Offroad motorcycle trailer build. Questions and Discussion

[LaOutbackTrail]

I've got a special project that I will begin working on soon, a support trailer for a motorcycle touring company.

I am wanting to upgrade the suspension on my 4x8 utility trailer for off hwy motorbike hauling.

So, looking through northern tool, they have an array of axles setups from leaf sprung to torsion. I am leaning towards the torsion axle for better shock absorption (without the need of shocks), load transfer, etc. The trailer currently has a 1500lb axle and 13" wheels and 5.14 tires. My load will be, at most 1200lbs, two 400lb bikes and possibly some gear. So, my thoughts that a 3500lb axle will be more appropriate. But the load will not be constant or even present at all if the bikes are not on the trailer when being hauled across the desert.

What I'm trying to figure out is the best setup for having an empty trailer (most of the time) that will tow nicely when on rough tracks going decently fast, and still tow well under similar circumstances with bikes loaded.

 

[LaOutbackTrail]

Part number two:

I'll be setting the trailer up with hubs and wheels to match the tow vehicle for obvious reasons.

Part number three:
I'm thinking a removable sort of ladder rack over the bed of the trailer and adding a ladder rack. Make it removable for easier placement of the bikes onto the trailer.

 

[R_Lefebvre]

Well, I can tell you I have a 3500lb torsion axle on my trailer, current weight is 1800lbs, and it rides really really smooth. It's actually a little bouncy and rolly. I have to run with a high tire pressure to help settle it down. But it's not stiff at all with the overweight torsion springs.

I have a Seadoo trailer with torsion springs, not sure on the weight... might be 1500lbs axle. When the Seadoo is off the trailer, empty weight of 400lbs, it's not too bad, but bounces right off the ground on big bumps.

 

[Mr. Leary]

A cheat that I can recommend is... load the trailer with some full water containers when it does not have bikes on it... when the water is just about gone, it will be time to load the bikes back up and head for home. Go for the heavy suspension... its not like you are riding back there... a little bouncing shouldn't hurt anything.

 

[R_Lefebvre]

A cheat that I can recommend is... load the trailer with some full water containers when it does not have bikes on it... when the water is just about gone, it will be time to load the bikes back up and head for home. Go for the heavy suspension... its not like you are riding back there... a little bouncing shouldn't hurt anything.

Except potentially drop the bikes. I've had hard hits make my tie-downs come unhooked on my leaf sprung utility trailer. To this day, I don't know why I can't find tie-downs with gated carabiners instead of hooks. I've been wanting to retrofit a set of tiedowns like this for a while now.

 

[goodtimes]

To this day, I don't know why I can't find tie-downs with gated carabiners instead of hooks. I've been wanting to retrofit a set of tiedowns like this for a while now.

I use 'cam straps' with polyester webbing. There are no hooks, so the strap has to make a round trip, so be sure it is long enough (I use 10' straps for the front of my bikes). Combine them with a pair of 'soft hooks' (which are nothing more than a short piece of polyester webbing with a big loop sewn in each end), and you don't need to worry about those hooks coming off any more.


If you are going to see some wide variations in the load weight, you might consider air bags for the suspension. It is a bit more complicated, and probably more expensive, but you can adjust the pressure to match the load.

 

[LaOutbackTrail]

Except potentially drop the bikes. I've had hard hits make my tie-downs come unhooked on my leaf sprung utility trailer. To this day, I don't know why I can't find tie-downs with gated carabiners instead of hooks. I've been wanting to retrofit a set of tiedowns like this for a while now.

The trick for that is to drill holes in the angle iron JUST BARELY larger than the diameter of the hooks. This keeps them from coming off trailer side. Use handlebar straps on the bike side...

 

[LaOutbackTrail]

Part number three- continued.

I'm thinking something along the line of this to carry some extra cargo.

I think having the rack sleeved so that the rack can be raised/lowered for use with or without bikes.

I'm also going to look into bobbing the rear of the trailer bed and angling the front corners.

 

[Mr. Leary]

As far as the rear goes... just taper the rear sides, and make a loading ramp that can be raised up and keep some cotter pins there to secure it in the up position. I like the design so far... Adjustable height would be a nice feature... just make something similar in design but heavier duty than a gazebo leg... maybe use more cotter pins... maybe make removable sides for the basket up top... cargo OR RTTs for your customers.

EDIT: No taper on the adjustable height rack... physics just don't work

 

[LaOutbackTrail]

As far as the rear goes... just taper the rear sides, and make a loading ramp that can be raised up and keep some cotter pins there to secure it in the up position. I like the design so far... Adjustable height would be a nice feature... just make something similar in design but heavier duty than a gazebo leg... maybe use more cotter pins... maybe make removable sides for the basket up top... cargo OR RTTs for your customers.

EDIT: No taper on the adjustable height rack... physics just don't work

I guess you're right about the taper. It'd be easier to build them vertically anyways. But, the reason I thought about that setup is to keep a better COG. Tapered front/back to center and left/right to center. If I were to go with that setup, one side would need to be hinged.

 

[EuroJoe]

taper

I guess you're right about the taper. It'd be easier to build them vertically anyways. But, the reason I thought about that setup is to keep a better COG. Tapered front/back to center and left/right to center. If I were to go with that setup, one side would need to be hinged.

Taper could work, they would just need to have a pivot at each end and a brace.

 

[ntsqd]

If you go with the Torflex type axle I would suggest adding shock absorbers. The reason that AT doesn't think that this axle is viable for overland travel is that all that holds the wheel/tire/spindle/trailing-arm assembly in place is the vulcanized rubber. They have experienced a failure of this and had a trailing-arm work it's way out of the axle housing.

My theory about the failure is heat induced de-lamination from rapid oscillation (like a washboard road). Putting a shock in the system will take some or most of the heat out of the rubber. My TrailBlazer trailer has a Torflex with shocks. It has thousands of miles on it (I wish that it had started out with a hub-odo). Many of those (~50%?) were Baja & Mexico mainland dirt road miles.

I'd be more inclined to do a lockable tongue box than the overhead rack. The overhead rack will make loading and unloading the m/c's a PITA. I'd also be careful about tapering the rear. Need to know what the longest likely wheelbase will be. Then add some extra just in case something longer comes along.

I'm liking Rob's hook replacement idea. Might just steal that one....

 

[LaOutbackTrail]

I found this info on Adventure Trailer:
http://adventuretrailers.com/suspension.html#rubber


ntsqd:
Shocks might be a good idea.

I think a rack wouldn't be that bad if it was a designed right. A tongue box wont work on this trailer... But, I might be able to do boxes on either side of the bed.

 

[Mr. Leary]

Boxes on either side couln't be very big on that little trailer... might as well put shelves and strap gear bags onto them... whatever... you will need more real estate for gear with the bottem filled up with bikes. I like the adjustable height idea because it would allow you to lower the rack down when you don't have bikes under there, making it less tippy off road. The point is... if you are going to pack 5 or 6 bikes in there, that also means you have to pack in 5 or 6 people's stuff, and some people bring a lot of stuff. More storage means a more comfortable trip for your clientelle.

 

[LaOutbackTrail]

Boxes on either side couln't be very big on that little trailer... might as well put shelves and strap gear bags onto them... whatever... you will need more real estate for gear with the bottem filled up with bikes. I like the adjustable height idea because it would allow you to lower the rack down when you don't have bikes under there, making it less tippy off road. The point is... if you are going to pack 5 or 6 bikes in there, that also means you have to pack in 5 or 6 people's stuff, and some people bring a lot of stuff. More storage means a more comfortable trip for your clientelle.

The 4x8 trailer can only fit 2 bikes easily 3 bikes are packed onto it.

Another trailer will likely be bought, a 5x12 single axle is an excellent size for this sort of thing, but needs proper setup as well.