Technical Questions on this SW Speedometer

Hi,
Does anyone know what the round door is for on the back? Should I be oiling this speedometer before it goes back in service?
Thanks

 

Any info?

 

This is a complete guess but does the door cover a an adjuster that can be used for calibration? Have you opened it and looked in?

 

Probably where the brake was attached originally. When installed in cop cars they were supposed to be stopped at the high speed with a brake in the mechanism. That was proof that the cop was chasing you above the speed limit.

 

Alchemy where did you hear that?

 

Correct, the side mechanism has a rubber stop that will hold the speed cup and the speedometer needle in place for the officer to show the driver that he was paced and what speed he was clocked at.
Some were electrically operated by remote switch, others by hand.

 

Thank you,
Is there anything I should service/lube before I use it as a speedometer? It has a ****on on top that I think was a manual stop as well as a wire going in the back.

 

https://youtube.com/shorts/HSbINoQYepY?si=o-GCTU0ZwLtKDzUr
I stink at this video stuff, but here is one I rebuilt/restored on the test bench, the stop on this one was electric for the set.

 

There is an oil wick but its only accessible if you take the speedometer out of the case.
Hook it up and see if it runs smoothly, any jumping in the needle or noise disconnect the cable so it won't do any major damage and have it repaired.

 

Thank you

 

Nice. Now when you hit a buck fiddy you can prove it to all your buddies.

 

/ATTACH] I followed the test procedure that @e1956v gave me above and I had some issues. Lots of noise and the needle jumped around. I sent it to e1956v and he quickly got it running like new again. Here are some shots on his test and calibration machine. Thank you Rusty for getting this done quickly and very affordable. I highly recommend Rusty if your speedo needs a service.

 

Thanks Duke
I was able to get calibration close in the lower speeds up to 70 then after 80 it starts to read 4 mph slow. If I got it closer above 80 it sacrificed accuracy in the lower speeds. So I always shoot for the lower speeds below 60 to be the most accurate.
I really appreciate you trusting me with your repair.

 

Thank you, that makes sense. If I am over 80, I am already speeding so how much doesn’t really matter