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BT7 tach question

  • Thread starter Deleted member 21878
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My tach is what i would call sticky... it moves but it is slow to move. when i shut the engine off, it will stick at maybe 600 rpm. i had thought it was the tach.. and maybe it is... but yesterday i was trying a few things.

i pulled the cable from the diz and spun with a drill. i found if i hold the inner cable away from the outer cable (away from the tach end), it would drop right back as it should. but if i pushed in on the cable, the tach would stick.

So basically any pressure in on the tach part causes it to stick. is this a cable issue? or a tach issue? the cable seems to spin fine. i hate to send the tach off for a rebuild if it is just the cable.

my last thought was maybe the inner cable is too long and when i insert it in the diz drive, it put pressure on the tach. (and it does not take much) So i put a washer or spacer on the diz end to see if that would help. have not tried it yet.

just wondered if anyone else has had this and what they did.

Thanks
 
I was going to suggest a spacer, curious to see if it helps.
 
As a follow up:
the spacer did seem to help a litle. the tach did not stick but it still was slow.

rather than jump in to a 200 dollar bill with Nisonger, thought i would try a new 20 dollar tach cable first. the new cable is better. the tach is not as slow as it was. guessing now if i want it better it will need a rebuild. but since my tach seemed to work better in the summer, think i will wait and see how it is then. if it is any better, i will leave alone. if not then maybe next winter it goes to Nisonger.
 
Did you lube the new cable? I used graphite
 
RestoreThemAll said:
Did you lube the new cable? I used graphite
Click to expand...

I recently had my tach overhauled and a new cable by Morris of West Valley Instruments. I observed the following:
After he built the cable, he took a small amount of grease (a gob on a finger) and rubbed it carefully along the entire length of the cable. He says it's important to not get too much as winding of the cable can force excess grease up into the instrument. The grease he used looked like all-purpose chassis or wheel bearing grease. It was not graphite or white lithium.
 
Drone Dog said:
As a follow up:
the spacer did seem to help a litle. the tach did not stick but it still was slow.

rather than jump in to a 200 dollar bill with Nisonger, thought i would try a new 20 dollar tach cable first. the new cable is better. the tach is not as slow as it was. guessing now if i want it better it will need a rebuild. but since my tach seemed to work better in the summer, think i will wait and see how it is then. if it is any better, i will leave alone. if not then maybe next winter it goes to Nisonger.
Click to expand...


If you feel confident in your skills with delicate instruments, you might want to remove your tach from the housing and:
1) clean the mechanism with a mild cleaner such as electric contact cleaner. Blow it out lightly with compressed air. Or buy an air can to blow it out with.
2) it might be possible to add jewelers oil to pivot points around the central needle.
3) fire it up again and see if it's perky this time.
 
steveg said:
If you feel confident in your skills with delicate instruments, you might want to remove your tach from the housing and:
1) clean the mechanism with a mild cleaner such as electric contact cleaner. Blow it out lightly with compressed air. Or buy an air can to blow it out with.
2) it might be possible to add jewelers oil to pivot points around the central needle.
3) fire it up again and see if it's perky this time.
Click to expand...
If you do this, paint the inside of the case white. It'll make it easier to read at night.
 
i have had it apart and did clean it. did not oil around the needle though. did not paint the case either. also did not grease the cable. i figured it was already greased. i can pull it back out and do that without much trouble though. sounds like another little project for some cold weather.
 
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