Trailer Time

The U-Haul tow dolly that I rented recently was $100 for 2 days use. It towed surprisingly well behind the van, but could use brakes. What made me think about building my own trailer were several posts on message boards about lightweight trailers. Here's one: GRM

There's pros and cons to building a single -vs- tandem axle trailer. Tandem axle trailers are heavier, more expensive but supposedly are more stable, can carry more weight and having a pair of tires either side ensures redundancy should you ever have a blow-out. The blow-out scenario is the only thing that gives me pause when I think about building a single axle trailer. For all other purposes, and especially considering the weight it's two wheels good, four wheels baaaaad (hah! Animal Farm).

So, I've been working on plans and pricing for a single axle trailer this week. I called Halbert Steel here in town - the steel should run $300 - $350. I stopped by Arkansas Trailer and a 3500# torsion beam axle with electric brakes will be $340. I'm over-rating the load capacity of the tires (that fear of a blowout again), a brand name set of 15" radial tires with "D" load rating (north of 2000# per tire) should be around $300 for the tires and wheels. So that puts me at about $1200, plus $100 for an electric brake controller and $100 - $200 for a sway controller. That's 15 weekends worth of U-Haul dolly rental. Is it worth it? I'm sleeping on it.

The other thing that concerns the dirtbag in me is this: what if I need to sell the trailer? I would think a single axle car hauler could be a difficult sell - a tandem axle is what most people want. I console myself with the thought that it's going to b at least 200# lighter (important since the tow rating of our van is only 3500#) and cheaper to build (by $400 - $600 would be my best guess).

I have a few other projects to complete before this one can grow wings, hopefully Harbor Freight will have their trailer accessories on sale before I start building!

As far as the design, I've decided on an open deck (12 - 18" wide strips for the tires), 14 feet in length and 6 feet wide with a 4 foot long tongue. I could go narrower but I'm worried I won't be able to get the car doors open, esp. if the trailer wheels are in the way. I could go as short as 10 feet, but the extra length is good for times when I need to balance the load on the tow hitch.

Most of what I've read says the tongue weight should be 10 - 15% of the trailer weight. i modeled this last night with the wife's kitchen scales, an 18" ruler and some rocks my daughter grifted from the local park. Knowing the corner weights and wheelbase of the car helped a lot. I ended up with the trailer wheels 7 feet back from the front of the deck, ie in the dead center of the deck.

I've also heard a rule of thumb is that the wheels should be one inch behind the centerline for every foot of deck length. Sounds confusing, but for a 14 foot trailer, the axle should be 14" behind the center line. I'll stick with the rocks and ruler method for now.

I've got a Google Docs spreadsheet going with my trailer design, weights of materials etc.