Chronometric Speedometer needle wiggle - Jaeger in MGTC

[Steve Simmons]

I've been using Morris for decades. His work is very good. Just got several gauges back recently, MGB upgraded tach and some 40s Studebaker stuff.

[Duncan M]

White (lithium) grease is the usual suggestion for the original type, where the inner cable can be removed and cleaned up and then re-greased. FTFU suggests it in their tech tips section--

https://img1.wsimg.com/blobby/go/095cf0 ... 4501722669

[Rob Reilly]

Well, I think I have identified that unusual screw thread of the mounting screws on my speedo and tach.
I found it in a 1946 copy of Machinery's Handbook page 1008.

French Standard Thread (Standard Francais)
Diameter 5mm = 0.1969"
Pitch 0.75mm = 34 tpi
Root Diameter 4.03mm = 0.1585"

and there is an explanatory paragraph:
"French Thread (S.F.) - The French thread has the same form and proportions as the American standard (formerly U.S. standard). This French thread is being displaced gradually by the International Metric Thread System."

Jaeger was originally a French watchmaking company, with a spinoff in England, so I guess that explains why they would use an old French screw thread.
The Jaeger history websites claim the Red Baron had a captured Jaeger tach fitted in his Fokker Triplane when he was shot down.

[frenchblatter]

Back in the 60s I was taught to use white high temperature grease on inner cables and then very sparingly.