bouncing tac

[dfcpac]

i just installed a used tac in my champ. i had a 65 in it and that tac was working fine. i converted it to a c 85 and put this tac in (used came cable) and at higher rpms above 2200 rpms it will vary up and down about 200 rpms. is the tac bad?

thanks
danny carley

[dfcpac]

i borrowed someone tac and yes the tac i have was no good. if anyone has a tac for a contential c85-12 with correct markings and low time i'd be very interested

thanks
dan carley

[jepropst]

The rotation on the A65 tach is opposite that of the C85-12.

[rkittine]

Hey Danny,

I know you got a new tach that turns the correct way as we talked about it. I had a bouncing tach problem one day, about the same thing you are experiencing and a little re-lubing of the tach cable fixed it.

Are you working this week? I will be flying Tuesday and Wednesday, weather permitting if you want to meet up for lunch half way.

Ciao - Robert

[dfcpac]

hi bob
sorry working all week, we don't take lunch

dan

[MikeB]

Dan,
Not to say your tack isn't worn and causing the bouncing but any sharp bends or stickyness in the cable assembly will cause the cable wind up slightly and then release momentarily which causes a vibrating needle. A new tachometer from Wag Aero is around $200 or so. Mine was off around 200 rpm so rather than having the old unit rebuilt for about $150 it just seemed to common sense to buy a new one considering warranty and all.

MikeB