Trailer Tongue Weight

[Down Under]

Just wondering what tongue weight in relation to your all up trailer weight you are using?

I've done some research and it appears that somewhere between 10 to 15% of the trailers GVM is the  recommended tongue weight.

I've got a commercially manufactured trailer which has an unladen weight of 75 kgs and a tongue weight of 14 kgs.  What I'm finding is that it takes very little weight forward of the axle to increase the tongue weight to around 25 kgs and that's just with a 40-45kg load.

I'm finding it very difficult to get the tongue weight lower, even with shifting a lot of the heavier items aft.  Am I alone here?  In the real world is it normal to run heavier tongue weights without adversely affecting the handling of the bike?

Cheers,

Tony

[WendyL]

Definitely try to keep the tongue weight low, otherwise the bike will try to throw you as soon as you pick up any speed.  I kept mine around 15-18kg at the most, tried to keep it down under 15 most of the time

[Sicman]

I will check my camper trailer for you after work Tony as its printed by the manufacturer on the trailer as well as recommended tyre pressure. You need to make sure the heaviest weight in the trailer is over the axle to get the balance right.

Cheers

 

[Down Under]

Thanks for the replies.

I feel I'm being limited by the design of the trailer.  Unladen tongue weight of 14 kgs with an unladen trailer weight of 75 kgs puts me close to a 19% ratio before I even start to load it.

I would have expected some weight bias over the tongue but 14 kgs just seems a bit too much?  Not a lot of room in the cargo box aft of the axle to balance things up.

Cheers,

Tony 

[ST2UP]

Tony do you have room within your guards to move you axle forward ?? Change the pivot point as an experiment ??


Just sayin 

[alans1100]

I had a quick look at bandicoot trailers about this and they give a figure of about 10% bias of the weight on the tow ball.

If I do that with my old 1988 classic trailer (90kg mass) plus max load of 200kg then I'd be looking at 29kg max on the tow ball. I have no idea of the weight of the trailer when it's loaded but it doesn't feel that heavy when I hitch/unhitch if I need to do that at a camp site etc. I'd be pushing to get 75kg loaded as most items are bulky but not heavy.

The draw bar and rear axle on the bike line up as best as I can get it and when two of us are on the bike and in the years I've been towing I've had no issues. Except for my current trailer being empty the day I picked it up and it swayed at any speed above 80 kph. Just make sure you adjust your preload on the rear shock and the re-bound setting as well.

http://www.bandicoots.com.au/Motorcycletrailers/FAQsaboutbiketrailers/Hintsfortowingandloadingtrailers.aspx

•From a technical standpoint, you're aiming for an evenly balanced trailer with a slight (10%) weight bias onto the bike tow ball. That means you need slightly more weight at the front than the back. Too much weight bias rearwards will be trying to lift the back of the bike, and too much weight bias forward will be trying to push the back of the bike onto the tarmac! It's all common sense but very important to bear in mind to ensure you tow your trailer safely.

[Williamson]

I had a quick look at bandicoot trailers about this and they give a figure of about 10% bias of the weight on the tow ball.

Yeah, around 10% seems to be the correct figure - it worked for me with the un-laden or fully-laden Classic trailer, and now with the Elite camper trailer.

If I do that with my old 1988 classic trailer (90kg mass) plus max load of 200kg then I'd be looking at 29kg max on the tow ball. I have no idea of the weight of the trailer when it's loaded but it doesn't feel that heavy when I hitch/unhitch if I need to do that at a camp site etc. I'd be pushing to get 75kg loaded as most items are bulky but not heavy.

I'm sure a 90kg (Tare) Classic trailer with a 200kg load is way too much, that would be 290kg gross vehicle mass (GVM).  I don't recall what was on my Classic's compliance plate but 95kg Tare (must be different model to yours), and 200kg GVM come to mind, ie. around 105kg of load.  (I envy you with 75kg load, perhaps your wife packs a lot smarter - hope Helen doesn't read this.)

I've now got an Elite camper trailer which is bigger, heavier and better ( for our purposes), and from my experience so far, around 10 to 12% works for me.  Here's a couple of pics of plate on the Elite camper trailer's draw bar:




Looks like Gross Vehicle Mass is the same as Aggregate Trailer Mass and Max Laden Weight.

The second plate indicates that the Max Tow Bar weight is 28kg, that's a max of 12.2%. 
 
On a couple of instances with the Classic trailer I'd calculated (weighed items as the went into the trailer) that I had around 220kg GVM travelling the highways from Melbourne to Canberra, and then from Canberra to Wee Jasper another 20kg ("Mick, you've got space, can you carry another slab of beer and bag of ice for me as well?").

I usually put the old bathroom scales under the draw bar / jockey wheel as I'm loading.
   

.... in the years I've been towing I've had no issues. Except for my current trailer being empty the day I picked it up and it swayed at any speed above 80 kph. Just make sure you adjust your preload on the rear shock and the re-bound setting as well.

Any problems I've had with sway were with the Classic and I put down to trailer tyre pressure.

The guy I bought the Classic from recommended 11PSI, he said that I looked sceptical (I was), he said do what he had done and experiment with pressures, I did, trailer swayed, I adjusted load, trailer swayed, tried that a few times, trailer swayed, dropped pressures to 11PSI, trailer stopped swaying.

[Down Under]

Thanks for your advice everyone.

Ironically, it's a Bandicoot trailer Alan.  From the factory the weight bias on the tongue is 19% before I even start loading it.  Without putting hardly anything forward of the axle the tongue weight is immediately up to around 20 to 25 kg.  I've checked all the dimensions and they're within spec.

When I first test drove the trailer I initially had a couple of 20 kg bags of garden mulch in it which I positioned right over the axle.  I managed to keep the tongue weight around 17 to 18 kgs.  It seemed to tow ok even with my trusty pillion on board.  I then tried loading our camping gear into it and the tongue weight just seemed too high, to the point where I couldn't even carry a light plastic esky on the supplied esky tray. 

I took it for a ride with the higher tongue weight and the handling was terrible, bar wobbles and the bike didn't want to hold a line in corners.  Tyre pressures were 20 PSI.  I put some of it down to a weak rear shock spring.  The chrome was even getting chomped off sections of the tow ball.

I'm was thinking of selling the trailer when I sold my ST but thought I'd hang onto it and give it a go with my DL.  I'm beginning to think that the trailer is overwhelming the capabilities of my DL1000 but as I've seen many lesser bikes towing similar sized trailers I thought I'd give it one more crack.  I've since fitted a heavier spring to the rear shock.  I'll try experimenting with the tyre pressures and rethink my approach to packing but having the forward half of the trailer almost empty doesn't seem right and defeats the purpose of having a trailer in the first place.  Back to the drawing board!  Please keep the suggestions coming.

Thanks again,

Tony 

[Brock]

Here is a solution, tho a little exreme   

Make a box than can bolt on the rear of the trailer, that can act as a number plate holder. Fill the box with lead (10 to 20 Kg) untill weight is correct.

I did say it was extreme.....

 

[Down Under]

Here is a solution, tho a little exreme   

Make a box than can bolt on the rear of the trailer, that can act as a number plate holder. Fill the box with lead (10 to 20 Kg) untill weight is correct.

I did say it was extreme.....

 

It's not that extreme at all Brock.  Bandicoot trailers manufacture a trailer called the "Outback Coot" which has a 10 litre water can holder bolted to the rear. 

When I purchased the standard trailer it was mentioned to me that the water carrier is useful for balancing up the trailer.....it was also much more expensive and I didn't really need an extra 10 kg of water to cart around.

 The words didn't really gel with me at the time until now.  Maybe their trailers aren't all that well balanced to start with or it could be me just being overly suspicious. 

Cheers,

Tony

[alans1100]

I'm sure a 90kg (Tare) Classic trailer with a 200kg load is way too much, that would be 290kg gross vehicle mass (GVM).  I don't recall what was on my Classic's compliance plate but 95kg Tare (must be different model to yours), and 200kg GVM come to mind, ie. around 105kg of load.)

The trailer rules have changed since my trailer was built so I have very limited info on what is now become a compliance plate. The rego certificate gives the mass at 90 kg and 200kg is clearly shown as the max load.



I must get that yucky piece of plywood replaced (previous owner) on the draw bar with some aluminium plate.

(I envy you with 75kg load, perhaps your wife packs a lot smarter - hope Helen doesn't read this.)

Apart from a couple of overnighters from Karratha (when we lived there) to Perth, and a weekend in Stawell back in 2006 Heather hasn't needed to worry to much about packing for more than a couple days. So a couple changes of clothes is about the norm.

Any problems I've had with sway were with the Classic and I put down to trailer tyre pressure.

The guy I bought the Classic from recommended 11PSI, he said that I looked sceptical (I was), he said do what he had done and experiment with pressures, I did, trailer swayed, I adjusted load, trailer swayed, tried that a few times, trailer swayed, dropped pressures to 11PSI, trailer stopped swaying.

I e-mailed Classic about the sway back in Jan 2011 and it was they that suggested the empty trailer was the main cause, but I forgot to tell them I had a fairly strong side wind that day as well so it more likely a combination of the two plus tyre pressure were also over 20 psi from previous owner. They confirmed tyre pressures to be in the 12-15 psi range depending on the load.

[alans1100]

Just how are you working out the weight on the tow ball? Something I have yet to do.

http://www.lets-getaway.com/caravan-complianceplates.htm

Ball Weight/Tongue Weight –  or Tow Ball Mass (TBM) is the maximum allowable weight to be placed on the tow ball.  It is the difference in weight between the  caravan/trailer on and off the tow vehicle The ideal weight for this is considered to be 10% of the weight of a fully laden caravan or camper trailer.  Care should be taken to check with some imported caravans as they may be considerably less than 10%.  Ball Weights of up to 120 kilograms can be measured with a set of household bathroom scales by resting the trailer coupler on the scale and placing the scale on a box so that the coupler is at its normal towing height.  The trailer must be fully loaded and level.  For heavier ball weights, place a household scale and a brick that's as thick as the scale three feet apart as shown in Figure 1.  Set a length of pipe on each and rest a beam across the pipes.  Re-zero the scale to correct for the weight of the beam and pipe.  Securely block the trailer wheels.  Rest the trailer jack on the beam as shown, 300mm from the brick and 600mm from the scale. 

[Down Under]

Just how are you working out the weight on the tow ball? Something I have yet to do.

I've used 2 methods with the same result:

(1)  A portable set of fish scales from BCF hooked under the tow coupling and the tongue weight measured holding the same at the correct height for towing. 

(2)  Using several blocks of wood stacked between digital bathroom scales and the underside of the tow coupling with it all set at the correct towing height.  (weight of timber subtracted from final reading)

Cheers,

Tony

[Grumpy]

This takes me back to my caravan days. All good to work out and necessary. Just remember that if you get the ball weight too light, the trailer will sway regardless of wind and tyre pressure. Weight on the ball is part of what gives you stability. Happy measuring and good luck with it all. I don't think I'll be pulling a trailer anytime soon.   

[Williamson]

....... Fill the box with lead (10 to 20 Kg) untill weight is correct.....

Beer is a good substitute for water.    Some sort of receptacle that can carry beer on the way to a rally, and wine (after a few winery visits on the way home would be ideal).
 

[atoyot]

This topic is interesting to me as well, as I'm yet to setup my new trailer, and the few things that I need to sort out are the ball weight, and the towball height to keep the trailer level. I've towed with the 4WD a fair bit, and I'm aware of the 10-15% rule, but I'm stunned that having as little as 20 or so KG on the ball can affect a bikes handling that much. Having said that, Honda only recommend 9KG for the top box, which is a lot higher than a towball, but extends beyond the back axle slightly less than a towbar. So maybe there's a mathematical formula based on a few measurements that might give us a maximum ball weight based on the bike not the towbar.

Have you contacted Bandicoot Tony? Just looking at their website now, they only have the Outback, which looks like the old standard, but offer options of spare and 10l carrier. I would imagine that 10l container where it is in relation to the axle, and the spare, where it is mounted in relation to the axle, would be about the same, in terms of balancing towball weight, but I'm just looking at some photos now, and there is bugger all room to pack things behind the axle. I can see what you mean, as it looks to me like the axle is too far back, when considering the cooler tray and the tapered front of the main storage box. I can't imagine that it would be a simple job to move the axle forward, as the chassis seems to taper inward just forward of the front spring mounts, so that would be the last option, but I think it might be simpler to follow Brocks suggestion, and put something on the back on it, so that you can place a variable load behind the axle as far as you can.

I'm no engineer, but the storage area is 1200 long, and doing some rough measuring on the screen, it seems the main area is 800 long, and the tapered front bit 400 long. The axle looks to be about halfway along the main bit, so say 400 from the back and 400 from the front of the 800mm main bit. Forgetting about the tapered bit being a bit smaller in capacity and potentially weight, I'd assume that the axle should be up to 200mm further forward. Take off the slight loss of capacity in the tapered part, but add on a few more KG for the cooler tray, and I'd reckon that 200mm further forward is probably close to the mark.

That 200mm is a lot, and if you were going to compensate for that by putting some weight behind the back of the trailer, I think a 20L jerry can holder is probably the more appropriate size to give a decent range of weights to get it right. 20kg 400mm behind the axle equates to "X" 1650mm in front of the axle?

Maybe we need to workshop this, as I'll be fiddling around in the next few weeks as well! 

[atoyot]

I hate it when a thought enters your head just before it hits the pillow, so here I am back with another thought that might help as well. Shortening the drawbar by a couple of hundred mm would also have the effect of decreasing the ball weight as you increase the weight behind the axles. Maybe someone who is much smarter than me could work this out, but in my head, I reckon that this is doable. Assuming it's too hard and costly to move the axle forward, more weight on the back of the trailer along with a shorter drawbar should have the actual towball weight drop by a reasonable amount. The only other dimension that doesn't come into the ball weight equasion, but might affect handling is the distance from the rear axle of the bike and the towball. I'm assuming that the main impact on the bikes handling whilst towing is the ball weight combined with the distance the weight is carried behind the rear axle actually reducing the weight on the front axle of the bike.

On a car, this effect is countered by using weight distribution bars. I won't go on too much about this, but they do work, and putting stiffer suspension on the rear doesn't change the weight balance towards the front. The question to me is whether 20 or so KG on the towball actually drops the back of the bike a bit, and lifts the front of the bike on the forks. This should be measureable with the trailer hooked up, and the bike held steady on both wheels. Maybe it's worthwhile doing the exercise just to see if it has any measureable impact. If it does, then short of using weight distribution bars (which I've never seen on a bike, probably for good reason), maybe moving the towball as close to the back axle as possible could improve the bike handling.

I dunno, but just thinking outside the square.

The other thing I was going to ask Tony, is the trailer level when it's hitched to the bike sitting on flat ground? If it isn't, that might also be effecting the weight distribution. Mine sits fairly low, so my towbar is at it's lowest setting, and it's still slightly low at the back of the trailer.

zzzzzzzzz

[Down Under]

G'day Andrew,

Thanks for your thoughts mate.  We're definitely on the same page as far as thinking is concerned.  I looked at shortening the draw bar but as little as 150 mm movement along the draw bar toward the axle results in an increase of 5 kgs at the tow ball.  So that options out.

Regarding the rear mounted carrier I positioned a 10 kg weight roughly were the carrier would be normally mounted on the trailer.  It did reduce the weight at the tow ball but the decrease was almost insignificant.  As you and others have mentioned a great deal more weight would be required to have a substantial impact.

The trailer hitch is level to the point of being almost perfect.  So no problems there.

At the end of the day maybe a lot of riders that tow trailers aren't too concerned about tongue weight and simply load and go.  If they don't experience any adverse handling they carry on and leave it at that.

I'm also inclined to think that the type of bike your using for towing has a lot to do with it.  The ST has plenty of power and is built for hauling 2 people, fully loaded over long distances.  The ST is a heavy bike and designed to have a lot of weight over the rear end and it seems logical that it would be more suited to hauling a trailer.

In comparison my DL1000 is a light machine, light frame and with tall suspension.  I strongly suspect that it is sensitive to rear weight bias.  It feels like the extra weight of the trailer, more so the tongue weight, is unloading the front end and causing a lot of the handling issues. 

I'm now resigned to the fact that the Bandicoot is probably the wrong type of trailer for my bike.  There's a lot of Bandicoot trailers out there with plenty of happy owners and from my short journey it appears they are more suited to heavier tourers/cruisers where tongue weight might not be such an issue.

Thanks for everyones help it was appreciated.  They'll be an almost brand new Bandicoot trailer for sale on Gumtree shortly if anyone is interested.

Cheers,

Tony

 

[atoyot]

Hey Tony, so you need a l-o-n-g-e-r drawbar!

I think that you're right about the type of bike as well, which makes me wonder why they don't develop gooseneck type trailers for off-road bikes. So for example, the hitch is just behind the pillion seat at that height. A bit like a fifth wheeler on a ute, and pushbike trailers usually hitch up under the seat somewhere.

I'll be setting mine up shortly, once I've got it lined and the towbar installed on the ST, so I'll see what weights I get,

[Down Under]

Hey Tony, so you need a l-o-n-g-e-r drawbar!

I think that you're right about the type of bike as well, which makes me wonder why they don't develop gooseneck type trailers for off-road bikes. So for example, the hitch is just behind the pillion seat at that height. A bit like a fifth wheeler on a ute, and pushbike trailers usually hitch up under the seat somewhere.

I'll be setting mine up shortly, once I've got it lined and the towbar installed on the ST, so I'll see what weights I get,

Mate, if I make it any l-o-n-g-e-r it'll look like a log truck! 

I should've sold it when the ST went but I couldn't part with an unused trailer.  Anyway, I've given it a go now so maybe I'll revisit the trailer thing when I'm ready for my Goldwing.

Let me know when your mobile again, would be good to catch up.

Cheers,

Tony

[alans1100]

Tony,

I looked at the trailer dimensions on the bandicoot site and it gives a max load of 175kg plus the 75kg tare weight you mentioned. If your trailer is fully loaded it's GVM should be 225kg. I don't think the trailer is braked, so does the trailer weigh less than the unladen weight of your bike.

Even my trailer with a max loaded GVM of 290 kg is just under the weight of my 299kg 1100. I did some rough measurements of my trailer and working from wheel centre I have 650mm to the rear bumper bar, 850mm to the front of the main body and then another 850mm to the coupling. I don't have the ice box option (on draw bar) on mine so I put the esky inside lengthways above the wheels with tent beside it (my two heaviest items).
-----------------------------------

Andrew,

When the trailer is hitch to the bike I have no discernible downward movement on the rear of the bike but the rear does lower a little when the two of us get on it. I've recently replaced my worn out OEM rear shock with a Progressive (brand) and I set the ride height for what seemed right for the two of us and I left the rebound setting at the mid point (3 of 5). The ride was a little to firm at that setting but seemed ok when we did the first trailer trip.

So after that first trailer test with the new shock I adjusted the rebound back to 2 and the ride for two up seems ok now. With the new shock being a lot firmer than the OEM I adjusted the hitch to the lowest setting. The next time I load the trailer for camping will be for the national rally so I'll see if there's any noticeable difference or not.

   

[Down Under]

Tony,

I looked at the trailer dimensions on the bandicoot site and it gives a max load of 175kg plus the 75kg tare weight you mentioned. If your trailer is fully loaded it's GVM should be 225kg. I don't think the trailer is braked, so does the trailer weigh less than the unladen weight of your bike.

Even my trailer with a max loaded GVM of 290 kg is just under the weight of my 299kg 1100. I did some rough measurements of my trailer and working from wheel centre I have 650mm to the rear bumper bar, 850mm to the front of the main body and then another 850mm to the coupling. I don't have the ice box option (on draw bar) on mine so I put the esky inside lengthways above the wheels with tent beside it (my two heaviest items).
-----------------------------------

G'day Alan,

The trailer GVM which I've been using is well below the unladen weight of my DL.  DL1000 wet weight is 234 kg and the laden weight of my trailer was no more than 115 kg.  (75 kg trailer weight + 40 kg of camping stuff).  Adding a 100 kg rider to the equation and the weight combination is well within safe limits.

As you can see the weight of the trailer + load doesn't seem to be the problem.  I'm sure it's the heavy tongue weight acting down through the bikes tow hitch increasing weight on the rear and acting like a lever which lightens the front.  It might be more to do with the design of the DL than the trailer.

Cheers,

Tony

[Sicman]

Sorry Tony - work got in the way as usual.
I tow an elite camper trailer. The markings are as follows:-

Max tow bar weight - 28kg - I used fish scales to get it right
Max laden weight - 230kg - I put over a weigh bridge to check this out
Recommended tyre pressure is 22 PSI

Its the model with nose cone and has brakes fitted so has extra weight.
Have you adjusted the suspension to counter the extra weight the same as you would for having a pillion on board?
When I have a pillion on or towing the trailer I adjust the suspension up 5 turns of the wheel.

 

[winston66]

One thing that I believe is very important is the ratio of the draw bar length, to the wheel track of the trailer.It has been said that it should be a minimum of one point eight time the track width and that a ratio of two times is even better. I can attest to the validity of this with the benefit of my own experience with my own trailer builds.
I believe that this ratio is even more important  than in ensuring that the weight on the tow ball is kept to a small percentage, I would personally prefer more weight to less..
The two trailers that I have constructed weigh in at around 200 Kg.loaded and with a draw bar weight of between 20 to 30 Kg track and tow flawlessly and in the main when under way I tend to forget that i have a trailer attached.
I suggest that you experiment with the Tyre pressures also as that can and will have a dramatic effect on the handling.
Hope that this helps.
Cheers, Winston66

[atoyot]

That sounds pretty good to me, Winstone66. The longer the drawbar, the more stable, and the same for the ball weight. Having a bit too much is better than too little, as they can get a sway up with too little ball downforce. Going off my rough calcs, the Bandicoot has about a 900 - 960mm track, which is pretty close to the 1650mm from axle to coupling, if that's how a drawbar length is measured.

Thanks for that Alan, as it looks like the ball weight is not a huge issue on the ST in relation to too much weight behind the rear axle. I don't have much data on my Aluma trailer, but when I start to do some test loads, I'll make some measurements.

I still look at the bandicoot and think the axle " looks" a bit too far back, but as you say Tony, if the drawbar were shorter, there's more weight on the ball, so I was heading the wrong way by suggesting it might be better shorter! Whoops!. Going on the experience of others here, the ball weight is within reason for ST's but perhaps too much for the DL.