Instrument Voltage Regulator

-
bbeep71 said:
I have a 66 Barracuda. Is the instrument regulator inside the gas gauge or on the back of the panel.
Thanks
Click to expand...


The factory instrument current regulator for my 66 Barracuda is in the Gas Gauge (I assume they are all this way). See the picture below. The regulator is the bi-metalic strip with heat wire to the left. This system works fine for many years (as witnessed by our old cars still working). What happens is that the heat wire wears out and breaks, then the bi-metalic strip does not open the points and the full 12 volts goes to the gauges and fries them. To disable this current limiter, you have to open the fuel gauge by drilling out one of the rivets and rotate the face around (with care not to bend the needle). Then you have to bend this bi-metalic strip so the points do not make contact. Then add an aftermarket current regulator to your instrument panel.

If any of this is incorrect, please chime in.

66Cuda-S

View attachment DSCN4240a.jpg
 
While I am in there I am planning on replacing the bulbs. Some have burned out. I found these on eBay but the service manual seems to list 158. The problem is I can't find anything that seems to relate to a 158 bulb. Are the ones in the eBay add correct or am I missing something?
 
jhdeval said:
Just like that. Thank you very much. Any thoughts on why my speedo isn't working? I understand the premise behind how it is supposed to work but I can't find any way to test that the speedo cable is doing its job.
Click to expand...

Should probably be a new thread so people can find it. What I found in my 65 Newport was that the bore had worn so much that the spinning magnet wobbled and caught the aluminum cup that carries the needle. Fortunately, the cup twisted but didn't break, so I was able to salvage it. The cable broke.

Since it broke at the gage, I was able to pull it out and feed a replacement down. You can feel when the square tip engages at the tranny end because it won't spin anymore. Cut it to length (one chance), put the square tip on and crimp it using the tool in the kit w/ pliers, then lube the cable w/ the special lube (oil & graphite) you can buy at most auto parts.

However, you must fix the wobbling magnet or your cup will break next time. I tried adding a bronze bushing, but without the tools gave up. I sent just the small magnet assembly to a speedometer shop in Bakerfield and they fixed it better than new, because original was a steel shaft spinning in an aluminum hole and the bronze bushing is oil-impregnated. I haven't seen a wobble since. Pre-internet days (>15 yrs ago), so easier today to find a place.

If you see your speedometer needle starts pulsing at low speed, better fix the magnet soon. That started in my 82 Aries and I found an even worse design. The spinning magnet was held in a plastic cup that had cracked. I wrapped sewing thread around the cup and used plastic epoxy. Fixed it and held many years until I junked the car since a blown head gasket and failed paint. Later cars dropped the analog spinning magnet for electronic sensors (mid-90's?). Great, but when those dashes fail, major expense.

To test your cable, the easiest way is to disconnect at the dash an place where you can see the end while you drive slowly. Hold it slightly to insure it turns against resistance. Easier than disconnecting the transmission end (most cars).
 
Just to add another note to the speedo cable thread, if you take the old cable out of the housing, clean the housing inside and out with spray carb cleaner or brake clean. When you get ready to put the cable back in the housing, put some good bearing grease in the palm of your hand and as you put the cable in the housing let it run through the grease.

Demonracer
 
Demonracer said:
Just to add another note to the speedo cable thread, if you take the old cable out of the housing, clean the housing inside and out with spray carb cleaner or brake clean. When you get ready to put the cable back in the housing, put some good bearing grease in the palm of your hand and as you put the cable in the housing let it run through the grease.

Demonracer
Click to expand...

Whaaat???. And get my hands all greasy! Yuck!!

Just kidding, Demonracer nailed it. I would only add this: Be extra cautious with carb and/or brake clean. Don't even THINK of spraying that stuff in a closed car!!! And, either one will eat any paint it contacts!

And it should be a separate thread. Moderator??
 
Well I found my issue with the speedo I think. I got frustrated the first time and pulled the cable from inside out a bit the other day when I took the cluster out again I pushed and it clicked back in place. There is bad news though I believe my instrument panel is shot. I used the diagram to get five volts and I am still getting nothing on the gauges I know the sender for the gas tank is working though. I get five volts out the back. So I guess now the question is anybody have a suggestion for a replacement either new or original (preferred)?
 
Like someone posted before, if the Instrument Voltage Regulator points don't open, the downstream gauges (Gas, Temp, & oil pressure (if present) get the full 12 volts. They then get "fried" (though _baked_ seems like a more accurate description). But first, have you tested the individual gauges? Take 'em out of the cluster and check the resistance across the "I" and "S" terminals. If there's a resistance reading in the neighborhood of 20 Ohms, the gauges should be OK - if no reading, baked gauges.

If you can use a digital volt meter, and test under power and load conditions the _DC Volts_ reading on the "A" terminals on the gas and temperature gauges should be all over the place as the points open and close.

I hope that helps!

ATB BC
 
The more I study this the more I am thinking it would be better to send my gauge to you.
 
RedFish said:
When you open your fuel gauge would you please post a pic in this thread like the one shown above ? TIA
Click to expand...


Found these posts, I am considering sending my gauge to you. Send me info on how you want to get paid to do the job, ie paypal, check etc.
 
You must log in or register to reply here.
-

Back
Top