Tach not working
Instructor
Joined: Dec 2003
Posts: 106
Likes: 0
From: Orange Park FL
I have a 75. I put in a new Tach board about a year ago. I't worked OK for a while, now its pretty eratic.
Had the car dynotuned about a month ago. The Mech. said my tach was off about 500-600 RPM.
I may have it rebulit or just replace it with an aftermarket one.
IMO these original tach's are pretty old technology and the replacement boards are cheaply made, so they don't do a very good job.
Had the car dynotuned about a month ago. The Mech. said my tach was off about 500-600 RPM.
I may have it rebulit or just replace it with an aftermarket one.
IMO these original tach's are pretty old technology and the replacement boards are cheaply made, so they don't do a very good job.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
I don't have an electric tach, but I think there is a chinzy little electrical filter on the signal line to it. Sometimes that thing goes bad or doesn't work properly and the signals get jumbled. If I remember what I read about it, you can't buy them but you can get the parts from Radio Shack to replace them and get it working correctly. (Pretty simple fix, I think.) Chime in you "elec - techs."
Instructor
Joined: Oct 2006
Posts: 219
Likes: 0
From: Jupiter FL
sometimes the damping fluid in the meter head dries up. This makes the take needle erratic. If it's the tach board, the ones from corvette central and ecklers are pretty much junk. Call J.Gardeners electornic tach repair. He's out pf PA and makes the best quality tach board I've found. His is the only one I use.
Pro
Joined: Jun 2005
Posts: 703
Likes: 153
From: Central FL
St. Jude Donor '06 thru'17, '23-'26
I purchased a Gardener's board from Zip, it worked like a champ after a little calibration. This article on corvettefaq talks about re-zeroing the needle when installing a new tach board. I used this info when I replaced mine.
http://www.corvettefaq.com/c3/RebuildSpeedo.htm
Also, some good info in this post. I know forum member Mike Mercury used to rebuild tachs(he may still do it), you might want to contact him.
http://forums.corvetteforum.com/show...ch+calibration
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
I don't have an electric tach, but I think there is a chinzy little electrical filter on the signal line to it. Sometimes that thing goes bad or doesn't work properly and the signals get jumbled. If I remember what I read about it, you can't buy them but you can get the parts from Radio Shack to replace them and get it working correctly. (Pretty simple fix, I think.) Chime in you "elec - techs."
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