smart51
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| posted on 15/12/07 at 08:37 PM |
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Cable speedo - how do you calibrate it?
My donor vehicle is a scooter. It has a very nice speedo in the instrument pack that I want to keep. The problem is that it is cable driven of the
front wheel, which I don't want to keep.
The front wheels for my 3 wheel project are much smaller (130/70-10 rather than 120/70-14). Also, my front wheels are off a mini but with the drive
shafts removed. How can I connect the cable drive and how can I change the speed? Any ideas?
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Bigheppy
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| posted on 15/12/07 at 09:17 PM |
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Watch out drunk on the keyboard
Is it reading fast or slow ?
if its fast you could drive slower. if its slow just go a bit faster
eaxmple taken from accoholic logik hic 
alcoholic, stupid boy Pike go stand in the corner 
[Edited on 15/12/07 by Bigheppy]
Sorry
[Edited on 15/12/07 by Bigheppy]
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rusty nuts
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| posted on 15/12/07 at 09:26 PM |
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Have had speedos recalibrated before by Speedy Cables. Wouldn't know if they can do yours? I think that some HGV tachograph service centers can
fit gears into the speedo cable to calibrate
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paulf
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| posted on 15/12/07 at 09:42 PM |
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Can you find a way to drive it from the back wheel?.Hilman imps had a speedo driven by a cable that went through the centre of the front wheel spindle
and that was driven by a drive dog in the bearing cap.
Paul.
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smart51
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| posted on 15/12/07 at 10:13 PM |
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The rear wheel is a different size again at 130/70-12. I'll look up speedy cables.
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onzarob
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| posted on 15/12/07 at 10:16 PM |
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quote:
Originally posted by paulf
Can you find a way to drive it from the back wheel?.Hilman imps had a speedo driven by a cable that went through the centre of the front wheel spindle
and that was driven by a drive dog in the bearing cap.
Paul.
You make it sound technical, its a square hole that the cable when through
But a great idea
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UncleFista
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| posted on 15/12/07 at 11:18 PM |
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Laterally thinking, how about printing your own (correctly calibrated) speedo dial ?
Should be cheap enough too
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
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JB
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| posted on 16/12/07 at 06:39 AM |
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Calibrating Your Own Speedo
I used to calibrate my own.
First you need to know how fast or slow it is reading. Drive down the road following someone you know is doing 30mph or use a sat nav. Note what your
speedo says, eg 50 mph.
Now back in the garage get an adjustable speed electric drill and run it so the speedo shows your reading at 30mph ie 50 mph. Now you have a
reference. All you have to do tweak the internals a bit at a time until the speedo shows 30mph at that drill speed.
Speedos have a magnet in them. To alter the reading you make the magnet weaker or stronger. I did this by stroking another magnet on it. Get it close
using this method then do final adjustment by tweaking the return spring.
Be warned it is a bit hit and miss ie knowing just how much to do, so do a little at a time. I wasted a few speedo heads experiemnting.
Alternatively just send it to Speedy Cables and it will come back spot on.
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smart51
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| posted on 16/12/07 at 09:28 AM |
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quote:
Originally posted by UncleFista
Laterally thinking, how about printing your own (correctly calibrated) speedo dial ?
OK, now that's a good idea. Does printing onto paper work or do I have to find somewhere that will print onto plastic?
[Edited on 16-12-2007 by smart51]
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JB
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| posted on 16/12/07 at 05:20 PM |
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quote:
Originally posted by smart51
quote:
Originally posted by UncleFista
Laterally thinking, how about printing your own (correctly calibrated) speedo dial ?
OK, now that's a good idea. Does printing onto paper work or do I have to find somewhere that will print onto plastic?
[Edited on 16-12-2007 by smart51]
We used dry transfer lettering commonly known as Letraset.
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smart51
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| posted on 17/12/07 at 08:03 PM |
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I've make up a new speedo fascia, rescales to match the 21% smaller wheels. Whilst I was at it, I swapped the major scale (km/h) with the minor
scale (MPH) to better suit British road. The reassembled instruments look nice. The new screen is attached.
Tightening up the last screw, feeling quite pleased with myself, I look at the odometer and my heart sinks. The new fascia doesn't correct the
odometer. Wereas it used to read in km, it will now record in 1.21 km steps or 0.75mile steps.
Is this a problem? I know they don't check it in MSVA, but is there a legal requirement for it to be right? It will either be 21% over or 25%
under the correct distance
edit: I've shrunk it to 1/8 size to fit on the screen, which makes some of the lines look wonky. At full res it looks fine.
[Edited on 17-12-2007 by smart51]
 
Rescued attachment speedo rescaled eighth size.JPG
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