New van - poor stability
 

Hi all, a bit of a vague one this but here goes anyway.

We have at late 2010 200hp XC90 which has 80,000 miles on it and full main dealer service history. Solo it feels like it always has with perhaps the exception being the ride is a little more harsh but that might be down to fitting XL tyres last year.

We have pulled a variety of caravans over the last 9 years, all 6 berth and about the same length but different weights from a 1300kg Lunar to 1500kg Elddis. All have had a bike rack on the back carrying about 30kgs (please let's not get into a debate whether that's a good idea as I've never had an issue previously).

This year was our first outing with a brand new Swift Challenger 590 - still 6 berth single axle but now about 1650kgs. In all cases towball load was about 85kgs.

Handling was horrendous to begin with, pitching was particularly bad so I moved some internal weight back a bit which helped but sway and pitch was still not great and on occasions it felt like the front wheels had gone light and were struggling to maintain a planted grip.

I'm really scratching my head as to what is different. Car is level, Nivomats are not leaking and it's just had the 80,000 mile service with a clean bill of health. Strangely as well as moving the weight back a bit thus taking some load of the back the handling improved as fuel burned off to the point that on a near empty tank it was a lot better. Could I have something wrong with the self-levelling suspension or rear shocks which aren't visibly obvious? Could the marginally harsher ride be an indicator for something which only comes to light once the car is loaded up?

Any comments ideas gratefully received.

I wonder if the dampers have gone stiff , does it feel to be the rear or the front which has the problem ? Have you tried bouncing the rear of the car with a friend to see how much compliance there is , comparing one side to the other , and do the same at the front .. ?

Hi Clan,

I've heard about dampers going stiff but wasn't sure if this was an XC90 problem or indeed if it was something that happened to the Nivomats. Somewhere else in the forum I read that if the rear is not leaking they will be as good as new.

I've just bounced on the towball - I weigh about 87kgs and I had the Mrs sat in the boot. Bounce seemed fine, certainly what I'd expect for a big heavy car.

Did the same on the front by opening the bonnet and standing on the front shut panel. Again it bounces ok although the front seems a little stiffer. I guess it needs to be though if you are going to chuck that big D5 engine around country roads without feeling like a boat.

You might be onto something though as when towing it definitely felt like the front had gone light which would equate to the back pitching but the front failing to react in the opposite way (back compresses - front needs to extend).

yes the front is hard to move but the rear should be fairly soft so that the damper movement can pump them up .

Thanks for the ideas Clan but unfortunately nothing terribly conclusive from that quick test. Would you think it likely to be the back or front causing the problem?

The load was 2 teenagers in the 2nd row (110kgs)
Awning poles and fabric, gas bbq, box of food second beer fridge and various heavy bits from the van in the boot (120kgs)
85kgs static load on the tow ball.

All together not as heavy as 7 people on board.

Is there a test my local indie can do? I shudder at the thought of getting the dealership to price up replacement shocks.

I would say the most unsettling feeling was that of the front end going light as the back pitched up and down. Clearly the front wheels weren't coming off the ground but it did feel like that. Directional stability (side to side) also appeared to suffer because of lack of front end grip - a bit like the tyres were much too hard but on double checking they were spot on.

I have towed a 1850kg caravan for many thousands of miles with my 2005 XC90 and could not hope to have a better towcar.
I would suggest that your problems are down to the loading of the caravan. Even if the hitch weight is correct, the distribution of the load can make a massive difference to the stability. Despite your reluctance to discuss the bike rack... you need to remove the bike rack and try again.
Generally the more nose-heavy the caravan, the more stable it is. Load up so that the hitch weight is just below the limit. Avoid weight at the extremes, especially the back

indeed that load on the caravan back will add and remove quite a bit of weight from the towball as it bounces up and down . heavy weight should always be over the caravan axle .. ( or in the car of course )

I kinda thought we would get into this but I can assure everyone I've towed several vans with bikes on the back with this car including our previous Elddis 576 with the same bikes for the last 5 years and the whole rig was as stable as can be. Something is definitely amiss this year and I think the new van is a coincidence.

However, to put our collective minds at rest I will take the van out with a bit of ballast over the axle, no bikes and 80odd kgs of nose weight. If it still tows like a barge I an only assume the car has an issue.

As I alluded to earlier, the car seems really harsh over bumpy roads solo as well and the front end doesn't seem as planted as it used to be. I used to run the tyres at 39psi (econ) but now it feels like an old truck unless the tyres are much softer.

I also have a set of winter wheels (17") and tyres so I can give that a go to discount the XL Goodyears.

BTW, sorry forgot to say, thanks gmonag for the thoughts, I'm always open to ideas.

Another thought, and this is one of the reasons I'm not convinced the bikes are the issue - when we left Grantham en route for the Vendee the first 120 miles or so were horrendous. As we burnt off fuel it got a little better (less weight in the back on the car, no difference to the van) then I moved the gazebo (about 25kgs) from the front of the van floor to aft of the axle and it got much better.

Sway and blow/suck from HGVs was a bit worse as the van was genuinely badly loaded now (not enough nose weight) but it solved the ponderous light front end on the car and terrible pitching.

Apart from dodgy shocks or some other car load sensor issue how could that be?

To reiterate, the car was loaded exactly the same as last year apart from our eldest who is now at Uni (90kgs less in 2nd row).

Can you test with one of your older vans or something similar in weight like last year? That should give a better feeling, to rule out car or van... :)