The speedometer is acting weird but not in the usually way. Its not erratic and doesn't bounce. Every single part of it including the gauge are nearly new. Here is the problem. It has been working fine up until tonight. On my way home from the local Saturday night car show, it did something that makes me think it lost its calibration or something. I was driving along at about 60 or so mph about to get on the highway. I accelerated pretty quickly and the needle jumped up to over 80 mph really quickly. Then it read about 90 mph and I was barely passing people on the interstate. Its acting like its about 10 or so mph off at about 75 mph. What would cause this?

 

Chinese made speedometer?

My best guess.....

 

What does it read when your sitting still?

 

Mine does something similar. If I drop the hammer on the throttle the spedo shoots up faster then I'm actualy accelerating. It has to do with the magnet setup of a manual speedo. However once I get out of the throttle it will come right back to where it should be. Not sure what's up with yours....could be the chinese theory...

 

Mine does the same thing, it's a factory speedo and has never been touched as far as I know.

 

When stopped it reads 0.

I'm starting to wonder if it is a cheesy gauge.

 

It almost has to be, I have seen cables "wind up" and break loose causing a very temporary high speed reading, but your symptoms are not even close to what would happen in this case....

Other than the above mentioned winding cable, I cant think of anything other than a defective head unit that would cause the spedo to read high.

 

I did some more experimenting and the odometer is still accurate. I'm thinking maybe a spring or something has become weak or disconnected. Could that be?

 

Could be the plastic speed gear - teeth are worn. Pull cable out of trans and take a look.

 

I don't think this is a gear or cable issue since it reads high for long periods of time.

It is going (imo) to be an issue with the spedo itself....

"new" doesn't always mean "good"... Especially with many aftermarket parts these days...