Topic: Viscosity of Silicone Oil in Instrument Dampers/Dashpot

[grcamna2]

I thought it would be worthwhile to resurrect this thread for sohc4 owners who are having Clock needle bouncing from the lack of damping fluid that has either evaporated or drained out.

I'm not quite ready to dive into my Tach. just yet as I am in the process of moving Monday but I wouldn't mind if someone wanted to revive this thread and start doing a speedo and tachometer repair just to get the message out there again for us who have other clocks that we would like to work on for ourselves; I like being able to do most of my own work whenever possible. 

[wrenchmuch]

The tach I fixed continues to work well. It is a k3 or k4 tach.
This tach has a cap on the damping pot. Others do not. Lecram has posted pics of  locks that have a crimped or turned down neck instead of a cap. This type will be more difficult to fill but once the bearing is removed from above there should be enough room to get the fluid in there. I filled the pot 2/3 rds full. No leaks so far. I removed the bearing assembly from the body of the clock. This requires some way of gently supporting the shaft and spring so the spring doesn't get stressed. I have some pics of the process and will try to post them. I make no claim regarding my way being the right one. I will post the images I have and hopefully the community can improve on the info. I would like to come up with an idea for refilling without taking the bearing apart. This would minimize the possibility of changing the tension of the spring and thus the accuracy of the clock.

[grcamna2]

Thank you wrenchmuch for adding more to this thread. 
Is the bearing always a press fit into the pot ?
I wonder if using a small bit of scotch tape to support the spring/needle assembly would be good to lightly cradle that delicate & precision piece that I don't want to change at all.I realize how important it is not to change the tension of that spring.
I look forward to hearing more from you about your way of working on the clock assembly.Do you think that there is a certain viscosity of this silicone damper fluid that will work well for any temperature range ?
Thanks for any input you may have...it helps me get closer to a long term repair  ,
           
                                                                                                Bill
                   

Do you know if AshimotoKo is still an active member here ?

[AshimotoK0]

Hi Guys, yes I am still here and a million apologies for not posting.

I have had major work hassle over the last couple of years which have caused me considerable stress. I am much better now and hence revisiting my bike projects for a bit of relaxation therapy!! (UK '69 750KO, '75 400/4 F, '69 CB250K0, '69 CB350K1 (US model))

It seems that Lecram has done all the testing we need on this and uses 50,000 silicone oil as used in RC cars.  My has he come on and done brilliant work on gauges, so pleased he has made a business from this and willing to share his knowledge with us.

Best Wishes AshD (UK)

[Phoenix]

So is anyone in a position to throw some pictures up to prove this really happened?

[CB750faces.com (Lecram)]

No damper:

http://youtu.be/8n9PMz3YtH0

With damper:

http://youtu.be/ZxLmwQgyu4c

My own experience and also the feedback from my customers prove that this works great: stable as a rock

[grcamna2]

Hi Guys, yes I am still here and a million apologies for not posting.

I have had major work hassle over the last couple of years which have caused me considerable stress. I am much better now and hence revisiting my bike projects for a bit of relaxation therapy!! (UK '69 750KO, '75 400/4 F, '69 CB250K0)

It seems that Lecram has done all the testing we need on this and uses 50,000 silicone oil as used in RC cars.  My has he come on and done brilliant work on gauges, so pleased he has made a business from this and willing to share his kniowledge with us.

Best Wishes AshD (UK)

Thanks for posting AshimotoKO.