The Ford Barn

jack wingard · 04-07-2020, 08:33 AM

New to Model A's. My speedometer is bouncy, sometimes it is steady but most time not. Is this normal?, or is there a problem. Thanks in advance.

rotorwrench · 04-07-2020, 08:56 AM

It could be a cable that is kinked causing some drag and twisting or it could be a problem with the bearings in the speedometer. If the drag cup is catching on the magnet rotor then it will cause your symptoms. The magnet rotor has to spin inside the drag cup without any contact and loose bearings can cause contact.

jack wingard · 04-07-2020, 09:31 AM

It's a floating kind of bounce it does not jerk as if there is a kink

katy · 04-07-2020, 10:22 AM

The first thing I would di is clean and regrease the speedometer cable (inside the housing).

Mark in MT · 04-07-2020, 10:54 AM

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Some times the speedo head will be stiff enough so that it winds up the cable like a torsional spring, then releases. This causes the speedometer to bounce or hunt and seek. Pull the head out of the dash, the input should turn easily with the tips of your fingers, if it doesn't, it is too tight. The tightness is usually caused by dry grease and swelling of the speedometer housing. The grease that the factory put in there 90 years has turned to rock.

04-07-2020, 08:33 AM	#1
jack wingard Senior Member Join Date: Oct 2019 Location: Stoneboro PA Posts: 120	1929 Sport Coupe speedmometer New to Model A's. My speedometer is bouncy, sometimes it is steady but most time not. Is this normal?, or is there a problem. Thanks in advance.

04-07-2020, 08:56 AM	#2
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,426	Re: 1929 Sport Coupe speedmometer It could be a cable that is kinked causing some drag and twisting or it could be a problem with the bearings in the speedometer. If the drag cup is catching on the magnet rotor then it will cause your symptoms. The magnet rotor has to spin inside the drag cup without any contact and loose bearings can cause contact. Last edited by rotorwrench; 04-07-2020 at 10:10 AM.

04-07-2020, 09:31 AM	#3
jack wingard Senior Member Join Date: Oct 2019 Location: Stoneboro PA Posts: 120	Re: 1929 Sport Coupe speedmometer It's a floating kind of bounce it does not jerk as if there is a kink

04-07-2020, 10:22 AM	#4
katy Senior Member Join Date: Jun 2015 Location: Red Deer, Alberta Posts: 5,043	Re: 1929 Sport Coupe speedmometer The first thing I would di is clean and regrease the speedometer cable (inside the housing). __________________ If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn!

04-07-2020, 10:54 AM	#5
Mark in MT Senior Member Join Date: May 2010 Location: Western MT Posts: 218	Re: 1929 Sport Coupe speedmometer Sponsored Links (Register now to hide all advertisements) Some times the speedo head will be stiff enough so that it winds up the cable like a torsional spring, then releases. This causes the speedometer to bounce or hunt and seek. Pull the head out of the dash, the input should turn easily with the tips of your fingers, if it doesn't, it is too tight. The tightness is usually caused by dry grease and swelling of the speedometer housing. The grease that the factory put in there 90 years has turned to rock. __________________ Mark in MT Always looking for another opportunity to be wrong.