Tell me something....does the actual VDO speedometer come in various calibrations/ratios or is it the drive units that have various calibrations/ratios?
Edited by - steve minor on 02/15/2002 10:34:25 AM
Steve;
The speedometer has the ratio. To change the ratio the speedometer has to be sent to a VDO repair facility and tell them which ratio you want.
Thanks Doug....I know I have my original 1977 somewhere but can't seem to put my hands on it right now....I came across a good deal on a NOS one but the ratio is unknown....I'd better leave it alone and keep looking for my original...
This may sound like a dumb question, but wouldn't the diameter of the wheel play a part as well? I recently purchased a replacement front wheel of the same size (21") as my original and as luck would have it, there was a speedometer drive with it.Is it safe to assume that my original speedo will be accurate?
VDO's usually have the ratio stamped on the housing. It will be something like 1.xx
Penton's ( at least the one's I have ) are 1.42.
Bob
It has been forcefully brought to my attention that the way I remember things is not always the way they actually were; but AS I REMEMBER IT, we used to change the gears in the drive to "calibrate" a speedometer; not so much to make it more accurate, but to attune it more closely to the Japanese speedometers which were usually used to lay out an enduro. (Right or wrong we always thought we were right and they were wrong :-)
Quotequote:
This may sound like a dumb question, but wouldn't the diameter of the wheel play a part as well? I recently purchased a replacement front wheel of the same size (21") as my original and as luck would have it, there was a speedometer drive with it.Is it safe to assume that my original speedo will be accurate?
Tom; Bob is right,the ratio of the Penton front wheel speedo drive is 1.42. If your replacement wheel is Penton and the speedo drive is VDO you are okay. In all my years of enduro experience I never heard of changing the drive gears. We did have route sheets with the layout mileage at the turns which you could reset the speedo. If it was constantly a tenth or two off you started to figure that into your corrected times. Of course that was long ago and things have changed.
Steve,
I was playing around with some VDO speedometers a while ago and posted some information you might find helpfull. here is a link to the message.
http://www.pentonusa.org/forum/topic.asp?TOPIC_ID=52&FORUM_ID=1&CAT_ID=1&Topic_Title=VDO+Speedometers+and+Drive+Ratios&Forum_Title=Penton+Forum
If that doesn't work just do a search on VDO speedometer and it will come up.
Mark