Thread: Disco towing

I regret that I am new to this great forum and the topic may have been covered many times before.

I have a 1990 Disco and I use it to tow my trailer sailer (all up weight is 1850). I used to use my Series 3 but that will be leaving home soon.

Both the truck and trailer are level when loaded.
I do take the outboard motor off the boat and place it in the nose (bow) of the boat for long distance travel because I am told the towball weight is light. Towing around the island I leave the motor mounted and travel slow.

The trailer seems to push me around particularly on rough roads. I am not very experienced at towing and am not interested in travelling at high speed with my pride and joy behind me.

It has been suggested that I should change the oil shocks to Bilsens and insert air bags in the coil springs. Rather than reinvent the wheel could people that have been down this path give me informed advise please.

I fear that my not knowing what I am talking about is an opportunity for a salesman to rip me off. The article on Caravan towing was very interesting. Thanks Ron Mc. Sorry if this thread bores the veterans.

Right up my alley

Hi Kev – I’ve spent a lot of time dragging heavy boats along the east coast – the heaviest (Haines Signature 850 at 4.4t) was not towed with a rover but the trailer was set up exactly the same as what I describe below.
The biggest problem with some rigs is that they are balanced (no ball weight) imagine a balanced see saw it can easily swing up and down and on poor road surfaces will want to swing side to side. 1850kg is the same (very close) as the empty weight of the D1 so the car has no weight advantage. Add to this the point that Trailer Sailers sit on trailers with the axle assembly under the middle of the rig so you also loose the advantage of a long drawbar – like would be found with a powerboat. By your comment that the vehicle sits level I’d say Your problem is because the boat & trailer are getting a mechanical (leverage) advantage over the car. This is compounded by the short wheel base and relatively big rear overhang (compared to wheel base) on the disco.

What I found -- by moving the axle assembly back (it won’t be much) you increase the drawbar length (lever that the car has to control the rig) and decrease the rear over hang (uncontrolled lever weight). You also add weight to the car tow ball – this is (in my experience) misunderstood. Bringing the ball weight up to (D1 max) of 150kg means that the see-saw no longer has the tendency to rock and swing, one end is now 150kg heavier, and the car tyres now have hold of that 10%. The down side is the you have ‘lifted’ weight of the front (car) wheels – this is the problem with high ball weight, It’s not just a case of the car and trailer not sitting ‘level’ - that’s a symptom. As Ron has detailed in the caravan thread a Load distribution Hitch will do exactly that – transfer weight back to the car’s front wheels (car will sit level again) You need to get weight on the front wheels again to maintain steering geometry and prevent braking lock up (no ABS I assume)
Tyre pressure should be lifted on the car and if the trailer tyres are anything other than rock hard the tyre walls will allow sway – I could always tell if the trailer tyres were less that 55psi. (will depend on tyre type and weight/tyre - tandem might not be load sharing)
When I purchased one of my boats (gvm 2.8t) it was set up with less than 20kg on the ball and at speeds over 80k was downright dangerous, would get side to side swaying up big time. We moved the axel assembly back (only about 6 inches) resulting in just under 250kg on the ball (add Reece WDH) – completely transformed the setup – very stable at 100 -110k and high side winds behind the D2.
Another issue could be the trailer itself – some of the lighter trailers flex a lot! As you can see in the drawbar pics I doubled it up – I did this with every boat trailer I’ve owned and set up for others, with his one I ran the 2nd draw bar back down the middle to just before the front axle assembly cross member. Two extra cross members were also added between the A frame and axle assembly to prevent the chassis from spreading as the whole thing flexes (and they do – a lot!) Total extra weight 34kg.
Depending how keen you want to get ---- I also added shocks to all wheels, once 2.5 to 4.5t of trailer starts to ‘bounce’ at speed you are in for an exciting ride even with a F250.

I set these (6 in all) rigs up to tow safely, stress free and fast. I (and friends that I set up rigs for) wanted to leave home and travel at 100-110 to our destination without having to worry about chewed out foundations on our ‘great’ highways – there was a heap of work went in to them but the result was astonishing. One of my creations (for my retired father) carries a 2.6t plate alloy cruiser and he tows with a (320,000km) disco 1 – he’s on his 2nd set of shocks....

Off the track – As a sailor you may pleased to hear that my powerboats are gone – replaced by my first set of sails

Pics 1,2 Drawbar with LDH - pls ignore the toyota...
3 the shock mount inside the chassis rail.