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
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.
James, Seattle, Washington, USA, Earth
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.
Dweller in the cellar
Home Page: http://www.seanet.com/~jasonrnorth
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
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.
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
borrowing a truck.
That misapprehension will cost me U$3600 (Three thousand six hundred dollars)
Even at Silicon Valley prices, I could have rented and gassed a truck for over
(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.
Why is that? (Think clutch and brakes).
Practically every part of the bike will experience larger stress values when
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
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
not loaded properly or if the trailer wheels are too far forward or not properly
Seventy bucks rents you six times the payload capacity in the form of a nice new
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
you will need to back up, uphill.) :)
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.
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
* ** ** ** ** ** *
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
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 >>--
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
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 >>--
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 >>--
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
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
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
Allot of guys doing the same thing here.
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
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.
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