Update on Towing with Prius

Just a thought, but if you could change things up a bit, there are much lighter motorcycle trailers (but not for rent though). I'll bet there are some decent signle bike trailers that weigh less than 150 lbs. But then, you'd need to store it.

 

Thanks for the report. I've been trying to figure out if I can tow a 1500 pound teardrop trailer. I guess you've verified that 2/3 of my goal works. Can you see the limit of what a Prius could handle? It doesn't sound like you've reached it.

Have you considered using a ScanGauge to monitor temperatures? Most towing packages start with a transmission cooler, which the Prius is clearly not designed for. My current idea is to use a Remco oil pump to circulate oil from a modified drain plug to an oil radiator, and back to a modified oil fill plug. The Remco pump is designed to provide transmission lubrication on cars towed behind an RV.

How about braking? Do you use electric brakes on the trailer?

 

The pump, hoses, and oil cooler are all standard items. The part that I haven't figured out is how to protect the pickup line from the drainplug connection. It needs some sort of skid plate protecting it. Wouldn't want to scrape off an oil line from the transmission...:scared:

 

I just finished building a small camping trailer. It is modeled after the classic teardrop trailer, but with all flat surfaces. The basic structure is a 4'x8' Harbor Freight trailer with 4x8 sheets of plywood forming a box. The weight turned out to be 560 pounds without a kitchen.

My wife and I traveled a total of about 600 miles with it this past weekend, and it worked out OK. Fears about the capability of the 2006 Prius to handle such a trailer turned out to be unfounded. The car has adequate power, braking, and handling for this size trailer. Traveling at 50-65 mph on freeway and high speed two lane (US 101 San Francisco to the redwoods just south of Eureka) was uneventful. Several times I mistakenly got up to 75 mph, and backed off only because that's pushing the 55 mph speed limit too much. I did pass a radar cop at 64 mph, and he gave no notice of me. The only time I floored the gas pedal was on a short uphill freeway onramp. Most of the time power was not an issue. The gas engine ran in the 3500-4400 rpm range frequently, so it was definitely getting a workout.

The biggest hit was the mileage of about 32 mpg. On previous trips to the same area I remember getting more like 47 mpg. Water temperature maxed out at 186 F, and usually ran at 184 F. Better instrumentation would be nice, but it didn't get done for this trip.

Adding a kitchen area in teardrop fashion will add a few pounds. The biggest problem we had was inadequate equipment to level the trailer. I spent one night on the low side, with wife and dog using me as a mattress. Reorienting the trailer to the campsite solved the problem for the next night. Now I understand why all those trailers are up on leveling jacks and stacks of lumber...

 

Though I wouldn't do it with my own prius, I'm pleasantly surprised to see other people having success towing with it. I posted this some time ago, I took this picture on I-95 in S. FL from my truck, this little guy was going 70-ish if my memory is correct. Firstly I can't believe he got that trailer up to that speed with a prius, secondly I'm surprised it had not melted down yet. I wonder if he made it to his destination?

 

I've often wondered about towing my Harley Street Glide with the Prius. It's around 800 lbs and a trailer around 400 would put the towing around 1200. Clearly, I'd be worried trying to tow more than 1 at a time (my friend has the same bike, and an 08 Prius), but with both of us, we could alternate driving the Prius vs one of the bikes.

This may be more feasible than I originally thought! With the G3 Prius, I could see pulling 1200 lbs if others are pulling 1000 lbs with a G2.

Now I just have to find the money for the hitch & trailer!

 

Great photo. Can't get away with that kind of thing here in the Rockies, 75 mph interstates with steep grades and rolling hills makes that a fishtailing waiting to happen.

 

Most all vehicles people tow with have automatic transmissions. The automatic transmission couples the engine to the transmission with hydraulic torque converter, which is basically a hydraulic pump connected to a hydraulic motor. Thusly, while accelerating all the power going to the road is actually being sent through the transmission fluid. There is no direct mechanical connection! (many cars have TCLC's now, but these do not work while shifting)

The Prius driveline has no fluid couplings and is mechanically connected. Basically the function of the torque converter has been replaced with an electric generator/motor. The transmission is actually way less complex than almost any other design out there and has few separate moving parts.

Because of this fluid coupling on a normal car, there is power loss that is called "fluid shear" that ends up as heat in the transmission fluid. If you demand more power from the fluid coupling there is more loss, thus the need to dissipate it in an extra transmission cooler.

I seriously doubt there is any benefit to this on a Prius as long as you aren't towing anything too heavy. (which you shouldn't be!)

Still, it's probably a good idea to have a ScanGauge so you can keep an eye on temps.

 

On the prius, if the small motor/gen quits, the psd will freewheel and zero ice power will make it to the wheels. I would assume that due to the design, the more power required from the ice, the more the smaller motor/gen needs to work. So when towing, my first fear would be too much heat generated by the smaller motor/gen. And gears under load do generate heat, so it is possible that the mechanical portion of the transmission could generate more heat than it is designed to dissipate. Maybe it's not significant, I don't know, would be interesting to find out!

 

I heard this will void the warranty. Is that definitely so?

I understand there is now a Class I hitch available for the Gen 3 and just because you have a hitch doesn't mean you tow; you could use it for bike racks, for example. Will simply the existence of a hitch genuinely void the warranty?

I may in the future get a C1 and a small utility trailer for trips back from the home improvement store. Even though it has no official tow capacity there's no way in the world towing under 1000 lbs under gentle driving with no passengers for 10 miles or less is going to do any damage IMO.

 

I'd say that if you needed had a failure of something that would've been warranted that was caused by towing, they'd wouldn't honor it as a warranty repair. It could qualify as abuse.

The official tow capacity is 0 lbs.

 

In the UK manual It says it should not be used for towing..

 

Bah. Brits don't care about pesky tow ratings anyway.

 

Thats priceless.<grin>

 

I don't think there is any real problem with the transmission on the Prius, it is a simple gearset similar to the ones in normal auto boxes and they can handle massive loads. The thing toyota is worried about is the chassis strength, the same reason braces and strut bars are so good for the Prius handling. This isn't something they want to bring to everyones attention.