What do the Blackout Markers Sit On?

1950 - 1952, M38, questions, discussions, regarding anything related to the M38.
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dpcd67
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What do the Blackout Markers Sit On?

Post by dpcd67 » Sat Jun 23, 2018 7:09 am

I need to know the dimensions of the rubber things that the M38 Blackout Marker lights sit on. Mine did not have anything under them. I assume they are little rubber bushings. The SNL says they are rubber.
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JMZ421
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Re: What do the Blackout Markers Sit On?

Post by JMZ421 » Sat Jun 23, 2018 7:09 pm

I just took this picture of the M38. Looks like 3/4 to 1 inch wide but I cannot see how deep it extends, John
blackout.jpg
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Re: What do the Blackout Markers Sit On?

Post by Radtech » Sat Jun 23, 2018 7:21 pm

They are around 3/4" dia,3/8 thick with 5/16 core hole.

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Re: What do the Blackout Markers Sit On?

Post by dpcd67 » Sat Jun 23, 2018 7:26 pm

Ok, good; thanks to you guys.
I will make a pair.
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Re: What do the Blackout Markers Sit On?

Post by Ben Dover » Sun Jun 24, 2018 5:32 am

Stop at NAPA or your favorite parts store, you will find fuel or PCV hose that will suit the set up. I have some NOS that need new rubber due to 60th birthday. They are PAD, Willys Part No. 800378 and 5/1/6" Fuel/Vacuum hose works nice, The Nuts are 5/16" 24 NF w/attached External Tooth Lock Washer.
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dpcd67
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Re: What do the Blackout Markers Sit On?

Post by dpcd67 » Sun Jun 24, 2018 7:44 am

Yes that is what I am going to use and I have the correct nuts; they were on it. Just no rubber at all.
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Re: What do the Blackout Markers Sit On?

Post by Ben Dover » Sun Jun 24, 2018 8:21 am

The mounting studs are not listed separately, original M-38 BO Markers with wire and Douglas connectors are very scarce, the M-38 battery box interferes with the later ones with Packard connectors.
The Toothed Washers may be necessary for a good ground.
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HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
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Re: What do the Blackout Markers Sit On?

Post by dpcd67 » Sun Jun 24, 2018 11:27 am

My connectors have been cut off; I will have to put new ones on. I have the correct studs though.
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Re: What do the Blackout Markers Sit On?

Post by Ben Dover » Sun Jun 24, 2018 1:58 pm

There is a possibility you can make a new pig tail with a brass brake shoe rivet an a length of salvage 14 Ga wire with the bullet connector in place. I have some xtra BO Markers that need this repair.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

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Re: What do the Blackout Markers Sit On?

Post by dpcd67 » Sun Jun 24, 2018 4:04 pm

Fortunately I only have to make the end opposite the bulbs.
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Re: What do the Blackout Markers Sit On?

Post by Ben Dover » Sun Jun 24, 2018 5:37 pm

I just checked a NOS spare, the stud sets into a 5/6" Boss on the bottom of the housing, a 1/4" thick section of 5/16" PCV hose should just about squash out to about the width of the boss.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
7 MIL SPEC MAINTAINED MV'S
COL. BRUNO BROOKS (ARMY MOTORS) IS MY HERO

dpcd67
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Re: What do the Blackout Markers Sit On?

Post by dpcd67 » Sun Jun 24, 2018 8:28 pm

Ok, I got it. thanks.
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Re: What do the Blackout Markers Sit On?

Post by mdainsd » Wed Jul 11, 2018 3:40 pm

I did mine a little differently.

Those early B.O. markers came in a couple of variations. One had a long stud in the bottom with a jamb nut securing it to the housing. Another I have seen and the type I used have a shorter stud, about 1" OAL again secured with a jamb nut. The later is what I used and was lucky enough to find NOS versions. I cut 1/2" ID black heater hose slightly longer than the thickness of the jamb nut (about 3/8ths). The hose is a good snug fit over the jamb nut. Then install with internal toothed washer and nut from below.

This works very well as you can tighten the lamp assembly down nice and tight. If you go with just tubing you over compress the tubing trying to get things tight enough. Over compressing the tubing leads to cracking almost immediately. The OD of the heater hose is exactly the diameter of the boss on the light. Best of all with the nut in there it centers the light perfectly in the opening.

Enjoy

Oh and if you really care, the M38s had the very first version of these. The door, or the piece that comes off the front to change bulbs, does NOT have a keying feature. You can actually put them on upside down. Few people know this it seems as they had the same part number, but they are rare as hens teeth.

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