PS Magazine - TB 43-PS-581

PS, The Preventative Maintenance Monthly

ISSUE 581

APRIL 2001
PS Magazine - TB 43-PS-581 - Page 4 of 32
Here are the materials you’ll need for this modification:
M939-Series Trucks.
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PS 581
APR 01
5
PS 581
HMMWV.
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ITEM
NSN
QTY
Metal bar
6 1/2 to 7 inches
(for .049-in bow wall thickness)
Metal bar
6 1/2 to 7 inches
(for .120-in bow wall thickness)
Cap screw
8
Locknut
8
F
ield problems with the vinyl covers for 4-man soft-top HMMWVs include
shrinkage from changing weather conditions, to “it won’t quite fit” when new.
Most units can’t afford to replace cargo covers just because they’re a little hard to
tie down.
Instead, they find a way to make do until the covers are worn out.
Here’s one way to alter the support bows to help make do:
Remove the bows and cut 1 inch off both ends. Then re-drill the
1
∕
4
-in bolt holes
at the bottom. Shrunken covers should fit fine with this modification.
But what happens when you get a new cargo cover that fits too loosely on your
altered bows?
You buy new ones, or you make do.
Here’s how:
ntil all basic M939-series 5-ton trucks have the anti-lock braking system (ABS)
MWO applied, some will use bias tires while others run radials.
Make sure you’re using the right tire, tube and flap on your trucks.
For basic models without ABS MWO applied (except M945)
Bias tire, 11.00x20, 12 ply—NSN 2610-00-262-8653
Inner tube—NSN 2610-00-051-9450
Flap—NSN 2640-00-158-5617
For basic models with ABS applied (except M945)
Radial tire, 11.00R20, with flap—NSN 2610-01-473-3997
Inner tube—NSN 2610-00-029-0563
M945 chassis without ABS
Bias tire, 14.00x20, 12 ply with flap—NSN 2610-00-204-2545
Inner tube—NSN 2610-00-051-9464
M945 chassis with ABS, plus all A1-series and A2-series with ABS
Radial tire, 14.00R20—NSN 2610-01-214-1344
Inner tube—NSN 2610-01-412-4635 (if needed)
Flap—NSN 2640-01-416-8178 (if tube is added)
All these tires use valve extension, NSN 2640-00-200-1934, and
1.
Cut 6 inches off each end of the bows.
2.
Insert a 6
1
∕
2
-in or 7-in metal bar into
each 6-in piece of bow you just cut off.
The diameter of the bar depends on the
wall thickness of the bow stock. See the
materials chart.
3.
Leave the bolt hole at the bottom of
each bow piece clear and drill a
1
∕
4
-in hole 1
inch down from the top of the 6-in bow
piece. Drill through the bow and bar.
Secure
the bow and metal bar with a cap screw and
locknut. See the materials chart.
4.
Butt the top portion of the bow up
against the 6-in bow piece and bar. Drill a
1
∕
4
-in hole through the bow and bar
1
∕
2
inch
up from the cut line.
5.
Remove the top portion of the bow.
Measure 1 inch up from the center of the
hole that’s
1
∕
2
inch up from the cut line.
Drill another
1
∕
4
-in hole in the bar.
1”
1”
1/2”
Now you can adjust the bows to their original height, or move them down to fit
shrunken covers.
Metal bar
6 1/2 to 7 inches
(for .095-in bow wall thickness)
581. 04-05 (C)
3/3/01
12:28 PM
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