Speedometer question

[David Mac]

My old Speedometer worked okay except the odometer. I sourced another speedometer unit but the odometer wouldn't fit in mine (different manufacture I guess). So I installed the complete new one. The odometer works great now however the speed indicator reads maybe 10-12 MPH fast. How can I remedy this? the old one was accurate.

David Mac

[DonaldSmith]

If your odometer reads accurately, that is, 1.0 mile for each mile traveled, but your speedometer is off, your speedo needs to be adjusted by an expert. He can change the tension on the speedometer needle, assuming the bearings are OK.

If your odoometer reads "long" in the same percentage that your speedometer needle reads fast, the speedometer gear at the transmission needs to be changed, assuming you keep with the same tires and rear end ratio.

I had my speedo rebuilt, and the speedometer needle was set to the odometer. That's all that can be done at the speedometer. My odometer ran 10% long and the needle 10% high, checking with a GPS. There were no available speedometer gears to get what I needed, so I bouight a ratio changer on line, to reduce the reading by 10%. Typical percentages like 10% up or down are available on line. For other percentages, a speedo shop can set up the appropriate little gears in the ratio adapter.

I had to rework the transmission access panel and edge of the floor opening to accomodate the ratio adapter (It's a Clunk-o-matic), but the bump does not show under the carpet.

Now the speedometer is right on.

[David Mac]

Thanks Don, I will try testing the odometer first then to the other steps.

Your advice is appreciated

David Mac