Post Mortem after towing.

Submitted: Saturday, Mar 09, 2013 at 17:29
ThreadID: 100989 Views:3714 Replies:9 FollowUps:10
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With all the vehicles rated three tonne plus towing capabilities I would really like to read reports on some of the "middle range" towing vehicles ie Navara,Mazda,Ford,Holden Colorado & others to just see what effect the stress of towing has on the structure of the vehicle. For example I have just had my towbar strengthened where it attaches to the chassis. Engineers whom I have shown the vehicle to scoffed at the chassis thicknes 2.5mm and the lack of structural support. When I showed them the Nissan identifying plate on the towbar stating 3 tonne towing capicity & ball weight not to exceed 300kg they say that Nissan could have done more to make the vehicle more apt to the stated capacity. I know I am not the only person who has looked at a vehicle towing a large heavy van & looked at advertising stated "Now with 3.5 tonne or 3 tonne " towing capacity. I have also been told that some of our emergency services had experienced problems when fitting up vehicle to use when fitting equipment such as bullbar & winch....ie the Toyota Workmate ute bullbar & winch exceeding the front axle weight criteria....late model patrols cracking chassis!!! Anyone heard similar reports or am I being lied to? As a consumer we purchase these vehicles & believe we are safe when fitting extras. Only to find out when we tow our 2.7 tonne van & hit a bump our towbar falls off!!!
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Reply By: Ross M - Saturday, Mar 09, 2013 at 17:53

Saturday, Mar 09, 2013 at 17:53
NTVRX
Despite lots of earlier comments the fact still remains the stated towing rating is for ideal conditions and not much load in the vehicle. There are various towbars available for these vehicles and generally the towbar itself is engineered in a way that far exceeds the vehicle chassis it is bolted to, hence the problems.
I have seen Navaras which had the whole towbar rip out of the chassis and also an Xtrail towing a covered tandem trailer. That tow bar, in it's entirety, was still attached to the trailer ball coupling with the trailer.

Many have 8mm or 10MM plate steel of the towbar bolting to the 2.5 of the chassis and the load is concentrated in the bolted region and not spread as half smart engineer would like to see. Stress fractures occur and generally relieve the stress by the towbar breaking away.
My pet item is also the shockers of the vehicle, which when towing aren't at all suited to the new mass they have to handle, particularly in an emergency situation.

My thoughts are, anyone who believes the towing rating on the modern crop of vehicles are deluding themselves if they think that stated figure covers all situations the vehicle may be asked to encounter. Derate it by half and then you may be nearer the realistic amount, eg, Landrover company and Army vehicles are rated around 50% of stated when anything resembling off road or arduous conditions are to be encountered.

The laws of physics reveal many shortcoming with many vehicles.

Your signature line is appropriate, The designs are genius but the uses the vehicles are expected to fulfill is where the endless stupidity starts galloping away.

Ross M
AnswerID: 506422

Reply By: Notso - Saturday, Mar 09, 2013 at 18:04

Saturday, Mar 09, 2013 at 18:04
It can happen to any vehicle I guess, friend had a 4.5 Diesel LC ute and the chassis broke off where the tow bar was attached.

I've towed with the Triton for 6 years now and the van weighs over 2 tonne, so far no issues, but that is nowhere near the 3 tonne you are talking about.
AnswerID: 506423

Reply By: Dennis Ellery - Saturday, Mar 09, 2013 at 20:39

Saturday, Mar 09, 2013 at 20:39
I have a 2008 model Troopy.
The chassis is RHS, 4mm plate 100mm deep and the top and bottom of the chassis is double layer (assume 8mm)
The Toyota 3.5 tonne tow bar is connected with 8mm plate – 3.5 tonne has to be a dynamic rating ie subject to 3 or 4 times the static load (only a guess but I assume that Toyota would engineer it correctly).
The bar is nothing special – its a Toyota standard item and when purchased new had the same 3 year warranty as vehicle.
I can’t speak for other vehicles but I tow a van that is 3.2 tonne loaded and don’t believe that there is a chance of it giving away when it’s being thrown around over bumps off the highway.
AnswerID: 506430

Reply By: Eric Experience - Saturday, Mar 09, 2013 at 21:29

Saturday, Mar 09, 2013 at 21:29
If you consider the dimensions of the tow vehicle and consider that the tug is probably over 3 ton, you have 6 ton being driven by that rear end. Then go and have a look at the rear end of a 6 ton truck. You will soon realize why the mature travellers use a vehicle based on a truck chassis or a better still a Sprinter. Eric.
AnswerID: 506434

Follow Up By: Dennis Ellery - Saturday, Mar 09, 2013 at 22:25

Saturday, Mar 09, 2013 at 22:25
It doesn’t quite work that way Eric.
If you tow a caravan behind a large truck you risk damage to the van’s A frame as the truck can be too rigid.
Some use a special towbar with a sprung joint to overcome the problem.
What is the towing capacity of your Sprinter?
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FollowupID: 783368

Reply By: splits - Saturday, Mar 09, 2013 at 22:51

Saturday, Mar 09, 2013 at 22:51
NTVRX
I think the biggest problem with these towing capacities is the lack of information coming from the car manufacturers.Ross M is right, the maximum capacity is for good conditions only but I have yet to see that written in the specifications or the owner's handbook. If you take the trouble though to contact the manufacturer, you get a different story entirely.

I was looking at a new Land Rover Defender ute a couple of years ago. I emailed Land Rover Australia with a few questions on its 3500 kg towing capacity. The reply said that was for sealed roads only. The maximum off road capacity was 1500kg! That is a two ton reduction. It was even less if whatever you are towing had overriding brakes. If that is not explained by a dealer, someone could be towing a 2500 kg off road van thinking they were 1000 kg under maximum with plenty in reserve when they were really 1000 kg over. I don't know if that could lead to insurance problems in the event of an accident.

I contacted Toyota about the capacity of my 10 year old Hilux. It is rated at 1800kg maximum which looks a lot more realistic when compared to the much higher capacities of its competitors back then. They said it can tow that weight off road but then added " do not tow at all" in soft dry sand. There is nothing about that in the handbook.

Regarding tow ball weights: There is a photo somewhere on the net showing the Leyland brothers crossing a sand hill in the desert. They had two Land Rovers coupled together with a length of steel tube instead of a rope. The second one was towing a large dog trailer. I have no idea how heavy it was but its pivoting draw bar looked like it might have been no more than about about 50 kg. This means they would have had only 25 kg on the tow ball.

That is one way a car could meet it advertised maximum capacity with very little on the ball.

You can be sure of one thing: there will be a way for all cars to meet their maximum advertised towing capacity. They will be capable of safely towing something somewhere that will be right on the maximum limits but they will not be able to tow anything of maximum weight regardless of shape, size or design over any surface and still maintain maximum safety and reliability.

It is a pity all of this is not explained by manufacturers, dealers, magazines etc.
AnswerID: 506439

Follow Up By: AlbyNSW - Sunday, Mar 10, 2013 at 09:23

Sunday, Mar 10, 2013 at 09:23
Part of the problem I think is that they want to promote these large towing capacities to get sales. I have heard a number of people choose another brand over a Hilux because of the advertised bigger towing capacity but if you take the time to do the research as you have done you soon find out that the lower capacities are more realistic for this type of vehicle and our conditions. Toyota Australia have derated the Hilux's towing capacity to what the identical vehicle has being sold in other countries.
People's expectations of these vehicles is too high but it is the manufacturers who have raised these expectations.
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FollowupID: 783381

Reply By: Olsen's 4WD Tours and Training - Sunday, Mar 10, 2013 at 10:11

Sunday, Mar 10, 2013 at 10:11
As a Tow-Ed instructor, I cannot add much to the comments above except to reinforce them, also check into speed limitations at max towing capacity, many vehicles are limited to 80kph at full towing weight. Also don't forget the tow ball downforce limitation. Some vehicles may have a maximum towing capacity say of 2.3 tonnes but be limited to just 90 kg downforce. Most vans require between 8 and 12 percent (average 10%) of the aggregate trailer mass to be on the tow ball - e.g.. a 2.3 tonne van will require something close to 230 kg on the tow ball for stability at speed. A 90k tow ball limit thus limits the actual towing capacity to something around 900 kg.

Buyer beware!
AnswerID: 506468

Follow Up By: Member - Oldbaz. NSW. - Sunday, Mar 10, 2013 at 10:33

Sunday, Mar 10, 2013 at 10:33
The speed limitations you speak of..are these statutory or a
manufacturers recomendation? I see many big vans on the Hume
that must be close to max load still doing 110+ kph.
I think the stated towing capacities are like the fuel consumption
figures ..barely achievable under the most favourable conditions.
I run at about 50% of stated capacity & think this is ideal, as others
have suggeated. cheers...oldbaz.
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FollowupID: 783385

Follow Up By: Olsen's 4WD Tours and Training - Sunday, Mar 10, 2013 at 12:01

Sunday, Mar 10, 2013 at 12:01
It is a manufacturers requirement. Ignore them and not only could you void your warranty and insurance but in the event of an accident may find yourself liable.

I see Holden Commodores and Falcons and Landrover Disco 3 pulling vans at max load all the time, but all are limited to (from memory 80 kph) certainly not 100 kph at max load I've spoken to many people who are completely unaware of the speed limitation and as such are sure to exceed it.

People don't do enough research when buying towing vehicles and vans. A training course is a good place to start. I had a fellow abuse me at a Caravan and Camping Show in front of my customers when I said that certain Falcons were limited to (from memory 80kph) at max load- I could not convince him otherwise, and he got quite angry with me. So I said, "I tell you what, you go get your manual from your glovebox, and if it says otherwise, I'll go to the microphone and apologise to you in public."- He did, and I didn't have to apologise. :-)
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FollowupID: 783395

Follow Up By: Dennis Ellery - Sunday, Mar 10, 2013 at 12:49

Sunday, Mar 10, 2013 at 12:49
Hi Oldbaz.
I tow a large van in excess of 3 tonne and don’t feel comfortable towing it over 85kph with a V8 Troopy – I wouldn’t be able to stop it quickly enough in an emergency. It has about 4 to 5 times the stopping distance of my wife’s little sedan.
Met a guy who with a new Landrover, stated he had no problem towing a similar van up to 130 k/hr
The guy seemed an intelligent retired businessman who lacked a lot of common sense.
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FollowupID: 783408

Follow Up By: splits - Sunday, Mar 10, 2013 at 20:56

Sunday, Mar 10, 2013 at 20:56
Dennis

I don't think I would be too keen to go any faster either. A Troopy looks like a big car until you put a van of that size behind it.

There are a few good comments on this site http://caravanersforum.com/viewtopic.php?f=2&t=34462 regarding large vans. It looks like another case of an inexperienced couple looking at towing capacities and van weights then thinking yes a 24 ft Kedron or similar van will be fine behind our Landcruiser.

Note the posts by Iron Mike on the 3 ton Isuzu truck he is currently setting up to tow his 20 ft Bushtracker and his reasons for choosing a vehicle of that size and type.
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FollowupID: 783487

Reply By: olcoolone - Sunday, Mar 10, 2013 at 12:19

Sunday, Mar 10, 2013 at 12:19
I think you are worry too much about something you don't understand.

When engineering a component there are many factors that come into play including rigidity, flex, strength, fatigue and resonance...... and not forgetting weight plus knowing what you want to achieve.

You can have something thats rigid, doesn't flex, has good strength but poor fatigue..... you can have something thats not rigid, does flex, have good strength and good fatigue.

With the onset of HSLA (high strengh low alloy) steels being used by them selves or with other structured materials; something that may look weak can in fact be very strong for it's given dimensions and weight.

Carbonising plays as bigger factor in flex, fatigue and strength as does design.

For an engineer to come to a conclusion that something is not strong enough just by looking at it and not knowing it's design criteria or material structure..... you should ask him if he knows the winning Xlotto numbers for next week....... I would not trust an engineer who has this ability without data to back his claim.

AnswerID: 506479

Follow Up By: NTVRX - Sunday, Mar 10, 2013 at 12:43

Sunday, Mar 10, 2013 at 12:43
Thanks everyone for your replies. To Olcoolone I am not worried about anything actually....I started the thread as a discussion point & one example of manufacturers presenting an item for sale to us consumers is this...a good friend of mine towing a 19'6" van loaded weight of 2100kg...towed by Nissan Navara dual cab diesel with manual box. Drove over a level crossing after executing right turn,so obviously not going fast towbar broke away form chassis onto the ground with van coupling still attached. I suppose what I am putting to the forum is do we take for granted and gospel what is advertised by manufacturers with checking first. I think a good example is that some sales personnel at dealerships do not know much at all about the product they are selling and often given false,misleading & dangerous to those who maybe don;t know either. One question would like to ask you is, do you think a monocoque constructed vehicle could be as strong or in some cases stronger than a vehicle with a chassis. I would be interested in your views as you seem more knowledgeable on this topic than me.
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FollowupID: 783407

Follow Up By: olcoolone - Sunday, Mar 10, 2013 at 13:19

Sunday, Mar 10, 2013 at 13:19
Yes a monocoque constructed vehicle can be as strong as a ladder chassis vehicle in some instances.

There are many reasons why monocoques are better.

Most utes have a ladder chassis as it is easier and cheaper to do plus use leaf springs in the rear.

Thailand where most of the utes are produced is the biggest market in the world.... for the Thai people to get big tax savings the ute has to be made in Thailand and it has to have leaf spring and drum brake rear end....... put coils and discs in the rear and it looses it tax break.
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FollowupID: 783416

Reply By: Member - Craig F (WA) - Sunday, Mar 10, 2013 at 12:32

Sunday, Mar 10, 2013 at 12:32
As consumers we need to take some responsibility in our actions and decisions. As stated many a time the advertised towing mass of a car is its maximum in controlled conditions. Throw in hills, weather, tyre conditions, weight distribution driving skill etc. and this all changes. The modern v8 4wd is more than capable of twice the legal speed limit but we all know this is not legal or safe on most of Australia’s roads as . We are also capped at 110. BUT when off road we use our skill and knowledge to drive to the conditions.
The same must be said for a van. If you want to buy and use one it is YOUR responsibility to research the tug that you will use and the capacities of said vehicle.
AnswerID: 506482

Follow Up By: Dennis Ellery - Sunday, Mar 10, 2013 at 13:05

Sunday, Mar 10, 2013 at 13:05
Hi Craig – I couldn’t have said it better.
Most people with structural problems buy vehicles unsuited to their task. Often based on price and not performance but when sht hits the fan they look to lay the blame.
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FollowupID: 783414

Reply By: gbc - Sunday, Mar 10, 2013 at 12:50

Sunday, Mar 10, 2013 at 12:50
Yes, nissans crack, and yes the hilux/prado front axle ratings were such that if you put a bullbar and winch on them the vehicle was beyond manufacturer's specs prior to adding a passenger in the front seat. Toyota revised this with a new axle rating and no physical change. That was a big headache for fleets once it was found out.

With regards your max towing in utes, that is a big can of worms, especially when touring and you'd like to carry gear in and on the car, in the fuel tank and carry the odd passenger.

Tow ratings on their own are not comparable across the board. You need to do some maths with GVM, GCM, Payloads and rear axle ratings. Then you will start to get a meaningful picture.

Vehicles like the ranger/colorado/triton etc arrive at their 'massive' tow ratings with zero payload at max towball rating. That means a driver and 10 litres of fuel in the tank - NOTHING ELSE. Only then can you hit max tow.

Hilux maintains a usable 600 odd K.G. of payload at max tow, which in effect makes them a much more viable towing proposition in the real world than the higher rated headline grabbers. Wagons are abysmal for carrying load and towing it at the same time.
Land rovers were mentioned - they are rated for towing at max payload, and derated offroad. I'm not a fan of LR reliability, but I think the whole world should move to the LR payload/tow rating system. Put it all in a spreadsheet, and the LR's come out on top by a long shot. The one's with the amazing towing advertisements (BT50/Colorado come to mind) have, in the real world, only modest towing ability once payload and ball weight are taken into consideration.
All vehicles are stamped, and all manuals must carry this information, so buyer/user beware - if you don't know this stuff (which apparently most don't??) then it would be in your best interests to find out how your tare weights are arrived at, and what your current weight is. There are going to be a lot of extremely embarrassed van draggers out there - I see them every day. Ubiquitous Cruiser wagon, tinny on roof, loaded to gunwales, towing big van = goooorne.
AnswerID: 506485

Follow Up By: olcoolone - Sunday, Mar 10, 2013 at 13:09

Sunday, Mar 10, 2013 at 13:09
Toyota have always be criticised for the Hilux have the lowest towing capacity in the upper end 4x4 ute market..... maybe there is sense to their madness.

For years you could only tow 2250Kg and only in the last few years they have increased this to 2750Kg when most others were around the 3000Kg-3500Kg.

We have a new Ranger that can tow 3500Kg and our 200 series Landcruiser can do the same..... the chassis's are like chalk and cheese in the Landcruisers favor.
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FollowupID: 783415

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