409/409

My speedometer is 5 MPH slow at 65 according to my GPS. My odometer registers 100 miles for every 150 miles I travel. It seems the odometer is way slower than the speedometer. Would a speedometer gear correct this? If it wasn't for the GPS I'd still be trying to figure out why I was getting 8.5 MPG.

toobroketoretire

If your speedometer is 5 mph slow at 65 mph you'll need a driven gear that has one to two fewer teeth. By speeding up your speedometer your odometer will speed up an equal percentage.

409/409

The weird thing is the odometer is slower by a much larger percentage than the speedometer. At 65 mph on the gps you would travel 150 miles in 2.3 hours. If the odometer only registers 100 miles in 2.3 hours, the speedometer should show 43 or 44 mph to be off by the same percentage. Maybe I'm all wrong on the math. Sometimes I'm not too bright. Please correct me if I'm wrong.
Thanks