Towing with low nose weight

[Buckman]

I don't think having that information would change the advice given, It all depends on how the given combination, actually behaves. There have been occasions when I have towed the same trailer with different vehicles, and the outfit behaved quite differently.

I also believe that some caravanners who believe that bigger is better may well be towing with nose loads that are greater than is strictly necessary all of which increases wear tear, and I'm sure in some cases they may actually be overloading which has the potential to damage the tow vehicle and could be dangerous.

Our ideal nose weight is 140kg and we are not overloaded. Many caravans are restricted to maximum nose weight of 100kg when ideally it should be over 100kg to fall into the 5-7% guideline. No way would this indicate the caravan is overloaded.

 

[RogerL]

I should have made it clear, the wear and tear (in some cases literally a tear!) I was referring to was on the car. Tow bar mounting points are often just through sheet metal under the car.

So you think that towing close to, but under, the car's noseweight limit will cause significant wear and tear whereas towing well under won't - is that what you're suggesting?

Towbar mounting points are Type Approved at the noseweight limit - this includes repeated cycle testing - and all third-party towbar manufacturers must use only those points - are you suggesting that the EU/UK Type Approval regulations are inadequate?

I understand the risks involved in exceeding the car's noseweight limit, or indeed the caravan hitch's limit if that's lower - I'm not advocating either.

 

[GaryB]

Towbar mounting points are Type Approved at the noseweight limit - this includes repeated cycle testing - and all third-party towbar manufacturers must use only those points

As a slight aside, but to just give a real-world example of this.

Back in 1998 I had a new Peugeot 406 1.9TD as a company car, it was registered in July 1998 and was BEFORE the type-approval start of August 1998. I purchased a new tow bar from a fairly local company advertising in Auto-Trader (this was pre-mainstream internet!). I fitted it myself and it's mounting points were two through a rear crossmember just behind the read panel (using factory installed mountings) and then two through the spare wheel well. This panel was very thin (probably 22 SWG) and I remember centre punching the holes for drilling and thinking that with a few more smacks of the hammer I could probably punch right through it. For 3 years we towed a 1997 Coachman Mirage 480/4 (MTPLM 1200kgs) and sometimes a trailer with no issues.

At 3 years old I took the spare wheel out while giving the car a good clean and was horrified to see the two tow bar bolts starting to tear themselves out of the spare wheel well. Each bolt was torqued to the correct limit and had large washers to spread the load, but the bolt holes had tears radiating backwards about 3/4" long. I removed the tow bar and contacted the manufacturer who simply didn't want to know, stating I must have exceeded the cars limits, which I hadn't. I went to the local Peugeot dealer who serviced the car and spoke to one of their fitters who told me that every tow bar they'd fitted DIDN'T bolt through the spare wheel well.

I purchased a Type Approved tow bar from Towsure and fitted that, this time it bolted through the rear crossmember AND also through the side "chassis" members, nothing went through the spare wheel well, the design was very different.

I suppose the point of this post is just to re-enforce the importance of the Type Approval process to prove the suitability of a tow bar's design rather than relying on engineering-judgement at the design stage.

 

[Buckman]

Would I be correct in thinking that the tongue weight on the towball should preferable be a lot less than the nose weight of the vehicle if it is a front engine vehicle?

This would ensure than even with the vehicle fully laden to its gross weight the rear axle can cope with the additional weight of the towbar and any weight placed on the towball and the vehicle will still look as if it is level.

As an aside on Wednesday while driving through Stourport on Severn there was a small pickup with the caravan built onto the rear and also formed part of the bin. The rear of this vehicle was almost scrapping the ground and the front looked as if it was only just touching the ground. so whatever he had in the rear must have bene very heavy. He definitely was exceeding the gross weight of the rear axle!

 

[otherclive]

Would I be correct in thinking that the tongue weight on the towball should preferable be a lot less than the nose weight of the vehicle if it is a front engine vehicle?

This would ensure than even with the vehicle fully laden to its gross weight the rear axle can cope with the additional weight of the towbar and any weight placed on the towball and the vehicle will still look as if it is level.

As an aside on Wednesday while driving through Stourport on Severn there was a small pickup with the caravan built onto the rear and also formed part of the bin. The rear of this vehicle was almost scrapping the ground and the front looked as if it was only just touching the ground. so whatever he had in the rear must have bene very heavy. He definitely was exceeding the gross weight of the rear axle!

Bringing an Americanism or Aussieism into the discussion will create confusion. I’ve always kept it simple irrespective of car. I load car towball to as close as possible to its specified limit, ensuring that I don’t exceed the specified load on the caravan hitch/A frame. One fwd car did tend to adopt a nose up attitude. It as a Saab 9000 which had a particularly long rear overhang. But I fitted MAD spring assisters. But the axle loads even when loaded were okay as I was weight checked by DOT VOSA as were and everything was fine. Although the SAAB didn’t have a rear axle 😂

 

[Lutz]

Towbar mounting points are Type Approved at the noseweight limit - this includes repeated cycle testing - and all third-party towbar manufacturers must use only those points - are you suggesting that the EU/UK Type Approval regulations are inadequate?

As you correctly state, the towbar mounting points are type approved, but the approval is conditional to the attachment configuration to be in line with the manufacturer's specification. This may involve the need for additional reinforcements to the vehicle's underbody structure which the towbar manufacturer may not have taken into account in his design because he considers himself to be responsible only for the towbar assembly itself and not for any necessary body reinforcements, the design of which may consequently not have been coordinated with the vehicle manufacturer.

Towbar type approval only covers minimum durability requirements of the towbar itself and the location of the attachment points.

Would I be correct in thinking that the tongue weight on the towball should preferable be a lot less than the nose weight of the vehicle if it is a front engine vehicle?

This would ensure than even with the vehicle fully laden to its gross weight the rear axle can cope with the additional weight of the towbar and any weight placed on the towball and the vehicle will still look as if it is level.

The vehicle manufacturer has specified maximum permissible front and rear axle loads and those limits apply whether there is a nose load present on the towball or the car simply has a fully laden boot. In other words, hitching a caravan to the back of the car wouldn't increase the rear axle load any further than what is already specified as a permissible maximum.

 

[JTQ]

Apart from tow vehicles with very long overhangs, so the leverage created is a significant multiplier of the increase on the rear axle, and reducer of the front axle loads, differing noseweight will not be much of an influence on the tow vehicles stability.
The undoubted instability in towed combinations from using too low noseweights IMO is driven by the instability arising in the trailer, not the towcar.
Clearly, once the trailer develops instability this will quickly destabilise the whole, including then the tow vehicle.

Myself I am a big fan of using short overhang vehicles for towing, other factors like for like, and very much in the camp of using substantial trailer noseweights, particularly with things like caravans with high centres of drag.

 

[Buckman]

Bringing an Americanism or Aussieism into the discussion will create confusion.

I am not sure where I have mentioned America or Australia in my post?

 

[RogerL]

I am not sure where I have mentioned American or Australia in my post?

Tongue weight is used in Australia and America (maybe South Africa too) instead of noseweight which we use in the UK.

 

[otherclive]

I am not sure where I have mentioned American or Australia in my post?

In relation to caravans in UK “ tongue weight” is rarely used.

 

[Buckman]

Tongue weight is used in Australia and America (maybe South Africa too) instead of noseweight which we use in the UK.

Surely the maximum load that a towball or tow bar can handle is the tongue weight? I thought nose weight only applied to the hitch weight of the trailer. After all doesn't nose weight indicates something in front?

Anyway found this and different definitions for the load on the towball. See https://www.caravanclub.co.uk/media/12354614/noseweights-mo__2_.pdf

 

[Lutz]

Surely the maximum load that a towball or tow bar can handle is the tongue weight? I thought nose weight only applied to the hitch weight of the trailer. After all doesn't nose weight indicates something in front?

If you want to be really pedantic, the official term is neither noseweight nor tongue weight but the static vertical load on the coupling point. That is how it is referred to in text of the regulations, but noseweight is the term that is conventionally used for both the load on the hitch of the caravan and that on the towball. After all, the two are the same although the limits may be different.

 

[ProfJohnL]

So you think that towing close to, but under, the car's noseweight limit will cause significant wear and tear whereas towing well under won't - is that what you're suggesting?
...

Of course not! But even loads within specification will start to cause wear and tear, and the bigger the loads, the greater the effect.

 

[JTQ]

Of course not! But even loads within specification will start to cause wear and tear, and the bigger the loads, the greater the effect.

Being rather pedantic, and I accept petty about this, wear could well be greater if a lighter loading leads to more "shuffling" thus clunking within the "bearing's" clearances than a higher loading that is just enough to stabilise things and hold it firmly seated.
Quite a realistic situation with a case like being discussed here, where a lighter nose load could well yield a bit more "activity" from the trailer.

 

[Lutz]

Being rather pedantic, and I accept petty about this, wear could well be greater if a lighter loading leads to more "shuffling" thus clunking within the "bearing's" clearances than a higher loading that is just enough to stabilise things and hold it firmly seated.
Quite a realistic situation with a case like being discussed here, where a lighter nose load could well yield a bit more "activity" from the trailer.

Any wear is more likely to be centred around durability of the underbody structure of the towing vehicle, and that is undoubtedly going to suffer more under higher nose loads. The colleague that I sat next to in the office before my retirement was responsible for vehicle development testing of towing attachments and he often reported sheet metal cracks when testing some of the towbars that were submitted to him for approval. Obviously the towbar manufacturer involved hadn't given enough thought to additional reinforcements that would have been necessary in conjunction with his design.