Caravan handling query

[RogerP]

My question is - does the chassis of a the van make a difference on the towing behaviour.

Reason for asking is that I'm not happy with how my Eldiss tows , the rear end of the van seems to move about far too much and if being passed by larger vechicles the whole set up gets a tad out of shape almost to the point of snaking (thakfully not yet). So much so that I've cancelled a holiday as the last outing was scarry and anything above 50mph became unbareable.

My car is capable of towing the van and sits at about 88% according to the the '85%' rule.

I've had both car and van checked over and both dealers say car / van are OK (I purchased van new last year and my car is a 2006 model with full dealer serving)

The fact I had similar , all be it to a lesser degree , problem with a Disco 3 earler this year leads me to think its van related but I cant find what.

I've gone to the extreme of unloading everything from the van to make sure its not loading or over loaded (which it isnt - I weigh my stuff before loading to make sure) but it still gets out of shape too much.

I'm at a loss what to look at next , so much so we are at the point of selling and giving up. I never had any problems with my 1st van (Lunas Solaris 1 on the Al-Ko chassis) and wonder if its the BPW chassis. Both my vans have been similar sizes and fairly close weights and I towed both with a Freelander 2 but the Eldiss has never felt as safe as the Lunar.

Does anyone have any suggestions or advice as I dont want to change car or caravan or give up before I've exhausted all avenues.

 

[foshy]

Hello Roger,

The obvious thing to check and keep playing with is the nose weight. I have an Abbey on an AKLO chassis and a friend as an Eddiss on a BPW chassis and they both tow fine at speeds above 50 mph without any movement. However back to my point about noise weight, I normally tow with a Seat Alhambra and the 'van had a heavy noise weight. My other car is a Volvo V50 and 1st time out the van towed awful behind the Volvo - similar to what you have described. I then weighed the noise weight with a cheap set of bathroom scales and reduced it down to 65KG. Now the Volvo tows the van fine but the Seat doesn't! I now load differently depending on what tow car I am going to use. It is a little trial and error, but don't give up, because once you get it right it will be fine. One other point, check the tyre pressures are correct on both sides. Good luck.

 

[colin-yorkshire]

hi roger

well where to start the best advice I could give would be to look at the differences between the two vans.

you say the chassis are different so did the first one have shock absorbers has this one?

what type of tyres are fitted? are the sidewalls softer different pressures?

size of wheels? ect.

I would look at all these first, how does the van tow empty with the correct nose weight?

and is there any difference in the type of stabiliser you use?

the reason I ask is because when we bought the bailey and towed it home it wallowed about like a walrus out of water, not being happy with that I first checked the tyres they seemed ok correct size pressures ect but when pushing the van side ways on the backend there was a lot of movement in the tyres side wall so after checking found out the van had been fitted with car tyres the weight rating was within limits but the max pressure was only 35psi and 4ply textile radials.

after changing them to 8 ply steel "C" type radials inflated to 45psi all the movement dissapeared and the van towed brilliantly exept for bouncing all the plates out of the cupboard this was cured by fitting after market alko shock abosbers the red ones,

problem sorted, I have towed the van over 5000 miles now in all conditions and it never moves offline ever.

colin

 

[RogerP]

many thanks for the responses so far.

just to add

The van was purschased new by me last year so I (rightly or wrongly) assume it has the correct tyres fitted (to alloy wheels if that helps).

The tyre pressures for the van are 65psi (according to the hand book and verified by the dealer) and I check before I tow both going away and coming home.

Car tyre pressures I check every week and they generally dont change , and I inflate in line with hand book and verified by BMW for when towing.

Nose weight -I have a guage fitted to the jockey wheel and have also checked using a stick and bathroom scales and both read the same (80kgs where the van is rated for 100kgs).

The hitch is the Winterhoff version as fitted new and the pads have been checked again by the dealer.

One other thing thats just come to mind is how the van tows , by that I mean it tows fairly level where as my Lumar was nose down bias.

My current car (and previous one) has active suspension fitted and will compensate when the rear is loaded but I'm led to believe active suspension is a good thing. But both my BMW and the Disco 3 towed the van level. I'm now wondering if this might be something to look at? if it helps the top of the towball is 450mm from ground.

 

[Lutz]

You say that the top of the towball is 450mm above the ground. This puts the centre of the towball at 425mm. However, you don't say under what conditions the towball is at this height. The centre of the towball should be between 350 and 420mm when the car is fully laden.

BPW is just as renowned a manufacturer as AlKo so that shouldn't make any difference.

Apart from the valid points that colin-yorkshire has mentioned, another issue which can have a marked affect on stability is if there is a significant difference in tyre load between the left and right hand side. Any difference over about 50 kg can be considered unfavourable.

 

[cooky1]

Roger, you dont say what BM your towcar is. I had a 530d Tourer and towed a 1500kg van. I changed the car to an X5 and my outfit is more stable. It must have something to do with the aerodyanamics, the tall car allowing the air to move differently over the van and making itmore stable.

If your car is a saloon the overhang behind the wheels will also affect stability. I think both my cars had 100kg weight limits on the towball. If yours is the same it might be worth having a bit more noseweight to see if that imroves things.

I also fitted shock absorbers to my van and that makes for a better tow, especialy when overtaking/being overtaken.

Hope you dont load things in the rear of the van to counteract the noseweight and get it correct as this would cause the rear of the van to move more than expected.

 

[ProfJohnL]

Hello Roger,

You have been reader and contributor on this forum for several years, so I am fairly confident that you already know much what I am about to write.

Your initial question was 'does the chassis affect the way a trailer tows'? Well yes it does, but how and by how much it affects it is not such a simple answer. But by the same token the car that tows it, and of course how the whole systems is loaded also have a major effect.

I don't realistically think the mechanical differences between an Alko and BPW chassis are going to make a vast difference, your difficulties are almost certainly down to the car, weights and loading arrangements.

We are in general lost for factual information from you, such as :

Kerbweight of Car

Max permitted weight of solo car

Max permitted towed mass

Max permitted nose load

MTPLM of caravan.

Let me remind you that 85% is not a 'rule' it is only a guideline. It is better to think of keeping the caravan as light as possible whilst observing the technical limits of your licence and cars specification. 85% is not a magic cure all. The difference between 85 and 88% is not much and I doubt that any driver could honestly tell the difference. However even though a towing ratio may be good, it does not necessarily mean that a particular out fit will tow well, that is down to the mechanical arrangement of the car and caravans and the distribution of weights in both, the mechanical conditions and the driving style.

In your last reply you tell us that you have an 80Kg static vertical nose load. Whilst this is well within the caravan chassis limit (100Kg). I also note that you the BMW has self levelling suspension. I hope you are not being fooled by this. SLS does not counter overloading, all it does is to adjust the ride height of the rear of the car. Even with SLS the tow bar has a manufacturers limit that must be followed. Most saloons seem to be rated to 75Kg, though you must find the figure for your specific car. It should be stamped on the data plate attached to the towing bracket.

I also note that you tell us the top of the towball rides at 450mm. This is over the top of the permitted EU range (350 to 420mm measured to the centre of the ball). What you don't say is if this is with the fully loaded car and caravan attached

Without specifics on weights, we can only offer general advice, which you probably already know, Keep the caravan as light as possible, any large masses inside the caravan must be packed as low down and as near the main axle as possible. Trim the loading to give as much nose load that keeps the outfit as stable as possible during towing, but also observe the manufactures limits for nose load.

There is no edict or regulation that says every tow car will match any caravan of the right weight. Sometimes even following the best advice some combinations of car and caravan just don't tow well. The only solution is to reduce speed so the outfit remains in full control.

 

[RogerP]

Hi Lutz

I measured the towball height with the car unladed , I also measured it as if we were going away , i.e loaded the car up with wife child and two dogs (dogs weight is at around 30kg each).

Each measure I also measured the ride height of the car at a marked point on each wheel arch and the roof rails.

I then coupled the van up and measureded the ride height at the same 4 ponts as above and they all read the same. (Sorry not sure how to measure the tow ball when coupled up)

Graeme , I've got a 520d SE Touring with Auto box.

I dont put anything heavy at the rear of the van or rather behind the axle. The awaning is over the axle itself.

The last journey we did I moved the awning and majority of our clothes in the car so I guess something like 50-60kg of stuff , and it made no difference.

Like I say it still occurs when the van is empty and I mean nothing in there I even took out the carpets and removed the curtains.

 

[cooky1]

Roger, don't really know what else to suggest as you seem to have checked most things yourself.

My 530 tourer had self leveling suspension and the van appeared to tow level, not nose down but it did not have the stability problems that you are having.

Any chance of you towing some one elses caravan with your car to see if it is stable or using someone elses car to tow your van to compare?

Graeme.

 

[xtrailman]

Rogerp

I have had a similar problem to you. Towing a 1333kg senator.

With my old xtrail i found 80/85kg nose weight gave a very stable rig set up. Ride height level. kerb 1650kg approx

However when i changed to the latest xtrail, with a slightly nose down ride height, and 80/85kg nose weight the rig was being affected by passing vehicles, not just lorries, but small vans!.

All i have done is increase the nose weight to 90kg+

The rig now tows stable. kerb weight new xtrail approx 1720kg.

 

[RogerP]

just wanted to give an update on my progress.

well having had the car into the BMW dealer who said there was nothing wrong I decided to get a second opinion.

Turns out the wheel alignement of the car was all out.

Spoke to said dealer who said , bring it in and leave us

 

[ProfJohnL]

There is bound to be some imbalance from side to side, just look at what is usually fitted on the door side, - Cooker, fridge and sink

that is quite few Kg, and depending on the layout of the caravan you may have the wardrobe and heater on the other side. that is bound to produce a slight difference in the compression of the suspension, but equally the suspension units them selves may have settled slightly differently due to variations in the 'rubber' compounds. A 25mm (1") difference however does sound more than usual.

,

fitted

 

[TD42]

There has been a couple of reports on other forums regarding problems with the rubber insert in the AL-KO axle tube being faulty & causing a similar problem one poster said that the insert on one side seemed to be disapearing into the axle tube.

I know you have been back to your dealer but it is worth having anothr check

 

[Lutz]

Either way, a caravan which is not level left to right indicates that there is something wrong somewhere. Certainly, one possibility is that there is something wrong with the suspension as suggested in the two replies above. But even if the suspension is OK and the caravan is still not level because one side is heavier than the other, a 1 inch difference would indicate that the load on one side is considerably higher than on the other and certainly enough to adversely affect the way in which the caravan handles. One can normally say that this difference should not exceed around 50kg.

 

[RogerP]

many thanks for the replies I think its yet another trip to the dealer (and another cancelled holiday as I'm working away from home this week but due to go away Friday!).

For info the van was totally empty when I checked this out.

 

[ValA.]

We had a problem with one side of the van being lower than the other (by more than an inch) and it was found to be due to faulty rubbers in the Alko suspension within the axle. It was replaced at the dealers, and the replacement was also faulty, so it was taken back to the Alko workshop in the midland on a transporter and replaced once again.

Apparently, according to Alko, the faulty unit(s) were part of a batch. It's some time ago now, but not impossible that it's happened again, given that they are still using the same format of triangular rubber inserts.

 

[forestgump]

long shot but other post say about loose cuboards and fixings and things comeing away from wallson elldiss

may be movement in side of caravan

 

[ValA.]

There are recent posts on another forum saying that a couple of Alko suspension units have been affected in the same way as ours - faults in the rubber units inside the axle. The original post was in July this year - and the problem has just been repaired under warranty.

Definitely a possibility if one side of the van is lower than the other. Get your dealer to check it out.

 

[Jim_374473646]

On the topic of Al-Ko rubbers.

Are they replaceable by normal garages etc, or is it more of an axle off job with specialist Al-Ko equipment?

Jimbo

 

[xtrailman]

Jim

If i recall correctly, the rubbers are put in under high pressure, alko replace/repair the unit.