Mike Chapman Posted January 2, 2007 Share Posted January 2, 2007 Vixters other half - 2007-01-02 4:26 PM I can tell you that on the odd occasion I have had to stamp on the brakes to let a lower life form survive, the car and trailer does give a hefty shove up the rear end of the motor home. That being 7.49 tonnes, I wonder just how a lighter vehicle at 3.5 tonnes would fair? I really need one of those skirts that catches all the crud fitted - anyone know where they are sold?? HNY VoH Hello VoH, Is it possible that the trailer is underbraked for the weight? From my experience of towing caravans at near 85% of the tow car weight I found that braking was actually better than with the car solo. The caravan brakes acted as an anchor rather than the caravan pushing the car against it's brakes. I am sure that Dave Newell with his vast experience could advise us on this matter. For the rear skirt take a look at www.motorhomesmudflaps.com and advert in back of MMM each month. Regards, Mike. Link to comment Share on other sites More sharing options...
Dave Newell Posted January 2, 2007 Share Posted January 2, 2007 In theory at least, if the over-run coupling and trailer brakes are adjusted correctly they should be capable of slowing the trailer at the same rate as the car, even under extreme braking. On first applying the brakes it is possible to get a "shunt up the bum" feeling as the trailer takes up the movement in the coupling, thereafter there should be no significant forward momentum applied to the towing vehicle by the trailer. By the same token the trailer cannot apply any additional braking effort to the towing vehicle because if it was braking harder than the towing vehicle then the over-run coupling would extend slightly and take pressure off the trailer brakes. One potential problem arises when you stamp on the brakes really hard, as in your driving test emergency stop for example. The over-run coupling then takes up the slack very quickly and can cause a momentary lock up of the trailer brakes. This is normally about where it all starts going wrong because the co-efficient of friction of a skidding wheel is significantly less than that of a non skidding wheel. In other words the actual braking effort being applied to the trailer wheels is significantly less than it should be and the trailer will not then "back off" from the towing vehicle leaving you with a car/motorhome braking hard and a Tonne plus of trailer pushing you with locked wheels. D. Link to comment Share on other sites More sharing options...
Mike Chapman Posted January 2, 2007 Share Posted January 2, 2007 Hello Dave, Happy New year to you and yours, I see your point exactly, not wise of me to talk about an anchor effect, should have said more that caravan brakes seemed to be adding to the braking effect. It seems logical that if the trailer brakes are powerful enough to exceed the requirements of braking the trailer weight then this would add to the overall braking performance or have I missed something? The point I would be interested in is some further advice on is whether it is necessary, for matters of stability, to match the trailer brakes (and possibly the trailer tyres) to those of the towing vehicle and how? How critical is the trailer weight and therefore momentum under braking assuming that the weight limitations of both vehicles are taken into consideration? I am currently considering occasional towing of a trailer/caravan with the Ducato. My last caravan was a Swift Challenger 480 and the towcar a VW Passat. I cannot ever remember getting that "Shunt up the bum" effect with this outfit but there again I do not remember ever having to do an emergency stop with it. Regards, Mike. Link to comment Share on other sites More sharing options...
Mel B Posted January 2, 2007 Share Posted January 2, 2007 Dave Newell - 2007-01-02 4:17 PM Still no explanation of "get a light" Sshortcircuit? D. Dave - perhaps he meant to get a light in the sense of - have a ciggy, or have a drink of light beer, or strike a match and blow him up!!! Pick whichever version you perfer! :-> Back to topic - we've seen the damage that can be caused when a caravan overtakes a car, not pretty at all, we've also experienced towing a car on a trailer that went a bit daft, ie it decided to do a 'duck waddle' which developed into a right stomp as the trailer alternately lifted one wheel then the other going down a gradient on a bend, caused by some daft idiot speeding by it which started it rocking in the first place. We managed to slow down very gradually and get control back but it was hellish frightening and scared us silly, and we were well within the speed limit. Even if we'd been towing with a motorhome rather than another car it wouldn't have prevented the waggle. Safety first - you may think you know what you're doing but do you really know what the idiots around you are going to do? 8-) Link to comment Share on other sites More sharing options...
Dave Newell Posted January 2, 2007 Share Posted January 2, 2007 Hi Mike and Mel and everybody, happy new Year to all. Mike, the trailer brakes will be matched to the trailer and its likely load. The momentum of the trailer is directly proportional to its mass and therefore it will self compensate on braking effort as it is the momentum of the trailer which compresses the coupling head and applies the brakes. The trailer can never apply additional braking to the tug because if more braking effort is applied to the trailer wheels than the tug wheels then the over-run coupling releases slightly and reduces the braking effort applied to the trailer's wheels. Mel, what you describe is exactly the reason I reacted the way I did to the suggestion that it is safe to tow at 70 MPH. One of the biggest problems is that as speed increases so your reaction time decreases dramatically and when you do find you need to react suddenly it tends to be a slight over-reaction, i.e. jumping on the brakes too hard and getting all out of shape. yours happened at sensible speeds and you were thankfully able to get it back under control but if that happened at 70 MPH you probably wouldn't. D. Link to comment Share on other sites More sharing options...
mike.T Posted January 2, 2007 Author Share Posted January 2, 2007 Happy new Year All Any chance we could get back to my original question ! How would towing a small car on a trailer almost a ton affects our motor van 3850kg Ducato the overall performance’s and Not Is ok to tow at 70 MPH !! as we seam to have drifted off too. Link to comment Share on other sites More sharing options...
Vixter Posted January 2, 2007 Share Posted January 2, 2007 Thanks to Mike for the info on Dirt Skirts, do you use one Mike? I will be asking the question in a new post. Ta, Vixter. Link to comment Share on other sites More sharing options...
michele Posted January 2, 2007 Share Posted January 2, 2007 Mike T , Motorhomefinder said he has no problems . it may on gone off topic more re speed . But safer than sorry springs to mind re the speed ? Daves quite right and was just expressing his views as he say's picking up the peices of accidents like this ..................NASTY.. so meander on down at a nice speed . Hopefully Motorhomefinder has given you the help you need . Why don't you do a little pre trial run up a local motorway, road . See what you think I am assuming you already have the trailer. failing that I can't help only like Dave with the law which I know you are aware of . Above all take it easy .. I drive Coaches with the trailer on the back and I can tell you even with air brakes I can make the coach stand on it's head but not the trailer ......... Above all take care ........ Shortcircuit get a light Link to comment Share on other sites More sharing options...
Mike Chapman Posted January 3, 2007 Share Posted January 3, 2007 Hello Vixter, Have posted reply in the Dirt Skirts Thread. Hello Dave, Thanks for the information. Regards, Mike. Link to comment Share on other sites More sharing options...
Steve OReilly Posted January 4, 2007 Share Posted January 4, 2007 Mike I don't know about towing a small car on a trailer with a motorhome, but I can tell you about towing a caravan with a 2.8 HDI Boxer based low-profile motorhome on the Peugeot medium wheelbase chassis. The maximum weight of the motorhome is 3400kg and the unladen weight of the caravan was about 1200kg. Prior to the journey, I was concerned about the stability of the outfit because of the length of the overhang of the motorhome. My stability concern was the result of towing another caravan with two different cars. Both cars were of a similar weight and the caravan was less than 85% of their weights. One car was super stable at any speed up to 80 mph (on a French motorway and there wasn't a lower speed limit in force for towed vehicles). The other car was decidedly twitchy at above 55mph when towing. I put this down to a shorter wheelbase and a narrower track. In the event, the motorhome towed the caravan from Wales, through England to the South of France without any problem at speeds up to 60 mph. I couldn't tell it was there except by looking in the mirrors. I also tow a motorcycle on a trailer behind the motorhome. The problem with this outfit is that I cannot see the motorcycle and trailer except as a reflection in shop windows. The paradoxical thing about towing with the motorhome is that my fuel consumption improves - perhaps because I drive even more smoothly and definitely because my speed remains below 60 mph. Driving north to south (and vice versa) through Spain without a trailer I suffer from the usual Fiat/Peugeot/Citroen problem of significant 4th gear work if I cruise below 60 mph or a faster drive with less gear changing but also less relaxation. I believe that the maximum speed limit for motorhomes has changed since I was last there in March 2005 and is now about 55mph. Hence, if you stick to the speed limit you can expect to use 4th and 3rd gears but the motorhome will take it. Hope this helps. Steve Link to comment Share on other sites More sharing options...
Mel E Posted January 4, 2007 Share Posted January 4, 2007 Dave, What is a safe speed with a trailer? Clearly the EU countries are totally unable to agree. Whilst the UK limit is 60 mph (M'Ways), there is no special limit on French or Belgian motorways, so it's 130 Kph (81mph) in dry conditions and 110 (68) in the rain. But then the French do kill 2.5 times as many on the roads each year as we do - for roughly the same population and with far more Kms of decent roads and autoroutes. Observation suggests that, on motorways and dual carriageways, the biggest single cause of major accidents is failing to keep a safe distance between vehicles, turning a single vehicle accident into a lethal multiple pile-up. And HGVs really are the biggest culprits here, with not even the thinking distance between them. And, Clive, the thinking + braking distances may be similar between HGV and car, but at any speed 44 tonnes has a lot more momentum than 1.5 tonnes and will do a lot more damage, even though the impact load is related to speed squared. On single carriageway roads, serious accidents seem to be most commonly caused by bad overtaking and porr reading of the road ahead. The road out of the village we lived in for over 25 years is very twisty. Accidents regularly happen by drivers simply going off the road, either solo, or forced there by an oncoming vehicle rounding a corner over the middle line. There is one or two every year and the roadside hedges bear testament to the impact points. Link to comment Share on other sites More sharing options...
Mel E Posted January 4, 2007 Share Posted January 4, 2007 mike T, You should have no problem towing your tonne or so. I have towed similar quantities behind our former m'home - an Iveco-based 4.2 tonner with virtually the same engine as the Ducato but lower gearing, and I never knew it was there. If you do find the need to make frequent gear changes, I suggest you have fitted one of the electronic systems that boost HP and torque without affecting MPG. For the last 3 years of our 7 with the Iveco, we had such a system and it meant we rarely had to change down from 5th, except on the steepest hills. Such systems cost arounf £500 fitted and can be taken off and re-programmed for your next vehicle, so it's a good buy. Link to comment Share on other sites More sharing options...
Mel E Posted January 4, 2007 Share Posted January 4, 2007 Clive, You say: "Just think, if we all doubled our speed we would be on the roads for half the time and the roads would only be half conjested." I'm afraid it doesn't work quite like that. At higher speeds the distances between vehicles increases disproportionately, so the number passing any given fixed point in, say, a minute, actually falls. So congestion increases. Some years ago, the London Underground carried out some tests using a load of school children to see how to maximise the throughput capacity of their pedestrian tunnels and walkways. They found that the maximum number passed any given point when they were jammed together and shuffling their feet forward; the minimum was when they all ran down the tunnel as fast as they could. Sorry about that! The answer is, of course, to build more decent motorways. We can afford the land since farming doesn't need it (15% has been 'set-aside' for the last 10 years or so). And the argument that more roads leads to more traffic is totally illusory: there are only a defined number of persons over 17 able to drive, and it doesn't matter how many cars are owned, since only that number of drivers can be on the roads at any given time. And we can simplify the Motorway construction programme by building 2-lane motorways for HGVs ONLY (over 7.5 tonnes) on busy routes, making their use mandatory and banning HGVs from the parallel m'ways. We then charge a toll for HGVs to use the M'ways, lower their road fund tax accordingly, and charge a higher price to non-UK registered vehicles to cover their use of non-toll roads. Ordinary motorways, only having to handle up to 7.5 tonnes, can be constructed (and repaired) to lighter standards making them much cheaper. But our 'experts' have shown a remarkable inability to 'think outside the box'. Link to comment Share on other sites More sharing options...
Steve OReilly Posted January 4, 2007 Share Posted January 4, 2007 Just a further clarification of speed limits in France when towing to add to Mel E's contribution. Vehicles towing a trailer with a combined weight over 3,500kgs are subject to the following limits:- Motorway - 110 kph Dual carriageway - 100 kph Town - 50 kph Any other road - 50 kph. Steve Link to comment Share on other sites More sharing options...
Dave Newell Posted January 4, 2007 Share Posted January 4, 2007 Thank you to Mel and Steve for correcting me on European mainland speed limits. I (apparently wrongly) beleived that they had similar speed limits, if not lower, for heavier/towing outfits. As for what is a "safe speed" for towing? probably 30 MPH would be ok under all situations but I, personally, would say it should certainly be lower than the limit for the road you are on. My reasoning is that this would dramatically reduce the chances of someone pulling out in front of you and causing you to brake hard and lose control. As I've already said I've personally seen this hapeen and its not a pretty sight. Overall I agree with Mel that the extra weight of the trailer and car should not create too much of a problem. Sadsly as I've already said "chipping" your motor is not possible s ogive that idea up. D. Link to comment Share on other sites More sharing options...
mike.T Posted January 5, 2007 Author Share Posted January 5, 2007 HI there Thanks for all the contributions it sounds like the extra ton should not make too much difference on the flat and just a bit up hill!! more gear changing. Its just a thought but I will be going 10mph slower at all the hills so would think this could make a big difference in pulling performance.? Regarding electronic systems that boost HP and torque Can’t fit them on the old idtd engine I have !! But thanks for the information. I think I will now be going down this route of towing a car Regards To all Mike T Link to comment Share on other sites More sharing options...
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