Speedometer jumping around help

michiganpat said
mine does the same, and occasionally I get a horrendous noise from the speedometer itself, but it is very intermittent. the other things I've observed:

1) I don't see any jerkiness of the motion of the odometer, it is smooth in operation
2) the Odometer reads about 3% low. on a trip last weekend, I observed the odometer and compared it to the mile markers on the interstate. 33 miles on the interstate registered 32 miles on the odometer.
3) the Speedometer reads a little more than 10% high. comparing to a GPS app on my phone, 60mph indicated in the car registers 54 mph on the GPS app, 67-68 in the car is 60mph road speed according to the GPS app, 80MPH in the car is 71-72 according to GPS, etc....

I could understand if the speedometer and odometer were off by the same amount (both 10% high, both 3% low), since they aren't, I'm assuming the issue isn't the cable, but the speedometer itself. does anyone have any advice on how to lube/correct the speedo to remedy this?

I can't answer all of your questions, but I can give you something to go on.

Before trying to make any corrections to the speedometer or odometer, be sure you're running the size tires you want. If your plans include a taller or shorter rear tire, any corrective measures you take will be undone when you change sizes.

Speedos can be lubed. That might take care of your noise, but the problem could be terminal. I believe you have a later car, and I'm only familiar with Rallye dashes, so use the search function to get specifics on how to lube your speedo.

Your speedo reading high problem can probably be addressed by changing the speedometer pinion gear to one with one or two more teeth. Take yours out, count the teeth, and put up a "Wanted" ad here for one with more teeth. You'll probably get a response pretty quickly. If not, there are Ebay sellers and reproductions available. Again, be sure you have the tires you want on the car before doing this.

Unless you're rallying and must use the odometer in the car, I wouldn't worry unless it's off by a lot. To me it's more important to have an accurate speedometer.