Bench test speedo

Status
Not open for further replies.
htown16

htown16

VIP MEMBER
Joined
Apr 29, 2009
Messages
1,483
Country flag
New start up and speedo is not working. I'd like to bench test it but can't remember which way to set drill to turn. Clockwise or anti clockwise?
 
Turn your rear wheel forward and view which direction the Speedo cable rotates. It is a good test to see if it is the Speedo gearbox is the problem and not the Speedo.
 
Try both directions until you get needle movement. Shouldn't actually do any harm as there is no mechanical connection between rotating cable and needle mechanism...it is magnetically coupled and we can turn rear wheel backwards without harming speedo (or tacho if engine is rotated backwards).
 
Turning the speedo input opposite the direction it should go won't hurt it at slow speed, like rolling the bike backwards, but not a good idea any faster than that. It'll stress the coil spring (hairspring) rotating it the wrong direction. And yes, the speedometer input is counter clockwise. Run the drill in reverse. Good idea running it off the tach cable, but don't rev it very high.
 
Arthur Gagg once told me that problems can occur when using power drills to rotate the speedo, and poor cables can also cause poor performance.
 
Poor cables or the wrong length sticking out of the sheath. It can be too long and damage things or too short and not work. Most drills won't have enough speed to get it up past maybe 30 mph as I remember. Seems I used an appropriate sized 'e-z out' to drive it.
 
Well, I think I found the problem. Even though cable and speedo gear box are new, the cable is not engaging in the box. Have a new cable coming.
 
I adjusted and set the actual mileage using an electric drill, turning CCW or anti-CW, when I installed new glass (and bezel and seals) in my speedometer. took several minutes to add the 14.7 miles to my original smith's speedometer. having issues with the tach rev counter - reading high and bouncing all over the place. going to try another cable, before swapping out the rev-counter.
 
Status
Not open for further replies.
Back
Top