Causes of caravan sway/yaw

[anitakent]

Hi all,

I have read through the forum, but cannot find a specific solution to my issue, hence my question.

I have just changed my towcar and on my first trip last week noticed my caravan swaying more than previously. My loading of the van has not changed and my new towcar (Volvo V70 2.4D) is heavier and more powerful than my previous one. I have checked the noseweight and it is nearly at the maximum for the car (90kg). I have been very careful with loading and follow all the guidelines.

Any ideas?

 

[Lutz]

If the outfit seems 'twitchy' despite a favourable weight ratio and adequate noseweight, other causes could be:

1. Tyre pressures too low (raise pressures to max load).

2. Too much lateral compliance in the tyres (try larger wheels with low profile tyres)

3. Too much lateral compliance in the car's rear suspension (not much you can do about that)

4. Relatively large overhang from the car's rear axle to the towball (also no solution short of changing the towcar).

 

[MikeA]

Hi Anita,

Lutz beat me to the main points I was going to suggest.

Just to re-inforce the tyre pressure one, do look at the label stuck to the door pillar when you open the driver's door. It gives the recommended tyre pressures for different loadings. I know that when we had a Volvo 940 estate the rear tyre pressures had to be increased quite significantly (compared to normal driving) when the car was fully loaded. It made a big difference to the stability of the combined outfit.

Good luck.

Mike A

 

[AdifferentJim]

Anita

I had a 2005 V70d5 and now have a new type V70d5. My current and previous 'vans are similar size and weight: mtplm 1500 and solid as a rock even doing 70 down the French autoroutes.

I note that you have a noseweight of 90kg. I recall seeing this in the literature for both cars but somewhere else it actually states 70kg. I have always stuck to the 70kg figure.

Give it a try and see if it improves.

 

[Mel]

I know nothing, especially in comparison to Lutz, but does a new towcar mean a new towball and is it the right one for the hitch? I only ask because we changed our car and didn't realise that we didn't have the right towball!

mel

 

[anitakent]

Anita

I had a 2005 V70d5 and now have a new type V70d5. My current and previous 'vans are similar size and weight: mtplm 1500 and solid as a rock even doing 70 down the French autoroutes.

I note that you have a noseweight of 90kg. I recall seeing this in the literature for both cars but somewhere else it actually states 70kg. I have always stuck to the 70kg figure.

Give it a try and see if it improves.

Thanks Jim. My van has an max weight of 1295 (which we don't load to) so should be as stable as your outfit. I will try reducing my noseweight as you have suggested, although I thought this would make the twitching worse. perhaps i have read to many different pieces of advice! Thanks for your help.

 

[ProfJohnL]

Hello Mel,

All EU towballs are the size i.e. 50mm diameter, The stem that supports the towball may be different to suit the caravans hitch if it has a combined stabiliser device fitted.

So if you did not tell the towball fitter you needed the longer stem, then they may well have fitted the standard size. which wont work with the stabiliser.

 

[Mel]

Thanks John. I found this out from reading this forum. It was a case of not knowing what you don't know. I thought an alko towball was just a make! Anyway we've sorted it now. Strangly the grating noise from the tow hitch (which I had put down to muck on the pads) has now stopped!

mel

 

[xtrailman]

Anita

I had a similar problem when i changed from the mk1 xtrail to the latest edition.

The caravan was twitchy, even small white van man could be felt passing.

The caravan was the same but the tow bar ball height was 1" lower than my previous witter, so rather than level the caravan tows nose down.

Just got back from a tour today and have found the rig is now a stable as it use to be. All i have done is pump more air into the tyres, more than previously but still below max load ratings. In addition i have increased the nose weight to 95kg.

So really, as already mentioned i would experiment with tyre pressures.