Tachometer bouncy/skipping
Thread Starter
Pro
Joined: Mar 2004
Posts: 686
Likes: 0
From: Southeast
Tachometer bouncy/skipping
My '71 vert's tachometer is bouncing/skipping. It's not a fast bounce and makes a strange grinding noise when it does it. I've tried a new cable, but it still did the same thing. I've got the tach out and apart. When I put the cable in with the gear not attached to the magnet/coil, it doesn't make the noise and seems to be turning fine by hand and with a drill hooked to it at slow speed. Once I put the magnet/coil assembly together with the gear, I get the strange noise that I can hear in the interior with the car running. Does someone make a rebuild kit for these? I can easily find the gear but not the magnet/coil assembly. But again, I'm not totally sure what's causing it anyway. Any ideas?
Race Director
Joined: Aug 1999
Posts: 18,126
Likes: 174
From: WI
My '71 vert's tachometer is bouncing/skipping. It's not a fast bounce and makes a strange grinding noise when it does it. I've tried a new cable, but it still did the same thing. I've got the tach out and apart. When I put the cable in with the gear not attached to the magnet/coil, it doesn't make the noise and seems to be turning fine by hand and with a drill hooked to it at slow speed. Once I put the magnet/coil assembly together with the gear, I get the strange noise that I can hear in the interior with the car running. Does someone make a rebuild kit for these? I can easily find the gear but not the magnet/coil assembly. But again, I'm not totally sure what's causing it anyway. Any ideas?
magnet/coil, can I assume you have a factory ti distributor? I have one NOS genuine GM Delco/Remy (not GM restoration made in China garbage) magnet and rotating pole piece available if you or anyone else is interested
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
My '71 vert's tachometer is bouncing/skipping. It's not a fast bounce and makes a strange grinding noise when it does it. I've tried a new cable, but it still did the same thing. I've got the tach out and apart. When I put the cable in with the gear not attached to the magnet/coil, it doesn't make the noise and seems to be turning fine by hand and with a drill hooked to it at slow speed. Once I put the magnet/coil assembly together with the gear, I get the strange noise that I can hear in the interior with the car running. Does someone make a rebuild kit for these? I can easily find the gear but not the magnet/coil assembly. But again, I'm not totally sure what's causing it anyway. Any ideas?
There are also two jewel bushings that play a part in this as well. If you look down at the middle of the center magnet there is a brass bushing there as well as the one that the spindle pass's through.
Both of these two bushing can be worn out and still cause the same issue you are having.
The bottom line is if I'm right, you'll need to service the tachometer with a new head which is something you can't do at home.
Willcox
Last edited by Willcox Corvette; Mar 24, 2017 at 11:30 AM.
