I finally have made some time to get some work done on these M105A2 trailers I recovered last summer.
I started with the best one and used it as my test subject. I wanted the M105-series because the bed is large enough to haul my quad and its associated gear without any trouble or effort. But, the air-over-hydraulic brake setup had to go in order to register it in my home state of Nevada (all trailers that weigh over 1500-pounds MUST have brakes on every axle). Electric-over-hydraulic actuators are widely available and would be an easy conversion, but they are very expensive and won't be feasible across 5 trailers!
I did find a great deal on some DICO Aero surge couplers with 2-inch ball hitch on a popular auction website, so I bought 3 of them. The master cylinders on these surge couplers are very similar to the master cylinders on the M105A2 trailers, and in fact I used the threaded cap from one to use with my pressure bleeder for the surge coupler. I may in the future purchase one or two of the more expensive heavy-duty surge brake couplers with the adjustable lunette hitches on them, but we'll see what happens after I finish converting the first 3 trailers.
So, for the first trailer, I welded on some heavy angle steel brackets under the front of the tongue, and drilled them out to accept 4 5/8-inch Grade 8 bolts, and used a piece of heavy 3-inch steel tubing to mount the surge coupler to (with more Grade 8 bolts). My intention here was to make the hitch removable so I could bolt it into a cradle on top of the trailer tongue and reinstall the lunette eye for my Deuce to tow it with, if needed.
After stripping out all of the air braking components and everything else I wouldn't need on this trailer, I fabricated clearance marker light brackets out of steel angle and welded them in place. I added regular civvy 12-volt LED clearance marker lights (amber in the front, red in the rear) to comply with DMV requirements. In the back, I left the 24-volt lights and wiring in case I tow this trailer with my Deuce, but added brackets to mount 12-volt LED tail lights (I have switched tail lights to better, more rugged ones than the ones shown). In the very back of the trailer, I needed to add 5 horizontal red marker clearance lights, so I used some 3/4-inch-diameter LED marker lights from another popular auction website vendor (these little lights are AWESOME! Very bright, and low-profile so that they can avoid being damaged...they've held up remarkably well so far!).
All wiring was soldered and double-heat-shrunk-protected...I staggered all solder joints so that they wouldn't rub against one another and cause a short in the future, since this trailer will be used for lots of off-roading in the desert. All wires were then wrapped in plastic conduit flex-wrap, and thoroughly taped up to keep the elements out. I caulked the back of each light where the wires exit to seal those as well. All wires are secured with vinyl-coated wire clamps bolted into the body and/or frame to keep them out of harm's way.
I removed the brake drums & hubs from each side to inspect the brakes. Everything looked brand-new and showed little use (each shoe thickness was more than 1/4-inch all the way around), so I re-installed the hubs & drums, packed everything full of fresh grease, then adjusted the brake shoes. I installed a hydraulic brake line from the surge coupler all the way back to the "T" fitting on the axle, flushed out all the old crap from the brake lines, and then pressure-bled the brakes with fresh DOT-5 BFS. I also adjusted the emergency hand brakes per the TM instructions; I can drag the trailer with my truck and the wheels stay locked up when empty. During a drive test in a nearby parking lot, when doing a firm stop from about 35mph, the rear trailer wheels will lock up when empty. So I figured I got something right at this point!
On the body, I removed all the rust spots I could and touched it up with Krylon & Rustoleum camo rattle cans.
Then off to the DMV, where it passed inspection with flying colors and I was able to get it registered with no problems. Now on to the other 2!
