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  1. #21
    Join Date
    Jun 2005
    Location
    Aberdeenshire
    Posts
    2,086

    Default Re: Towing a 450 with a motorhome/ A frame- steering probs!

    Quote Originally Posted by jackrussel1996 View Post
    Damper and balljoints ordered, also wiper blades. Cheers mate.
    Those TRW ball joints are OEM quality and mine had them fitted from new. Delivery times vary depending on from where they ship. About three days out of their UK depot. Nearly ten days if from France.

  2. #22
    Join Date
    Jun 2005
    Location
    at home
    Posts
    425

    Default Re: Towing a 450 with a motorhome/ A frame- steering probs!

    Two points to make here

    1. Oscillation whilst Flat Towing Smart fortwo

    Due to its short wheel base and critical steering/suspension geometry a very few smart 451, approximately 2 in 100, are sensitive to steering oscillation at low speed. This is where the steering bounces from lock to lock with the steering wheel acting as a flywheel. The car can rock substantially from side to side. This is not a fault with the towing system but is a feature of your particular car. To date we have only seen this happen on the smart 451 (2007 to 2014 model)

    In the majority of cases, 4 out of 5, this occurs due to driving style. For example where the motorhome is accelerated out of a turn before the whole rig is in a straight line causing a kind of whiplash effect on the car. Or the cars wheels run down the edge of ruts worn into a vehicle lane by HGVs, or the car hits some other feature of the road such as pothole, speed bump etc.

    Oscillation tends only to occur at low speed, generally less than 15mph as above this speed the gyroscopic effect of the rotating wheels prevents oscillation occurring.

    If oscillation does occur; STOP. DO NOT attempt to accelerate out of the situation, this will make matters worse and may result in damage to the towed vehicle, A-Frame system or the towing vehicle.

    The solution in these cases is to stop, then proceed very slowly until the full rig is aligned straight and then accelerate smoothly in a straight line.

    In the remaining cases where the above does not resolve the situation this oscillation tendency can normally be tuned out by a combination of adjustment of tyres, tyre pressure, geometry check/setup or minor toe out setting.

    Approximately 1 smart in 1000 cannot be resolved and if you are unfortunate to have this 1 car it is unfortunate but you may have to change the smart or change for a trailer.


    2. The UK Department of Transport consider a Class M1 vehicle fitted with an A-Frame that is correctly braked and lit to be a Class O2 trailer.

    Under the Vienna Convention, Contracting Parties shall be bound to admit to their territories in international traffic motor vehicles and trailers which fulfil the conditions laid down in Chapter III of this Convention and whose drivers fulfil the conditions laid down in Chapter IV; they shall also be bound to recognize registration certificates issued in accordance with the provisions of Chapter III as prima facie evidence that the vehicles to which they refer fulfil the conditions laid down in the said Chapter III

    My work here is done
    Alan Manton

    Alan@Smart-Tow.com



  3. #23

    Default Re: Towing a 450 with a motorhome/ A frame- steering probs!

    Quote Originally Posted by w142jpk View Post
    Two points to make here

    1. Oscillation whilst Flat Towing – Smart fortwo

    Due to its short wheel base and critical steering/suspension geometry a very few smart 451, approximately 2 in 100, are sensitive to steering oscillation at low speed. This is where the steering bounces from lock to lock with the steering wheel acting as a flywheel. The car can rock substantially from side to side. This is not a fault with the towing system but is a feature of your particular car. To date we have only seen this happen on the smart 451 (2007 to 2014 model)

    In the majority of cases, 4 out of 5, this occurs due to driving style. For example where the motorhome is accelerated out of a turn before the whole rig is in a straight line causing a kind of whiplash effect on the car. Or the cars wheels run down the edge of ruts worn into a vehicle lane by HGV’s, or the car hits some other feature of the road such as pothole, speed bump etc.

    Oscillation tends only to occur at low speed, generally less than 15mph as above this speed the gyroscopic effect of the rotating wheels prevents oscillation occurring.

    If oscillation does occur; STOP. DO NOT attempt to accelerate out of the situation, this will make matters worse and may result in damage to the towed vehicle, A-Frame system or the towing vehicle.

    The solution in these cases is to stop, then proceed very slowly until the full rig is aligned straight and then accelerate smoothly in a straight line.

    In the remaining cases where the above does not resolve the situation this oscillation tendency can normally be tuned out by a combination of adjustment of tyres, tyre pressure, geometry check/setup or minor toe out setting.

    Approximately 1 smart in 1000 cannot be resolved and if you are unfortunate to have this 1 car it is unfortunate but you may have to change the smart or change for a trailer.


    2. The UK Department of Transport consider a Class M1 vehicle fitted with an A-Frame that is correctly braked and lit to be a Class O2 trailer.

    Under the Vienna Convention, Contracting Parties shall be bound to admit to their territories in international traffic motor vehicles and trailers which fulfil the conditions laid down in Chapter III of this Convention and whose drivers fulfil the conditions laid down in Chapter IV; they shall also be bound to recognize registration certificates issued in accordance with the provisions of Chapter III as prima facie evidence that the vehicles to which they refer fulfil the conditions laid down in the said Chapter III

    My work here is done
    Cheers, Alan.
    Not too worried about the legalities, over here it may only become an issue in an accident. Those who then decide, could help by statibg categorically and quotably if it is or is not legal in the UK. Dream on....

    I think experiments as suggested need to be tried, but don't relish a departure from the (presumably) correct wheel alignment, the front tyres on this car are the only ones I have ever had that wear in perfect textbook fashion, nice and even, and long lasting to boot.

    I do not blame the frame, it has to be the 450. Not necessarily faulty, but as you say, it may be that this is the one. We usually take a bigger car when we go and drive one each, but now I am looking at going single handed due to circumstances here. A trailer would solve it, but it needs storing when on site, and securing too. They are popular targets for theft.

    I could train my dog to drive!

    The oscillation happened at low speed, straight line, was not lock to lock, but just about 45 deg. either way, but enough to stop me trying again, just in case. I will perhaps try, in the dark when no one is looking, getting the OH to drive the towing car, and I sit in the smart, and see how much force is put into the movement, and see if it feels like a bungee will stop it. Then try messing with tracking, pressures, etc., one at a time, and see where we go.

    Cheer folks! Any further insight won't hurt, y'know......Thanx!

  4. #24
    Join Date
    Dec 2016
    Location
    Hampshire
    Posts
    371

    Default Re: Towing a 450 with a motorhome/ A frame- steering probs!

    Quote Originally Posted by jackrussel1996 View Post
    I will perhaps try, in the dark when no one is looking, getting the OH to drive the towing car, and I sit in the smart, and see how much force is put into the movement, and see if it feels like a bungee will stop it. Then try messing with tracking, pressures, etc., one at a time, and see where we go.

    Cheer folks! Any further insight won't hurt, y'know......Thanx!
    Now here's something that might be worth trying - put some weight in the Smart. Perhaps your water and waste containers with 10-20 kg of water in each in the footwells. (This occurred to me as when I read your post I immediately thought "I bet it'll behave perfectly because the driver's weight will change the dynamics" - Murphy's Law.)
    2016, ForTwo cabriolet, 900 turbo, DCT, Prime Premium, unmodified.

  5. #25

    Default Re: Towing a 450 with a motorhome/ A frame- steering probs!

    Quote Originally Posted by dpmike View Post
    Now here's something that might be worth trying - put some weight in the Smart. Perhaps your water and waste containers with 10-20 kg of water in each in the footwells. (This occurred to me as when I read your post I immediately thought "I bet it'll behave perfectly because the driver's weight will change the dynamics" - Murphy's Law.)
    There may well be summat in that. It sometimes only takes a minute difference in mass or distribution thereof to effect a comlete change in oscillation frequencies; motorcycles can tank-slap weave for sometimes undeterminable reasons, and be as hard to pinpoint, but something small can make a vast change. I have experience of this! Cheers.

  6. #26
    Join Date
    Sep 2017
    Location
    Near Norwich
    Posts
    57

    Default Re: Towing a 450 with a motorhome/ A frame- steering probs!

    Can I suggest you go to Octobers Motorhome show at the NEC, the national towing or trailer association have a stand there and can give you all the CORRECT facts rather that those on here that have no experience. Sorry guys no offence meant!
    It pays to be Smart

  7. #27

    Default Re: Towing a 450 with a motorhome/ A frame- steering probs!

    Quote Originally Posted by postnote View Post
    Can I suggest you go to Octobers Motorhome show at the NEC, the national towing or trailer association have a stand there and can give you all the CORRECT facts rather that those on here that have no experience. Sorry guys no offence meant!
    Its not a problem for me, the legal stuff I am OK with, as its legal in the UK, and the techy stuff is about all that can be gleaned, as there is only so much I can do with things that can be altered anyway. If it turns out I cannot get a reliable result, and there remain constant nagging doubts, then what is the point? I will give it a go and see where we end up.
    Besides, if I go to the MoHo show, I'll end up feeling worse! Because- 1,,,there are bound to be folk there doing what I am trying to do, without a sniff of my problems with theirr rigs, and 2- I'll see all the flash/nice/covetable stuff I can't afford, and come away feeling very dissatisfied with my lot!
    Believe me, I have been there before........Cheers mate!

  8. #28

    Default Re: Towing a 450 with a motorhome/ A frame- steering probs!

    Quote Originally Posted by TheAlmostInvisibleMan View Post
    Doesn't mean it's in good working order though, or even present.
    Your surmise re the damper, was found to be 95% correct. (95% in as much as I changed the balljoints too while it was apart, so don't know if that had an effect). And now it behaves itself, and tows OK. Phew. Yer, it would do after I bought a Brian james trailer! (With another Smart on it, stuck there with stuck brakes, alternator, & lost key synch; they came as a pair, seller would not split). So, having got thus far, the original car has now bust a front spring, and someone ran into me motorhome, which also failed its MOT half an hour previously!!
    Time to go back to bed. Or the bottle.

  9. #29
    Join Date
    Dec 2016
    Location
    Hampshire
    Posts
    371

    Default Re: Towing a 450 with a motorhome/ A frame- steering probs!

    Start with the bottle - bed comes later
    2016, ForTwo cabriolet, 900 turbo, DCT, Prime Premium, unmodified.

  10. #30
    Join Date
    Sep 2016
    Location
    Burnley
    Posts
    647

    Default Re: Towing a 450 with a motorhome/ A frame- steering probs!

    Quote Originally Posted by dpmike View Post
    Start with the bottle - bed comes later
    The latter happens only in the case where there was not enough of the former. Floor is the expected outcome after sufficient consumption.

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