Tach Filter
Thread Starter
5th Gear
Joined: Jan 2005
Posts: 5
Likes: 0
Tach Filter
New to the forum, New Vette owner with many questions to come. I purchased an 81 that has MANY electrical problems. I have fixed the power windows and have now moved on to the non working tach. I bypassed the filter and it works ok. What does the filter do? What if I don't replace it? If I have to replace it where can I find one?
Thanks
Mike
Thanks
Mike
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
A couple of weeks ago, there was a thread that had an electrical diagram and you can build your own for about $5. Hopefully that person will post the diagram for you again. I will see if I can find the thread and I will post the link here.
Burning Brakes
Joined: Nov 2004
Posts: 1,028
Likes: 0
From: San Antonio Texas
i believe the filter is primarily designed to reduce/eliminate electro magnetic interference (static) with the radio.
some applications require that you remove or bypass the filter anyway. With some MSD ignitions, the filter must be removed or bypassed for the tach to work correctly.
my guess is, if the tach's working without it, you can leave it out.
some applications require that you remove or bypass the filter anyway. With some MSD ignitions, the filter must be removed or bypassed for the tach to work correctly.
my guess is, if the tach's working without it, you can leave it out.
Safety Car
Joined: Jul 2002
Posts: 4,269
Likes: 3
From: St. Charles IL
Cruise-In 5-6-7-8-9-11-12 Veteran
A CI-6 Car Show Winner
I've heard the filter takes out voltage spikes that could damage the circuit board for the tach. Here's a link to a guy that makes them, probably more then 5 bucks though. You could also search the junkyards, most GM tach equipped cars of the same vintage have suitable tach filters.
http://my.execpc.com/~rodney1/corvette/
http://my.execpc.com/~rodney1/corvette/
Le Mans Master
Joined: Jun 2002
Posts: 8,339
Likes: 24
From: I can walk to MA
Here is an older thread on an alternate filter schematic.
http://forums.corvetteforum.com/showthread.php?t=913235
I did an analysis of the filter, showing the suppression of high voltage spikes.
The main purpose is to protect the tach circuit, but high voltage
spikes in the cabin would certainly affect the radio, too.
Do you NEED one ? Maybe not, but it shouldn't hurt to have the
proper filter installed.
If you can solder, you can make your own.
http://forums.corvetteforum.com/showthread.php?t=913235
I did an analysis of the filter, showing the suppression of high voltage spikes.
The main purpose is to protect the tach circuit, but high voltage
spikes in the cabin would certainly affect the radio, too.
Do you NEED one ? Maybe not, but it shouldn't hurt to have the
proper filter installed.
If you can solder, you can make your own.
