Early 1971 240Z and Rheostat

[Dr. 240Z]

Hi,

If there is anyone who has changed the dashlights rheostat and didn't find it too difficult - I need your help please.

As is, I've removed the driver's seat and placed numerous cushions and folded towels down to make lying on my back relatively comfortable. After that it's all up hill - access is tight and visibility is limited.

There must be an easy way; I just haven't read about it in any forums or been able to figure it out for myself. Everything else on the old girl works so I'd really like to have her 100%.

Thanks,

George

[FastWoman]

On March 17, drink lots of green beer, and sing a few sad, Irish folk songs. A little leprechaun might just take pity on you and help you out.

I've never done the job, but I imagine your rheostat is just like any other. It probably attaches via a nut on the front of the panel (beneath the knob, which you would either pull straight off or remove with an allen set screw on the side.

I suspect you don't really need to remove the thing. If you use a mirror, you can probably see the windings and an arm that slides over them. I bet the windings are just a bit dirty. You can clean them with WD-40 and a rag (don't spray it on surrounding dashboard materials), or with Deoxit if they are dirtier than that. Another time-honored method for cleaning them would just be to "exercise" the rheostat back and forth, back and forth -- maybe a hundred reps.

[zKars]

Option 2. Don't fix it, just disconnect it and re-connect the two dash-side leads to effectively bypass it. This just puts the dash lights at maximum brightness. Unless you have replaced your bulbs with fancy LED's or the like, you won't likely find the dash lights too bright. If anything you may actually be able to see your gauges at night for the first time!

[Dr. 240Z]

Option 2. Don't fix it, just disconnect it and re-connect the two dash-side leads to effectively bypass it. This just puts the dash lights at maximum brightness. Unless you have replaced your bulbs with fancy LED's or the like, you won't likely find the dash lights too bright. If anything you may actually be able to see your gauges at night for the first time!

Jim,

What you suggest is the exactly where it stands. However, like I stated at the beginning, it's the only thing that's not working, and I have a new (used/ebay) rheostat to repace it with.

I can't imagine Nissan made this task as difficult as it appears - It would have cost them a fortune to replace if they had to pull the dash out when these were under warranty.

Cheers,

George

[Zed Head]

I have a 76 Z, and I haven't even been able to get the two leads off so that I can short them. It seems to be the most difficult component to work on in my car. Can't see any windings, it's all covered, can't reach any mounting screws, can't reach the wires. Might be easier on a 240 without the relays and bracketry in the way.

[zKars]

George my response was a test of your resolve. Now that we understand shortcuts are not your thing, you have a heck of a job ahead of you. I'll have to take a picture of the back side of a dash so you can at least see how the thing mounts and what you're up against to get its two mounting screws out.

Now since the windings are all exposed, you "could" flush it in place with a contact cleaner, some small ID plastic hose to aim the spray, a mirror, a light held in you teeth, goggles to protect from splash, spray and twist the handle back and forth. etc etc etc... DId I mention that alot of contact cleaners are hard on kinds of plastic, don't spray it just anywhere....

Then all you have to do is re-connect it! Simple, eh Zedhead?

[Dr. 240Z]

Hi Jim,

I returned under the dash for another look and noted a wing-nut that appears to hold the tachometer in place. That being the case, I think if I were to remove the wing-nut the tachometer might (hopefully) be removed via the front of the dash. With the tach out of the way, the rheostat might then be readily accessible. Does this approach seem reasonable to you?

Regards,

George

[240260280z]

These should help.

Back of tach after conversion to single wire (red one)

Back of tack before conversion (In situ).

Note the grounding copper spring metal on the collar of the lights.

You can also see the Tach calibration screw with a dab of ink showing where it was set in 1971.

The rheostat in a "fox hole" making it very challenging to attack. The tach above is clearly in the way.

The rheostat and a broken wire that disconnected from one of it's terminals

More detail of the tach light bulbs

The two wing nuts are also shown.

Edited March 5, 2013 by Blue

[Dr. 240Z]

Hi Blue,

I just came in from the garage to find your pictures - Thanks so much.

Here's the good news: Changing the rheostat on an early 1971 Z is not a difficult procedure!!

Follow these steps:

1) Remove the driver's seat and place cushions in front of and behind the front of the seat support cross member for comfort.

2) Lay on your back and slide forward so that your head is up against the clutch and brake pedals.

3) Using your left hand, reach up and remove the two wing nuts that screw onto the two threaded posts which support the tachometer.

4) Carefully push the tachometer forward so as to remove it from the front of the dash.

5) Once it's out of the front, make a drawing of what wires go where in the rear of the tachometer.

6) Remove the wires and then remove the tachometer completely out of the way.

7) Using a stubby Philips screwdriver, reach through the hole in the dash for the tachometer and remove the two supporting screws that hold the rheostat in place.

8) Unplug the two wires to the rheostat and remove the plastic knob on the stem. Now remove the rheostat via the same hole as you used to access the two Philips screws.

9) Reverse steps 1 through 8 to install the new rheostat and re-install the tach.

Voila!!

Cheers,

George

[240260280z]

Excellent. I bet Escalon is smiling down on you!

[Mikes Z car]

Dr. 240Z,

Thanks for taking the time to write up what you did to get the rheostat out. I am probably the only one who is dying to know why it quit working.

Mike

[Dr. 240Z]

Hi Mike,

I think the failure of the original rheostat resulted from a form of burn out in the resistor coil. Note the coil in the old one does not extend to the nut in the 1:00 position. Secondly, the arm which slides over the coil as the control knob is turned was loose and not rotating properly.

Hopefully, Mike, the pictures will make up for my rather weak explanation.

Cheers,

George