Trailer Project
Serpent Express Retro Kit (2 of 3 posts)
Vinyl Top
Initial sneak peak of the top in its box, looking good! Laid out the top on the deck to acclimate with garage temp turned up. Set top over loosened frame for continued acclimation. Corners and peaks settled into place nicely.
Top in box
Top laid out
Top on frame loose
Fastening Top
My Aluma had 3 fastening typical scenarios, front, front corners, and sides. Front being most challenging.
The front frame is 2” x 5” aluminum requiring longer drill bits. Has a center channel underneath, with ½” wide channel access exposing the true bottom an inch up into the channel. Also reinforced with internal structure, so drilling was more difficult.
It was critical to drop the bolts centered in the channel to get washers and nuts on w/o cutting the ½” channels open. By aligning foam tape to the outer frame edge, that was a hard reference point, dictating the base bar and clamp, and therefore clamp hole, locations. I centered the base bars on the foam, snapped the clamps on, and marked the holes where they naturally fell.
Fortunately, after drilling those front holes, they dropped through ‘dead center’ into the narrow channels below, allowing me to (barely) fasten them. It took fingertips, taping washers in place, and several tries to thread the nuts.
It took various wrenches to manage inside the channels, and taped wrenches until I got in place with both upper and lower wrenches, and various extenders, but managed all myself. A sense of accomplishment on those front bolts.
Front channel and holes
The front corners just required specific length hardware, yet were easily accessible.
Front corner holes
The sides were middle of the road challenging, and there were a lot of them. I computed hitting centers on the variable-width underside structural cross channels, by using 9’ hole spacing. Centering those maximized the tight fingertip access and allowed for large washers.
I set weight on the bolt heads to get 1-2 threads to protrude below to start the nuts, and avoid popping-up when barely touched. Taped washers on (using a guided missile type blind thrust with one fingertip, many tries on the most challenging locations) and the threaded nuts blind with fingertips. Tightening allowed more threads to pull down as the foam compressed.
Side holes
Used a roto-hammer in drill mode worked well, especially on the more challenging fronts with long bits. Used blue tape for marking on and keeping bits from traveling. Did 5-6 steps from small pilot bit up to final hole bit for the ¼” deck bolts. This kept the bits under control and achieved accurate holes/locations.
Started with big box store Cobalt bits and cutting
oil, wasn’t doing the job and breaking smaller bits. Got fastener specialty store Cobalt M-35 steel bits and Boelube Paste, a Boeing developed drilling & cutting lubricant. That setup worked very well, no more broken bits, lubricant paste stayed on bit no mess and superb drilling effectiveness.
Roto-hammer, Boeing lube and instructions
Larry included extra clamps in the kit, for 50 total. I used all 50 given my spacing used. The top’s 5 access doors allowed doing all but a handful of the fasteners by myself. A lot of twisting and stretching, fit by feel, various extensions, seemingly always upside down, but it all worked.
Base bar clamps loose
Base bar clamps fastened
Base bars fastened – outer corners
Base bars fastened – outer sides
All hardware was stainless from McMaster-Carr. Was very happy with their stainless flanged nylocs with black nylon. I found a group of tools that managed the deck fastening pretty well, per photo.
Hardware & tools
Fastening Frame
With the base bars fastened down, it came time to drill, place, and fasten the bolts in the welded deck uprights. These go through both the fitting tubes and inserted conduit frame uprights, to hold the frame securely in place. There is a small amount of play by design.
One decision was whether to drill before or after the top was tensioned. If after tensioning it seems they would take their natural shape and have less fastened tension (maybe good with aluminum fittings). However, doing them first would make managing the remaining frame easier and more stable. After much back and forth, the answer presented itself.
I could tell I was going to need to use some extension all around to tighten/smooth the vinyl top. So, I did those deck fitting bolts first, pressing each upright to its outermost play position in the fitting while drilling (the corners pressed out at 45 degrees). This was done with a kneel pad and my head, both hands on the roto-hammer.
The 4 corner upright bolts are spec’d carriage bolts with smooth rounded heads to avoid damaging the top. Those ideally require squared holes. I used a Dremel and mini files to square out the corner fitting holes.
Corner round hole
Corner square hole
Dremel & mini-files
Bolted - corner
Bolted - non-corner
Initially I tensioned the upper frame slightly front to back, tightening connectors as I went. Not so tight as to over stretch it. Just to smooth it out some, I will retension the top after some trips with vibration and weather cycles. I’d left the top in its box for months before starting, so there were some fold lines. Many came out during acclimation and initial tensioning. The rest will work out with use and retensioning.
Top initially tensioned
Rear Door
I put a lot of thought into the rear door hold down. The standard spec is to drill holes in the side frame for the rear base bar to protrude through with trailer clips on the outsides. That works pretty well. However, it seemed to be a single fixed position that could be under/over tension depending on the fitting height or if the top stretches. The ones I’ve seen were almost over-tensioned, and tended to expand the holes in an aluminum trailer frame due to wear over time. Also, releasing the rear door can be a two person job at times, particularly if the bar sticks in the pouch, and puts added movement in the top and of the base bar in the pouch which all can tend to wear more over time. Granted, with a fixed position base bar, one can always re-tension at the upper rear frame, yet I was looking for a more real time flexible door fastening solution.
My goals included no side-to-side material movement to open, and an easy, one person, variable tension fastening method. Stainless steel Terry Body hold down springs & hooks were used to hold the rear door down with a firm and flexible tension approach in basically a straight down hold fastening solution. I used a shop for winch mounting and rear door fastening solution. They came up with this rear door solution without hesitation as I was explaining the goals!
As opposed to the ½” hollow conduit (which is a bit over 11/16” OD) as typically spec’d, I first planned to use a ½” solid aluminum round bar in a 6061-T6-cold finish which has 0.50” OD. However, as the shop recommended, we used flat aluminum stock with dimensions 1-¾” wide x ⅛” thick. That used more of the tall rear pouch for added rigidity. It was thinner, so dropped the bar/pouch perfectly into the rear channel in my trailer design without being tight and scuffing/wearing the vinyl pouch.
My Serpent door was specifically designed to extend a bit past the deck to drop into that channel given my trailer’s design. This all worked to create a pretty good natural weather seal for the rear door. Also, the mounts used for the tension fasteners bolt through the flat bar putting the downward force on the bar. The ends of the bar don’t extend past the pouch so it has a clean appearance, plus the bar won’t slide out with the through bolting.
My goals for opening and holding up the rear door were a simple, competent means that’s easily workable by one person. Again, the shop came up with an elegant solution. It was achieved using 24 lb neodymium magnets and nylon straps on each side. One magnet is attached to the upper inside frame with a nylon strap attached to it and another magnet attached to the loose end of the strap. The door is rolled up and the straps wrapped around with the loose end magnet attaching to the fixed frame magnet, magnetically clamping through the vinyl top. It holds firmly and is simple to manage in seconds by one person.
The rear access holes in the side base pouches, and the hollow side base bar ends seemed exposed to weather and grime. I installed metal conduit caps to protect those. That left small pouch openings above the base bar. I may fill with a clear sealant, maybe Flex Seal. I’m not going to worry about it on the rear door base bar pouch. There is a slight open area at the rear corners below the end of the door zipper. I’ll monitor that and either not worry about it or may cut some foam or such to insert on the inside to block when the rear door closes for a complete weather seal.
Rear door - flat bar hold down with tensioners
Rear magnetic door holder straps
