Thread: LR Disco '94 to Haul Dirtbike

Well - remember I had a small 1600cc car not a big Disco - the carrier was home made and was connected to the tow bar tongue as well as some angle iron welded to either end of the bar - remember there were no load ratings at the time.

With just me in the car it drove OK but with some people and gear it sat down on the springs and would bottom out sometimes. No a problem for your disco.

The main issue I had was lifting the bike up onto the rack as I tended to be by myself. It fell over a couple of times but not onto the car.

I used to cart it between Newcastle and Melbourne and back on the old Hume Highyway (goat track) - no freeways then - often full of guys and gear so it would bottom out - the guys in the back used to complain but I just turned up the radio.

When I got moved to Cairns I thought I would have problems going that distance so I bought a box trailer and used that.

The main issue you will have if you do go ahead is nit being able to open the back door with your bike in place.

Garry

Thanks for your thoughts.

This is a hydraulic lift and so no lifting is required (just wheel bike over platform, lock it in and boost the ram up to lift everything).

I guess - the major hurdle is the rating capacity and insurance, etc... :_((((

Oh well - back to the trailer idea.....

Byte

I personally wouldn't be over concerned about the 130kg "nose weight" versus the rated 120kg. Remember that the 120kg capacity could well be in conjunction with a 3500kg trailer (Thats the rated towing capacity of the Hayman Reece on my 98 D1) - Consider all the other loads that the mass/inertia of a 3500kg trailer with exerts on the hitch as you brake corner etc.

What I would be concerned about though is the fact that the bike rack is mounted to the hitch only, like a big cantilever. So the centre of mass of your bike (I guess somewhere around cylinder head level on the bike) will be a 300-500mm above the hitch. This means that when braking accelerating or cornering the bike and rack will be trying to bend the hitch up/down and or torsionally. This could be an issue.

A trailer only gets to exert forces on the hitch sideways through a very small lever arm - about 50mm as the load all has to be transmitted through the centre of the tow ball.

However it is one you could minimise by finding a way to fix the top of the bike (handlebars and rear of seat) to the rear of the Disco. Maybe to the spare wheel mounting ?

thanks jonse for a different viewpoint.

i have researched alot about this hauler unit and they go back to around 2006 ish - no reports of the hitch arm braking/fatiguing.

alot of people carry much heavier bikes than mine on these hauler units - with a heavier collective mass figure at COM, without any issues.

but, your points are valid and well worth considering.

curious - if you believe the 120kg vertical capacity on the tow ball is related to towing a trailer, can you give me an example what sort of force (and from what event) would result in the nose weight of 120kg?

And, regarding the weight bearing support you referred to fixing top of bike to rear of the vehicle - can you make any recommendations?


Byte

on trucks legally at least in QLD it is 4in/100mm over the sides. 3ft/1m over the back without a red flag and signs. there is a measurement for overhang on the front but its that long ago i cant remember it.
caravans have a max width of 8ft main body same as trucks. our roads are poorly designed to handle much bigger than this

Originally Posted by Byte

thanks jonse for a different viewpoint.

i have researched alot about this hauler unit and they go back to around 2006 ish - no reports of the hitch arm braking/fatiguing.

alot of people carry much heavier bikes than mine on these hauler units - with a heavier collective mass figure at COM, without any issues.

but, your points are valid and well worth considering.

curious - if you believe the 120kg vertical capacity on the tow ball is related to towing a trailer, can you give me an example what sort of force (and from what event) would result in the nose weight of 120kg?

And, regarding the weight bearing support you referred to fixing top of bike to rear of the vehicle - can you make any recommendations?


Byte

Re the nose weight - I was thinking more that with the theoretical 3.5 ton trailer hooked up with it's 120kg nose weight being towed along every time you corner or accelerate or brake (even with overrun or electric brakes) there is horizontal forces on the hitch from the 3.5T mass of the trailer. The bike will also apply forces to the hitch but as it only weighs 130kg they'll be much smaller.

Fixing the top of the bike to the vehicle - I'm assuming you have to remove the spare from the rear door - Could be as simple as tying the bike to the spare wheel mounting (with a bit of padding) This would reduce the bending and torsion forces on the hitch dramatically

When the car corners the bike is either trying to pull a wheelie (or stoppie) twisting the hitch in the same axis as the crankshaft in the cars engine. When the car brakes or accelerates the bike is trying to fall over bending the hitch up or down

Consider how easy it is to pick the bike up by lifting the handlebars, compared with how difficult it would be to lift the bike up by holding the bottom of the tyres and twisting.

thanks for replies.

the plaque on reece towbar has a schematic with an arrow pointing down onto a diagram of the towbar. Beside this arrow is '120kg Max'.

Would this schematic not imply vertical forces and not horizontal forces?

What material would be used to tie bike from rear to bike?

Re: overhang - i will speak to our roads people in Pert on Wednesday to check out what the laws state for WA roads.


Byte

If this was something that you will be using on a regular basis then a custom made rear bar with added side chassis braces would be better than just using a square hitch to take all the forces that will be applied to it, a few months ago i saw a patrol with a large road bike of 750-1100cc sitting on a rear bar with a tinnie on the roof so it is doable.