# Speedo issues: 66 GTO



## 1qwik99 (Mar 12, 2012)

66 GTO. Speedo needle dances from 0-20 mph. It's good from 20-70 mph, then dances after that. Is that a lubrication issue or a calibration issue? installed new cable a couple of years ago, no change. Do you use graphite to lube the thing?
Thanks


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## Indecision (Oct 24, 2010)

Curious about this as well.. I have similar bouncing issues though it's more consistent across the speed ranges. Especially in the 50-70 region... I notice it's significantly worse when it's cold out.


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## Lemans guy (Oct 14, 2014)

The plastic speedo gears in the trans can make your needle act up. They are an easy change and inexpensive, you just have to get under there. Make sure you match the plastic gears to your rear end ratio and trans.. I had some mismatched plastic hers and the speedo did just that, did not move until I got to twenty then jumped up. The gears were wrong.

These are little plastic gears, the and cost 15 to 20 dollars. Something to check and consider.


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## geeteeohguy (Feb 2, 2008)

Usually, the bouncing needle is in the speedo head itself, due to dried out 50 year old lube. Remember, these cars were expected to last about 8 years, not 48! Peter Serio is the Pontiac gauge guru and rebuilder, and a great guy. He can be contacted on the now Ames forums. It could be a cable or drive gear, as mentioned, as well, but not as likely. Good luck.


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## Matthew (Feb 11, 2011)

I think if you do a internet search on the subject, you will find the cable is most common problem with a bouncing needle. Since it is very easy to check the cable, I would certainly recommend starting there before pulling your speedometer. Disconnect the cable from the trans, pull the cable out of the housing and check for wear. Clean, lubricate and re-install. If it does not fix the problem, move on to the more complicated stuff. Matt


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## geeteeohguy (Feb 2, 2008)

Matt, OP stated that a new cable didn't change anything. Bounced before and after........


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## Matthew (Feb 11, 2011)

Right. He may have a hard bend in it that is binding. Pulling the cable out of the housing may reveal wear. If nothing else, he gets one more shot at lubrication. Pulling that speedometer should be the last step.


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## Goat Roper (Oct 28, 2014)

Mine was doing the same thing and the guy that was in there before me routed the housing wrong under the dash.
I moved it to it to the other side of the column and that fixed it.
He also installed the new heater control cable upside down and it was also binding, he made removing the control easy though by only reinstalling two of the four speed nuts.
Damn tight under the dash with factory air so I had to remove the ducts and that exposed the rest of the hackery.
What a can of worms, at this point I just removed the dash and started at the top with a new speaker and worked my way down.


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## geeteeohguy (Feb 2, 2008)

I agree with you guys that it's super tight and no fun under the dash....and I would exhaust every other option before pulling the cluster!! Good point!


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