Ballast when towing?

Lambert wrote:

The thinking behind full gvm of 1420kg is that the tyres are being pushed into the road more and are less likely to lock up or rather work harder when the abs fires. Allegedly. On some of the hills round here I can occasionally feel the trailer pushing for that split second as the overrun moves into play as I crest a climb also occasionally the Bridgestone do run out of talent but that's usually on flatter ground if I have to slow from full speed quicker than I would otherwise. That's a tyre thing though not really a loading thing. I guess trial and error may be in my future.

Sounds more tyre related. I can also feel the caravan "running into the back", but never felt like it was causing issues with grip on the tyres.
MY experience is the Jimny brakes are "adequate", so working trailer brakes and correct nose weight help. Always feels like the trailer when it brakes pushes my Jimny at the rear into the ground. Nose weight when the livestock moves around is a little more complex unfortunately.

My Jimny empty prior to fitting EBC it would struggle to fire the ABS in an emergency situation on the Yokohama's, so grip was never the issue. I've even heard the caravan lock a wheel up under violent braking, ABS on Jimny still not triggering. I try not to do this, but other road user can sometimes change even the best plans when towing.

yakuza wrote:

And with a braked trailer my experience from driving a VW T5 of twice the jimnys weight, is that where the T5 can stop the trailer enough to activate the trailer brakes, the Jimnys weight is not enough allways to compress the brake damper on the trailer.


 

That's not the cars fault. Overrun brakes will work with any car but need regular servicing and adjustment. When working correctly you should barely notice they are there. If you can feel the trailer pushing slightly before they come on, or pushing and not coming on at all, it's a sign that the coupling needs greasing, the shoes need adjusting or the cables are seized.

A big factor determining how well a car tows is the rear overhang, e.g. the distance from the rear wheels to the tow ball. The short overhang on the Jimny makes it very planted and stable when towing. Defender 90s are also good for this reason. I occasionally tow my firewood trailer with my Ford Galaxy. It's considerably bigger, heavier and more powerful than a Jimny, but with more than twice the overhang the affect of the trailer is very noticeable and can make the ride quality quite unpleasant. Being FWD it also loses traction with the addition of the trailer, where as the extra weight over the Jimny's drive wheels makes it grip better.
In my experience double cab pickups are uncomfortable and impractical without a trailer on and even worse with one on.

Question from Johnny Foreigner: are electric trailer brakes not used at all in the UK?

They are more fiddly to set up than overrun brakes, and do have certain drawbacks, but they do offer some advantages too. But it does not sound like anyone in this thread uses them. Just curious.

Edit: I just want to make it clear that I am not criticising, just asking.     Also, to keep with the thread topic, electric brakes would have an advantage with an "unballasted" tow Jimny in a case where one unexpectedly had to brake in a curve: overrun brakes will tend to shove the light rear end of the Jimny in such a situation, but an electric brake setup would cause far less drama.  So, electric-vs-overrun might be a factor in the "do I ballast my Jimny" decision.

Again, I'm not advocating one or the other, just asking whether electric brakes are an option on UK roads.

Slightly old article and focused on American caravans, but I'm sure the legislation would apply for all trailers.

www.gov.uk/government/publications/ameri...brakes-and-couplings

Operating brakes

It is common on American caravans and trailers with electric brakes to have an electrical device mounted in the towing vehicle which the driver operates manually to apply the brakes of the trailer independent to the brakes on the tow vehicle. This is prohibited in Europe where the regulations demand that the service braking system must be applied without the driver removing his hands from the steering control.


Mounting sensor devices

Alternatively, American caravans and trailers with electric brakes can have an electrical device mounted in the towing vehicle which senses deceleration in the towing vehicle and transmits a signal to the caravan/trailer braking system to operate the brakes. European requirements demand that this type of device must be mounted on the caravan/trailer.


Supply of electricity for electrical braking systems

The electrical energy required for the electrical braking system must be supplied to the trailer by the towing vehicle. If there is a battery on the trailer which is fed by the power supply unit of the towing vehicle, the power from the battery must be disconnected during application of the service braking system.


Time delays

Some American caravans and trailers rely on a signal from the towing vehicle stop lamps to initiate braking on the caravans and trailers. Owners of such vehicles need to be aware that the system may not meet the requirement for brake response time. European regulations demand that the time delay between the time at which the driver applies the brakes and the time at which the braking force on the least favourably placed axle reaches the level corresponding to the prescribed brake performance must not exceed 0.6 seconds. This could be difficult to achieve on systems that have to wait for the stop lamps to operate before the electronic control unit is activated and the system produces the prescribed brake level.

I was under the impression that UK drivers had the option of electric trailer brakes -- which are not allowed here in the EU -- but I realize now I was thinking of some Aussie forums I have been on.

By the way, I have used the electric brakes extensively when traveling in the USA, and I assume the reason they are not allowed here in the EU is because they are too cheap and effective. French and Germans prefer things that are complex and expensive, so they can write more regulations about them, so we don't get fun toys here.  Like 4-door Jimnys for example...

But UK people don't have such bureaucratic overhead, so it should be easier to have such things.  (So why not a campaign to force Parliament to allow the Maruti extended Jimny?  You could block the roads with Jimnys like the French farmers do with their tractors.)

Just another thought... I've only ever had non-abs Jimnys, which have the load sensing valve on the rear brake circuit. As such, the extra nose weight of the trailer will shift the valve to increase the braking force on the loaded rear axle. ABS equipped Jimnys do not have this valve, so the brake bias will not change to account for the trailer. This strikes me as an inferior setup, as the the only way you'll benefit from the extra grip of the rear tyres is when the front tyres start skidding.

I'm also unsure why you think ballast should be added to the rear of the car. Isn't the trailer already doing that? And as the trailer brakes come on, it will increase the weight transfer onto the car.

Busta wrote:

Just another thought... I've only ever had non-abs Jimnys, which have the load sensing valve on the rear brake circuit. As such, the extra nose weight of the trailer will shift the valve to increase the braking force on the loaded rear axle. ABS equipped Jimnys do not have this valve, so the brake bias will not change to account for the trailer. This strikes me as an inferior setup, as the the only way you'll benefit from the extra grip of the rear tyres is when the front tyres start skidding.

I'm also unsure why you think ballast should be added to the rear of the car. Isn't the trailer already doing that? And as the trailer brakes come on, it will increase the weight transfer onto the car.

Jimnys with ABS don't need the load sensing valve. ABS works by sensing each wheel and applying the principle of cadence braking. As such it is much more accurate than a simple load sensing valve.. The brake bias will change to suit the situation and not to just front/rear  but to each wheel as required. As a wheel starts to lock up, the ABS kicks in and the braking effort is modulated so lock up is controlled. 
Many problems associated with towing, whether it is a trailer or a caravan are due to lack of brake maintenance. When a car brakes, the overrun operates and applies the brakes on the trailer. If the brakes on the trailer operate correctly, they should be responsible for all the necessary braking on the trailer, the cars brakes slow the car and the trailers brakes slow the trailer. I built an "A" frame to tow my SJ behind the LC. The SJ's brakes were operated by a bowden cable that was operated by movement of the "A" frame sliding joint. The system was very smooth and car braking was no different indicating that the SJ,s brakes were working as they should.

Roger

Lambert wrote:

The thought was that if the car as a unit was heavier it both increases it's traction and also allows the overrun to push harder against a greater inertia. Think double headed trucks moving a piece of mining equipment where the front truck has a weight block over the rear axles instead of a 5th wheel. It provides the front truck with inertia for stopping and traction for pulling. Scaled-down obviously and not double-headed though a tandem jimny tow rig would be something to see.

I understand the principle of using ballast to make the tow car heavier. I'm just not sure why you'd want to add that ballast to the rear of the car, other than because it's the easiest place to put it.
A truck is designed to carry around 1/3rd of the trailer weight through the 5th wheel, so for a standard artic that is in the region of 10t. When pulling on a bar it is not getting any weight transfer from the load, so it needs weight over the driven wheels just to function. Your Jimny is designed to work perfectly well with no load or trailer on the back. Adding a trailer increases the load on the rear axle and slightly reduces the load on the front axle. Even with a trailer on, it's still the front wheels that do most of the stopping so in my mind it would make sense to add the ballast as far forward as possible.