Oregon Road Trip, Towing Home - 2014 Ram 1500 EcoDiesel Long-Term Road Test

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Oregon Road Trip, Towing Home - 2014 Ram 1500 EcoDiesel Long-Term Road Test

We towed a loaded trailer back from Bend, Oregon, which was one of the primary reasons why our 2014 Ram 1500 Ecodiesel got the nod for this trip.

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bankerdanny

It is too bad you couldn't duplicate this run in a new F-150 with the 3.5 EcoBoost, because I am betting that while the Ford would tow just as effortlessly, that the mileage would have been much lower.

grijon

This is my new favorite post, to date; thank you for this stellar write-up!

nomercy346

Thanks, very informative write-up Dan!

one thing though, I know you have lots of experience with suspensions... could you please give some more tech detail on how the coil sprung suspension of the Ram is better for towing? I'd have thought the panhard rod setup and it's inherent lateral motions during compression would actually induce some extent of sway to the whole truck trailer-combo...
I don't tow but my old Grand Cherokee has lots of side-to-side motion over uneven pavement... Anyone who has driven a vehicle with coil sprung solid axles (especially both front and rear) will know what I mean. I often wondered how that works out with a trailer.
I always thought that's one advantage of leaf springs as they allow for less lateral movement of the axle.

throwback

Impressive. Now, who bought the Subie, and when do we read about it's first race??

allthingshonda

You should have done a video to show how much the auto level control has to raise the truck when it is close to maxed out in towing and payload capacity. This is a good example of how quickly you can overload a truck if you're not careful. But Dan did a good job keeping track of weights and loading the trailer properly. And Ford's Ecoboost engine is a beast and has a higher towing and payload capacity than this truck. Fuel economy would have been in the teens though. I got a feeling you're going to see GM drop their twin turbo V6 in the Silverado soon. Their new/old 5.3 Vortec just can't compete with Dodge and Ford's engines. Hey GM, good job with the pushrods but I think it's time to move on.

actualsize

nomercy346 said:

one thing though, I know you have lots of experience with suspensions... could you please give some more tech detail on how the coil sprung suspension of the Ram is better for towing? I'd have thought the panhard rod setup and it's inherent lateral motions during compression would actually induce some extent of sway to the whole truck trailer-combo...

By comparison, leaf springs have a harder time controlling lateral deflections because the vertical distance from the tire contact patches to the spring eye bushings at the ends of the leafs is pretty large. There's a lot of leverage working on those leaf eye bushings, which can't be ultra-rigid in any case because of other jobs they must do. There's a fair chance of parallelogram deflection if you imagine the tire contact patches as the bottom corners and the leaf eyes as the upper corners.

This isn't an issue with the Ram because the panhard rod that comes with coil spring suspension (the 5th link when they say 5-link suspension) is a direct brace against lateral movement. It's its only job.

Yes, a panhard bar changes length slightly as the suspension moves and forces the panhard bar to swing through its arc. But it generally takes a lot of suspension movement to make a meaningful change, and even that can be minimized in two ways: 1) use a very long bar so its angular sweep and length changes are minimal and 2) orient the bar so it is level at ride height -- the lateral deflection will be very tiny from the point of view of a bar that's level to begin with.

This is where jacked-up off-roaders run into trouble. Without corrections, a lift-kit will result in an angled panhard bar at resting height, at which point the lateral deflection increases markedly with suspension movement. Add to that the fact that off-road suspension movements are much larger than those incurred on smooth paved freeways. Finally, narrower compact SUVs and Jeeps have shorter panhard bars than wider full-size trucks, so they will always be more sensitive to all of this.

The Ram's bar is long and level at rest, so lateral deflections caused by vertical suspension movement is minimal. Even more than that, vertical suspension movement doesn't matter so much when towing because the truck's suspension isn't moving up and down as a crosswind gust hits, when a speeding 18-wheeler's bow-wave hits, when the truck settles into a long steady-state corner, etc. In these situations the panhard bar is pure gold.

actualsize

allthingshonda said:

You should have done a video to show how much the auto level control has to raise the truck when it is close to maxed out in towing and payload capacity. This is a good example of how quickly you can overload a truck if you're not careful. But Dan did a good job keeping track of weights and loading the trailer properly.

Our Ram Ecodiesel does not have the 4-corner air suspension option, so no auto-leveling is going on. The rear coils are shouldering the tongue weight and deflecting as designed with no compensation.

The 10% tongue weight figure is important to achieve no matter what the truck or SUV looks like when loaded. Tongue weight is important to stability not because of the weight itself, but because of what it represents. Tongue weight is a measure of the position of the trailer's center of mass relative to the trailer tires, and 10% tongue weight means that the trailer's center of mass is located sufficiently far forward of the trailer axles (in this case the centroid of the two axles) to be stable. The trailer's CG point needs to be located far enough ahead of the trailer tries so they stand a change of offsetting the pendulum/swaying tendency of the trailer, and 10% is the agreed-on minimum, with 15% being necessary for the boxiest high-profile travel trailers that have very short tongues.

The compensation of the optional air suspension or a load equalizing hitch (neither of which I had) does not alter the position of the loaded trailer's center of gravity caused by it's resting tongue weight. Instead these systems redistribute the effects of that tongue weight so the truck's front and rear suspensions are more evenly loaded; they get rid of the sag and make sure the all-important front steering axle is sufficiently loaded. This rig would have needed an equalizing hitch had this trailer been much heavier or had more tongue weight. It would have needed an equalizing hitch had the Subaru been parked forward, and I would have NEEDED to do that for stability'e sake if the tongue weight with the Subaru on backward had been much less than the 10% minimum.

I had no scale to confirm the tongue weight, so instead we made estimations based on what we knew about the Subaru's weight distribution, the location and mass of the parts box and extra tires, the tongue weight of the bare trailer, etc. And after all that I was fully prepared to unload and spin the Subaru around if it the trailer didn't tow straight. It was perfect (very, very stable), so I didn't give it a second thought. It had to be in the near neighborhood of 10% or this would not have been the case.

nomercy346

@actualsize Thank you Dan for going into all that detail in your response... it makes sense to me now.