I have a 73 small block automatic and the speedometer has a chatter at all speeds. Before I tackle getting behind the dash I was wondering if someone could suggest the most probable causes so I don't head in the wrong direction. Thanks
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Re: 73 Speedometer Chatter
This has come up several times and you'll find prior threads in the archives...
The symptoms could be from several problems.
(1) The tripometer hasn't been 'exercised' in a while and it's spring loaded reset hasn't fully returned causing sporadic 'drag'. Push the reset cable to its fully engaged upper position and see if the problem goes away. If so, remove the reset cable and give it a good lube job.
(2) The speedo cable lacks lubrication and/or is worn/chewed causing it to 'slip' as it rotates. Disconnect both ends of the speedo cable but LEAVE the outer sheath installed and remove the inner drive cable. Visually inspect each end of the cable for wear (are the corners 'chewed' or rounded?). If there's appreciable wear, measure the inner cable and go to your local auto parts store for a speedo repair kit of equal or greater length and make up a replacement inner cable.
Flush old, dried, lubricant out of the sheath and blow the inside dry with compressed air. Lubricate the replacement inner drive cable (lubricant is available at your auto parts store) and re-insert the cable into the sheath. Reconnect both ends and see if you achieved a 'fix'.
(3) The speedometer's 'head' is worn out. Yuk, that means pulling the speedo cluster (R&R instructions are in your copy of the '73 Chevrolet Chassis Service Manual) and having the speedometer repaired. You can do this in one of three ways:
(A) Take the speedo (or the whole car) to an authorized speedometer repair shop and let them turn-key the job for you. Hint: there were a LOT of AC-Delco/United Delco shops independently owned coast to coast and many are still in operation with the parts and calibration equipment necessary to do the job. Figure $50 + parts on average...
(B) Send the speedo cluster to an instrument service shop, you'll find several advertize in the NCRS Driveline magazine for an overhaul.
(C) Attempt the job yourself...some of the catalog parts houses sell replacement speedo heads for the do-it-yourself mechanic. -
Re: 73 Speedometer Chatter
Jack, Thanks so much. I had tried to check the archives but must have been using the wrong words "chatter" as I got zip. All of your suggestions sound great. I have a couple of questions. How does the trip odometer cable come out? Is it difficult? Also how about disconnecting the speedometer cable up on top, do I just need to unscrew the cable from the back of the speedometer or do I have to disconnect it and move it away from the back of the speedometer?Comment
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