1961 Newport Astro Dome speedometer gone beserk .

Bucket

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I took my 61 Newport on a 400km round trip the other day .
Before this i had installed a new speedo cable which i lubed .
The speedo had been running smooth for a couple of weeks before this .
On the way down i noticed a ticking noise from the dash area.
On the way back this turned into a loud sort of grating noise and the needle was going beserk .It was going from 60 right up to 120 and and jerking all over the place .
When i parked the car the needle stayed around 25 .
I took the cable off the back of the speedo and when i spun the gear with my fingers , sometimes it would rest back at 0 , sometimes it would stay around 50 .
I will say this car had sat for around 7 years before i got it on the road about 1 month ago .
I still have the original cable outer.
One thing i did notice on the original cable , is the cup that screws onto the back of the speedo is deeper than the cup on the aftermarket cable .
Could the gear on the speedo have been rubbing on the cable inner because of this difference in depth ?
Is there a way to fix my speedo so the needle runs smooth ?
Cheers,
Greg
 

CBODY67

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If you heard a metallic grating noise, then the bushings in which the speed cups turn might be worn enough that they are touching, which they should not be doing.

The rear speed cup has the magnet in it, which moves the front speed cup (to which the speedometer needle is attached to) to indicate speed. The odometer runs off a plastic gears turned by the speedo cable itself, directly. A clockspring around the speedo needle spindle returns the needle back to "0".

During the 1990s, we had similar issues with the later 1970s+ squarebody GM pickups. The rear bushing (plastic, in this case) would allow the rear speed cup to get out of alignment and start to touch the front speed cup, causing the needle to swing wildly and make noise. We'd take then to a speedo shop which would rebuild them with bronze bushings, for longer life. No big deal, as it turned out. Was about $60.00 USD back then, IIRC.

Now, to find a speedo shop that has the necessary bushings to do the deal . . .

Just some thoughts and experiences,
CBODY67
 

saforwardlook

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I would suggest contacting JC Auto Restoration in Lynwood, WA.

He specializes in restoration of the Astradome instrument clusters:

Home - JC Auto Restoration, Inc.

His shop is on limited hours during the covid issues so it may take a couple tries to get hold of him currently I understand, but he is far and away your best resource in matters concerning these clusters. They are known for their issues such as you are experiencing and not usually straightforward for fixing them. I haven't had such issues yet because my vehicles with those clusters are still pretty low miles.
 

Bucket

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Thanks for the responses .
There is a business down here in Australia that does the same work as JC , i will try them first being as our dollar is crap at the moment , plus the shipping involved .
If not i will give JC a call .
At least i know what i should be looking at now .
 
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