What ute modifications should I make to tow a heavy caravan?

QUESTION

Hi John,

We are getting mixed info from diesel mechanics about what mods to have done for towing a large caravan with our 2021 Toyota Hilux Rogue.

One place recommended a transmission cooler and an exhaust upgrade. The other told us not to bother with trans cooler and exhaust and just get a torque converter lock up kit.

Confused we started researching this but can not find an answer. Which would be most beneficial? And also, what is the difference between the lockup kit and switching to manual mode in the auto?

Any advice would be greatly appreciated. Thanks.

Kellie

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ANSWER

Kellie,

I’m going to choose my words very carefully here, because you’re probably not going to like them.

I have a degree in mechanical engineering, so it’s fair to say I see the world differently than you. That’s not a criticism of you.

‘Pig’ type trailers (with centralised axle groups, such as caravans and boats) are intrinsically unstable in pitch and yaw. This means, the heavier they are, the greater the risk they are able to push the towing vehicle off the road.

In my view it is insane to tow more than 2500kg with any ute. It may be legal to tow 3000-3500kg. But it is also foolish. My strong advice would be to think about safety instead. It’s worth noting that the way safety works, you can go 9,999km (or something) quite OK with an unsafe combination. That’s not much consolation if the trailer encounters a ‘worst case’ scenario of compounding factors over the final 1km, and you end up on the roof, wrapped around a tree…

Anatomy of a holiday towing disaster: How you can prevent one >>

Physics doesn’t care if you make all the wrong choices and crash, nor how eloquently you argue the case for the choices you make.

The powertrain should be able to manage all towing assignments within Toyota’s designated limits, without modification. Another crazy approach that non-engineers take is to solve problems before they even exist. Like, you’re already talking about modifying the vehicle, and you don’t even know it cannot do what you need it to do - that’s nuts.

The aftermarket industry wants you to buy all kinds of crap. But if you change the exhaust or fit a lock-up converter (whatever) and then there’s a powertrain problem (faulty DPF, transmission failure, engine overheats and blows up, etc.) Toyota will throw your warranty under the bus and the $20k repair bill will be entirely your problem.

So, basically I’d leave the vehicle standard, and for the sake of your own safety I wouldn’t to more than 2500kg, irrespective of whether the specs say you can, or not. Physics says: Towing more than that is ridiculous.

I know this is not what you want to hear.

A lockup kit eliminates slip in the torque converter (by locking it up). Manual mode is just you selecting what gear the transmission is in. They’re different things. If you select fourth gear manually, the torque converter still slips...

All these suggested mods are approaches designed to reduce transmission oil temperature.

Don’t solve problems that don’t exist, and which may never exist. A bunch of brainiacs in R&D have already worked really hard to eliminate them.

Sincerely,

John Cadogan

PLANNING TO TOW THESE HOLIDAYS? GET SCHOOLED.

The Applied Physics of Heavy Towing >>

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My Complete Heavy Towing Guide: GVM, ATM, towballs >>

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