Speedo and rev counter calibration

[@mads501010]

Den her video kommer som kaldet, tak for det

[@jaggass]

What a brilliant idea of using a high speed drill to power the speedo.

[@rbrtcrowther]

Many thanks for this excellent video. . I've just changed the differential ratio in my land rover. And you've just confirmed my theory on how to calibrate my speedometer. . Many thanks

[@cryptoex5820]

lovely vintage car , i love it

[@srlane61]

Beautiful work Per, your dashboard looks perfect. What are the actual adjustments to the spiral spring? the two screws, left and right, what do they do? Did you just "play" with the screws until you understood it? Or can you explain how to adjust them? But otherwise, I get it! so you love it.

[@tomview1]

Two pieces of information required to do this accurately, the rpm of the drill/drive mechanism and the the calibration figure for the instrument. Veglia/Alfa Romeo typically 1000 turns to the kilometre - there speedo should read 60 kph at 1000 rpm. 1000 rpm = 1 kilometre per minute or 60 kph. Having a variable speed drive allows you to shack accuracy throughout the range of the instrument. In the instrument repair trade Veglias are often referred to as "Vague Liars".

[@srlane61]

Thanks Tom, it's the tachometer I'm trying to calibrate - on the rear it says 1:4 - so the tacho drive on the engine divides by 4 and the gauge re-multiplies. There is no "typical" ratio for the speedo - that all depends on the diff ratio - so the speedo drive in the gearbox needs to match the diff - without doing that you'll be miles off. The tacho works exactly like the speedo - I had the same issue as Per - adjusted the "offset" by removing the needle and replacing - but I have the issue he was worried about - non-linearity, so I think I need someone who understands how to make/replace the spiral springs - I know I don't.

[@tomview1]

Richard Lane The engine will have a 2:1 drive coming from the camshaft drive (already 2:1) so 4:1 being crankshaft to tacho ratio. You don't need to replace the hairspring to calibrate the tacho - You only need a calibrated drive source. To reduce the indicated rpms shorten the hairspring, to increase the indicated rpms remove the hairspring and acid/etch it - I used nitric acid. Speedo the same as you said, how ever the calibration figure will almost certainly be 1000 turns to the kilometre. This is normal for Veglia, it is far simpler to have a changeable worm drive on the transmission than to change the odometer drive assembly for different vehicles. This is an industry standard throughout the world. Excepting England where Smiths was the predominant instrument maker, they used an eccentric cam drive for their odometers allowing for calibration changes by simply changing one component.(Only the British would do this) I have repaired many speedos from many different vehicles, I am an instrument repairer. These figures are very common. Euro cars - 1000 turns per kilometer USA and Australian - 1000 turns per mile OR 625 turns per kilometer (Same speedo, different dial and odo drive) Japanese 637 turns per kilometre OR 1020 turns per mile (Older vehicles) British.... Read the number on the speedo dial 1437/mile 1600/mile 1281/mile... stupid poms. These figures also correspond with electronic speedo calibration for vehicles with Hall Effect senders.

[@TornadoCAN99]

Looks like a decent way to get the gauges more accurate. I need to do this to my classic Mini Cooper as the engine speedo drive mechanism does not match the gauge in the dash. Gauge reads about 10-12% too slow. Makes it hard to avoid speeding tickets. Folks were telling me I need to have a proper drive gear installed in the engine drive. This is a very difficult/costly thing to do. I'll be trying your method. But I guess it will not correct the odometer accuracy...not so important I guess.

[@tortron]

Maybe not in your case, but many motorcycles read too high, but the odometer is correct

[@vwkenart]

I'm confused lol I have a vw 1969 vw bus and the speedo reads 20mph when I'm actually doing 74mph so how would I adjust it

[@Giancarlo1991CCCCCCC]

Why they have old odometers only 5 digits? (99.999 mph max)

[@brandonrobishaw7606]

Miles driven not miles per hour. Simply you were expected to purchase a new vehicle at or before that point.