After market compass

[scot_c]

Has anyone installed an after market compass? I'd like to disconnect Onstar and also get a more accurate compass for off road. I'm talking about a magnetic compass that would fit on the dash or windshield. My previous experience has been with some vehicles there is too much interference from metal or other sources to be able to adjust the compass accurately.
If you have, where did you place the compass?

 

[Brandon2489]

They have a standard backup compass in airplanes that have way more electronics than vehicles and they have no problems with interference. Although they also use a deviation chart for correction if need be. I honestly doubt you need it to be that precise. If you are installing one or making adjustments a regular screwdriver will cause issues. You should be using a brass screwdriver. Your best bet would be to mount one on your windshield with a suction cup. See what it says with truck running. Then check to see what it is with truck off. Do this procedure for each 22.5 degrees on the compass. While you are doing these checks write down how far the degrees are off while truck is running vs not. Then make a correction chart. If you really want to understand it and get nuts with it then read this article. https://www.flyaeroguard.com/learning-center/deviation_vs_variation/. It will explain it for you.

 

[scot_c]

Thanks for the info. I've used magnetic compasses in boats and on land and am familiar with variation/declination and deviation The problem I've had in the past was the magnetic compasses being so far off due to metal or magnetic interference in the car's structure that I couldn't find a place to put it that didn't cause more deviation than could be corrected (with a brass screwdriver). I don't need a lot of accuracy, mainly want to disconnect onstar which means losing the car's compass from what I've been told.
I'm hoping to find either a particular model that has worked in a Tahoe/Yukon or at least someone who has used one successfully.

 

[Imlow78]

Shannon

 

[scot_c]

Shannon

Thanks. I bought one of these for a Subaru and couldn't get it compensated anywhere I placed it. Where did you locate yours?
They're good compasses, I ended up putting mine on a small sailboat. It, Richie brand, is the exact compass I want.

Scot

 

[Imlow78]

Thanks. I bought one of these for a Subaru and couldn't get it compensated anywhere I placed it. Where did you locate yours?
They're good compasses, I ended up putting mine on a small sailboat. It, Richie brand, is the exact compass I want.

Scot

Google.

Shannon