tissy Posted January 18, 2009 Share Posted January 18, 2009 Can anyone help me ? I have a low profile Hymer van with a garage I want to put a motorbike on the back and not in the garage ,how do i work out the effect of moving the weight back from the rear axel at a given distance so i dont overload the rear axel even though i have not overloaded the van (?) Link to comment Share on other sites More sharing options...
Guest JudgeMental Posted January 18, 2009 Share Posted January 18, 2009 Not sure of the math but someone who does will be along soon........but if a Ford based van the standard rear axle is 2250kg (from memory *-) ) where if you have a Fiat its 1950kg unless a maxi chassis. what does the bike weigh? tow bar approx 30-40kg? Rack...the same probably more? Plus bike? you then have to allow for additional weight because you are loading behind the rear axle (fulcrum effect) an easy calculation is that the weight is effectively doubled:-S And if you are hoping to do all this with a full garage in a 3500kg van I would think it unlikely......... You say to know the weight of loaded van...what is it? and rear axle as well? if the math works you will need air suspension as well, or handling will be horrible. Sorry! just noticed it's your first post WELCOME! :-D Link to comment Share on other sites More sharing options...
tissy Posted January 18, 2009 Author Share Posted January 18, 2009 Im getting more cofused after revisiting the ford manual and the data plates inside the passanger door.PLate inside door reads 4co b 3500kg KLR R 4500KG AA 1750KG V2 2250KG Plate ont he van body 3500kg 1 - 1750kg 2- 2250kg i am assuming that 2250 relates to the rear axal .what states the dry weight of the van with all the conversion on this chassie? The bike weight is 115kg and there is the tow bar and rack total approx 100kg in the garage i want to carry another 50 kg by the way the van is a Hymer 572 (?) (?) Link to comment Share on other sites More sharing options...
Keithl Posted January 18, 2009 Share Posted January 18, 2009 Hi Mark and welcome to the forum. Running thru' your weights in order, 3500kg is the GVW, ie the MAXIMUM you can load the vehicle to, 4500kg is the GTW, the Maximum of vehicle plus trailer, so if the vehicle is at GVW then Max trailer is 1000kg. 1750kg is your MAXIMUM Front axle weight 2250kg is your MAXIMUM Rear axle weight (Note that the sum is greater than the GVW to allow flexibility in loading). The only accurate way to find your unladen or dry weight is to visit a weighbridge as the figure in any manual will only be a guide and not legally binding. It will also be useful to get separate axle weights while you are at the weighbridge to help establish the effect of adding your bike rack. If your rear axle weight is already near 2035kg (ie 2250kg - 215kg) then you will definitely not have sufficient to add your rack. If you search the forum there have been a lot of posts on weights and the different terminology used (GVW, MAM, MTPLM, etc). Hope this helps, Keith. Link to comment Share on other sites More sharing options...
Guest JudgeMental Posted January 18, 2009 Share Posted January 18, 2009 "i am assuming that 2250 relates to the rear axal .what states the dry weight of the van with all the conversion on this chassie? " But this (2250kg) is the weight that your rear axle can be legally loaded to...only a visit (fully loaded) to a weighbridge will tell you what you have left to play with. Both sets of measurements you quote are identical. The 4500kg means you can tow 1000kg. (3500kg + 1000kg) But not carry an additional 1000kg! lol At the end of the day if you do not have the spare capacity there is always a trailer...... But you say you know your loaded weight........what is it approx? Have you been to a weighbridge? Link to comment Share on other sites More sharing options...
colin Posted January 18, 2009 Share Posted January 18, 2009 Some one has done a spread sheet, mel or brian? But here's what you do to ensure you will not be overloading rearaxle. Load van to how you expect to travel, visit weight bridge and get individual axle loadings. Now you need to calc added rear axle loading with bike and rack, to do this you need three measurements to give a accurate figure (or two to give 'safe' figure) no1 measure wheelbase no2 measure from front wheel to estimated centre of mass of rack no3 measure from front wheel to estimated centre of mass of bike (no2/no1xmass of rack)+(no3/no1xmass of bike)= additional weight on rear axle Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 19, 2009 Share Posted January 19, 2009 tissy: Your Ford Transit-based Hymer Van 572 is a reasonably long front-wheel drive motorhome built on a chassis with a not particularly long wheel-base and with a quite narrow rear track. I do not know whether carrying a 115kg motorbike (plus the 150kg of tow-bar/rack/load) at the rear of your motorhome will overload its rear axle beyond its 2250kg limit, but it will take a fair amount of weight off the driven front wheels and it is likely to have an adverse impact on the vehicle's softly-sprung rear suspension. If you go ahead with your plan, you should not be too surprised if traction is significantly worse on slippery surfaces and hills. Also, to counter the effect of the extra weight at the rear, I repeat JudgeMental's advice that you should fit 'air springs' to firm up the rear suspension. Otherwise you may well find that the vehicle wallows badly when cornering and that its overall handling is unpleasant. Link to comment Share on other sites More sharing options...
Mel B Posted January 20, 2009 Share Posted January 20, 2009 Hi tissy - welcome! I just found a copy of the motorhome loading Excel spreadsheet that Mel E kindly sent me a while back, which you can use to calculate the overall loading taking into account the overhang etc. If you drop me a PM with your email on it I'll send it to you. :-D Link to comment Share on other sites More sharing options...
Rainbow-Chasers Posted January 21, 2009 Share Posted January 21, 2009 Check the tow balls downward pressure resistance. There is a common problem with tow balls shearing, although they can pull say 3.5t - they cannot actually take much downward force. I do recall seeing 75kg somewhere. Have a search online and see what you can dig up! Link to comment Share on other sites More sharing options...
Clive Posted January 21, 2009 Share Posted January 21, 2009 If the garage is big enough to take the motorcycle but you have already filled it with other clutter I can only suggest that you are heading for a disappointment when you visit the weigh bridge fully loaded with bike on back. BUT When it comes to calculating the affect of adding additional load then the calculations are not that difficult. There are several methods of doing this calculation and here is one of them. Having visited the weigh bridge and weighed each axle individually you will have two figures, one for front (1) and one for back (2). Make sure you are fully fueled and watered and that all passengers are aboard. The rating plate for the vehicle will give the maximum permissible load for the front axle and also for the rear axle. It will also give a maximum all up weight (MAM) which will be less that the sum of the two axle figures but which must not be exceeded. To calculate the effect of adding additional load you need to know the weight of the bike and the rack (4) and know where its centre of gravity is. You need to know the distance behind the rear axle that this centre of gravity will be. Multiply the weight (in Kg) of this bike and rack by the distance behind the centre line of the rear axle (in Metres). This will give you a figure (3) for "FORCE x DISTANCE". You will also know that adding weight behind the rear axle will reduce the weight on the front axle. Measure the distance between the centre lines of the front and rear axle (wheelbase) (in metres). Now divide figure (3) by this distance and you will have the amount by which the front axle is lighter. Subtract this from (1) to get the new front axle weight (4). Now add weigh bridge figures (1) and (2) and the weight of the rack and bike (4) together to give you a new total vehicle weight (5). Subtract the new front axle weight (4) and what remains is the weight on the rear axle (6). If I have got this wrong I am sure Mel or someone will put me right! Good luck Clive Link to comment Share on other sites More sharing options...
ron. Posted January 21, 2009 Share Posted January 21, 2009 By a rough calculation, and allowing for leverage, I think you will be adding around 250kg to your back axle weight. On that basis I'm sorry to have to say that I dont think that you will be able to do it and stay legal. However, as said previously you really need to weigh your van fully loaded and then you will be able to work out a more realistic figure. Link to comment Share on other sites More sharing options...
tonyishuk Posted January 21, 2009 Share Posted January 21, 2009 With thanks to Watling Towbars http://www.watling-towbars.co.uk/motorhome_axle_loads.html rgds Added as an afterthought, I think that there is a formula in the forum archives for this. Link to comment Share on other sites More sharing options...
Guest JudgeMental Posted January 21, 2009 Share Posted January 21, 2009 Where has tissy gone......Think we have scared him oft :-D Link to comment Share on other sites More sharing options...
colin Posted January 21, 2009 Share Posted January 21, 2009 Clive - 2009-01-21 8:12 AM If the garage is big enough to take the motorcycle but you have already filled it with other clutter I can only suggest that you are heading for a disappointment when you visit the weigh bridge fully loaded with bike on back. BUT When it comes to calculating the affect of adding additional load then the calculations are not that difficult. There are several methods of doing this calculation and here is one of them. Having visited the weigh bridge and weighed each axle individually you will have two figures, one for front (1) and one for back (2). Make sure you are fully fueled and watered and that all passengers are aboard. The rating plate for the vehicle will give the maximum permissible load for the front axle and also for the rear axle. It will also give a maximum all up weight (MAM) which will be less that the sum of the two axle figures but which must not be exceeded. To calculate the effect of adding additional load you need to know the weight of the bike and the rack (4) and know where its centre of gravity is. You need to know the distance behind the rear axle that this centre of gravity will be. Multiply the weight (in Kg) of this bike and rack by the distance behind the centre line of the rear axle (in Metres). This will give you a figure (3) for "FORCE x DISTANCE". You will also know that adding weight behind the rear axle will reduce the weight on the front axle. Measure the distance between the centre lines of the front and rear axle (wheelbase) (in metres). Now divide figure (3) by this distance and you will have the amount by which the front axle is lighter. Subtract this from (1) to get the new front axle weight (4). Now add weigh bridge figures (1) and (2) and the weight of the rack and bike (4) together to give you a new total vehicle weight (5). Subtract the new front axle weight (4) and what remains is the weight on the rear axle (6). If I have got this wrong I am sure Mel or someone will put me right! Good luck Clive Well I do weight and balance as part of my day job, after reading this four or five times I think you've got it right! Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 22, 2009 Share Posted January 22, 2009 I think Ron's suggestion that the motorbike + rack will place an extra 250kg on tissy's Hymer's rear axle is likely to be optimistic. Let's take the 115kg weight of the motorbike alone and completely ignore tissy's guesstimate of 100kg for the tow-bar & rack and the 50kg in the rear garage. Let's now assume this 115kg load will be positioned at the Hymer's rear wall, and let's overlook the obvious fact that the motorbike will be significantly further back than that. This scenario would result in a load-increase on the Hymer's rear axle of 174kg and a load-reduction on the front axle of 59kg. Mel Eastburn's "It Ain't Heavy - It's My Motorhome" MMM 2004 articles include formulae to calculate the effects of adding a 'rearwards-load' to a 2-axle motorhome. w = wheelbase of motorhome d = distance of extra load behind the rear-axle's centre line. E = weight of Extra load. F = Front-axle reduction in loading caused by E. R = Rear-axle increase in loading caused by E. A Hymer Van 572 has a wheelbase of 3750mm and (according to my calculations) a rear overhang of 1926mm. The weight of the motorbike (E) is 115kg. F = -E x (d/w) ------ hence -115kg x (1926/3750) = -59kg R = E - F ------ hence 115kg - (-59kg) = +174kg The same calculations using 115kg + 100kg + 50kg (motorbike + tow-bar & rack + load in garage), and similarly placing this 265kg total at the motorhome's rear-wall position, produces a 'lift' of 136kg at the front axle and a rear-axle load-increase of 401kg. Admittedly this is rough maths but, by the time the weights of the bike and rack are moved outwards from the Hymer's rear wall, it's probably not far out. The Van 572 has a similar Transit chassis to my Hobby's, though the Hymer has a 20cm longer rear overhang and its garage provides more rear storage capacity. My motorhome's rear-axle loading was 1740kg when I weighed the vehicle in fairly well-loaded state. All of this suggests that tissy's plans may seriously threaten the Hymer's 2250kg rear-axle weight limit (though, frankly, I'd be much more concerned about how the vehicle performed after all that extra weight had been stuck on the back). Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 22, 2009 Share Posted January 22, 2009 A further thought on this - 100kg for a tow-bar & motorbike rack (tissy's 2nd posting) seems a helluva lot. Hymer's January 2007 brochure quotes - for Van models - 26kg for a tow-bar and 40kg for a removable motorcycle rack. Tissy's comment suggests that the rack is additional to the tow-bar, but that still only adds up to 66kg. Link to comment Share on other sites More sharing options...
ron. Posted January 22, 2009 Share Posted January 22, 2009 Exactly Derek, which brings the figure to within about 20kg of what I said, and your figure includes the weight of a removable rack which is not necessary. Ron Link to comment Share on other sites More sharing options...
tissy Posted January 25, 2009 Author Share Posted January 25, 2009 Thanks to you all for your help ,i have not been scared away just went to the weigh bridge so i could get the facts as you all advised. I loaded the van as we would travel and weighed the the van including the tow bar which is fitted,and the passangers .The results were: total weight 2960kg front axle 1290kg rear axle 1630 kg I know the scooter is 115kg The only thing i dont know is the rack weight (lol) Link to comment Share on other sites More sharing options...
tissy Posted January 25, 2009 Author Share Posted January 25, 2009 Sorry i also forgot to add the measurments i took: centre to centre of the front and rear wheels 3750mm centre of rear wheel to back of van 1950mm centre of rear wheel to tow hitch 2150mm scooter will be centre line 250mm back fom tow hitch (lol) Link to comment Share on other sites More sharing options...
ron. Posted January 25, 2009 Share Posted January 25, 2009 Tissy On the face of it you would appear to have enough spare payload for what you want. However, did you weigh it with all the people onboard that you intend to carry? A full fuel tank? Full gas tanks? Full fresh water tank, etc? The only other comment I would like to make is that, going by your figures, your rear axle loading is going to finish up some 70% heavier than your front axle loading when bike and rack are added. Even though you might be within your payload figures this is not the sort of weight distribution that I would be happy with and I would be worried about the steering effects. I'm sorry to put a dampener in the works but better it sorted now than when it's to late. Ron Link to comment Share on other sites More sharing options...
Philman Posted January 25, 2009 Share Posted January 25, 2009 Hi Tissy, did you notice that the 2 axle weights do not add up to the total weight? Apart from that your front axle weight is already very close to the recommended minimum load ( 41% of total ). By the time you have added the scooter and rack behind the van I suspect you will have nowhere near enough weight on the front axle. This will cause poor handling especially in wet conditions and you will almost certainly find great difficulty in getting off grass pitches if they are wet. Phil. / Link to comment Share on other sites More sharing options...
colin Posted January 25, 2009 Share Posted January 25, 2009 Now thats what I call a van with a decent payload! You should be well within limits even if the rack was cast iron, but as said above, will have effect of tail wagging the dog, so you must consider if it will suit how you use/drive van. Link to comment Share on other sites More sharing options...
woodstock dave Posted January 8, 2014 Share Posted January 8, 2014 Hi MelB, Weight Distribution Spreadsheet request Sorry to jump onto your thread, but I see that you tracked down Mel Eastburns spreadsheet re. weight distribution and wonder whether it is still available and how it might be obtained. Having found that I was running 100Kg overweight at a recent weighbridge visit, And having to empty the van to allow major damp and Nearside rear ALKO suspension torsion bar renewal (naturally, both sides done) repairs, I Weigh-bridged "Empty + Mrs and dogs + 50% fresh water in tank + No2 Leisure Batt." . "Empty+" was3240Kg. My MGW is 3400Kg Available payload remaining after above is just 160Kg. This rather concentrates the mind on careful loading, What is essential and where to place it. In the past the luton has had too much in it as had the long rear overhang area. Generator, 3tonne jack, Tirfor 5Gall DieselCan and microwave will likely be pensioned off. No wonder I posted "MORE POWER PLEASE" a while back. I have been revisiting my spreadsheet skills, but now find them lacking. My camping world now lies in 30 refuse sacks, weighed and tagged, for serious review of every items "necessity" I shalll greatly appreciate any assistance in locating anybodys spreadsheet effort. Layout and presentation are ok, Its the formulae that I'm struggling with. My spare email address is rowan.essie@gmail.com Many thanks Dave Link to comment Share on other sites More sharing options...
Mike88 Posted January 8, 2014 Share Posted January 8, 2014 When I was considering something similar Swift told me............."The front axle load in all conditions must be between 40% and 70% of the total weight to ensure adequate road holding and the GVW must not be exceeded." Link to comment Share on other sites More sharing options...
tonyishuk Posted January 8, 2014 Share Posted January 8, 2014 Maybe an easier way to calculate loadings http://www.svtech.co.uk/motorhomes.html about 2/3 the way down the page is a small downloadable program Rgds Link to comment Share on other sites More sharing options...
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