NEWS | Dec. 3, 2020

HMMWV: Lower Front Ball Joint Mounting Bolts

Dear Half-Mast,
I’ve been working on an M1097R1 HMMWV for my unit. I noticed that outer cap screws are installed from the top down and inner cap screws are installed from the bottom up just on the lower front ball joint. We’ve also seen all four cap screws installed from the bottom up in other HMMWVs.

I'm hoping you can tell me the correct way the screw caps should be installed. 
                                                                                                                      Mr. M
Dear Mr. M,

Let me ease your mind.  There’s no safety issue here.

The reason the mounting bolts (or screws as you’ve called them) are installed differently on the HMMWV’s front lower ball joint is to ensure clearance and access to the nut for torquing.

The direction of the mounting bolts makes installation on the assembly line easier and prevents the lower ball joint mounting bolt from touching the hub in extreme wheel rebound conditions (mounting bolt contact with the hub isn’t a concern with the upper ball joint). Extreme wheel rebound conditions exist when the wheels bounce more than usual, like on really rough terrain or when being dropped from an air lift.

This configuration applies to the two mountings that are separated by about three (3) inches. They are the two outside bolts in the picture below, circled in red.
M1097R1 Mounting Bolts
Photo Courtesy of TACOM

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