Speedometer gear - wrong speed

Merc Cruzer

Merc Cruzer

Well-known member
I have a 1953 Merc with a Merc-O-Matic. The speedometer is showing 5 mph slower that I am going. It has a 20 tooth speedometer gear in it currently. Do I need to go to a 21 or 19 to correct the reading?
 
Unless you changed something it probably means your speedometer needs to be repaired. If you changed your rear end ratio you need to change the gear.

Charlie Stephens
 
Merc, I did exactly what you are thinking then the speedo read the other way......go figure !!!!!!!!!! Maybe Charlie's right....
 
Walter:

I just checked with a local Speedo shop and he confirmed that I need to reduce the number of teeth.....however he did say that at 50 mph each tooth is worth 5% = 2 1/2 mph. I checked the parts book and it does show that an 18 tooth gear was made, but the lowest one being made today is 19, so looks like it will be the 19 tooth gear. I feel the reason for the change in the reading is the tires...went to radials....so they are not the same radius. Had to do this same thing on my wife’s 70 Cougar XR-7 when we restored it and change the tires and rims. Thank you
 
I found a listing in my Sacramento Vintage Ford Catalog on page 400. It lists 18-19 teeth. The 18 is part # 587-18 and cost $12.95. The phone number is 916-853-2244.
 
Hello merc Cruzer I have a 53 that will be junked out wendsday. I have not removed inside stuff like switches or clock other stuff. I also have skirts in good shape not for sale just shiping cost also have, two merc O matics.If parts are needed I have them.
 
Hughes:

Called Sacramento Vintage Ford and was ready to order the part (by the way I did order the catalog) and they informed me that it is for a Model A 28'-31' and would not work in may 53' Merc...so it's back to the 19 tooth gear that I can get locally..thanks for the tip

 
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