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Old 02-24-2003, 03:32 PM   #1
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Newbie Tow Advice Needed

As long-time admirers of airstreams, my wife and I are considering embarking on a new adventure and purchasing one. So many questions, but we'll keep it simple for now. The first question is about towing size:

We've tried to decipher GVWR and GCWR on websites and on our vehicle and since they are all different, we come up with more different answers than there are months in the year. If anybody is willing to share some knowledge with novices, we sure would appreciate it.

We have a '97 Ford E350, 5.4 Liter V8, extended cargo van, with a 138" wheelbase and a step bumper - affectionately known as "Big White". We are hoping to use this as the tow vehicle.

The door label indicates that the:
GVWR=9,400
FR-GAWR= 3,550
F-GAWR=6,084
I'm not sure what rear axle it has, but the sticker notes something like 39?

What is the largest airstream that this vehicle will comfortably tow? What is the max tongue weight? Obviously we have to subtract cargo, but we desperately need an unloaded starting point!

And thanks to Maurice in OH for discussing the merits of wheelbase. Accordingly, this vehicle will only tow a 27' length trailer. What happens if the "110" for a 20' trailer, with 4" more for each additional foot" rule is stretched a bit?

Our second question pertains to purchasing advice (big topic, we imagine). Without opening a can of worms that probably gets opened three times a month. Can anyone direct us to an FAQ about merits of the various double models and things to look for when purchasing - we'll even consider rejuvenating a vintage project. Any recommended dealers in the east?

And sure, we'd love to hear about your favorites!

David and Rebecca
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Old 02-24-2003, 03:53 PM   #2
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I remember TrailerLife doing a tow test on a van just like yours but with the V10 some years ago. It was a big purple beast with a good size "white box" in tow. I do remember hearing that with the relatively long distance from the rear axle to the ball on the extended vans they weren't the best choice for towing. What you want is long wheelbase and short rear axle to ball lengths. Even without a trailer the handling characteristics of the big vans have been in question for some time now, especially when used in the 15 passenger mode. Too much weight on the rear end could spell disaster which also could be induced and aggravated by driver error.

I know you have already got your van and all said some tough decisions may be in store.

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Old 02-24-2003, 04:00 PM   #3
 
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More info on weights than you want to know (got this from some website, forgot where):

GVWR: Gross Vehicle Weight Rating
GVWR is the weight rating established by the chassis manufacturer as the maximum weight (including vehicle, cargo, liquids, passengers, etc.) that the components of the chassis are designed to support.

GAWR: Gross Axle Weight Rating (for each axle)
This is the maximum weight rating that components of each axle are designed to support (i.e., tires, wheels, brakes, springs, axle). This is determined by the lowest design capacity of any component. In other words, if the wheels have the lowest design capacity of any component on that axle, installing tires with a higher load capacity does not increase the GAWR.

GCWR: Gross Combined Weight Rating
GCWR represents the maximum allowable total loaded weight rating of the motor vehicle and any trailer it is towing. GCWR minus GVWR represents the allowable weight for the towed vehicle.

GVW: Gross Vehicle Weight
GVW is the actual weight of a fully loaded vehicle (i.e., vehicle, cargo, liquids/fuels, passengers, towed vehicles, tongue weight, etc.) The GVW must not exceed the GVWR.

GAW: Gross Axle Weight
GAW is the actual weight of a fully loaded vehicle carried by a single axle. Due to the many ways that weight can be distributed within an RV, GAW can often provide a false sense of security. Even though the weight of the total axle may be within the axle's rating, it may be overloaded on one side.

We towed a 29' for several years with a 1 ton Chevy van 454, 146" wheel base. According to Maurice's rule, we were just on the mark.

The main problem we had was in mountains. We had the AC remove to get more air to the radiator. Had to run the heater in worse cases!!!
Our case is a bit different : the van was always very loaded (we carry a store in it).
We still think that this type of van makes a great tow vehicle (we keep it as a spare).
You should have good luck with your van, a lot of people unfortunally tow with much smaller vehicles.

Chantal
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Old 02-24-2003, 04:26 PM   #4
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A lot depends on the gear ratio as well. I had to move my 59 with a 94 E150 van with a 5.0. according to the vehicles ratings I should have been fine. I figure I was a max of 4200lb of trailer. Locked out the overdrive and that poor van was having a heck of a time with the load on a hill and was spark knocking (ping) horribily on any sort of grade. Now in the vans defence It had old gas (it had not been driven in 2 months). Its a conversion van so it was a little heavy on it's own. It had 3 adults and a ton of tools in it as well.
I think it's main problem was gearing. I suspect it had something like 3.42 gear maybe a 3.08. That same van with a 3.73 or a 4.10 probably would have been fine.
THe higher the number of the gear ratio the faster the engine will spin to turn the tire. It makes the work the engine has to do to move the weight easier.

In my Blazer with 4.10 gears 32 inch tall tires, 3 speed tranny and a 350 CID engine I had no problems towing a car 270 miles and was pulling something like 4000 lb with the dolly. I was pulling much steeper grades for much loger time and never got into the spark knock problem.

Find out the gear ratio of the van. If it's 3.73 or better yet 4.10 and you stay around 5,000lb on the tralier you will probably be fine. 5.4 is a fairly good motor with good torque at low rpms (torque is what moves weight).

Typically the higher the model number the stronger the truck is in Fords line up. A E350 should be rated as a 3/4 too 1 ton. With that sort of rating I would expect at least a 3.73 gear might even be a 4.10.

Some tips is put the biggest trasmission coller in that will fit on the tow vehicle if it has an automatic. NEVER tow in overdrive on hills. Might be able to use OD in the plains if you have the right gear ratio.

Invest in a good hitch. While I'm not really new to towing I am new to weigh distribution hitches and towing trailers this long. These folks about have me sold on the Reese dual cam. Expect to spend close to $300 for a good hitch systems with a good sway control.
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Old 02-24-2003, 04:54 PM   #5
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Hello David and Rebecca

There is some good info here already for you but the one negative item that stands out that Chas mentioned is the extra long overhang on your vehicle. The following paragraph explains...

Rear Overhang Ball to Axle:
A shorter overhang is better, but which is really better - a short overhang and a short wheelbase, or a long wheelbase with a long overhang?

Look at the overhang as a percentage of the wheelbase. For example, a 116" wheelbase and 40" overhang comes out to a 35% overhang ratio. A 130" wheelbase with a 50" overhang comes out to a 38% overhang ratio - in this case not as good as the shorter wheelbase. Of coarse, an even better combination would be a 130" wheelbase with a 40" overhang, which would come out to 31% overhang.

Knowing this my guess is that the rear overhang of your van is about 60 inches (distance from the centre of axle to the ball). This would give you a 43% overhang ratio. Not that great. This factor along may suggest going with one on the smaller Airstreams.

Hope this helps
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Old 02-24-2003, 05:11 PM   #6
 
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For sale:

(rare) Chevy van with a 146" wheel base, and 50" overhang.
That gives you a 34% ratio, and a really long wheel base.
....with a 54' turning radius.

Just joking. We keep it.

Chantal
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Old 02-24-2003, 05:47 PM   #7
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Femuse does have a point but it won't be of much help to you. The extended GM vans benefit from an extended wheelbase as well, not just a regular van with the frame and sheetmetal extended like your E-350. My brother had a 99 Dodge 1-ton maxivan and it was loaded down with tools. Probably the scariest thing I have ever driven.

Chas
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Old 02-24-2003, 07:47 PM   #8
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First, the rule of thumb I posted isn't mine, but it's one of the most common you'll run across. I personally think it's OVERLY conservative. OTOH, the other rule of thumb that your wheelbase should be 1/2 the distance from the center of your ball coupler to the center of the rearmost axle, is OVERLY optimistic. Split the difference.

Now onto your van. While longer overhang is a good thing, and the longer the trailer, the more you want, you have too much of a good thing.

By the time you'd add a Hensley hitch to it, the overhang would probably be near 6' and over 50%. With a Hensley, overhang isn't an issue with sway, but it is with weight.

Longer overhang gives the tongue weight more mechanical advantage over the truck, but it also gives the spring bars the same large mechanical advantage to equalize that tongue weight. However, when you're looking at this much overhang, you're dealing with larger positive and negative forces due to the longer leverage. On bumpy pavement that can translate into a lot of frame flex over that extended length, and potentially metal fatigue. I'd stay below 700 lbs tongue weight and that would include the near 200 lb weight of the Hensley.

The second reason is the small engine. The 5.4L probably has either a 3.55:1 or 4.10:1 axle. I wouldn't tow more than an International with the 3.55:1. And while the 4.10:1 is a better, IMHO, it's really barely enough for a 25' Safari if hills are involved, even with only two people and fuel, no cargo in the van.

If you want to tow a 28' or longer Classic, I'd be looking for a more suitable tow vehicle, with a big block gas & 4.10 or better gearing or diesel engine & 3.73:1 or better gearing.
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Old 02-24-2003, 08:00 PM   #9
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Talking It's in the gears!!

I love this stuff !!

I tow a 28' Excella with a 5.3L 1/2 ton Chevy 4:10 gears and I pulled the MT, ID & Canadian Rockies with NO problems.

The truck temp gauge didn't even more!!

I truly believe it's more to do with the reargears than with anything else.

Can't wait to read the reply's-John
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Old 02-24-2003, 08:25 PM   #10
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I found the old 1997 Trailerlife in my stash. It is sleeting here and not much to do so I am a little bored. It shows a 74" ball to axle measurement (over six feet!) and a 138" wheelbase. All the tow specs relate to the V-10 so I won't print them. It did say you would be better off with the shorter version of the van. I myself have always dreamed of having the shorter E-350 with the powerstroke diesel, an XLT or even better, a Chateau, (which I don't think they make in a 3/4 or 1 ton), probably the ultimate tow vehicle, just doubt if the wife would want to use it as her daily driver.

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Old 02-24-2003, 09:40 PM   #11
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Re: It's in the gears!!

[QUOTE]Originally posted by John
[B]I love this stuff !!

The truck temp gauge didn't even move!!

John.... I am proud to say the same thing re my van. Even towing at 65MPH on a hot day ( 95F ) with 3 adults in the van our temp guage stayed right on centre. Also when I stopped for gas I pulled the tranny dip stick. The fluid was not hot or cold.... just finger temperature. You gota luv this new technology. Years ago my dad would be watching the temp guage religously pulling a 2,000lb 16' travel trailer.

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Old 02-25-2003, 10:18 AM   #12
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Gulp...

Okay, here's what I'm learning. "Big White" is too short in wheelbase and too long in overhang to ferry around a long airstream....sniff.

Let's say that the economic gods dictate that we keep Big White, for now. If we hit the Lotto, this could change! :-)

Am I correct in interpreting that a 25' Safari or International, might work? Other recommended lengths?

I'd love to know what my rear gear is (3.55 or 4.10?) How can I find out, short of taking it apart? Anyway to look up the VIN number (1FTJS34L5VHA82692) for my '97 E350 5.4L one ton extended van to find out the rear gear?

I measured the rear axle center to the step bumper ball which is 65". With a wheel base of 138" this gives me a 47% relationship - not so good. Now, I assume that the proper anti-sway tow bar will extend that even more, right?

I do know that the van is a full one ton and the springs are stiffer than a cold winter wind in Chicago!

One random forum question: Any way to print these great messages?

David
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Old 02-25-2003, 10:26 AM   #13
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David... Back in the 70's Ford used to use one of the rear end housing bolts to secure a metal tag that had the rear end ratio stamped on the tag. I'm not sure if they still do that.
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Old 02-25-2003, 10:33 AM   #14
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tag?

Wayne's correct. There is a dog tag bolted onto the rear end cover, look to the numbers closest to the bolt. The ratio is some of the first numbers, something like 3.55, 3.73, 4.10., which I believe are the only choices as your rear axle is identical to the ones used in the F series like mine. There could be an "L" between the numbers which denotes a locking differential.

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Old 02-25-2003, 10:39 AM   #15
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Thumbs up

Chas... I had a feeling you would be one that would know for sure about the tags. I bought a rusty Boss Mustang in 1975 for parts. The 9 inch rear end had one of those tags. ( 3.50 ) was the ratio. It was the nodular nine inch with 31 splined axles. They were the biggest axles I had ever seen.
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Old 02-25-2003, 11:01 AM   #16
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A dealer can probably pull that info up with the VIN. However, you can put a chalk mark at the bottom of one rear tire, and a chalk mark on the side of the driveshaft, and see how many times the driveshaft rotates for one revolution of the tire.

Even a conventional hitch will wind up with the ball about 6" behind a step bumper ball. The Hensley will add close to a foot to that.

It's a lot easier to trade tow vehicles than it is Airstreams. If you get one now that's smaller than you can ultimately tow, you may regret it.
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Old 02-25-2003, 11:01 AM   #17
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If for some reason that tag is missing there may be a build sticker somewhere on the vehicle. On GM's it's on the glove box door. Not sure where it would be on a Ford product. One of those codes will be for the gear ratio and one will also indicate if it has a Locking diff. Another would indicate towing package. Dealer should be able to help you on deciphering that sticker. The Vin will have some information like body style, Engine class (Gas, Diesel), Plant it was built at. Ford might be able to run down the information off the VIN but it does not typically carry details like gears in it.

Also some manucatures will put the number of teath on those diff tags. Divide the larger number by the small number and that will give you the gear ratio.
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