towing van/susp upgrade?

Steve

The thing that decides whether you need to do something about the towing setup isn't whether the L/C looks like it's dipping at the back, it's whether the front is higher with the van on (with the 4 bars connected) than it is with the van off. If the front's higher, then you've lost load from the front axle and therefore steering contact for the front wheels - potentially dangerous. The reason this happens is that the ball weight of the van is well behind the rear axle, and the vehicle tends to pivot around the rear axle when the weight is applied, lifting the front. Think of pushing down on the handles of a wheelbarrow - the front wheel will have less weight on it.

To check this out, find a level place where you can put the L/C and the van; measure the distance front the top of the front wheel arch to the ground with the van disconnected. Then connect the van and the 4 bars and measure the distance again. If it is more than about 10mm or so greater than before (ideally it should be the same or less than before), then you've lost enough weight on the front axle to need something stronger than the 4 bar setup - they are usually only able to cope with about 110kg ball weight and my guess would be that your van is probably 150kg+ on the ball. In that case, I'd suggest using a HR weight distributing hitch - although in really rough terrain you'd need to take the bars off, they don't have enough articulation. But at least you're travelling slowly in those areas so the loss of front wheel weight isn't as serious.

Suspension modifications have no effect on the transfer of weight from the front wheels caused by loading up the towball - they are useful for raising the overall clearance and/or coping with extra load put into the L/C but they can't affect the weight transfer issue.

Hope this helps, or at least provides some food for thought.

Gaz.

Steve,

Forget towing for the moment.

An upgrade to factory suspension will have you believing you have a new truck.
It will handle and ride noticeably better around town as well as off road.
In addition, a modest lift of 50mm will give you that little bit of extra clearance.

You can achieve this in stages if finance is an issue.

First of all put in a new set of shock absorbers. Something like 41mm gas filled, adjustable OME's, or similar. (Forgive me for mentioning a brand, I'm not necessarily promoting them)
This will give you an immediate improvement in ride and may be all that you desire.
You will even wonder why you hadn't done it before.

If you wish to give more clearance you can then replace your springs with beefier ones and increase the ride height moderately at the same time.

Now include the towing scenario. If your rear suspension feels as if it still drops a little, you can improve this in two ways.
1. Use torsion bars (is this what you mean by ride bars?)
2. Install a set of Polyair Airbags to the rear.

The shock absorbers at least will provide you with the biggest improvement and due to the larger diameter will provide better damping and less fading because they will not overheat as much. You will be looking for corrugated tracks to try them out.

I just sent my front Bilsteins away to be rebuilt as they had lost their damping after 60 k klms and put the OEs back on. Unbelievable even the stuffed Billys were better than origional. As you guys may have realised from previous posts I am not big on unnecessary accessories. Good suspension under a 3 ton truck is necessary. Cheers Rob

Jayco actually recommend puting as much as you can in the car, not the caravan. Anything that is put in the caravan should be central, above the axle.

Hi Steve

You've probably guessed by now that this particular issue can arouse quite a few varied responses. Without wanting to go on and on about the various ways of dealing with trailer ball weight, there are a couple of things to bear in mind:

1. for towing stability, the accepted 'rule of thumb' is that 10% of the trailer's loaded weight should be on the towball. So it's OK to adjust ball weight by shifting load, so long as you keep around 10% on the ball;

2. for safety you need to ensure that you don't reduce the road contact of your front wheels, and the measuring approach I described in the first response is the way to do that.

Outside those two principles, anything you do to improve the suspension of the tow vehicle can only be good, but provided it's in good condition it will be OK for towing. My feeling is that for towing, better shocks particularly would be worthwhile - a heavy van on the back tends to make the tow vehicle move up and down more, and this means the shocks are working hard.

One other thing to keep an eye on is the Gross Combined Mass (GCM) of your rig - it's the all-up loaded weight of your L/C (including driver, passengers, fuel and luggage etc) and caravan, and to keep within the law it should not exceed the rating for GCM of your L/C - insurance companies love to find issues like this to avoid payouts in the case of a mishap.

Cheers

Gaz