Corbin speedo gears for 1915 Indian headstrom bike

[eric007]

Hi, hope someone can help.

Can someone tell me what is the correct size (number of teeth) for the rear wheel drive ring gear for the corbin speedo setup for a 1915 Hedstrom big Vtwin.

What number of teeth are on the little fibre driven gear on the right angle pickup/ that drives the speedo cable.

thanks

Eric

[Spacke2speed]

Eric
If I remember correctly, the rear wheel gear is a 56 tooth ring gear. The ring gear is concave in the inside and can be disassembled into two half to be able get around the brake drum to mount it. I do not remember the correct pitch that Corbin uses, but the ring gear says Corbin on it.
You need to find the fixed number of revolutions per mile of your speedometer. That is the number of turns your speedometer makes to registered one mile. There is a normal industry standard number which if I remember correctly it is either 1320 or 1750 revolutions per mile, but you need to count them on your speedometer. Then there is the number of turns that your 28x3 tires (or the size you are using) turns to cover a mile. The number of teeth on the rear wheel ring gear. Put that all together and you have the number of teeth the fiber gear needs to be for the angle drive.
The correct Corbin speedometer for a ’15 Indian is an early nickel plated 80 MPH Corbin. The face is made of brass, not aluminum. At the bottom of the speedometer face, the Corbin emblem is a big “C” with the words “ORBIN” inside the “C”. There are also differences on the inside, as there are early guts and later guts. There are two over size high head bolts that mount the speedometer head, not screws.
On the speedometer head, for the rear wheel drive, the cable adapter on the speedometer is the same diameter, while the front wheel drive cable adapter is tapered.
The early angle drives has a disconnect feature, when the cable is pulled away from the drive, the angle drive will disconnect inside. This feature is so when the motorcycle is at the shop on its rear stand and they run the motorcycle, it will not record on the speedometer. When the cable is pushed back towards the angle drive, the angle drive starts working again.
Sorry, I can not send you pictures, I looked around in some of my boxes for the early Corbin setup I had put away for a project I have, but was unable to find it.
Spacke2speed

[eric007]

Thanks for your info. Will file it for reference while I am looking for my bits. Eric

[Spacke2speed]

Eric007
I just thought of two more things on the Corbin speedometer setup on your ’15 Indian that I did not mention.
First, the speedometer head is mounted to the curved frame tube just in front of your seat. The mounting bracket is a thick sheet metal bracket with clamps on each end, not a cast bracket. The speedometer head is slightly rotated so the speedometer cable clears the seat.
Second, the mount for the rear wheel angle drive is a simple almost right angle casting with end caps. Not a universal type with a lot of parts that is completely adjustable.
Spacke2speed