Substitutions – Page 5 – HMMWV Systems

November 15, 2018January 6, 2019

Upgrade: Replace Transfer Case Cooling Line Hose Clamps with Fuel Injection Clamps

A common problem with standard hose clamps is that they will often tighten up unevenly, cock sideways, and require excessive torque to seal. Here, we have replaced the hose clamps on the transfer case cooling lines with fuel injection clamps (14-16mm range). While these generally cost considerably more than a standard hose clamp, they offer improved sealing and reliability. They can be bulk sourced at a number of online sites, often at a greatly reduced price.

The picture aboves shows where we replaced the original hose clamps 4730-01-118-8278 [4730011188278] with 14-16mm (9/16″-5/8″) fuel injection clamps. The original clamps were apparently installed at the factory from the top side of the frame prior to installing the body. We re-oriented the clamps so that they would be easier to adjust or remove & reinstall from under the vehicle.

These are still the original hoses that came with the powertrain. Although we had new hose to replace it with, we did remove and inspect the hoses. The hose itself remains “live” and showed no sign of cracking, so we retained the original hoses and installed the new clamps.

November 5, 2018January 6, 2019

Interchange: Fan Solenoid Mounting Clamp to SAE Size Hose Clamp

Both the fan control solenoid and mounting clamps had already been scavenged from the 1038.

Finding a replacement solenoid (Fig. 177, Item 5) 4810-01-192-5817 [4810011925817] was relatively simple, and just about every supplier stocks it.

It would be nice to find a cost-effective substitute, but as of yet, we have not located one that would be both cost-effective and a simple retrofit.

The clamps holding the solenoid to the body were also missing. The parts manual (Fig. 177, Item 6) does a call out for 4730-00-204-3491 [4730002043491] but fails to specify its size.

After researching the NSN and manufacturer number of C32P, we identified this clamp as a 40-64mm or (1 9/16″ to 2 1/2″) stainless gear clamp. This clamp is an SAE 32 hose clamp. We acquired a box of ten Breeze brand clamps for our application, although only one is required. In fact, it appeared during our research that Breeze or its parent company may have actually been suppliers of this clamp to the government as 4730-00-204-3491.

October 20, 2018December 20, 2018

The Rear Spring Clips, or “Why so expensive?”

Without a doubt, on a weight basis, these are the most expensive part of a HMMWV. The Parts Manual calls out for six spring tension clips 5340-01-209-7808 [5340012097808].

Figure 149 showing location of CLIP,SPRING TENSION REAR (“G”)

We were only able to source these clips from a single vendor, and they wanted over $10.00 each plus shipping. We sent RFQs out, and prices came back as high as $35.00 each. We then searched brake clip and fastener vendors to see if we could identify a cheaper source or a suitable substitute and were unable to locate any.

The only purpose these clamps serve are to attach the vent lines from the hubs and differential to the brake lines to keep the vent lines from becoming detached or torn off. We found a suitable (but not necessarily authentic) method of attaching the vent lines to the brake lines.

LH Rear substitute “G” clamps
RH Rear substitute “G” clamps

Although we would have preferred to use the proper clamps, the end result is virtually the same. Spending $60 to $210 for the proper clamps in these locations simply was uneconomical and would have made no sense. Should we locate a source for these clips or a more suitable substitute, we will update this section. Needless to say, these clips are not visible once the body is installed.

Keep in mind, however, cable ties are not totally incorrect for a HMMWV. There are several call-outs in the parts manual for use of cable ties (e.g., STRAP, TIEDOWN, ELECT 5975-00-074-2072 [5975000742072] — used to hold hoses together).

October 20, 2018December 19, 2018

Vent Tubing: Hub, Differential, Transmission and Transfer Case

Our project vehicle had been stripped of most of the vent lines, and some it appears may never have been correctly installed. (See: missing fitting and hose on front differential vent caused water infiltration).

Accordingly, we had to source and locate replacement or substitute hose and tubing for installation. All of the hoses and tubing are indicated in the parts manual as either P/N CPR104420-1 or P/N RB1450-1-4IDX1-20D.

Upon visual inspection, CPR104420-1 was identifiable as air brake tubing used on semi-trucks. One of the brand names for this is an Eaton product called Synflex®.

Synflex® used to vent rear differential and hubs and transfer along frame.

Upon further research, it was determined that CPR104420-1 is 1/4″ diameter tubing. (note this tubing is measured by O.D., not I.D.) Whereas CPR104420-2 is 3/8″ diameter. (CPR104420-2 is used as the main tube running parallel to the frame to vent the fuel tank).

We were able to identify RB1450-1-4IDX1-20D as being manufactured by Armstrong, and carries an NSN for bulk lengths as 4720-00-684-4033 [4720006844033]. This essentially is a durable 1/4″ I.D. hose, which has the appearance of 1/4″ fuel hose or similar.

There is a number of vendors that make a suitable replacement, although we noted the caveat of not using fuel line because it may not remain flexible enough over time for use on the front hubs. (they will constantly be flexing as the vehicle is steered).

It was suggested to us to consider use of silicone vacuum or vent hose. Silicone hose was simply not readily available at the time of manufacture and design of the HMMWV. Vendors cautioned against using silicone hose for oil or fuel carrying. The primary reason for not using silicone for fuel is that it simply isn’t rated for pressurized fuel. We determined that 1/4″ silicone hose would be appropriate for venting purposes, and noting its widespread use in commercial and agricultural applications gave us a level of comfort of its reliability.