I wanted to start a thread for 1948 thru 1951 compass repair and/or adjustments.

Things I would like to cover are who made it, how to adjust it, how to repair it, plus cosmetic detailing, and comments in general.

Thanks
Ron

 

Pictures

Bottom

Rear

Front

 

The two top questions I have are the "bubble" as seen in front view and why the letter disc does not rotate?

I think the non rotating is due to weak magnets and if so how to recharge the magnets.

I would think there must be some bubble to prevent bursting but does it need more fluid and what fluid to use and how to add fluid.

Thanks
Ron

 

Search terms are “wet compass repair”. You will find certified repair locations and some tutorials.

 

I would look in Hemmings Motor News under Services. There are guys in there that repair speedometers and I imagine some of them also repair compasses.

 

Today wet compass instruments are still used in marine and aeronautical applications. Most likely you will find repair facilities and repair kits associated with those fields. These are usually certified repair shops which translates into a loss of Franklin Brothers on your end.

 

All good hints and pointers.

What I am looking for in this thread is information specific for the Oldsmobile style compasses for the years 1948 to 1951.

However it can be expanded to cover all years of oldsmobiles.

I would like it to contain detailed instructions and hints such we owners can preform our own maintenance and perhaps restoration.

At this point in time I have not found anything specific to Oldsmobile and very little for any of it's sister divisions.

I would like to avoid the school of hard knocks. A shop manual for compasses.

Ron

 

Use non magnetic tools. For instance, use a non magnetic screwdriver. You can purchase the fluid and some gaskets. The gasket you require could be an oddball size. New magnets needed? The last step is to align the compass. In the aircraft avionics world, this is called “swinging the compass”.

 

Most GM compasses were made by Sherrill or Hull, who both also supplied the US military.

Chevrolet naturally had to be different and used Dinsmore, and for a cheaply made instrument those are now outrageously expensive because they were a 57-64 Chevrolet dealer option. I think Pontiac may have offered them too.

I don't think AirWay (made by Sherrill) or Airguide Instruments supplied OE automotive compasses though they're common. Airguide was primarily into home weather stations (thermometer-barometer-hygrometer combinations). I've picked up a few of those over the years.

But, as Tri-Carb has pointed out, most compass repair and calibration service is oriented to marine and aircraft units which equals $$$.

I've seen threads on the HAMB and youtube videos on how to fix these. I think the most difficult part would be finding the damping oil.

 

Timely topic!

Science Channel shows "How It's Made" on Sunday afternoons. Season 7 Episode 10 was on today. Took us into the Ritchie compass factory in MA and showed assembly and calibration of one of Ritchie's big nautical compasses.

Yah, HIM is my Sunday afternoon guilty pleasure TV... Learning how audio vacuum tubes are made now. They had to go to the Czech Republic to find a factory.

 

Top to bottom paperwork exists to historically document these GM Oldsmobile compass assys in question.

Oldsmobile offered these in this style 1951 and 1952 only, as part of a mandatory package with the steering wheel watch option, which was then the wheel, the correct for body turn signal lever, and compass assy in place of dashboard clock in the same mounting. The compass was also available alone apart from the wheel both as a option or over the service counter, then also presumably as a dealer add-on option. Owners have retrofitted these almost since new to 1949-52 Oldsmobile vehicles both 88 and 98.

These use COMPASS FLUID only. Not alcohol of any of endless types, mineral oil, baby oil, glycerin, on and on. Of all the ways the internet leads people astray from known and settled knowledge, this is surely one of the worst so be careful. Shops involved in the 'yellow tag' servicing of aircraft instruments have and use compass fluid in aircraft mechanical units. Many rare historic irreplaceable marine compass units have been permanently ruined by ignorant tinkerers attempting to add liquid of the wrong type to the compass in question, and this bears mentioning pertaining to these compasses as owners have ruined them the same way but with different effects from the use of the wrong fluid.

The Oldsmobile service manual calibration method for these in-dash compasses involved the use a portable growler, which the service garages of the day certainly had, but not so common today. People then and now expect this simple inexpensively constructed device to have traceable standards accuracy. A novelty and functionally loose directional aid.

 

Could a someone post the service manual procedures. I have the 1949 manual for my car but would rather not buy the 1951/1952 manual for this info.

Thanks
Ron