Bad Tachometer
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Bad Tachometer
Here is another in the series of helping a non-mechanical guy with his first Vette...
The Tach isn't working. The guy I bought it from said that he tried to fix but couldn't figure it out.
What should I check for to identify where the problem is and to correct?
The Tach isn't working. The guy I bought it from said that he tried to fix but couldn't figure it out.
What should I check for to identify where the problem is and to correct?
Le Mans Master
Joined: Nov 2000
Posts: 5,210
Likes: 104
From: Fort Worth TX
St. Jude Donor '06
Father & Son St. Jude Donor '09
Re: Bad Tachometer (ridadyna1)
You have a mechanical tach. The cable comes through the firewall and attaches to your distributor. The gear that engages with the distibutor mainshaft gear is the typical culprit. unhook your cable from the distributor (may be easier said than done) and look at the male end inside the cable, it should be square, if it's rounded off you need a new cable. If not, then pull the brass cross gear assembly off of your distributor (it may have come off with your cable). There are several parts that make up the cross gear. The part you want to look at is the internal shaft gear that makes contact with the distributor mainshaft gear. The internal shaft is usually the culprit and needs replaced, $30-40 for a new part. If it looks ok, then if you have a hex bit that will fit in your drill and engage the cable, connect it to the end of the cable and rotate the cable with the drill while someone watches your tach. If the internal shaft looked good, and the drill made the tach work, then it's probably the mainshaft in the distributor and I can no longer help you, you need a gearhead and not a novice like me. If the drill didn't turn the tach, then you should go under the dash and unhook the tach end of the cable (a real pain in the azz) and see if it is rounded off. If it's not rounded, do the drill hook up again and see if the cable turns, if not you have a broken cable and need a new one. If it does turn????????? then the tach itself may be worn and I'm out of ideas. :confused:
My internal shaft was worn pretty bad and I have a new one on order right now. :D I'm hoping that will solve my tach problem. The internal shaft purposely isn't as stout as the distributor main shaft gear and hence it wears out making it fairly easy to service the tach. :cool: GM did do some neat things, just not fit and finish. :lol: :lol:
My internal shaft was worn pretty bad and I have a new one on order right now. :D I'm hoping that will solve my tach problem. The internal shaft purposely isn't as stout as the distributor main shaft gear and hence it wears out making it fairly easy to service the tach. :cool: GM did do some neat things, just not fit and finish. :lol: :lol:
