Hull M4 Compass

Many of us like to have a few field mods on our jeep; it promotes great conversations at car shows and the like. One of the cool additions to a jeep is a compass. Pre-WW2 there were quite a few manufacturers of compasses suitable for auto use. One of the most popular was made by Hull in Warren, Ohio. The military, WW2 M4 compass was basically a Hull Streamline, painted in olive drab, with special rubberized mounts for military vehicles. It has been noted that some military Hulls remained in their original brown or black Bakelite colors.

Here are a few war-time jeeps with a dash-compass installed. They were also found mounted to the windshield vertical posts, both driver’s side and center.

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Hull Streamline compasses are easily found on ebay, but what’s hard to find are the proper mounting brackets, especially the militarized ones. These military brackets should have some form of rubber shock mount.

To the left you can see the two common rubberized mounts. This image is taken from Ray Cowdery’s classic All-American Wonder, Vol II, p212.

The top image shows the mounting rod inserted into a rubber cylinder, which is then held by the dash mount.

The second type has the mounting rod embedded in a rubber ball, which is then held by a clamp.

Here’s are two excellent resources for restoring a Hull compass:

1. Restoring a Hull compass, from 1945GPW.com

2. Restoring a Hull compass from Team-BHP.com

Personally I have found it very difficult to restore these compasses. I have several, and it’s tough to open the brass and glass bowl to clean and replace the fluid. After more than 70 years the thin brass is very brittle, and I’ve torn one of them trying to open it. I’ve been talking with a lot of folks about 3D printing or otherwise casting a replacement threaded section, but to no avail. It’s one of those things, though, which I intend to keep trying.

Here’s my best compass, mounted to my GPW on the center windshield post. It’s nearly flawless, but it really does need a rubberized mount. Without it, there is excessive vibration in the unit. I’ll add to this post when I find a solution.

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