MTPLM dilema

[GaryB]

Prof are you sure that if you leave the hammer on the nail for long enough it won't push the nail in ?😅. Seriously some manufacturers have been rejecting claims for 'failed axles' ( rubber inserts) on the grounds of 'Overloading' or 'Potholes' good job Fraser brown can refurbish such axles at a reasonable cost

It does make you question the actual rubber material. I restore classic cars and always fit original (unused new old stock) rubber suspension components as the reproduction ones fail after only a thousand miles or so, the rubber itself just doesn't appear to be as robust/hard wearing as the original.

 

[Newtonian]

When specifying a static weight limit such as 1300kg, the manufacturer will already have taken into account that peak dynamic loads will be well in excess of that value.

Cool thanks. Although no one actually answered my question, so I will probably just remove the motor mover anyway 😂

 

[Buckman]

Cool thanks. Although no one actually answered my question, so I will probably just remove the motor mover anyway 😂

If single axle, removing the motor mover will only save you about 30kg. You could get a roof box for the car to carry a load of extra gear?

 

[Boxerman]

on this subject of which I have very little knowledge we have just bought a Bailey 640 the previous owner paid £65 to Bailey to get an upgraded weight plate, taking its max weight up by nearly 100kg how’s that work when it’s exactly as it was when it left the factory seem a bit odd that it’s this simple

 

[Lutz]

on this subject of which I have very little knowledge we have just bought a Bailey 640 the previous owner paid £65 to Bailey to get an upgraded weight plate, taking its max weight up by nearly 100kg how’s that work when it’s exactly as it was when it left the factory seem a bit odd that it’s this simple

If nothing was technically changed then the caravan wasn’t upgraded at all. The MTPLM displayed on the sticker was only brought into line with what was shown all along on the legal (statutory) plate. Without the so-called upgrade, the sticker displays a purely artificial value based on NCC’s formula, and applicable for marketing purposes only. One can achieve the same result at no cost by simply removing the sticker on the side of the caravan (so long as there is still a statutory weight plate elsewhere on the caravan (usually in the front locker). It will show all the details that are legally required.

 

[otherclive]

on this subject of which I have very little knowledge we have just bought a Bailey 640 the previous owner paid £65 to Bailey to get an upgraded weight plate, taking its max weight up by nearly 100kg how’s that work when it’s exactly as it was when it left the factory seem a bit odd that it’s this simple

It means your axle is capable of taking the increased loading. So the caravans MTPLM was less than the maximum load it was able to take. This makes it more attractive to car owners whose cars were not heavy enough if the 85% guidance was used. There was a period when cars were getting lighter with each successive model iteration. In some cases 200 kg or more removed from a typical mainstream C class car. So you can see how this might have influenced peoples decision on what MTPLM caravan they could tow. The makers considered this preferable to letting owners having a higher MTPLM but not towing it fully laden. It also helped those that did not have the full BE licence.

In the same period caravan payloads reduced in some instances I’d see payloads on some caravans down around 125kg. Which is pitifully low considering a battery and mover could take 60kg. Hence to my mind it led to a situation where you would see a couple putting a roof box on the car to aid carrying equipment that I would have carried in the caravan. It put me off changing one van at five years and decided to keep it for another four years. It had a 250 kg payload when upgraded by Bailey.

One thing ensure your tyres load index is sufficient to carry the upgraded payload and increased MTPLM. When I had my Bailey upgraded the new MTPLM was within 20 kg of the combined tyre LI. So I had new higher LI tyres fitted.

 

[trevormonty]

A gas bottle in a roofbox is hardly a safe place to transport it

Why.

 

[Lutz]

It means your axle is capable of taking the increased loading. So the caravans MTPLM was less than the maximum load it was able to take.

A declared MTPLM which is less than what the caravan is able to take cannot be a true MTPLM. A maximum is maximum. The lower of two values can’t have been a technical maximum, which is what the term MTPLM implies. A change in the true MTPLM doesn’t make sense unless accompanied by a technical modification

 

[otherclive]

A declared MTPLM which is less than what the caravan is able to take cannot be a true MTPLM. A maximum is maximum. The lower of two values can’t have been a technical maximum, which is what the term MTPLM implies. A change in the true MTPLM doesn’t make sense unless accompanied by a technical modification

We’ve been around this chestnut numerous times, but the reality is that many owners don’t understand the significance and take the door label as gospel.

 

[Lutz]

A gas bottle in a roofbox is hardly a safe place to transport it

Why.

If the car is involved in an accident, the bottle will fly through the air like a slingshot, breaking through the roof box in the process.

 

[Lutz]

We’ve been around this chestnut numerous times, but the reality is that many owners don’t understand the significance and take the door label as gospel.

One doesn’t need to to reflect on the subject for very long though to come to the conclusion that a caravan can’t have two MTPLMs without a technical change.

 

[ProfJohnL]

Why.

Apart from the point that Lutz has made, gas cylinders should always be transported with the valve upper most (except Liquid take off cylinders used on fork lift trucks) just in case the valve is leaking as dumping liquified gas (as opposed to vapour) is incredibly dangerous and at least in the UK its illegal to transport an LPG cylinder that is not properly secured in a space designed for it.

 

[trevormonty]

If the car is involved in an accident, the bottle will fly through the air like a slingshot, breaking through the roof box in the process.

Not if its strapped in place. If accident is that bad I'd be more worried about 1100kg caravan in tow that is trying squash car.

 

[Lutz]

Not if its strapped in place. If accident is that bad I'd be more worried about 1100kg caravan in tow that is trying squash car.

I doubt whether any anchorage points in the roof box, if provided, are substantial enough to restrain a gas bottle. Contrary to a gas bottle, a caravan has got its own brakes. So long as they are in good working order they should contribute substantially to being able to stop itself without squashing the car.

 

[Buckman]

If the car is involved in an accident, the bottle will fly through the air like a slingshot, breaking through the roof box in the process.

Who even suggested that one could carry a gas bottle in a roof box? That has to rate as one of the most ridiculous things I have read on any forum!

 

[otherclive]

Some roof box manufacturers do crash test their boxes but the results can be quite revealing. See this crash test report on boxes by a Swedish organisation. Alll that goes in my roof box is soft stuff like hold-all, throws, dog bed, etc. I strap it down but generally it’s conformal to the roof box shape anyway. It’s crash tested by TUV but only to Citysafe standard.

Testfakta

Testfakta - Best in Test - is an independent testing and research company specialized in laboratory testing and evaluation of consumer products.

www.testfakta.com

 

[Buckman]

That test is totally pointless as who travels at about 28mph. Generally we travelled at about 60mph carrying awning, poles, groundsheet etc max 60kg in the roof box. However you are more likely to brake hard on an A road while travelling at about 40-45mph. A test at that speed would have be more approriate.

 

[ProfJohnL]

Who even suggested that one could carry a gas bottle in a roof box? That has to rate as one of the most ridiculous things I have read on any forum!

see #15 Parra 1

 

[otherclive]

That test is totally pointless as who travels at about 28mph. Generally we travelled at about 60mph carrying awning, poles, groundsheet etc max 60kg in the roof box. However you are more likely to brake hard on an A road while travelling at about 40-45mph. A test at that speed would have be more approriate.

Don’t shoot the messenger. Similar tests are at 50km per hour. They are all mainly focused on crashes in cities where statistically most crashes occur. Hence one test is called Citysafe. Having seen NCAP crash test videos of cars I really cannot envisage a roof box doing anything other than breaking free of its restraints and disintegrating at higher speeds. . Even this eye wateringly expensive Swedish roof box test goes nowhere near the speeds you mention.

#1 Secured cargo - MIMsafe Carrier - Crash tested

Secured cargo with MIMsafe's luggage and ski box Carrier. Designed for ultimate safety, keeping items safe on your roof.

mimsafe.com

 

[Buckman]

see #15 Parra 1

Thanks and I am very surprised that the poster in question even considered tsking such a risk as it must be rated as one of the most damgerous things toicarry in a roof box as it is a potential missle or lethal weapon that can wreak havoc and destruction.

Don’t shoot the messenger. Similar tests are at 50km per hour. They are all mainly focused on crashes in cities where statistically most crashes occur. Hence one test is called Citysafe. Having seen NCAP crash test videos of cars I really cannot envisage a roof box doing anything other than breaking free of its restraints and disintegrating at higher speeds. . Even this eye wateringly expensive Swedish roof box test goes nowhere near the speeds you mention.

#1 Secured cargo - MIMsafe Carrier - Crash tested

Secured cargo with MIMsafe's luggage and ski box Carrier. Designed for ultimate safety, keeping items safe on your roof.

mimsafe.com

I wasn't having ago at you, just the nature of the tests.

 

[ProfJohnL]

Whilst I haven't closely studied the document yet, the revelation the test is carried out at 28mph was surprising, but the reality is most very few collisions occur at very high closing speeds. Generally the drivers involved have started braking and as such the speed will be reducing and could easily be as little as 40kph at the point of contact when the maximum deceleration due to contact will occur.

Frankly, I personally would not be worrying about the content of my roof box if I was involved in a high speed incident.

 

[Buckman]

Whilst I haven't closely studied the document yet, the revelation the test is carried out at 28mph was surprising, but the reality is most very few collisions occur at very high closing speeds. Generally the drivers involved have started braking and as such the speed will be reducing and could easily be as little as 40kph at the point of contact when the maximum deceleration due to contact will occur.

Frankly, I personally would not be worrying about the content of my roof box if I was involved in a high speed incident.

I am surprised that you state you would not worry about the contents flying out and perhaps injurying or even killing other people. what a strange comment?

 

[ProfJohnL]

I am surprised that you state you would not worry about the contents flying out and perhaps injurying or even killing other people. what a strange comment?

I didn't say that. Please stop putting words into my mouth.

 

[Buckman]

I didn't say that. Please stop putting words into my mouth.

However you certainly indicated that you would not care about what may happen to the contents of your roof box or did I misunderstand?