Via Veloce by Wille R. www.veloce.se Internet since November 1995 and still here. alfa romeo spares
The speedometer, happy reading or true speed? The speedometer is notoriously known to be reading too high figures.
The same goes for the tacho as the main principals of the speedometer and
tachometer are essentially the same. Speeding too fast is not so popular
according to the law, so why don't you check your speedo. Besides,
imagine to drive with your 'spouse or girlfriend at 140 kph with the
speedo reading 110 kph! "Notice how cool and calm I'm driving,
eh?" What about new tires? Check how your speed will change with a different
tire option. The new tires you're looking for might perhaps have some
great effects on your speedo reading. If it turns out that you tire size
will lead to miss calculating the speed, it is quite easy to adjust a
mechanical instrument. Just follow the instructions below.
| When your speedometer indicates KM/H or MPH, you would be cruising at KM/H or MPH. |
There are also some other car manufacturers that have steel rims and wheels that will fit your 105 Alfa Romeo. It's all here.
In order to check the tachometer, use an electronic one to confirm the discrepancy. Electronic tachos are inexpensive and easy to install. I use one in the engine bay when I tune the engine.
The Roundtail spiders have different final ratios like any other Alfa Romeo. Check the table to find out your speed at 2.000 revs and then you may have to adjust your instrument. The figures are approx. naturally, so use your common sense. The tires have some influence too on the speed. The table shows the speed in 5th gear with the standard wheels. However, this does not effect the relationship between the engine revs and the speed.
| Model | Final ratio | Final ratio, metric | Approx. kph at 2.000 revsand 5th gear | Approx. mph at 2.000 revs and 5th gear |
| Duetto and 1600 GT |
9 / 41 | 4,55 | 66 kph | 41 Mph |
| 1750 Spider Veloce and GTV |
10 / 41 | 4,10 | 70 kph | 44 Mph |
| 1300 Spider and GT Junior |
9 / 41 | 4,55 | 59 kph | 37 Mph |
| 2000 Spider and GTV |
10 / 41 | 4,10 | 70 kph | 44 Mph |
| 1750 and 2000 Berlina |
10 / 43 | 4,30 | 68 kph | 43 Mph |
Assuming your tacho is reading correct, just cruse along at 2.000 revs in 5th gear and see if you need to increase or decrease the speedometer. When you have verified the discrepancy, go back to you garage and remove your speedo. There are two nuts to undo at the back of the instrument before you take the whole unit out from the dash.
This is how I do it. The procedure is for the Jaeger instruments, common on AR Spiders. I have however not tried this on Veglia Borlettis, but I assume that they are much alike. Then just cool down and turn on some good music like Duane Eddy or Jerry Lee Lewis.
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