Prof,
I'm not playing games if vehicle is a tank of fuel lighter then its a lighter vehicle and would give a different % match,
Of course the car is lighter just as it’s heavier with all occupants on board and the boot is fully laden, but both changes don’t affect the weight ratio which is based solely on the kerbweight.
The conventional weight ratio calculation is based on the kerbweight figure of the car vs the MTPLM of the caravan. It is and always has been based on paper figures not measured weights. Consequently whatever you put in a car or leave out will not change the industry weight ratio figure. The industry advice is is based on that calculation and not real world measurements.
Real world weight ratio is based on measured weights, and may not bear a close relation to the industry calculation. In the real world then as a car is driven and its fuel load reduces, then yes the measures ratio would change. However any outfit that becomes unstable as fuel is used could not have been adequately matched before the journey started.
Real world weight ratio is based on measured weights, and may not bear a close relation to the industry calculation. In the real world then as a car is driven and its fuel load reduces, then yes the measures ratio would change. However any outfit that becomes unstable as fuel is used could not have been adequately matched before the journey started.
I've had 5 Saabs, and I would probably be still driving one if the company hadn't been shut down by GM. I had two 9000 shape Saab's, and they were great cars. as Clive says great space, and whist neither were Turbo's they still had plenty of pulling power to tow.
I would have to take issue with the 9000 being true SAABs, they were Lancias where SAAB tried its best to sort it out. Last true ones were the lovely 900.
Like the Prof, if true SAABs were going today we most probably would still be clients.
We both remember ours with a lot of affection, despite being a naff towcar for predominately 5 van site and rally caravanners.
Like the Prof, if true SAABs were going today we most probably would still be clients.
We both remember ours with a lot of affection, despite being a naff towcar for predominately 5 van site and rally caravanners.
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Camel behave; we're talking unstable caravans and you are talking matches, and lighter fuel as a pun on the incendiary level-took me a while but!
It was a joint design by Saab and Fiat Only seven body parts were common as Saab beefed up the impact protection. Most mechanicals were Saab specific too
Saab 9000 - Wikipedia
Much as I said, SAAB tried very hard to sort it out if only seven body parts and all but no mechanicals made it across from Fiat's Lancia team.
........it is simply not true to state that weight added to increase rear axle loading reduces the front axle load or creates a bouncy ride.
Drivers get used to driving their vehicles with lightly loaded rear axles and a weight bias towards the front of their vehicle. Load the rear axle and the front axle weight will also likely increase as some of the weight will likely be infront of the rear axle.
Front wheel drive cars will likely be prone to more wheel spin if the car is heavier or towing a caravan or both........entirely due to the fact they are moving a heavier mass.
Drivers get used to driving their vehicles with lightly loaded rear axles and a weight bias towards the front of their vehicle. Load the rear axle and the front axle weight will also likely increase as some of the weight will likely be infront of the rear axle.
Front wheel drive cars will likely be prone to more wheel spin if the car is heavier or towing a caravan or both........entirely due to the fact they are moving a heavier mass.
Add weight to the hitch and in some cases the boot, the rear axle load increases and the front axle load decreases, it is all down to lever arms.
As important, force rather than weight, force from the van's dynamics does the same loading and unloading the axles.
.......I try not get too theoretical as this is a Caravan forum not an Engineer's debating society.
I was writing in terms of a caravan outfit that already has its nose weight set and additional loading of the boot area was placed sensibly.
Very few tow cars have their rear wheel arches in the rear passenger compartment and the boot area entirely behind the axle.
I was writing in terms of a caravan outfit that already has its nose weight set and additional loading of the boot area was placed sensibly.
Very few tow cars have their rear wheel arches in the rear passenger compartment and the boot area entirely behind the axle.
I'd broadly agree with that except when additional mass is added to the car between the cars axles,the load the mass creates is proportionally distributed between the axles. Additional load on the driving wheels (ala sitting on the bonnet of a FWD car) will create extra grip, and reduce the degree of driven wheel slippage.
Some might be wondering if discussions about wheel spinning is relevant to the thread. In my opinion it is because essentially caravan instability is about loss of control by the tow vehicle. That equates to loss of tyre grip.
As tyre grip is directly affected by the vehicle weight acting through the tyre and onto the road, weight distribution is an important consideration.
As tyre grip is directly affected by the vehicle weight acting through the tyre and onto the road, weight distribution is an important consideration.
I am sorry, but any constructive "85% debate"into caravanning mass ratio, will be steeped in engineering, because the physics involved dictate towed unit stability.
I certainly don't agree that few tow car boots are not located aft of the axle, many have most of their boot aft of the axle
One that for many years won towcar of the year, has it's boot 100% aft of the axle.
I certainly don't agree that few tow car boots are not located aft of the axle, many have most of their boot aft of the axle
One that for many years won towcar of the year, has it's boot 100% aft of the axle.
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.....of course the laws of physics are ever present.
Using your vehicle example in the context of towing a caravan and where any load is placed there are several options and they all affect axle loads.
5 people in the car with a caravanners typical load in the boot will increase the rear axle load and will not lighten the front axle load relative to an empty car.
No rear seat passengers, then loading in the real world would involve lowering the rear seats and" the load place sensibly" ..........to quote my own previous post.
My general point in the context of towing ratio's is.......load the car not the caravan.
I see many tow cars carrying virtually no load in the rear and I agree with the Prof when he states..................
"As tyre grip is directly affected by the vehicle weight acting through the tyre and onto the road, weight distribution is an important consideration".
............and I would add especially on the rear axle of the tow car.
Using your vehicle example in the context of towing a caravan and where any load is placed there are several options and they all affect axle loads.
5 people in the car with a caravanners typical load in the boot will increase the rear axle load and will not lighten the front axle load relative to an empty car.
No rear seat passengers, then loading in the real world would involve lowering the rear seats and" the load place sensibly" ..........to quote my own previous post.
My general point in the context of towing ratio's is.......load the car not the caravan.
I see many tow cars carrying virtually no load in the rear and I agree with the Prof when he states..................
"As tyre grip is directly affected by the vehicle weight acting through the tyre and onto the road, weight distribution is an important consideration".
............and I would add especially on the rear axle of the tow car.
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As advised by our dealer on purchase of our first caravan-we have always loaded the car rather than the caravan. We even put the awning on the front seat to keep weight distribution as even as possible over the car-witha seatbelt round it of course!
We have never had any noticeable problem due to the fuel tank getting near empty when towing. I can see the point but think you would have to have a bad match from the beginning for it to become a problem. We always start out with a full tank as refueling with a caravan on the back can be tricky in some places and have run the tank down to quarter full or a bit less with no noticeable problem. 50 kg sounds as if it might make a difference but as a proportion of the cars weight it is not a lot and unless you have a very light car then there should be no problem.
i think he was tongue in cheek-but hasn't confirmed-re read his post and there is a poss wordplay on fuel match and lighter as in incendiary. Could be wrong but most fuel tanks are in front of the rear axle under the passengers seat-sweeping statement-Honda Jazz /Civic differ etc for the magic seats.
Hello Jezzer,
I don't believe Camel was trying to be humorous, it certainly did not come across to me that way, and I judging by the other comments his post received, I suspect others also missed it if that was indeed his intention.
At times, I believe humour can be fun and useful, but it needs to be clear (e.g. use of emoji's) and not rely on hidden meanings or exclusive experiences which may not be understood by all readers or even the intended recipient. Some types of humour just do not work on written forums, as the recipient cannot see, hear touch or smell the sender and so have means of judging what the intention is. In some circumstances it might cause unintended offence.
When it comes to technical discussions it makes answering some contributors difficult when they don't give all the relevant information, or if they deliberately try to make it a twenty questions quiz.
It's far better to try to be clear and give as much relevant information as possible so sensible answers can be formulated.
I don't believe Camel was trying to be humorous, it certainly did not come across to me that way, and I judging by the other comments his post received, I suspect others also missed it if that was indeed his intention.
At times, I believe humour can be fun and useful, but it needs to be clear (e.g. use of emoji's) and not rely on hidden meanings or exclusive experiences which may not be understood by all readers or even the intended recipient. Some types of humour just do not work on written forums, as the recipient cannot see, hear touch or smell the sender and so have means of judging what the intention is. In some circumstances it might cause unintended offence.
When it comes to technical discussions it makes answering some contributors difficult when they don't give all the relevant information, or if they deliberately try to make it a twenty questions quiz.
It's far better to try to be clear and give as much relevant information as possible so sensible answers can be formulated.
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