My speedo died on the way home. Before it died it read perfectly. When I got home I started to replace the components. I thought that it might be the cable, so I replaced it. That wasn't it. Next, I pulled the housing holding the speedo gear. I was checking it out to see if that was mutalated or broken, or something. There was nothing wrong with that so I did not replace it. I then was just looking around and looked inside the tailshaft and saw that the speedo gear on the output shaft was moving around. It turned out that the gear was cracked and that is why it was not latched onto the output shaft. I then took off the tailshaft and everything assosiated with it, then replaced the gear. It is the same one that I took off.
After I put it all back together, I took it for a drive and my parents were in their car. It should read correctly because the cable and the gear that I replaced were identical to the ones I took off, right?

WRONG, it does not read right. It's about 15 MPH too slow. For example, going 45 MPH the speedo read 30 MPH.

Is there something in the speedometer itself that needs to be adjusted before you put the cable back in?

My dad was thinking that the speedo might be set at negative 15 MPH and not zero. It also gives a reading between the trip button and the dot that means zero MPH. I was going about 5 MPH or more(estimated) before it got to zero.

I also have 3.23 rear gears, a 15 tooth green gear on the output shaft, and I believe a 38 or 36 blue speedo gear(I can't remember off the top of my head and I didn't write it down.)
My transmission was also replaced in March, and it read just fine.

I know for a fact that the gear I put on is set right on the output shaft. Is there a possibility that the speedo gear is not set right?

I have not been able to talk to a mechanic or the parts guy(who is a tranny guy) because I did not get home until after they closed.

Thanks,
Jesse



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85 Z28, 305 TPI A4
pretty stock with a few toys
15.2@91mph
http://photos.yahoo.com/j_hougnon

http://screamindeamin.cz28.com/images/jesse/

 

doens't anybody know????

 

OBZ,

You'll either need to remove the speedometer and repair it (or have it repaired) or install a replacement speedometer. What likely happened is when the tailshaft gear broke the speedo cable was driven backward violently and may have slipped the magnetic cup on the indicator shaft in the speedo head. It's not terribley difficult to remove the speedo, or to repair the unit and re-zero it, but it can be time consuming and delicate work.

The obvious advantage to repairing your speedo is that the odometer will be correct (or very close) to the actual mileage of the vehicle. A replacement speedo can be preset to the same mileage as the existing spedometer, but it is almost as delicate as repairing the existing unit.

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Later,
Vader
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"Let the bodies hit the floor!"
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