 How to repair Tach Bouncing/Dampening?, Can't find the thread |
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| Eddie914 |
 Jun 17 2010, 12:36 PM
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#1
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Unregistered  |
The tach on my 914/6 (conversion) has lost it's dampening. The tach needle is nice and steady as long as the engine rpm is constant. When the rpm changes quickly (such as when gear changes are made), the needle bounces. It takes a fews seconds to settle.
I remember reading a thread about adding a resistor to the circuitry to repair the problem. Even though a 3.2 six has been installed in the teener the engine electronics and induction are still "old school" ... 40mm Weber carbs and points, condenser & CDI ignition. The tach is an early 70's 911 model with a 7,200 rpm redline. Can anyone help me out/ Thanks Eddie |
 
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| detoxcowboy |
Jun 17 2010, 01:40 PM
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#2
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Senior Member  Group: Members Posts: 1,294 Joined: 30-January 08 Member No.: 8,642 Region Association: Africa |
http://nhspeedometer.com/914/1.htm
North Hollywood Speedo installs them.. did mine and it works perfectly |
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| underthetire |
Jun 17 2010, 02:35 PM
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#3
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914 Guru Group: Members Posts: 5,062 Joined: 7-October 08 From: Brentwood Member No.: 9,623 Region Association: Northern California |
I remember that too. It was a capacitor though,not a resistor. I can't find it anymore either.
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| underthetire |
Jun 17 2010, 02:43 PM
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#4
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914 Guru Group: Members Posts: 5,062 Joined: 7-October 08 From: Brentwood Member No.: 9,623 Region Association: Northern California |
Now I remember, the resistor was kind of a fake out to run V8's and use the stock tach. The bouncing problem was a dried up I think 1UF capacitor inside the tach. Thats bouncing during RPM changes. Bouncing tach all the time was points/or alternator/or VR going bad.
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| dr914@autoatlanta.com |
Jun 17 2010, 03:01 PM
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#5
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914 Guru Group: Members Posts: 8,111 Joined: 3-January 07 From: atlanta georgia Member No.: 7,418 Region Association: None |
If it has lost it suddenly but worked before it may just be dirty contact points. However Palo Alto has added ballest to tachs that we have had converted without having to find the very expensive three blade capacitor installed on the factory six relay boards.
QUOTE(Eddie914 @ Jun 17 2010, 11:36 AM)  The tach on my 914/6 (conversion) has lost it's dampening. The tach needle is nice and steady as long as the engine rpm is constant. When the rpm changes quickly (such as when gear changes are made), the needle bounces. It takes a fews seconds to settle. I remember reading a thread about adding a resistor to the circuitry to repair the problem. Even though a 3.2 six has been installed in the teener the engine electronics and induction are still "old school" ... 40mm Weber carbs and points, condenser & CDI ignition. The tach is an early 70's 911 model with a 7,200 rpm redline. Can anyone help me out/ Thanks Eddie |
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| Michael N |
Jun 17 2010, 08:28 PM
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#6
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Certifiable Group: Members Posts: 1,426 Joined: 6-June 04 From: San Jose, Ca Member No.: 2,164 Region Association: Northern California |
I think this is the link. Bouncing Tachometer Link I soldered in a capacitor and it dampened my old tach about a year ago. At first I went too much dampening and the tach was too slow to respond to the revs. I then changed to a different capacitor and the tach is now perfect. Spokes photo in post #7 helped a bunch.
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| Eddie914 |
Jun 18 2010, 09:23 AM
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#7
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Unregistered |
Thank you everyone!
You are the best! Eddie |
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