messenger is correct. The original diagram from the 77 FSM has the magnet clutch connected to the blue wire and the BCDD cut connected to the white/black. It looks like a simple matter of mislabeled solenoids, because also in the original FSM, the A/C clutch is above the BCDD, and the BCDD is above the thermal transmitter. On your doc, the BCDD is above the A/C clutch. If you leave all the wiring alone and simply swap the labels between the BCDD and A/C clutch, everything will be correct.

There's no way I would ever blast a condesor with anything. Lightly or not. I'm no A/C expert, but since you didn't get any other responses...

Wayne, Thanks for the effort! Before this thing makes it to far though, there's something that doesn't look right to me. Seems the font style or weighting has changed between this version and your previous version. For example, take a look at the combination switch matrix and compare that area to the previous version. (Not E's version... that one has a different problem.) Your original one looks great, but the newest version has a font type that is so bold that it blurs one character into another. It's too bold, if that makes sense. There's a possibility that this is a user specific problem to me, so if it looks fine on your screen, then let me know and I'll send you a screen capture of what I'm talking about. Also, is there any reference on the document itself that indicates the change in revision? If not, I would recommend that. Doesn't have to be much, but something on the doc and not simply in the file name? Is that possible? Thanks again for all your help with this!!

Nobody? I'm the only one who has ever had such problem??? On a related note... I've got aluminum wheel cylinders. Does everyone else have the same, or are they steel?

Excellent. That's an even better solution! An HVAC guy with small hands. Another crisis averted!

Blue, Thanks for the help. I'm familiar with both styles of cylinders and what I'm working on are the 77-78 style with the two opposed pistons. I had the earlier single piston floating cylinder style in my 74. In the pic, you can only see one of the pistons, but I assure you... I've got two pistons and two seals per corner. The rebuilds I bought were Wagner 96618. I also got a box of parts from my previous owner that included some NOS brake parts, and in there were another set of Wagner kits (looked older than the ones I bought), and the Tru-Torque kits. I think I've got at least five rebuild kits, some unopened NOS still in sealed packaging and they are all the same... And none of them are correct for my cylinders. And like I mentioned above, I dismantled and stored a set of 77-78 cylinders from a parts car a while ago, and when things started getting confusing, I pulled that box off the shelf to see if it could add any info. The result is that the pair of cylinders in that box were identical to the ones on my car, including the pistons and seals with the larger hole in the center. Looking at the pics at Rock Auto, all the rebuilds they have appear to be the small hole style. Something seemingly this simple, and it's just not making sense?

One of the rear wheel cylinders on my 77 280 was leaking a little so I bought rebuild kits for both sides. I've got kits from both Wagner and Tru-Torque, and the basic P/N is 96618. Pulled the pistons out of my wheel cylinder and pried off the old seals. Then I noticed that the hole in the center of the old seal is much larger than the hole in the new one and it would be an enormous stretch to fit one of the new ones onto the piston. Also, the new seal is thicker and doesn't fit the groove in the piston. I've got a set of old cylinders from a parts car and the pistons and seals in them are the same as what's in my car. In other words, I have the correct cylinders and pistons on my car. I didn't try real hard to stretch that new seal onto my piston, but I don't think it's going to work. Did they change the piston design somewhere along the line and I missed the memo? Did I somehow get the wrong rebuild kit, and if so, what's the correct one? Here's a pic showing the old and new Hard to tell in this pic, but the new seal is thicker than the old one: Here's one of the packages and you can see the other part numbers it's compatible with: What the heck???

I would be careful with the brake cleaner and the AAR... There's some wiring in there and I don't know how the insulation will like being soaked with the solvents. Use a little and quickly shake out the excess, but I wouldn't dunk it in a can of carb cleaner. I remember that cool pic you were talking about from Fastwoman... I did some digging and found it in the "Post pics of your engine bay" thread. http://www.classiczcars.com/forums/thread45781.html Even though the routing is a little different, the function is still textbook "78 style". AAR pickup is off the flex tube upstream of the dirty PCV overflow. I like it too!

Sorry I couldn't be of more help. So if you do end up pulling the dash... What year are you working with? I just pulled dashes out of both a 74 and a 77, and the 77 was easier. The 74 required disconnection of a bunch of electrical connectors at the steering column, and by the time 77 rolled along Datsun had gotten a little smarter and rerouted all those connections to the firewall. The only electrical connections you have to mess with in 77 are three large connectors all located at the junction box above the passengers right knee. Leave all the HVAC stuff in place. You don't have to mess with any of it to pull the dash. In fact, you can even leave the faceplate with the map light and fuel warning light in place. Leave the glove box in place as well. Don't forget to disconnect and reconnect the speedo cable. What else...? If your clock doesn't work, it's a lot easier to remove with the dash out of the car. If you find an evaporator core in the top of your HVAC system, then you used to have A/C.

Gotcha. Well my 77 still has all the original 77 routing, and I'm nipple-less, so I guess my car never got the treatment. I wonder if anyone ever came up with a way to plumb to the dirty side of the air cleaner without confusing the L-jet.

Here's a pic of the water control valves. The spring loaded over-engineered device on the right is controlled by the temp slider, and the flying saucer shaped diaphragm actuator on the left shuts off all the water when you turn the A/C on regardless of where the temp slider is positioned. I'm no expert on the HVAC system, but I'm still thinking that maybe you shouldn't have any vacuum stuff in there at all unless the car has A/C. Maybe your car had A/C at one time, but a previous owner removed some (but not all) of it? You've got the vacuum switching valves in the engine compartment Is the hose going to the diaphragm the one having troubles with?

Thanks for that info. So was there actually a recall for this? Was everything supposed to be updated to 78 specs?

280~Master, you are running the stock configuration for 76, which is the same as 77. Interesting to note that you have the unused nipple on the flex tube at the front of the throttle body. Seems your flex tube has been replaced at some point with a newer one. I wonder if maybe Nissan stopped making the original tube without the nipple, and just started supplying only the one with the nipple. They would only have to stock one part that way. Anyway, you've got the correct setup for 76, but you could re-route for 78 if you chose to. BTW - Nice tape on the AFM... Looks just like mine, except I'm rockin' green instead of red!