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Noisy Speedometer 39 Century


John R Murray
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I bought my 39 Century last fall and it has been running well. With the start of cold weather, however, once the speed reaches about 35 mph, the needle buries and a loud whirring sound starts. I would appreciate any suggestions for eliminating that short of disconnecting the speedo cable.

Thanks in advance - John

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Welcome aboard John.

I'm not sure what you mean by "buries".

I'd pull the speedo cable and check the inner cable is not dry and or broken. It may just need a clean and a lube.

I have some AC Speedo manuals I can email if you decide to pull the instruments.

Danny

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I would suspect that removal, lubrication, and reinstallation of the cable would solve your problem. If not, I recently wrote a repair/maintenance article on solving a problem with my 1937 Buick Speedometer. I would be happy to send you that if you would like. I don't have any experience with 1939 Buick Speedometers but would suspect that they are similar.

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Danny, thanks. The speedometer needle goes all the way to the high end and stays there until I slow down to 10 mph or so. Once the car gets good and warm inside, the problem goes away again. Since it can function normally under warm conditions, I was assuming there was something in the mechanism itself, but it certainly can hurt to pull the cable..

Yes, please send me the manuals. Much appreciated.

John

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I've also found that a drop or 2 of WD-40 in the back of the needle works helps too but that involves dismantling the instrument cluster and a little care.

(The original lubricant in there goes off after 70+ years)

This can often lead to other problems like wanting to clean the glass which results in loss of numbering....... Ask us here how we know that :)

It only takes a poofteenth of sticktion to make the needle go erratic.

Danny

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I would suspect that removal, lubrication, and reinstallation of the cable would solve your problem. If not, I recently wrote a repair/maintenance article on solving a problem with my 1937 Buick Speedometer. I would be happy to send you that if you would like. I don't have any experience with 1939 Buick Speedometers but would suspect that they are similar.

Matthew, that article could be very helpful, so please send it and thanks for the prompt response.

John

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John,

I had the same problem.

Cold weather "buried the needle" at anything over 30MPH.

I pulled the speedo, and found that the cable had pumped the thing full of grease.

It is wound to pump lube up the line, and I had over lubed it a year ago.

Disassembly is not at all difficult, and you will find that there is a cup in the back that the 2 magnets attached to the drive cable rotate around.

I pulled them off the drum and cleaned the assembly with MEK to get the grease out from between them and the drum.

Lubed the various pins with 3 in 1 oil and stuck her back together.

Toughest part was laying on the brake pedal. A couple of bath towels made it more comfortable.

Wish I had taken pic's

Best of luck,

Mike in snowy Colorado

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