Speedometer question

[xspike77x]

So I picked up this speedo gear and gauge. It will fit a 5/8" axle so I would like to try and put it on my Bonanza build or Superbronc. Both parts are a CEV. I don't know much about these so would I be correct if I am figuring that these were made to work accurately with only a certain wheel size? Is there any way to adjust these to make them work with different wheel sizes? Logically I would think that they are set with a certain ratio and are therefore for only a certain wheel size. Additionally, is there any chance anyone would know what this was originally used for? How I can determine what wheel size it would work correctly on? (without trial and error that is). Both are NOS parts too.

 

[Clyde]

I would START your quest by:
-One revolution of your sending unit will equal a fraction of a mile on your speedometer/odometer gauge.
SO------------------------

#1) accurately measure - exactly how many revolutions of the sending unit lever (on the little grey gearbox) will equal 1/10ths of a "mile" registered on your odometer.

Turn it by hand , or battery drill, or whatever; slowly and count exactly the revolutions it makes UNTIL it reaches a good 1/10ths "mile" measuring point on the odometer.

#2) That ratio of "complete turns" of the lever to one mile on the odometer , will tell you the math of the gears, and thus let you latter find the tire diameter (or tire circumference) the unit was set-up for.

Looks like you will need a speedometer cable to attach the sending unit to the gauge?

 

[xspike77x]

That is an excellent suggestion, thank you. I appreciate it.

 

[Clyde]

A note:
Once you get an idea of the "tire size" that the speedometer was made for (I'm just guessing it's maybe for a bicycle/moped and may be a common 26" tire????:shrug, forget diddling with the speedometer part, because the odometer is normally the root of all the workings.
{odometers in those were often closer to accurate than the speedometer part cause the speedo's could have a weird spinning dial "thing" )

 

[Fat Boy]

Looks like the one on my 1972 Coleman 5.30 with 3/4 inch axle 10 inch wheels and I have several like it on my Broncco's and other bikes with speedometers that I have . They most always have a number or gear ratio stamped in the brass end or in the aluminum somewhere . they work pretty well but they like to stick and snap the piece that goes around with the wheel .

 

[Clyde]

@ Fatboy:
WOW ,that ID sure makes my guesswork Obsolete !
Your answer sure puts xspike77x speedo closer to use than my workaround for an "unknown".
:bowdown:

 

[The Restore Kid]

I don't know about changing the (odometer) part to ever be acurate without the right size wheel.. But when I built my Suicycle, the speedo that BELONGS to the wheel was wayyyy off.. 20 mph would show like 50.. :doah: So I kept removing slightly more, and slightly more of the coil spring running the needle, then mae my own face, worked good for about two weeks, then the cable broke.. :glare:

 

[roccosbike]

I have a whole set up like that brand new for a motobecane... its for a 23" wheel

 

[The Restore Kid]

I have a whole set up like that brand new for a motobecane... its for a 23" wheel

what do ya want for it? :mellow: How long is the cable?.. OPE!!! :lol: I should probably give Spike first dibs at it huh? :laugh:

 

[xspike77x]

Well the gear for sure fits a 5/8" axle. So there is a number stamped onto a brass part of the gear and that number is 372, no idea what that means.

Then there is a number on the back of the speedometer head, looks like an ink stamp of some kind, and that is 6-72.

I was thinking of the turning by hand approach and I don't think that will work because the odometer does not have tenths of a mile, additionally, it will turn so slowly, how do I know when it is officially at 1 mile?

Yes, I do need to get a cable. I know where to get one, need to figure out if I am going to proceed with this or not though first.

 

[roccosbike]

The speedo I have is a Huret...the cable is 23".Its made for a motobecane scooter with 23" wheels...Speedo go's from 0-80 MPH and has a hole in the housing to install a push in light to backlight the speedo.I bought it for my scwinnbike but ended using a honda SL100 front wheel and speedo.