1977 280Z Bouncing speedometer

[240zadmire]

Greetings

 

so I finally roll off the car from the “assembly” line.  It’s definitely feel “different” than a modern sedan.  I’ll save this for other discussion.

 

what I notice is that the speedometer is “bouncing” or “jumping” as I accelerate.  I don’t think this is normal.  Searched and seem like some suggest to put a resistor about 10k ohm at the coil ignition.  Not sure if that is the good idea.  Which bring to another question.  Seem like there is an extra capacitor around the coil ignition.  I cannot seem to be able to find another plug to connect to this.  Please see the photo.

 

much appreciate

 

regards

 

 

Edited August 9, 2020 by 240zadmire

[EuroDat]

Do you mean speedo or tacho?

I can't see how the coil would influence the speedo, being a mechanical driven device.

Can you also give some details about the car. Your user name is 240Zadmire, but the photo is clearly a californian 280Z. Going by the inductor terminal block left of the coil.

That spade terminal goes on the ballast resistor for the coil.

[Pop's Z]

Speedo "bounce" is usually due to a lack of lubrication. It has nothing to do with the coil. After I lubed my speedo cable the "bounce" went away.

Cheers, Mike

[EuroDat]

Here is a photo of the spade connector and how it connects to the ballast.

[Pilgrim]

Yes to the comments above.  Speedometer in your car is a cable drive and electronics do not affect it. Slide the cable out at the transmission end and lubricate with graphite, NOT GREASE OR OIL.

I hope the OP responds. 

[240zadmire]

It’s an early ‘77 280Z.  A California car.

 

look at the diagram and the coil’s resistor, it needs to go to one one the 2 pins already occupied?

 

regards

[240zadmire]

It’s a speedometer.  It is not smooth.  Jumping as I accelerate.  I figure it need lubricate but fear of the rubber gear broken.  Will exam and lubricate 

 

stay tune 

regards

 

[Zed Head]

40 minutes ago, 240zadmire said:

look at the diagram and the coil’s resistor, it needs to go to one one the 2 pins already occupied?

Condensers have one side to a positive source and the other to a ground.

Pull your speedometer cable from the transmission end and while you're there you can pry the gear out of the transmission and inspect it.  They do get chewed up sometimes.  It's difficult to get the speedo gear assembly out, you might need to use pliers and a rag to protect the aluminum.  Twist and lever to get it out.  You'll probably bang your knuckles when it comes free.

[cgsheen1]

4 hours ago, 240zadmire said:

 

I this picture, you're holding the GROUND WIRE. (please don't try to connect it to the ballast in any way!)

Notice that the wire on the other side of the condenser is BLUE and connected to a Black/Blue wire coming out of the harness. NOTE: Nissan used BLACK wires WITH STRIPES for voltage! (Black/White B/W) = Battery voltage at IGN ON in all cases, Black/Yellow (BY) = Start Signal (battery voltage to starter solenoid) + bypass voltage to certain things at START, also Black/Blue (BL) and Black/Red (BR). None of these are grounds!)

Judging by the length of the black wire you are holding, that may go to a spade on the distributor. I would put a new female spade on the end of that wire personally.

(Edit: In the shop, I use Meguiars Hyper Dressing - which is an excellent cleaner and protectant (for all things vinyl, plastic, and rubber (and PVC wire insulation)) - to clean and rejuvenate exposed wiring coming out of the harness. Makes the harness look nice too. But the point would be to clean the wire so it's very easy to tell color and/or stripe.)

Edited August 9, 2020 by cgsheen1

[240zadmire]

@cgsheen1

youre right.  I looked back my archived photos and it wasn’t connected to that Resistor terminal.  For the live of me, I cannot remember where it should goes.  Base in your logic, it can connect to engine or chassis?

 

regards

 

[cgsheen1]

It connects to a spade on the distributor.  That particular condenser is to help eliminate electrical noise from the ignition process - coil and distributor.  (There's another one on the Alternator.) There should be about three or more other wires running from the area of the coil to the distributor area. they have to do with the electronic ignition and a yellow wire to the temperature sender for the coolant gauge in the cockpit. It would normally be bundled with those wires. I don't have the Factory Service Manual right at my fingertips ATM, but it's a good reference - you should download it.

 

[240zadmire]

I’ll go with your suggestion to make a spade on the distributor.  Does it matter where to mount or? Either on one of the 2 bolts to mount the body or that screw on the picture.  ?!