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General Category >> Rubber Side Down! >> Inner workings of Savage speedometer
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Message started by Yonuh Adisi on 01/15/10 at 20:36:43

Title: Inner workings of Savage speedometer
Post by Yonuh Adisi on 01/15/10 at 20:36:43

This thread http://suzukisavage.com/cgi-bin/YaBB.pl?num=1262493819 got me wonder so I decided out of boredom to tear apart an old Savage speedometer. (can not successfully open it up without destroying the chrome bezel keeping the speedo glass in place). This is what is inside, as you can see, there are no electrical components, it is completely mechanical.

http://c4.ac-images.myspacecdn.com/images02/115/l_4c94fbd6d5ab4a589a59383680086e6f.jpg

http://c1.ac-images.myspacecdn.com/images02/137/l_3ef02112b187473dba48686552126744.jpg

http://c3.ac-images.myspacecdn.com/images02/113/l_31954f3c1f2f4f06905d0f366ebe5cfa.jpg

http://c1.ac-images.myspacecdn.com/images02/143/l_c7815a2751f7469a969411361deab0bc.jpg

Title: Re: Inner workings of Savage speedometer
Post by verslagen1 on 01/15/10 at 20:59:21

That drum in the middle is magnetic ain't it?

Couldn't tell you how fast to spin the drive shaft, but you might take a drill motor and chuck the drive shaft in it and let 'er rip to see what "speed" you can go. Since a chain drive has gotta make it about 10% slower, try a tape head demagnitizier and briefly bring it up to the drum for maybe a second. Then run the drill again to see if it still works or if you slowed it up any. Try again only longer. Keep at it notin' where you rub the demag and fer how long. Have fun.

Title: Re: Inner workings of Savage speedometer
Post by smokin_blue on 01/16/10 at 06:01:36

Vers, yes they are magnetic. I have torn apart about 3 others from the early 70's forward and that wheel is a magnetic drive connection with the spring countering the magnetic force as the RPM of the magnet increased. It is amazing they are as accurate as they are!!! I can also understand why they are going to electronics too!