Trailer build rev 2, possible production

EDIT: For pictures check out post #25.

This is the second trailer I've built. The first one I built can be viewed over in the original Trailer Build thread. I incorporated some changes with this one, mainly the suspension. The 500# torsion axles I put on the last one were just too stiff and I wanted something that would ride smooth even with only a little weight in it. I'd like to get some feedback on this thing so I'll start posting some info and pics. Ultimately I'm considering trying to make this into a production trailer but I'll expound on that later.

I decided to go with a trailing arm suspension with hydraulic damping. I used LED lights again, but mounted them on the frame instead of the box this time. The cargo box I'm using is a SportRack SkylineXL and the plastic seems thinner and less sturdy than the old Sears box I put on the other trailer so I opted for a stronger mounting point, plus I didn't want to run the wiring inside the box on this one if I could avoid it. I ran all the wiring internally of the frame so nothing is exposed except the pig tail. I wanted to do that on the old trailer but capped the tubing before I remembered that was my plan! I don't ave any pictures with the box on it yet, those will come, I just didn't think to snap any during my fit-up.

I haven't put the box on it yet because I've been doing some test video to see how well this thing rides. So far I'm rather impressed. When hitting a large pot hole or hump it can get a wheel off the ground, but when it lands again it doesn't bounce but stays nicely planted. When I weighed all the components the total weight came out to about 130-140 lbs. I'd have to go find my notes out in the garage for specifics but I believe the cargo box is about 30 lbs or something, so the trailer frame itself (as I'm testing it) is about 100 lbs or a bit over. For being entirely empty I've very pleased with the performance, since it should only improve when more weight is added with the box/cargo. I've been trying to film the trailer without the box installed to be able to see how the frame and suspension react to the road. I'll add the box once I'm done.

I filmed a ride pulling the trailer with my GoPro attached to the bike but I had two issues: 1) large bumps the bike rode over would jar the camera too much and shake the whole image to the point where you couldn't see how the trailer reacted, and 2) I apparently haven't figured out how to use the GoPro software because when I imported the files and deleted them off the camera, they also go deleted from the computer when I closed the program. Today I attached the camera to the back of the trailer with a magnetic mount I made up and got some decent footage from the trailer's perspective to get a better idea how smooth things are. One thing I learned is that magnetic mounts aren't very strong on thin wall steel. The GoPro took a tumble down the road and thank God it survived even though it came out of the case. It lives to film another day but my testing is on hold until I acquire a replacement case unfortunately.



I'm going to keep posting info as I figure things out, but I would like feedback from people in the community. I'm seriously considering trying to manufacture and market this thing commercially. I'm thinking I could fill a gap in the market between the cheap ride-like-crap Harbor Freight tag along trailers (that also look terrible in my opinion) and the expensive trailers that actually ride nice like the Bushtecs ($3,000+).

I had a few goals in mind in building my own trailer: 1) build a trailer that rides like the high end trailers and won't beat up my camping gear, 2) looks professionally build and not like some home hack-job (what I think the HF trailers look like), and 3) be as affordable as possible. The main thing that allows me to get the price down is using a roof top cargo box instead of a fancy custom fiberglass shell. While it's not as pretty or aerodynamic, using an off the shelf cargo box is a heck of a lot more economical. I've gotten a lot of positive comments from people that have seen this thing and encouragement to try building them. I'm thinking I'm probably not the only one that wants form over function (but with limits on how low they will go on the form) so that's where I'm wanting your feed back. I'm thinking I could build these and sell them somewhere in the neighborhood of $1800. I don't know if that is a reasonable price, but it's my starting point based on what I've seen on the market and my current estimates for production costs.

One thing I know I would have to change to my design is the lights. To meet FMVSS the lights need to be a minimum of 15" off the ground; right now the tail lights are about 10" when attached to the bike and the amber market lights are about 13" or so. I'm thinking to solve that issue I could basically build a "bumper" that rises behind the cargo box instead of sitting under it. That will make more sense when I post a picture of the trailer with the box on. Raising the tongue (like a dog leg up from the box cradle area) could get the amber lights up too. If I shorten the tongue length to get the whole trailer length under 6' I don't have to worry about amber marker lights, but I want to leave enough room where a cooler rack could be installed in front of the box (I'm thinking an accessory option, since I don't personally want the cooler outside the cargo box.

I'll try to fop the box on the trailer and get a couple pictures tomorrow, but I will note that the bolts that hold the box to the frame also secure D-rings inside the box for securing cargo; six total.

Okay so I got a few more pictures and some more specs. Total width to the outside edge of the fenders is 58", wider than I would like but necessary to nest the shocks between the box and the wheels with the box so low to the ground. Total weight is actually less than my old trailer! Grand total comes in to just a hair under 136 lbs with box and mounting hardware. Empty weight distribution is 120 lbs on the axles and 16 lbs on the tongue.













So what do you guys think?

I think it's cool. I'm assuming the box would be easy to paint. You know how people want stuff to match.

I suppose that would be an option. Paint would have to be very flexible as the plastic flexes a lot when the box is open. Personally I like the grey plastic; no worries of scratching a fancy (and expensive) paint job and it won't fade in the sun. I was thinking of offering colors for the frame, but not really the box. Keep the ideas coming.

Very interesting project.

It may be just the photo perspective but the trailer tongue looks very long?

Also, how much clearance is there between the trailing arms and the cross member? It looks like the trailing arms might hit the cross member on a large bump.

Yeah the tongue is long. I did that so there would be room to mount a cooler rack if I ever decide to and to help keep the tongue weight manageable and more forgiving for weight distribution when loading the box. Empty the tongue weight is about 13%. The trailing arms will come up to about 1/4" from the cross members if the shocks completely bottom out. If I remember right, there's about 3" or 3.25" of wheel travel.

Can you mount the lights on the wheel fenders, would that get them high enough?

I think for that price range, your competition will be this: https://www.kompactkamptrailers.com/#!kadette/c1mn6

I am in the process of restoring one, and it does not have a metal framework underneath, just the torsion axle and the tongue/jack. The torsion axle is a 400# The box is reinforced with plywood and covered with resin, then bolts directly to the axle with 3 or 4 bolts. Also, what kind of electrical plug are you using? We use a 5 pin round. Maybe this pictures will help you if you decide to change anything.

Axle



Underside

What is the advantage of the 5 pin round plug? I have a standard 4 pin flat so a ball coupler can be put on and it can be towed behind the car.

Unlike a car, a motorcycle doesn't have the integrated brake/turn signal output, so you need 5 wires to run all of the lights.

eflyguy said:

Unlike a car, a motorcycle doesn't have the integrated brake/turn signal output, so you need 5 wires to run all of the lights.

Click to expand...

You also want an isolator to protect the bikes wiring system. Also, very nice work. What are the dimension between the shocks? And overall length?

eflyguy said:

Unlike a car, a motorcycle doesn't have the integrated brake/turn signal output, so you need 5 wires to run all of the lights.

Click to expand...

Well ... not true. I have a 5 to 4 converter. I can tow my trailer with my bike or my car.

Yes, if the converter "merges" the independent signals to traditional trailer wiring. I meant without additional hardware.

Standard 4-pin is:

Ground

Running

Left

Right

... and brake is left and right at the same time.

On the MC, we need:

Ground

Running

Brake

Left

Right

5 pins.

Assuming that you want the least possible aerodynamic drag from the trailer box, you might want to reverse the box so that tapered part is trailing and build some type of a rounded front faring ahead of the square end. I know this is somewhat counter-intuitive, but the largest part of drag coefficient is not pushing the air ahead of the object, it is from the vacuum you create in its wake.

Good point with the brake/turn signal thing. I put one of the converter/isolator kits on the FJR so I don't have that issue. Guess I forgot it has five inputs!

Overall length is just over 7 ft. and the width between the shocks is about 41 inches.

Yeah, now that is the way to do it so you can use the trailer with cars as well. I've actually thought about building a trailer to pull a single bike, that I could pull with my FJR.

(As well as with a car)

This trailer towed beautifully out to Colorado for NAFO last year, but when I got home the tires were about toast after 3000 miles. Finally got around to digging into the alignment today and found the right wheel had about 1/8 toe in between the leading and trailing edge of the rim. That explains it. Got it corrected now just need to clean it up so I can sell it! I have a few ideas I want to try for a version 3, especially now that I have the equipment to weld aluminum.

Well, trailer is up for sale. $1,100 if anyone is interested. Got the toe corrected so the alignment is correct now (should have double checked that BEFORE going to Colorado). I added a cooler rack right before heading out to Colorado so I haven't posted any pictures of that addition yet. Let's see if I can post a picture...seems my previous pictures on PB are still working for now.

Someone needs to find a new photo hosting site.