Plans to build a Trailer for a Motorcycle to tow?

Hey everyone,

I want to build a trailer that my motorcycle can tow. I'm hoping to create it from aluminum, but I've never built ANY trailer and any and all (well, most all) suggestions from the group would be gladly accepted.

I'm unsure about the axle / wheel set up for something this small and finding a pre-made trailer that I could modify is nearly impossible without spending a fortune.

This trailer will be a flatbed approximately 2 1/2 feet wide and 5' long. I suspect I'll never be carrying more than 250 pounds on it.

I'm a sculptor and sometimes I need to head to a gallery 300 miles away... so, I thought, why drive my 6000 pound truck when I can ride my 45 mpg motorcycle.

Thanks!

James, Seattle, Washington, USA, Earth

www.jameskelseystudios.com

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RainLover wrote:

Build it as a sidecar instead. More stylish, and you'll probably be able to find an existing design to copy.

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I'd spend some time at motorcycle shows, and get ideas from commercially made trailers...

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Start by looking at the design and construction of trailers similar to the one you are envisioning. Before starting, consider the unit will prolly have to be DOT certified, and consider the legal aspects should something go wrong. JR Dweller in the cellar

RainLover wrote:

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RainLover wrote:

There are a number of motorcycle trailers out there, ranging from single wheel types that are basically a suitcase with a hitch and a wheel to stuff that looks like half of a Gold Wing. But none that I'm aware of that are flatbed cargo carriers. That being said, there's nothing about motorcycle trailers that is particularly special other than that they have to either lean with the bike or not lean completely independent of the bike. Most of the two wheeled trailers I've seen use a hitch that will rotate perpendicularly to the direction of travel. Something like a U-joint is typically used.

Suspensions are all over the place, ranging from none to torsion bars to rubber biscuits. You definitely want to build something that's not going to bounce when it's empty or you'll get to stress test your health insurance.

Something like this: http://tinyurl.com/ycdqwk might be worth looking at for ideas if nothing else. On the other end of the spectrum of design is this: http://tinyurl.com/2sbmam No dealers near you that I know of and they're half a continent away, though.

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RainLover wrote:

James, my sedan is in the shop right now getting a new transmission.

See, I figured I would save a mint by towing stuff in a trailer rather than renting or borrowing a truck.

That misapprehension will cost me U$3600 (Three thousand six hundred dollars) this afternoon.

Even at Silicon Valley prices, I could have rented and gassed a truck for over *fifty* (50) trips for that amount of moolah. (Sad when you consider I rented trailers a total of four (4) times.)

Please learn from my mistake.

--Winston

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One assumes that your car has/had an automatic transmission and you didn't lock it into gear?

Not relevant to bikes :-)

Mark Rand RTFM

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Mark Rand wrote:

Correct.

Why is that? (Think clutch and brakes). Practically every part of the bike will experience larger stress values when towing a trailer than without it, yes? The engine and transmission will have a load placed on it the same as if it were headed uphill when accelerating and downhill during deceleration, due to the additional mass.

Don't even get me started on the dynamics of safely converting the kinetic energy of the trailer into brake heat on deceleration or the potential for 'whipping' if the trailer is not loaded properly or if the trailer wheels are too far forward or not properly aligned.

Seventy bucks rents you six times the payload capacity in the form of a nice new pickup with enough gas to do the average chore safely and quickly.

I'm here to learn, so feel free to correct me on this, (but first think about how often you will need to back up, uphill.) :)

--Winston

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On Wed, 02 Apr 2008 21:08:19 +0100, Mark Rand

Well, not literally, but pullin' a trailer behind a bike does come with a price, sidehacks too. They're not really designed for such shenanigans, but with a religious dose of preventative and regular maintenence, it can be done safely.

Wheel bearings and tires take th' brunt of it first. Ya just have to stay on top of those. Swing arm bushings/bearings take a hit too, as well as steering neck bearings. Some of those items ain't easily replaceable, or even serviced, either.

I pull one of these: www.uni-go.com/ but it doesn't have anything close to a 250 lb net weight cap. That little bugger doesn't weigh that much fully loaded, gross.

Snarl

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wrote:

Picking on "Winston" section:

Enlighten us about your 'mistake', Winston - What kind of sedan, what kind of trailer? Age, powertrain type and mileage on the car? If it already had 150,000 miles on the typical automatic, the transmission going out may well have been normal wear and tear, and the trailer may not have had anything AT ALL to do with the failure. Or you didn't know to TAKE IT EASY when towing at the ragged edge of vehicle capacity, and killed it through abuse.

Clue: When it was my daily driver, I towed small trailers all the time for years with a 61 Corvair - 102 HP air-cooled (fan forced) and 2-speed Powerglide. When done correctly size is not a consideration, you just have to remember to leave plenty of room.

Did you have an auxiliary transmission cooler on the car? The one in the radiator is not enough if you are towing.

(I had to change the transmission rear cover on the Corvair to a Truck/Greenbrier rear cover to get the trans cooler fittings - Car cases didn't have the fittings, just a bypass slot.)

Did the trailer you were using have brakes? Same thing, it's a given on large trailers towed with large cars (Legally Required on any trailer over 2,000# - 3,500# - check your state laws) but should be installed on small ones towed by small cars. It saves both the car's brakes and the transmission if you were downshifting too much and too hard.

* * * * * * * * * * * *

General Design thoughts section:

Rainlover: What kind of bike do you plan to use for towing? Liquid or air cooled? Wet or dry clutch? Can you install larger radiators and/or fans? Aux oil cooler? Aux trans oil cooler (if it's a divided sump)?

Can you get an oversized charging coil (alternator) for it? (They do make them for Harleys, big Beemers and Kawasaki 1100, the extra juice is needed to run the radios and lights on police bikes.)

They started making small trailer axles with brakes (both electric and surge) for large tent trailers, the same brake parts can be applied to a ~36" - ~48" wide axle for a motorcycle trailer. You call up Dexter Axle or one of the other actual trailer axle makers and tell them exactly what you want, give them a Credit Card, and in a week or three a truck pulls up to your house with a big heavy box.

The usual tackle for that size trailer would be 4.80X8" tires on 8" x 3-1/2" rims, 4 on 4" stud spacing, and they would give you 1080 pounds capacity for trailer and cargo. Using 4.80X12" tires gives you a lot more room for brake drums (and a bit more weight capacity) but would raise the trailer up a bit.

Those two standard size tires are available almost anywhere (Wal- Mart etc.) if you blow one, but you still want to carry a spare.

And if you want the Center of Gravity to stay really low, they make rubber torsion-box suspension axles (Dexter "Torflex") rather than standard leaf springs & slippers - though you have to watch your chassis design (and make the main rails a bit heavier) as there is a much higher torsional load since it's one attachment point ahead of the wheel center line.

You can even get the rubber spindle/suspension units as two separate stubs without an axle shaft between them, and have the box/bed between them practically on the ground - this is how they build the "Drop-bed" utility trailers that lower onto the pavement. But that's going to produce even higher torsional loads on the chassis rails, which will need to be stress engineered so it won't make like a pretzel going down the road - which is bad...

No surge brakes on something that small, I've never seen a tongue for them that will swivel... And you really do need a way to activate the trailer brakes by hand that surge just won't do - unless you trip the breakaway arm, but that's a one-shot deal.

You could go with the new "Electric Hydraulic" brakes (Carlisle "Hydrastar" or Dexter Axle "ElecDraulic") if you can take a ~20-pound weight penalty for the electric pump unit on the trailer (and find a place to put it) - they use hydraulic disc brakes on the trailer axle that are a lot easier to maintain.

The electric brake controller could be a bit tricky to spec on a motorcycle, I would NOT use a straight inertia controller - it might mis-read the front fork dive and over-brake the trailer. And the 'Sandwich' pressure sensor that goes on top of the brake pedal is out, it won't fit on the brake lever.

They still make the kind of electric trailer brake controller that has a pressure sensor that tee-taps into the brake lines for a proportional braking signal, but I'm not sure whether you would tap it off the front or rear brake circuit on a motorcycle - your hands are trained that when the rear of the bike gets squirrely you ease off the back brakes, and IMO that might not be the right instinct if a trailer started to jackknife and push the rear end around.

When a trailer starts getting squirrely behind you, you want to apply MORE trailer brakes (up to lock-up) to get it back in line. And if you have room you ease off the tow vehicle brakes till it quiets down - but not if you are in a Panic Stop situation.

You might want to remote the "Panic Button" for the electric trailer brakes "Full ON" to a thumb button (like the horn) you can stab while keeping both hands on the grips. On a car it's a lever or a button on the front of the brake controller under the dash, but taking a hand off the bars in a panic situation could be a very bad idea.

--<< Bruce >>--

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Bruce L. Bergman wrote:

(...)

D'oH!

2000 Toyota Camry 4 cyl. 4' x 6' steel rental trailers. 3 speed automatic with overdrive. ca 120 K on the clock.

I now suspect that towing a trailer is abuse. Live and loin.

Ah. Now he tells me. :)

Never!

Downshifting?

--Winston

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wrote:

Don't worry, I'll be gentle. I'm here to "learn ya" and anyone else who reads along might pick up a few valuable pointers for later. It's simple to not abuse the equipment, just takes some forethought.

Well, you said elsewhere that the final drive gears ("differential") went south. Those normally don't *ever* die. Who has been doing the oil changes on the car - You, the Dealer, or (this is the one that can be big trouble) the untrained teenagers at the local 'Spiffy Lube'?

Some of the Toyota front-drive cars are tricky, and I'm not sure if yours is one of them - they use ATF in both the transmission and as the gear lube on the differential compartment side of the case. So you'd pull a drain plug and see red fluid coming out and figure it's coming from the transmission... But there is a divider and an oil seal between the two compartments, and a separate fill plug.

If they (or you) drained the ATF from the diff side and didn't know they have to pull a pipe plug and fill the other side of that divider with ATF too, your final drive gears could have been running dry - and that most assuredly WILL quickly kill them.

Heck, I've been screaming that one from the watchtower for decades - the fluid-to-coolant transmission cooler inside the radiator is NOT sufficient for towing, they can only get down to slightly above coolant temperature, and that can still be 240 degrees on the cooler output... You need a fluid-to-air radiator style cooler to dump the mass quantities of heat you'll need to get rid of.

And every welding and hitch shop I've ever visited has big posters up - of course, they're also /selling/ and installing the coolers, but they make sure you know it really is necessary.

The only time the added cooler isn't needed is when the car already has the factory towing package with the added cooler. And while a lot of SUV's and trucks come that way, most small import sedans don't.

The other "Towing Package" items like the oversized radiator and more aggressive fan & fan clutch you can live without - if you take it easy and watch the temperature gauge like a hawk when climbing hills - and back off if the needle starts climbing. And if you ever have them replaced you use the HD parts.

Same thing with the HD alternator & battery for little utility trailers like that - but not if you're driving a lot at night with the added tail and stop light loads, or trying to power electric brakes and recharge the 'house battery' on a travel or tent trailer between overnight dry-camping stops. Then you do need an oversized alternator to put out enough juice to get them both charged without starving the car's starting battery.

You have to ask for a trailer with brakes. On a rental, they are likely to be hydraulic surge trailer brakes, with a controller/master cylinder built into the tongue coupler. They work fine for normal uses, and require no special equipment on the car.

Note that some rental equipment companies (coughU-Haulcough) are notorious for (among *many* other things) renting trailers with non- functional surge brakes, even after multiple reports from prior renters that they don't work. Pop the fluid fill cap on the master cylinder and it's dry as a bone - but the inspection sticker was checked off last week...

If you want to test surge trailer brakes do not engage the reverse lockout lever on the controller and try backing the trailer on an uphill - unless it has the extra cost brakes that don't engage in reverse (doubtful on a rental) it should fight you with much chirping and chattering of tires. Or pull on the Breakaway Cable till it locks and try driving forward, same fight. You have to push a latch to release the breakaway lever.

Oh, and the breakaway cable DOES NOT EVER hook to the hitch or bumper where you hook the safety chains - the whole shebang (bumper hitch and brackets) can and does fall off occasionally, and if the cable is clipped on the bumper the breakaway will never activate...

Tie the breakaway cable off to either a permanent 1/4" or better forged eye-ring into the body (a nice place to "hide" a permanent one in plain sight is to double holding on the license plate) or a heavy nylon webbing strap tied to the trunk or tailgate latch assembly.

The ring or strap will snap too, the forces are too great - but it has to be sturdy enough to snap only /after/ pulling that breakaway lever into the latched position, or pulling out the breakaway switch pin on an electric brake trailer.

Trucker's Rule: You go down the hill in the same gear you go up it. You can relax that rule in a passenger car or pickup, but not by much. Especially if your trailer is near or at the maximum weight allowed for your car.

On the flats or a slight uphill, if the engine hunts in and out of OD, lock it out and stay in 3rd. And if it hunts in and out of second or first climbing a hill, lock it in the lower gear and you can ease off the gas a bit, get better fuel economy than when your foot is planted flat on the floor. Repeated shifting under full load is bad, heats things up a lot. Worse when the torque converter has to unlock before the shift, the converter makes a LOT of heat when it slips.

Let compression braking keep you at a safe downhill speed, you drop out of Overdrive into 3rd or 2nd to hold a steady speed, and you shift at the top of the hill so you aren't slamming the gears and rapidly zinging the engine RPM's up when the shift engages. If it's going to be close, tap the gas and increase revs as you downshift so it drops in easy, then remove the gas.

Keep your feet OFF the brakes going downhill, downshift and let the engine do most of the work except for tapping the brakes to trim speed. If you ride the brakes hard down the hills and get the brakes red hot, and then need to make a full stop they May Not Work - heat fade and/or boiling brake fluid may make the brakes go partially or fully away.

Needless to say, This is Not Good - start looking around for the "Runaway Truck Escape Ramp" signs at the bottom of the hill, you may be learning how they work "up close and personal"...

(Pea gravel, two or three feet deep. Steer for the center. When you come to a stop get the hell out of the car and on the other side of the safety wall NOW, in case another truck comes in after you do.)

Not to mention when riding the brakes on hills you'll chew through brake linings and rotors/drums at a frightening rate. If you hot-spot or warp the rotors/drums they can't be turned, only replaced. They ain't cheap, especially if you pay someone else to do the brake work.

If you don't have a tachometer to watch it, be sure you know the maximum speed for each gear and never go faster down a hill than the engine will let you accelerate in that gear - it IS POSSIBLE to over-rev the engine to destruction on over-run, because the rev limiter can only cut fuel - and going down a hill the weight of car and trailer is pushing you faster without adding any fuel.

--<< Bruce >>--

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"Bruce L. Bergman" wrote:

<lot of good stuff snipped>

The executive summary: Towing with most any *car* is risky at best, especially in these days where high MPG numbers mean no safety margins in the design for towing loads.

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wrote:

The response - yes, if you plan to go to the local Dragstrip and make 1/4-mile trap runs with the trailer attached.

With small cars and the necessarily small trailers that are all they can handle, you have to consciously take it easy on the equipment.

If your average car broke that easily with no or little passenger load and a full trailer, they wouldn't last long with the same weight carried as 5 passengers and a trunk stuffed with luggage, either. And people would be making valid warranty claims if the car couldn't carry the rated passenger and cargo load.

The weight loads are roughly the same, the only difference being where it is stowed. Yet the car makers have the balls to say you can carry four passengers and 1000# of luggage, but you can not tow a trailer with the same load.

How to drive a car the right way:

There's an apocryphal story about Ivan Ironman Stewart and a manual transmission Class 8 Toyota race truck in the old Baja 1000, where he felt 2nd gear start to get lumpy and noisy (like it was going to go away) soon after the start of the race. He slammed through the race as usual - except as he soft-pedaled it into, on, and out of second gear for the entire race. One brain fart, one moment of inattention to the task, and his day is done.

He completes the race and won the class, pulls onto the trophy stand, gets all the adoration and pictures...

...The pit crew goes to pull the race truck off the trophy stand and put it on the trailer for the trip home, and even after a warning the driver grenades second gear on the first try, which immediately turned the whole box into shrapnel - nothing works.

They had to push it onto the trailer.

--<< Bruce >>--

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RainLover wrote:

When my son was at senior school here in the UK aged 15/16, some 10 yrs ago he built just such a trailer for his school CDT project in his summer holidays. to go behind his honda CB 185. The first thing he had to do was look up the transport regulations as to what maxsize ie length width and gross weight applied. Once these paremeters were in place I made him design this trailer around a de dion axle ,panard rod and 2 rear 185 suspension units. also 2 front cb 185 front wheels with solid aluminium disks pressed into the brake drums machined to take 2 bearings a larger inner and smaller outer. the trailer frame was 1,1/2. by 1/8th bed iron, arc welded up all filled in with 1/2in marine ply. We ran out of bed iron and I suppied him with proper mild steel.!! he berated me for making him weld the most difficult of iron first!! All part of his training. Then he had to make up the "U" bracket to connect the trailer to the tow point behind the rear wheel.

Looked very smart when it was finished, his cdt master at his school didnt believe he made it. I had to write to his school pointing out what he had done and how he had done it.

But of course hes my son! and already had a 14 yr engineering appenticeship here since he was 2 yrs old. Not only can he use all my machinery but I have made him think out technical solutions to problems like his trailer. If any of you have sons teach them all you know best investment you can make.

ted Dorset UK ,

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wrote:

True Both my sons weld far better than I do, probably lack of practice on my part - I improve after about 30 minutes.

Youngest son is a motor mechanic - but not your average one, he hates servicing & repairs. His speciality is turbocharging, for his own car he built the inlet manifold so no pipe was more than 1mm off true balance and I think he got 211kW on road from 2 litres before the back axle decided to go PING,TINKLE.

Current modification is making a 36mm Jackeroo axle fit the 26mm Gemini stuff, turn down outer diameter to fit Gemini wheels, re-drill for 4 studs not 6, make spacer washers to allow the different bearings to fit etc. etc.

This is where he works http://www.c-red.com.au/index.php

Alan

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On Wed, 02 Apr 2008 09:19:09 -0500, RainLover

I did a Google search on 'build motorcycle trailer' This link looked interesting. http://www.xs11.com/tips/norm/mtrailer.htm

--
Wayne D.

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there are lots of pics here, www.singlewheel.com scroll down on the left-hand frame to "scooter and motorcycle trailers".

b.w.

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Allot of guys doing the same thing here.

http://forums.delphiforums.com/MCTrailertowing/start

I built a one wheeled trailer to pull behind my Harley Davidson Ultra Classic, to haul camping gear. It gets used to haul tools to my mom's house once in a while too. Many people just buy a trailer kit from Harbor Freight and modify it for their needs. Greg

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There have been literally hundreds of motorcycle trailers built from the small H/F trailers. The 40"X48" with 12" tires is the most popular to work with that sells for 159.00 on sale. Some people leave them their stock width and others narrow them.

Dick

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