Mar 182001

This page contains excerpts from PS Magazine (a monthly magazine published by the US Government for Army personnel involved in maintenance) which describe how to perform a necessary brake vent modification on M44-series 2.5-ton 6×6 trucks such as the M35 cargo trucks or my M109A3 shop van. I used to have a couple of pages with many PS Magazine excerpts with 2.5-ton and HMMWV tips, but they are no longer necessary now that you can download individual articles from 1988 on at the PS Magazine web site. I kept these particular excerpts here because the vent line modification was published in 1983, and is not yet available on the PS Magazine web site. It’s a very good idea to check the PS Magazine index for other articles which may apply to your truck. For example, there’s an article in issue 542 (January, 1998) which describes a necessary brake light switch modification which replaces the old hydraulic pressure actuated switch, which could blow out and leave you rolling without brakes!


File Size Issue/Page Description
image iconBrakeVentCheck.jpg 105k PS 555 (Feb 99), p5 Checking for brake vent line modification
image iconBrakeVentFix1.jpg
image iconBrakeVentFix2.jpg
PS 364 (Mar 83), p18-20 Brake vent line modification

Here are more detailed descriptions of the parts needed for the M44A2-series version of the modification. I have not performed this modification yet, so please comment if you find any mistakes.

# Name NSN Description
1 Copper tubing 4710-00-203-3172 3/8″ OD, 72″ long
2 Adapter 4730-00-336-9558 1/4″ NPT female to 3/8″ OD compression fitting
3 Bushing 4730-00-196-0930 1/4″ NPT male to 1/8″ NPT female
4 Breather 4820-00-726-4719 1/8″ NPT male threads, includes filter, I do not know if this includes a check valve
5 Screw 5305-00-145-8368 5/16″ self-tapping hex head, 3/4″ long
6 Clamp 5340-00-833-8476 rubber-covered, 0.406″ nominal ID
7 Tiedown strap 5975-00-133-8687 4.5″ black nylon cable tie
8 Adapter 4730-00-289-1930 1/8″ NPT male to 3/16″ OD 42° flare
9 Adapter 4730-00-289-1254 1/4″ NPT male to 3/8″ OD 42° flare
10 Reducing elbow 4730-00-278-4694 90° 1/4″ NPT female to 1/8″ NPT female
11 Nipple tube 4730-00-278-3213 1.1″ long 3/8″ OD copper w/ 24 TPI UNS threads on each end, 150 psi rating


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