Veglia rev. counter ratio convertion

steph

steph

Hero member
Location
Torgny, Belgium
Hi all,

Has anybody some experience in converting a Veglia rev. counter 4:1 to 3:1 ratio ??

Any help or comment would be appreciated.

Thanks

St?phane


 
I wasn't aware they came in ratios.

I've pulled a couple of cable driven apart and there is no direct mechanical link. They have a magnet that turns inside a windage cup.

Instrument techs can adjust the magnetic field to increase the effect. This works against a return spring and a balance is found to calibrate. Silicone grease is injected into the bearing to dampen any waving by the needle.

On a speedo there is a direct mechanical link to the counters but the needle works the same, magnet and windage cup. That's why the speed needle and the trip meter don't necessarily match.

That's my experience with them anyway.

Rod

 
Stephane,

It is possible, within limits.

As Rod has pointed out, the needle action is controlled by a spring.  This spring can be released at the solidly located end and re-located to give a stiffer action.  This in turn gets the "ratio" closer to the required 3:1.  I checked my instrument in my lathe, it now shows exactly 6000rpm at 2000 lathe rpm.  Effective rpm differs a bit below that figure, can't check at higher speeds, 2000 is top speed for my lathe!

piet
 
Thanks guys for your (very) useful comments.

To Piet

Thanks for checking on your lathe. :-)
If the 0-6000 rpm range is correct the 6000-7500 range should be correct too shouldn't it ?

RE "re-location" of the spring (I haven't opened the rev. counter yet ... don't know how ...) how do you proceed to point the right spring position to reach the ratio needed ?
Empirically ?

St?phane


 
Stephane,

Unfortunately, the range is not correct, only the reading at exactly 6000rpm.  Think the range is not too far off, though.  At least not enough to bother me.  Reckoned if it was OK at 6000, I wouldn't be doing too much wrong in the way of over-revving.  As the needle only begins to move at around 2000, there's not much range to begin with. :D

Once you remove the screw-on bezel and remove the works from the body, you will find a quite big but thin and delicate clock spring.  This is held at one end in a slotted peg.  You then release the spring from the peg and re-locate it, about 3-4 mm further up.  Check for accuracy at a given speed and repeat if necessary.

piet
 
sfcpiet said:
Once you remove the screw-on bezel and remove the works from the body,
Click to expand...

Thanks Piet.
I tried ...
Can't remove the body.
And I am afraid of damaging this beautiful piece of machinery.

It maybe could be more effective (or convenient, or appropriate, or whatever) to (re) make a proper rev. counter drive with the correct ratio ?
BTW what is rev. counter drive ratio ?
Somebody knows ?

Cheers,
St?phane




 

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Stock Laverda tach ratio is 3:1.

Exception is the 500 Formula which got a Veglia Competizione in the race kit plus the appropriate gearing.

piet
 
Steph said:
Hi all,

Has anybody some experience in converting a Veglia rev. counter 4:1 to 3:1 ratio ??

Any help or comment would be appreciated.

Thanks

St?phane
Click to expand...


Hi all

I have the same question than Steph but for the convertion between a ND Honda 750 Four and a ND Laverda

Thanks

Xavier
 
If anyone interested (Xavier ?).

The use of a gear ratio adapter (slow down 25%) seems cleaner for me.

-> http://www.clarkbrothers.net/ratio_adapters.html

S.
 
Steph said:
I tried ...
Can't remove the body.
And I am afraid of damaging this beautiful piece of machinery.
Click to expand...

Stephane,

Do you have a Competizione or just a normal Veglia?

If it's just a normal instrument, not much use messing around with it, terribly inaccurate.  Not worth the hassle imho!  Veglia = Vague Lie  :D

piet
 
If the bezel is a thin tinny bit simply crimped over the stamped sheet metal body, you've got the el cheapo...

Rev range and red line could be specified by the company that originally bought them for their bikes.

The Competizione has a screw on bezel with a cast(?) alloy body, much more sophisticated and worth the effort.

Post a piccie of the rear, easy to tell.

piet
 
Stephane,

Does yours look anything like this?  http://www.ebay.de/itm/200713320605?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2648

piet
 
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