Z1 gauge damper

I took apart a 73 Z1 tach because it had needle bounce. Anyone know what fluid or light self leveling fluid was used?  I tried using an NGL #1 grease which works but I'm sure isn't right. After seeing the design it looks like there is no seal on top of the damper. A good reason to never store any of your gauges on its face because the fluid will migrate out. Also looking for source for the seal. Bob used to work on all my instruments but sadly is is no longer with us. Any help appreciated.

Differential fluid 100k vis is what most of us use. You can find it at your local RC racing center or on line.  The brand I use is JTP. there is a whole write up here on gages. Might want to try a search. I drill a small hole and use a needle to fill the cavity. I seal id with a small piece of Aluminum tape and coat the edges with super glue. 

Yeperra, Good Morning! They had 3 different drive mechanisms used in the production of the True Z (72-75) and had different fluid cups. Earliest being a "bullet" type. second had a glued-on cap and last a clear rubber cap that you could lift off. You say needle bounce. Yes, this can be attributed damper fluid loss but can also be needle "spike" which can be mechanical. If you can grab the flared bell that rides over the top of the spinning magnet and move it back and forth then the cast hole where the Stainless steel pin goes into is worn out. This worn casting hole allows the inside of the bell to wander further then closer to spinning magnet causing erratic needle movement. Too worn and it'll actually contact the spinning magnet which will result in sporadic "spiking" of the needle. Just recently had the day off lounging and watched a handful of the DIY fellas take on various motorcycle gauge "restorations" on Youtube. WoW..such incorrect information, blind leading the super blind, ha. Carb cleaner and 3-in-1 oil "lubricating" oil abound. You DON'T lubricate these mechanical mechanisms of this type, just makes a mess. As you've probably already found, grease is the incorrect product for damper refilling, it has the incorrect properties and does nothing but also just makes a mess. Any hoot, what's the face of gauge look like, cracked/distressed? Whoops, just noticed You'd sent me a PM! I'll contact You today and provide more info pertaining to these then you'd ever wanted to know, ha Clay       

Hi yeperra,
Please check your personal messages.
Thanks
Bill/KZQ

Yes the lower casting can be worn. I have found one of my gages with a very worn casting. I was able to make a brass bushing for it. Clay has other methods. Lots to learn when servicing these old gages.