Brodhead Pietenpol Association

Original Posted By: Steve Ruse
To:Pietenpol List Subject: Pietenpol-List: shaky tach needleG'day, Pieters;The needle on the (mechanical) tach on 41CC looks like a hula dancer's hips whenup at cruise RPM. I get a general idea of the engine speed by reading inbetweenthe swing of the needle tip arc but it sure does a shaky shake. I also knowthat it reads 200 RPM high at cruise because I checked it with a digital,optical tach. The error is low at low RPM but gets larger as I approach 2100-2200RPM and above. I know nothing about how these tachs work and have not pulledout the cable to see what the ends of it look like.Can the cable be cleaned and lubricated and maybe take some of the "hula hips"action out of the tach needle, or is it a sealed assembly? Would the cable haveany effect on the accuracy of the tach reading or is that strictly a functionof the instrument?Thanks for any help. I think I'll go snoop the Sac Sky Ranch website to see ifthey have anything about this.Oscar ZunigaAir Camper NX41CCSan Antonio, TXmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________Date: Tue, 10 Jun 2008 09:30:26 -0400

Original Posted By: "Gene Rambo"
G'day, Pieters;The needle on the (mechanical) tach on 41CC looks like a hula dancer's hips whenup at cruise RPM. I get a general idea of the engine speed by reading inbetweenthe swing of the needle tip arc but it sure does a shaky shake. I also knowthat it reads 200 RPM high at cruise because I checked it with a digital,optical tach. The error is low at low RPM but gets larger as I approach 2100-2200RPM and above. I know nothing about how these tachs work and have not pulledout the cable to see what the ends of it look like.Can the cable be cleaned and lubricated and maybe take some of the "hula hips"action out of the tach needle, or is it a sealed assembly? Would the cable haveany effect on the accuracy of the tach reading or is that strictly a functionof the instrument?Thanks for any help. I think I'll go snoop the Sac Sky Ranch website to see ifthey have anything about this.Oscar ZunigaAir Camper NX41CCSan Antonio, TXmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net________________________________________________________________________________

Original Posted By: Oscar Zuniga
yea, you can pull the center out of the cable and put some moly grease on it. You can also spray a l;ittle lube in the tach itself at the drive end, not too much. That should stop it.Gene ----- Original Message -----

Original Posted By: Oscar Zuniga
Oscar, I used to run a speedometer shop and your complaint is common. Pull yourcable core out and hold one end in each hand. Pull your arms out as far asyou can. Hold one end still and twist the other. Assuming your cable is about5 ft, you shouldn't be able to turn it more than half a turn. If it is more,the core is acting like a spring and drives the tach in waves. The problemcould also be the magnet striking the cup if it is a magnetic style tach. Pullthe cable loose from the motor and drive it with a cordless drill. If youhear a repetative jingle and the needle still bounces, it is the magnet strikingthe cup. You can take the cable core to a speedo shop and they can make onecheap. Tell them it is for your boat. A good shop won't make one for a plane.If it is in the tach, you can try to take it and have it repaired, but itis hard to get parts and find someone qualified and willing to do it. Let me know what you find. If you can't find anyone down there, I know a coupleof people here in Dallas.Good luck, Jeremy in Dallas Sent via BlackBerry from T-Mobile-----Original Message-----