Weights and measures, the sequel

Julie, Anthony, Airstream

The Rig

2017 Airstream International Signature 23FB (links to the one we actually bought)
GVWR: 6,000 lbs.
Unit base weight (dry weight): 4,806 lbs.
Hitch weight: 440 lbs.
Length: 23’9”
Width: 8’
Height: 9’9”

2016 Chevy Colorado Duramax Diesel
2.8L Duramax Diesel. In the Chevy Colorado 6-speed implementation it produces 181HP and 369 LB-FT of torque at 2,000 RPM.
GVWR: 6,200 lbs.
GAWR FRT (steer): 3,400 lbs.
GAWR RR (drive): 3,500 lbs.
Maximum trailer rating: 7,700 lbs.
Maximum tongue weight: 900 lbs.
Maximum payload: 1,421 lbs.
Length: 17′ 9” (212.7”)
Width: 6′ 2” (74.3”)
Height: 5′ 10” (70.6”)
Side note, the diesel Chevy Colorado comes with an integrated trailer brake as standard.

ProPride 3P – 1000 hitch

CAT scale readings

Chevy Colorado & 23FB Airstream International
Steer axle: 2,740 lbs. (81% of rating)
Drive axle: 2,820 lbs. (81% of rating)
Trailer axles: 5,140 lbs. (86% of rating – GVWR)
Gross weight: 5,560 lbs. (90% of rating – GVWR)

On May 31st, 2015, we took our old rig over a CAT scale with an identical 86% trailer axle loading. Those results below, showing our current setup is more balanced.

Ford F150 & 28′ Airstream International
Steer axle: 3,440 lbs. (92% of rating)
Drive axle: 4,240 lbs. (105% of rating)
Trailer axles: 6,564 (86% of rating – GVWR)
Gross weight: 7,680 (100% of rating – GVWR)

How does it tow?

Overall, very well indeed. It doesn’t struggle, it doesn’t sway, and it’s level.

Power

The 2.8L diesel engine and 6-speed transmission combination does the job but does not permit for the silliness of the Ford 3.5L Ecoboost (a lot of boost, no eco). The Ford was able to tow at 75mph up Wolf Creek Pass. We haven’t tried but it is clear the small diesel Chevy will not. On most highway onramps we are merging at highway speeds (65 – 70mph).

Transmission temperatures have remained reasonable* on hot days and consistent with the bigger Ford. Sample readings from the Chevy below:

Air temp.: 97F
Transmission temp.: 215F
Speed: 65mph

Air temp.: 100F
Transmission temp.: 217F
Speed: 64mph

* I asked Chevrolet (via Twitter DM) what the maximum operating temperature for the transmission is. Chevrolet’s response, and it’s cool they provided one to a Twitter DM, was there isn’t one published. The most credible guidance I could find was to match maximum operating temperature with break-down point of the transmission fluid. In the 2016 Chevrolet Colorado, this fluid is Dexron VI, which breaks down around 265F.

The average MPG while towing was 16.5, and about 26 not towing. The F150 Ecoboost setup (Max Tow package gearing) delivered just over 13, not towing, and about 10mpg while towing. So the Chevy setup is remarkable. But as I mentioned earlier, that comes at the cost of power.

Sway

Another high point has been the ProPride 3P hitch. I will enthusiastically validate this hitch eliminates sway. The trailer has now been driven from New Jersey, to Iowa, to Arizona. Through wind and rain it does not sway. When the wind gusts, the sensation is like driving a SUV being pushed by the wind. You don’t feel the trailer being pushed independently of the truck.

At $2,700 the PP3P was expensive. I don’t know how much better it might be than the alternatives – I haven’t tested them. But the PP3P does work as advertised and that’s what I bought it for.

Weight distribution

The truck is level, which is good enough for me, and weight on the the front and rear axles is perfectly balanced (see above). Weight distribution is easily adjustable using a wrench should the load change.

Unlike the previous rig, I have not yet had to measure wheel arches, add helper springs or install larger trunnion bars to maintain level towing.

– Anthony, Waukee, Iowa

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A New Airstream

Airstream & Chevy

It’s been over two years since I have written anything here. I see my last post was about maintaining lead acid batteries, so it was probably time to take a break.

We do have an overdue update. Last year we sold our 28′ Airstream International back to the dealer. It was a very sad day.

There was no particular reason. We just weren’t using it. Iowa doesn’t have any “nature” left. Iowans use campers to tailgate, which we don’t do. I struggle having expensive things sitting in storage, to be maintained and slowly rot. So we sold it.

Fast forward a year to May, 2017. We bought our second Airstream. Unlike our first, we bought this Airstream just for fun, not to perform a full time lifestyle experiment.

So we wanted something more nimble, that could be towed easily with a smaller tow vehicle. I didn’t want to sign up for a lifetime of big truck ownership.

We sold ourselves on using it for a couple of big trips each year and as a weekend winter cabin. We imagined spending more time in the years ahead if job flexibility permitted.

We settled on the Airstream International 23FB. The largest of the small (8′ body) Airstreams, paired with a ProPride 3P hitch to a 2016 Chevy Colorado diesel.

Did this combination work? Yes – very well. More to come.

– Anthony, Waukee, Iowa

Towing gas mileage

Airstream over the Mississippi

Based on the search terms leading to this blog I see a few people are interested in our gas mileage.

Note that our truck is a 3.5L Ecoboost “Max Tow” King Ranch package. So the gearing is different (3.73) and its heavy.

Not towing we get around 13MPG.

While towing we average about 10MPG on the flat at reasonable speeds (70MPH).

This drops to about 8MPG at 75MPH (which is legal in many places where we drive, albeit ill-advised when towing).

On grades/severe headwinds/absurd speeds I have seen as low as 6MPG. We have tested all three conditions simultaneously – see next note.

Going up Wolf Pass in Colorado at 70MPH we must have averaged something around 0.1MPG. Maybe less – the MPG graph in the dashboard wouldn’t populate.

– Anthony, Waukee, Iowa

Weights and measures

Cactus Cafe, Springer, New Mexico

Towards the end of our full-timing adventure I became more interested in weights and measures and based on the Google searches directing people here, it seems I am not alone.

This may be because we acquired more heavy things (like a generator, heavy collapsible ladders, etc.) and dumping everything in the bed of the truck was certain to cause overload.

The only way to understand this problem was to start measuring. The results are attached at the bottom in three formats. I’m including the Microsoft Excel and Apple Pages files in case you might be interested in using this template for your own purposes.

Before you can use this yourself you must know your own front (steer) and rear (drive) GAWR, as well as GVWR and GCWR. These should be found on the driver’s side door of your tow vehicle. You can read a bit more about this in my previous posts here and here. In order to take the readings you need to go over a CAT scale, which are ubiquitous along interstates at truck stops.

Conclusions:

In 3 of 5 readings we exceeded our rear (drive) GAWR. In the worst instance by 190 lbs. or 105%. In the same instance we exceeded the GVWR by 30 lbs. Both are fairly trivial but not desirable. I will note that in this instance performance and handling were not noticeably affected.

Simple redistribution of load brought us back under. Remember, due to leverage, load in the trailer places less weight on the tongue of your tow vehicle. Careful load distribution goes a long way.

An interesting conclusion from this data is that I cannot see how you could ever cross this Ford F150’s GCWR of 17,100 lbs. towing a camper. You will certainly cross the rear and front GAWR and GVWR well before.

These readings also led to my conclusion that I would probably opt for a 250/2500 for towing this particular trailer, doing it all over again. Although it can be towed safely and the truck delivers exceptional towing performance, it does require some attention to load distribution. There are some that argue this actually makes it a safer option, since people with bigger trucks often don’t bother distributing load optimally.

Data files:

PDF format

Apple Numbers format

Microsoft Excel format

– Anthony, Waukee, Iowa

Hellwig helper springs

Hellwig Helper Springs. Lake Anita State Park, Iowa

We’re all trying to avoid a saggy rear end, so I finally installed the Hellwig 61902 Pro-Series Helper Springs with Silent Feature.

These were straight forward to install without raising the truck or removing the wheels.

The installation took me about 90 minutes but would have been far less with the proper tool – namely an appropriate socket for my torque wrench. Instead I was forced to tighten all the screws using an adjustable wrench because I couldn’t invest the 20 minutes driving to AutoZone. Brilliant.

I simply followed the instructions and installed the springs to their minimum tension.

I only have one set of measurements so far but the result is that the rear wheel arches are 3/4″ higher than the front wheel arches with the Airstream in tow.

This is the best measurement I have ever taken, in contrast to previous results.

Date Rear arch Front arch Difference Trunnion bars Helper springs
8/31/2014 36 1/2″ 37 3/4″ – 1 1/4″ 800 lb. No
9/7/2014 36 3/4″ 36 3/4″ 0 1,200 lb. No
2/7/2015 37 5/8″ 36 7/8″ + 3/4″ 1,200 lb. Yes

You can see from the table above that switching from 800 lb. to 1,200 lb. trunnion bars on my Reese hitch did level the load by forcing more weight to the front. Compare the first and second readings and note in the second that the back end is higher and the front end lower than the first reading.

The third reading shows the effect of adding the springs. You see the front springs remain more compressed due to the 1,200 lb. bars, but the rear springs compressed about an inch less than before due to the Hellwig helper springs.

These results are an imperfect test. The first two readings were taken on a “full-time” load out. The second reading on a “weekend” load out. Imperfect but I believe still valid. Almost all the weight difference would be found in the trailer itself and even a few hundred pounds more in the trailer would result in something fairly trivial on the tongue due to leverage. So the effect on rear axle load should be marginal.

So I am confident the springs are effective. There is a lot more room for tightening should the load increase substantially.

It’s important to note that I am attempting to ensure a level load to reduce headlight glare to oncoming traffic. I am not attempting to exceed the rear GAWR.

One final quick technique you can use to assist with leveling: inflate the rear tires 5 PSI over the front tires, ensuring the tires remain within the manufacturer’s maximum pressure.

– Anthony, Waukee, Iowa

Our F-150 after 51,188 miles

Pawnee National Grassland, Colorado

On September 7th, 2013, I took delivery of our tow vehicle.

In honor of its one-year anniversary I thought I would share a few statistics and an opinion on our setup.

Mileage

Annual mileage: 51,188
Towing mileage: 20,836

Daily average miles: 140
Daily average towing miles: 57

Weights

First, a quick primer on three terms.

  • GVWR stands for Gross Vehicle Weight Rating. This is the maximum your vehicle can weigh fully loaded.
  • GCWR stands for Gross Combined Weight Rating. This is the maximum your vehicle and a trailer can weigh together.
  • GAWR stands for Gross Axle Weight Rating. This is the maximum weight that can be put on a specific axle.

You really shouldn’t exceed any of these ratings. So, for example, you may be under your GVWR but over the GAWR on one of the axles. Not ok – load must be redistributed.

With that, my readings:

Average towing GVWR: 7,472 lbs. (98% capacity)*
Average towing GCWR: 13,864 lbs. (81% capacity)*

I should note that the truck’s GCWR (17,100 lbs.) exceeds the combined axle ratings of the truck and trailer (15,400 lbs.). So with our trailer, GCWR is not a limitation. GAWR and GVWR will be hit before GCWR.

* These numbers were averaged from five CAT scale readings spread over several months.

Fuel

Gasoline consumed: 4,133 gallons
Average MPG: 12.4
Total spent on gasoline: ~$14,176*

* We track spend but have not broken out our Audi vs. truck spend. $14,176 was estimated by taking an average gasoline price of $3.43 multiplied by 4,133 gallons.

Unscheduled repairs

  • 1 set of front brake pads replaced
  • 1 front rotor machined
  • 1 transmission fluid flush
  • 1 windshield replaced

Opinion

This truck is capable of towing a 28’ Airstream International. Over 20,836 miles of towing it has handled two high-speed emergency stops very well, pulled up and braked down Rocky Mountain passes gracefully and suffered no significant mechanical issues. Over 30,352 miles not towing it has been pleasant to drive.

But I wouldn’t buy one again for our application. Why? It’s payload capacity is too limited, as you can see from us being at 98% of the GVWR on average.

Getting under the GVWR, and the rear axle’s GAWR, required careful distribution of load in the trailer. For example, when towing we put our bikes, the generator and a heavy toolbox in the trailer behind the trailer axles. Ideally these would stay in the truck bed.

Using 1,200 lb. Reese trunnion bars I have the following CAT scale readings on the front and rear axles:

September 7th, 2014

Drive axle (rear): 3,940 lbs. | GAWR: 4,050 lbs.
Steer axle (front): 3,580 lbs. | GAWR: 3,750 lbs.

Not much room at all. 95% capacity of the front axle and 97% capacity of the rear axle.

I have also not yet managed to completely eliminate rear-end sag. The pavement to wheel arch measurements taken at the same time are as follows:

Front: 37 1/4”
Rear: 36 3/4”

It’s not bad. The rear is sagging 1/2” which isn’t visibly noticeable, but that is apparently sufficient to make the headlights blinding to oncoming traffic.

One solution to this problem will be to add helper leaf springs, which I plan to do.

Lastly, I have some concerns about the longevity of the components with this amount of load.

Doing it again I would have bought a 250/2500 series truck for increased payload.

– Anthony, Pomona State Park, Kansas

our setup

This post was modified from the original on 2014-03-10.

photo-1

Quick summary of what we are rolling around the Glamour States in.

Tow Vehicle: 2013 Ford F150 4×4 Supercrew with Ecoboost engine.

Trailer: 2013 Airstream International Signature 28W Espresso.

Hitch: Reese Strait-Line weight distributing hitch.

Scout vehicle: 2012 Audi A4 Prestige S-Line.

– Anthony, Keystone State Park, Oklahoma