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| | | | Joined: Nov 2010 Posts: 339 Shop Shark | | Shop Shark Joined: Nov 2010 Posts: 339 | Does the speedometer drive just screw into the SM420, if so does it come out easy? I have a speedometer that jumps around a lot but I think its the speedo head itself. but thought I would check the gears on the drive to make sure. 53 3100 root | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | There is a gear that can be unscrewed from the case of the transmission (to inspect the teeth). There is a gear inside the rear of the transmission and it cannot be removed without removing the u-joint yoke at the rear of the transmission. | | | | | Joined: Oct 2010 Posts: 202 'Bolter | | 'Bolter Joined: Oct 2010 Posts: 202 | It does on the SM420 on my 54 3100.
Checking the gears is a good idea. I had to use a deep thin walled socket to remove the speedometer cable drive. The other gear is held in place by the u-joint yoke. Speedometer gears rarely wear out though. The problem your having is more likely a wore out speedometer head, as was the case on my truck, or it could be the drive cable. Jim Carter Truck has refurbished original speedometer heads. I would avoid the Chinese reproductions. they also have the cables.
Walt Williams
| | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | Well Walt, I think you've miss understood what Tim replied. The 'drive gear' is pressed on to the yoke or U-joint flange and can only be removed by removing the yoke and pressing the drive gear off. http://www.pbase.com/dennygraham/image/148876672If your's slips on and off the flange then something is worn. If it were not a press fit, what would keep it from slipping on the flange when in motion? So....I believe you're thinking of the 'driven gear' which can be easily removed with a 15/16" box wrench. http://www.pbase.com/dennygraham/image/160677688dg
Denny G
Sandwich, IL
| | | | | Joined: Nov 2010 Posts: 339 Shop Shark | | Shop Shark Joined: Nov 2010 Posts: 339 | My bad, yes it is the driven gear. I will remove and check it out for damage. Thanks y'all. root | | |
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