Tachometer cable questions

jrenwick · Post by **jrenwick** » Sun Jan 07, 2007 4:46 pm

In the process of lubricating my tach cable, I damaged the plastic piece that fits over the end of the cable that goes into the drive housing on the accessory case. It's a tube maybe 3/4" long, square on the inside to fit over the cable end, round on the outside with a spline to fit the slot in the drive. Anybody know a source for this part? I may go to a local speedometer shop tomorrow and see if they have them.

Does anybody know offhand the length of the tach cable for a '55 170B? So that when I go to Wentworth to buy a used one, I can at least get the right length without having to pull mine out and measure it!

Thanks for the help!

jrenwick · Post by **jrenwick** » Sun Jan 07, 2007 11:01 pm

OK, I've looked at this some more, and I realize now that the part I'm describing is unique to the brand of tachometer shaft I'm using. I'm going to need to pick up a replacement shaft somewhere -- probably Wentworth, because I really need it tomorrow. The one I have is 37" long.

Happy flying!

John

Post by **GAHorn** » Mon Jan 08, 2007 12:16 am

Aircraft Spruce can supply a new tach drive cable and ship it overnight express.

Abe · Post by **Abe** » Mon Jan 08, 2007 12:54 am

I guess that I've been hoping that my tach would settle down after the cold weather comes to an end, but since you're discussing them, here's what mine is doing....and since we've got 3-more months of cold weather...My tach started to jump constantly not to long ago....about 50-75 RPMs each way....it settles down a bit after 10-minutes of run time, but never settling down completely.....For those who may have experienced this before, did you have to lube your cable, replace your tach cable or get a new tach? What's a good cable lube to use and after the recent engine rebuild, my wallet is a real thin so I may just have to lube the cable and ride this one out.

CraigH · Post by **CraigH** » Mon Jan 08, 2007 1:51 am

Abe,
I had the exact problem you describe. After lubing the cable, replacing the cable and overhauling the tach, I finally replaced the &*(#(@ thing. Should have done that in the first place.

Post by **Bruce Fenstermacher** » Mon Jan 08, 2007 2:07 am

I've not tried it but according to Keystone Instruments in Lockhaven the lube to use with the local FAA blessing is Petroleum Jelly.

Abe · Post by **Abe** » Mon Jan 08, 2007 3:32 am

Thanks for the info Craig & Bruce...you gotta love these airplanes, just gotta figure out how to get Judy to like them as much as I do

....

sphillips · Post by **sphillips** » Mon Jan 08, 2007 2:56 pm

My tach started the "jump" as well, then failed, I thought. Removed the cabe housing and found the cabe broken. Pulled the tach and found the fitting for the cable frozen. Used mouse milk on tach cable fitting and slowly worked the fitting until it loosened. Installed new cable assy from AC Spruce, works like new.

HA · Post by HA » Mon Jan 08, 2007 4:20 pm

graphite works pretty well and won't thicken up in cold weather. I spray the cables with dry Moly lube too before I reinstall them with the powdered graphite for a double whammy

but if you pull the cable and it has any bulges or fraying, get a new one and save yourself the time and effort

jrenwick · Post by **jrenwick** » Mon Jan 08, 2007 8:59 pm

gahorn wrote:Aircraft Spruce can supply a new tach drive cable and ship it overnight express.

Cheap, too! This is surely the best way to go.

Turns out, the speedometer shop in Saint Paul that everybody here knows about is closed and gone for good. There's a shop in Minneapolis, but they couldn't properly match the diameters of my cable; plus they charged more than Spruce. I'll bet the demand for this sort of thing is shriveling up, and it may become history sometime soon.

Wentworth had a used cable from a '55 170B, but it was $50 plus tax. Maybe I could have talked them down by telling them it was more expensive than a new one....

Thanks for all the help!