Towing with 2001 Sienna

There is no easy way to increase a vehicle's towing capacity after the fact. I don't know what the towing package entails, my guess is that the biggest difference is a larger transmission fluid cooler. The limiting factors in trailer capacity are transmission capacity, braking ability, and suspension.

An aftermarket transmission cooler and air bags for the rear suspension may help, as will getting surge brakes installed on the trailer if not already equipped with them.

I still would not tow more than the factory recommended maximum trailer weight.

(Cue standard trailer towing primer now. I should bookmark this...)

Most "tow packages" consist of bigger radiator, more powerful cooling fan and a slightly more aggressive thermostatic clutch if it's a mechanical fan, an external automatic transmission cooler, more powerful alternator and a higher capacity battery.

The automatic transmission cooler should always be added if you tow. You can change the other items as needed, one at a time.

If you plan to charge the lighting battery in the trailer or run a

12V powered refrigerator while driving, you will probably need the larger alternator. If you plan to drive it hard while towing in hot weather, you may need the larger radiator.

Some tow packages come with heavier rear springs - but they will ride like a buckboard when the tow vehicle is empty. Rather than overload springs, it is much better to attach airbags on the rear suspension like the Firestone Ride-Rite if they are available for your car. Then you can infinitely adjust the suspension from no load to full load. (Read the instructions - 10 PSI minimum, they can't be left at zero.)

The brakes on the tow vehicle are the biggest limitation - even with the "Tow Package" they do not beef up the braking system. And when you need to stop in 150 feet, you /need/ to stop in 150 feet. Especially if 155 feet is where the collision starts.

If the loaded trailer weight is anywhere near the trailer towing weight limit of the tow vehicle, get brakes installed on the trailer. They make brake kits for small pop-up trailers with 8" or 10" rims, and any good RV Supply or mechanic can install them - it takes a bit of welding to change the coupler to the surge brake (master cylinder) version.

Hydraulic "surge" brakes are the simplest overall because they do not require an electric brake controller on the tow vehicle - antilock brakes on cars do not allow tapping into the hydraulic circuit to sense the brake application needed.

There are other non-hydraulic sensing methods for electric trailer brake controllers but they have their drawbacks, like adjusting a pendulum sensor (a knob that kids like to spin and play with whenever left unattended) or getting used to a brake pedal extender with a force gauge inside.

The other thing you need is a secure place on the body to attach a bridle ring for the breakaway actuator cable. You do NOT connect the breakaway cable to the trailer hitch, hitch receiver, or hitch bumper

- if the receiver or bumper physically becomes detached from the car (and it does happen) the emergency brakes will not actuate. Your car goes left, the trailer goes right, and it gets REAL messy.

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How much does the pop-up trailer weigh? I thought tent trailers[*] (I gather that's what you're referring to) were pretty light, and could be towed by cars that conventional travel trailers couldn't. Indeed, I always thought that was one of their selling points.

[*] (although this one is bigger and more elaborate than most)

Geoff

There are also air *shocks* available. My father's Mercury station wagon is equipped with those, for trailering a boat. They can be filled as needed from the air hose at any gas station.

Geoff

Right - but there are two reasons I deliberately did not mention them: (A) they're not nearly as available now as they were 25 years ago, and even back then there were not too many choices. You had to guess and try, and with a limited selection the valving of the shock section was not always a good match to the car.

And (B) Air shocks are only suitable if you are willing to make custom beefed-up mounts for them, otherwise you WILL have problems. Shock mounting points have never been up to the task of carrying a load, and they make them even lighter now because with normal shocks they hold up just fine. But add air shocks and put a bunch of miles on the vehicle, and broken shock mounts are normal, even expected.

Then you find out just how expensive odd parts like that are, and/or you have to interrupt your vacation trip while they air-freight in a replacement and then find someone to crawl under there to change them, or to weld it back together temporarily.

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Replace the rear springs with progressive springs, I did on my 01 Sieena and they're great. The stock springs are mush. The progressive springs rides pretty much normal at light loads, but stiffen up as the van is loaded. Call around and find a spring shop that knows what they're doing, LT

: There are also air *shocks* available. My father's Mercury station : wagon is equipped with those, for trailering a boat. They can be : filled as needed from the air hose at any gas station.

[air shocks aren't as available as they once were]

Hmmmm, interesting. My experience with the things is admittedly limited. However, my father never had any problems with his. More to the point, there are loads and there are loads. It seems to me that the additional stress placed on the shock mounts by the weight of a typical small boat like my father's 16-foot runabout, or a modest travel trailer, or particularly a tent trailer like the original poster mentioned, would be minimal. Hell, people pick up the tongues of such trailers without difficulty in order to lift them onto the hitch ball.

That being said, I'd never heard of air bags until you mentioned them, and they do strike me as a more sound approach.

Geoff