[RennZ]

tommyhp2 said:
PS: Has anyone towed 3500 lbs in the new hybrid AWD? How does it feel? The old ICE AWD can't tow that much, IIRC, that's why we got the FWD instead.

Hi,
We have a Limited AWD and recently went on a trip to Myrtle Beach from northern WV. I installed the Eco Hitch and hooked up our 12x6' aluminum trailer (1000 lbs), loaded it with our golf cart (1200 lbs), full coolers, storage tubs packed with equipment, tools and camping stuff. the van was then loaded with four adults, two teenagers and luggage. Pretty sure we were at or a little above max GCVWR.

I just sold my '17 Ram 2500 Mega Cab diesel as our camper is now in its' permanent home at the beach and just didn't need that beast anymore. We used to live near Rapid City, SD and have driven though the Rockies plenty of times: Pikes Peak, Aspen, our favorite Dillon (that Dam town), etc.

• Our route took us through and over some taxing areas for any tow vehicle; if anyone has driven from Mt. Airy, NC through Mt. Hope, WV, you know what I'm talking about.
• The rear of the van sagged noticeably, but handled, braked, and performed well overall.
• Our avg. highway speed was 65-75mph which the van was able to maintain even up the longer grades.
• The engine noise was very noticeable as it was well into the PWR zone up hill and when the regen quickly maxed out going down. (this is all controlled by the ECU to maintain within operating limits, so I wasn't really concerned)
• I think if I were to try this same setup on the Eisenhower Tunnels Approach, I could maintain 55-60mph without too much drama. Without trailer brakes, I'd reduce speed considerably on the decent though!

- I purposely did not concern myself with economy on this trip as I wanted to compare the van with our V8 Durango which normally makes this trip. So, an equal time was my goal. - easily met.

• The Durango averaged this trip (loaded/towing) at about 13mpg.
• The Sienna made it to at 21mpg and from at 21.5mpg which was somewhat surprising being our home is 1200' higher than MB.

Overall, I'm pleased with the Sienna's towing, but will 100% be installing airbags in the rear springs before our next trip down.

- Do note that if you do tow much, you need to follow a more frequent maintenance schedule. (Eng. oil, front/rear transaxle fluid, etc.)

Happy towing,
Z

 

[tommyhp2]

tommyhp2 said:
PS: Has anyone towed 3500 lbs in the new hybrid AWD? How does it feel? The old ICE AWD can't tow that much, IIRC, that's why we got the FWD instead.

Hi,
We have a Limited AWD and recently went on a trip to Myrtle Beach from northern WV. I installed the Eco Hitch and hooked up our 12x6' aluminum trailer (1000 lbs), loaded it with our golf cart (1200 lbs), full coolers, storage tubs packed with equipment, tools and camping stuff. the van was then loaded with four adults, two teenagers and luggage. Pretty sure we were at or a little above max GCVWR.

I just sold my '17 Ram 2500 Mega Cab diesel as our camper is now in its' permanent home at the beach and just didn't need that beast anymore. We used to live near Rapid City, SD and have driven though the Rockies plenty of times: Pikes Peak, Aspen, our favorite Dillon (that Dam town), etc.

• Our route took us through and over some taxing areas for any tow vehicle; if anyone has driven from Mt. Airy, NC through Mt. Hope, WV, you know what I'm talking about.
• The rear of the van sagged noticeably, but handled, braked, and performed well overall.
• Our avg. highway speed was 65-75mph which the van was able to maintain even up the longer grades.
• The engine noise was very noticeable as it was well into the PWR zone up hill and when the regen quickly maxed out going down. (this is all controlled by the ECU to maintain within operating limits, so I wasn't really concerned)
• I think if I were to try this same setup on the Eisenhower Tunnels Approach, I could maintain 55-60mph without too much drama. Without trailer brakes, I'd reduce speed considerably on the decent though!

- I purposely did not concern myself with economy on this trip as I wanted to compare the van with our V8 Durango which normally makes this trip. So, an equal time was my goal. - easily met.

• The Durango averaged this trip (loaded/towing) at about 13mpg.
• The Sienna made it to at 21mpg and from at 21.5mpg which was somewhat surprising being our home is 1200' higher than MB.

Overall, I'm pleased with the Sienna's towing, but will 100% be installing airbags in the rear springs before our next trip down.

- Do note that if you do tow much, you need to follow a more frequent maintenance schedule. (Eng. oil, front/rear transaxle fluid, etc.)

Happy towing,
Z

Nice! Thanks for the feedback. That MPG is very nice for towing. When I was towing 3500 lb trailer, I think I was getting around 14 MPG on the highway.

 

[20swrt]

Will a weight distribution hitch help in this situation (sagging rear) ?

 

[RennZ]

Will a weight distribution hitch help in this situation (sagging rear) ?

I had a WD hitch for a couple of my trucks. Yes, they do level the vehicle, but puts more stress on the receiver attach points and hangs down an additional 3-4 inches. I think the rear springs are too soft to safely use a WD hitch as the amount of weight you would need to transfer to the front axle to ride level would severely affect handling. And if you're like me and load your trailer close to max, when you have a WD hitch some of the vehicle weight is transferred to the trailer also...

 

[Mikeyee]

I’ve flat-towed with my little 2400lbs drift car a few times. Worked great and managed 20mpg even with track spares/tools and a few buddies.

Pulls fine. Even got up to speed from the shoulder relatively easily when had an issue with my chains.

 

[floridanative]

WDH would absolutely help when adjusted properly. Even more so when towing at or near the limits of the car and trailer. When selected and adjusted properly, they will increase safety in all respects. I would not consider towing near the limit of the Sienna without WDH.

The Ecohitch is definitely rated for weight distribution as are (I think) several other options for the gen4 Sienna.

-Mike

 

[RennZ]

WDH would absolutely help when adjusted properly. Even more so when towing at or near the limits of the car and trailer. When selected and adjusted properly, they will increase safety in all respects. I would not consider towing near the limit of the Sienna without WDH.

The Ecohitch is definitely rated for weight distribution as are (I think) several other options for the gen4 Sienna.

-Mike

My issue is not with the Eco Hitch rating even though it still uses the same mounting points as the factory receiver with the lower rating. The issue arises when the rear spring rate is too soft and you attempt to level the vehicle. This disproportionately places more weight on the front axle and trailer axle than the rear of the van. And when this happens, it can cause the rear to lose traction during an evasive maneuver or when turning while braking. I have used WD hitches for 20+ years and have seen enough to know, but there are always those that just have to learn things the hard way.
If the Sienna had a well-designed progressive rate spring, there wouldn't be much of an issue. But that would have added cost...

 

[floridanative]

My issue is not with the Eco Hitch rating even though it still uses the same mounting points as the factory receiver with the lower rating. The issue arises when the rear spring rate is too soft and you attempt to level the vehicle. This disproportionately places more weight on the front axle and trailer axle than the rear of the van. And when this happens, it can cause the rear to lose traction during an evasive maneuver or when turning while braking. I have used WD hitches for 20+ years and have seen enough to know, but there are always those that just have to learn things the hard way.
If the Sienna had a well-designed progressive rate spring, there wouldn't be much of an issue. But that would have added cost...

You shouldn’t necessarily be “leveling the vehicle “ but that could mean a lot of different things to a lot of different people. Just get the front wheel well height back to where it was before hitching up. That makes sure that you are not removing weight from the front axle. Rear spring rate is really irrelevant. Yes, it will sag, but it is going to be far safer with WDH than without. And the sag will definitely be less than without.

But, I do agree that a stiffer rear suspension would be better (and yes, progressive even better than that but that is far too much to ask from Toyota). That’s why I run airbags in my rear springs and I wouldn’t tow anything more than the lightest trailer with a minivan without them.

-Mike

 

[jseyfert3]

I had a WD hitch for a couple of my trucks. Yes, they do level the vehicle, but puts more stress on the receiver attach points and hangs down an additional 3-4 inches. I think the rear springs are too soft to safely use a WD hitch as the amount of weight you would need to transfer to the front axle to ride level would severely affect handling.
And if you're like me and load your trailer close to max, when you have a WD hitch some of the vehicle weight is transferred to the trailer also...

Well, sort of. I was going to say this was wrong, then stopped and did the math before answering. Turns out the answer is yeah, you’re increasing the load on the trailer axle over a trailer without WD, but this extra load is probably considerably less than the trailer tongue weight if you set up the WD hitch correctly.

See my attached math, including free body diagrams. Pardon my sloppy handwriting and somewhat disorganized work, it’s been a while since I took Statics in college and I had to clear some cobwebs from my brain to do this. On my example I used a 4000 lb towing vehicle that has 2000 lbs on each axle (no trailer), with a 1000 lb trailer set up with 10% (100 lbs) of tongue weight. For distances I used 10’ from the trailer axle to the hitch ball, 5’ from ball to rear axle, and a 15’ wheelbase on the tow vehicle. I used the assumption of maximum recommended weight distribution, which is making the front axle of the tow vehicle weigh the same with the trailer as it was with the vehicle unloaded.

With these weights and distances, a vehicle towing a trailer with no weight distribution would have 900 lbs on the trailer axle, 2133 lbs on the towing vehicle rear axle and 1967 lbs on the front axle.

Using weight distribution to bring the front axle back to 2000 lbs, the trailer axle would be 933 lbs and the rear axle of the towing vehicle would be 2067 lbs. So the towing vehicle would not be level, since it has extra load in the rear, but as mentioned you do NOT want to use WD to bring the vehicle completely level, since to do so would load the front axle more that it is loaded with no trailer.

You can then use airbags or stiffer rear springs to keep the rear of the towing vehicle closer to the non-trailer ride height. But the WD hitch would help considerably on its own.

You would have to severely improperly overuse WD to actually make the rear of the vehicle lighter than it is without a trailer.

Summary is that the appropriate use of a WD hitch will greatly help with maintaining tow vehicle angle, but not completely eliminate it, you need airbags or different springs for that. But the primary purpose of a WD hitch is to put the weight back onto the front axle to maintain traction and steering, and doing so will add some weight to the trailer axle but not anything that’s concerning, at least in this example.

As @floridanative said, it doesn’t matter how soft the springs are, using WD will still help considerably, because you will always have less weight on the rear axle with a WD setup than without. Spring stiffness has nothing to do with the weight that are applied to the axles, only the vehicle sag. And if you have half the weight difference on the rear axle with linear springs, you have half the sag (assuming the WD is adjusted to keep the front axle at the weight it was without a trailer).

If anyone has any questions on my math, let me know. Statics is fun, and pretty straightforward. I started doing this and initially couldn’t remember how to do it, before my teachers voice came into my head, repeating what he drilled into our brains during Statics: “the sum of the forces in the Y direction equals zero. The sum of the forces in the X direction equals zero. The sum of the forces in the Z direction equals zero. The sum of the moments about any point equals zero.” After I remembered that it was super easy, especially as we only have 1 direction the forces are acting in for this calculation. Dynamics is where it gets really interesting though, because for accelerating objects the sum of the forces and/or moments does not equal zero…luckily we don’t need to worry about that here. 😂

 

[RennZ]

Well, sort of. I was going to say this was wrong, then stopped and did the math before answering. Turns out the answer is yeah, you’re increasing the load on the trailer axle over a trailer without WD, but this extra load is probably considerably less than the trailer tongue weight if you set up the WD hitch correctly. .....

Yes, as this was the question I was addressing:

Will a weight distribution hitch help in this situation (sagging rear) ?

As a believer in WD hitches for heavy loads normally weighing more than the tow vehicle itself, I don't believe one is the correct answer for the Sienna.
Air bags or better yet, a set of ZF Nivomats (if they have a set with proper specs) would be more than enough to both stabilize and level the van. - Remember, if the trailer and vehicle are not on the same or parallel planes, stability under braking and turns are affected.

 

[floridanative]

It’s not either air bags (or other suspension help) or WDH… the correct answer is “both”. Just stiffening the suspension without WDH is not going to be as good as a stiffer suspension with WDH.

-Mike

 

[jseyfert3]

I guess it depends how much you are towing. I’m not saying airbags are bad by any means. I’m saying the best setup would be a WD hitch and airbags, since airbags will only correct vehicle sag. Airbags don’t transfer any weight so even though the van may ride close to the non trailer ride height, the front axle will still have less weight that it did before towing. A WD hitch is the only way to keep this from happening.

To be fair, I haven’t towed much with a Sienna yet. Just Uhaul trailers when I moved. I have towed many thousands of miles with a 2013 Honda Pilot and a camper weighing approximately what it did (~4500 lbs), and a decent amount with a 2020 Silverado 1500 and a camper weighing considerably more than it did (~8500 lbs). Neither had airbags but both had WD hitches.

I thought the reason for leveling a trailer was for ground clearance, and on multi-axle trailers to keep from loading the trailer suspension poorly. And on the towing vehicle side a massively unlevel vehicle was a sign of overloading and/or the need for WD. Why would not being in the same plane cause stability issues?

As another point, the 4th gen Sienna manual says to use a sway control device on trailers over 2000 lbs, and since sway control is most commonly (though not exclusively) combined with WD, may as well just use WD when towing heavy trailers with the Sienna. It’s definitely going to help sag a lot, plus as mentioned will keep the front axle loaded properly, which will also help vehicle stability and steering.

EDIT: I guess my main points are that you said WD will overload the front axle and trailer. It won’t, if properly setup. And you said WD won’t help with sag. It will most certainly help with sag, without overloading front or trailer axle. It won’t completely eliminate it without overloading the front axle, yes. I agree with you there.

It’s not either air bags (or other suspension help) or WDH… the correct answer is “both”. Just stiffening the suspension without WDH is not going to be as good as a stiffer suspension with WDH.

-Mike

Yes, exactly. Well stated.

 

[Craigrrr]

I use

a weight Dist Hitch and air bags and custom made coil spring spacers n the rear.

 

[saidiadude2]

In the scenarios given, how much would progressive springs cost for 3rd gen Sienna? Would you have to replace the front springs also?

 

[RennZ]

- Leveling the trailer is much more important than just mere ground clearance.
-- If the vehicle rear is lower, the trailer will basically use the hitch as a lever under hard braking; lifting weight that would normally transfer forward, off the front axle. = push/loss of control.

• Leveling the vehicle does indeed transfer weight, especially dynamically (while maneuvering)
• A WD hitch on a vehicle with a 350lb tongue limit is like moving a sack of potatoes from the front to the back of the trailer.
• Properly loading the trailer with more weight in front of the axle without exceeding tongue weight is the best way to limit sway.

EDIT: I guess my main points are that you said WD will overload the front axle and trailer. It won’t, if properly setup. And you said WD won’t help with sag. It will most certainly help with sag, without overloading front or trailer axle. It won’t completely eliminate it without overloading the front axle, yes. I agree with you there.

Never did I say "if properly set up" that anything would be overloaded - unless the trailer is already at its' load limit. And never did I say a WD "won't help" with sag. What my statement says, is that IF you use JUST a WD to LEVEL the vehicle, the axle weights would be dangerously disproportionate.

I stand by everything I have said. I believe having a leveling rear suspension (shocks or bags), properly loaded trailer, and the proper height hitch to have the van and trailer sit level is the best solution.
Adding a WD hitch on such a light load (3500lbs) can be upset by going from a full to quarter tank of fuel or dropping off a passenger and is unnecessary.

I think I've said all I can on this matter.

 

[jseyfert3]

Good luck and best wishes.