speedo calibration

having just stripped & cleaned my speedo I'm at the point where I need to calibrate it. Now -- I have a piller drill with the following speeds, 3830, 2290, 1430, 890, & 530. what I need is someone far cleverer than me to tell me what speeds I should see on the speedo when i connect via a cable to the drll

over to you :twisted: :twisted:
Terry

How did you calibrate your drill? :lol:

pvisseriii said:

How did you calibrate your drill? :lol:

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With a certified, calibrated tachometer :wink:

Myford said:

I have a piller drill with the following speeds, 3830, 2290, 1430, 890, & 530. what I need is someone far cleverer than me to tell me what speeds I should see on the speedo when i connect via a cable to the drll

Click to expand...

I hope your pillar drill has a reverse setting?

I make it:

Cable RPM/MPH

530 = 31.8
890 = 53.4
1430 = 85.8
2290 = 137.4
3830 = 229.8 :shock:

Anyone disagree?

Tyre size to complete calculation?

Thanks Les,
Reverse setting? B*gger! never thought of that
However we do have a reversable 3 phase beast at work but will need re calculating speeds.
a five year old could run rings round me at maths, but I can drive a calculator. If you could spell out the formula in idiot terms I'm sure I'll work it out.
Keith, I didn't say in my first post but its running on standard 19" tyres so there shouldn't need to be any correction factors, yes?
Also before I box it up, the only part I oiled was the main input bush, I considered oiling the pin/pintle bearing where the pointer shaft sits in the centre of the magnet, but decided against it. anyone whose stripped one got any thoughts?
Terry

The "1000" marked at the bottom of the dial near the instrument number signifies 1000 cable turns per mile.

At 1000 cable turns per minute the speedo should (theoretically) be registering a reading of 1 mile per minute, or = 60 MPH.

So, if 60 MPH = 1000 cable RPM, then 1 MPH = 16.666 cable RPM (1000 divided by 60) therefore: 10 MPH = 166.666 cable RPM, 20 MPH = 333.333 cable RPM, 30 MPH = 500 RPM,...etc.....

Myford said:

I didn't say in my first post but its running on standard 19" tyres so there shouldn't need to be any correction factors, yes?

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If the speedo was calibrated as detailed above, then I calculate that a 4.10 x 19 TT100 would result in the speedo reading approximately 2%-3% slow.

Also before I box it up, the only part I oiled was the main input bush, I considered oiling the pin/pintle bearing where the pointer shaft sits in the centre of the magnet, but decided against it. anyone whose stripped one got any thoughts?

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Maybe a very light oil (3 in 1?) That is what I used on my Veglia. Not sure if yours is a Smiths or Veglia but on the latter the shaft bush/insert can loosen in the cup and consequently it rotates but the cup lags behind and eventually slips totally at higher revs. I had mine originally checked by Speedo repairs in Frimley and he calibrated at 70mph. That's as good as it gets with Veglias and mine is high at 30 mph (33 reading) and underreads 2-3% from 80 onwards. All you can do is remove and refit the needle on these.

Thanks for the idiot guide Les, even I can grasp it.
Keith, thanks for the tips, is Frimley Mr Pople? If mine goes completly tits up I can always pour the bits in a bag & send it to him :lol:
Terry