Closed Thread
 
Thread Tools Search this Thread Display Modes
 
Old 08-19-2015, 11:22 PM   #57
Rivet Master
 
Currently Looking...
Mission , Texas
Join Date: Jun 2015
Posts: 836
VW Touareg diesel and 31 foot Airstream

Quote:
Originally Posted by gmw photos View Post
But to my point, "if we stay within the stated limits", then we can infer that we are indeed more likely to have drivetrain reliability, be within chassis strength requirements, etc.

All the rest of this stuff is "guessing" in order to support a belief system of suitability.

Which is about when I asked the dreaded question about a TV rated at 7,700# towing a 10,000# trailer - who cares unibody or frame.
Side note, I don't know about all years of Ford Super Duties, but there was a time when the frame on the F350 and F250 were the same, only axles, springs etc. were lighter duty on the F250 - supposedly 1999 was at least one of those years, a contributing factor to why I bought mine.
I also remember in the late 70s to early 80s the cars made in Germany were spec'd different for sale in Germany than those slated for the USA. No idea how it is now. You could buy one in Germany spec'd for the USA, drive it for a while and import it yourself as used - savings was pretty nice. In case that helps with the idea of same make model not identical in different countries.
Play nice, be safe ...
__________________

__________________
nrgtrakr is offline  
Old 08-20-2015, 10:17 AM   #58
jcl
Rivet Master
 
Currently Looking...
Vancouver , British Columbia
Join Date: Oct 2012
Posts: 1,050
Quote:
Originally Posted by nrgtrakr View Post
Sure it may be possible, but has anyone ever wondered why a vehicle with a frame is capable of towing so much more than a unibody?
Quote:
Originally Posted by nrgtrakr View Post
Which is about when I asked the dreaded question about a TV rated at 7,700# towing a 10,000# trailer - who cares unibody or frame.
Wasn't it your above post that raised the whole question of a unibody vehicle towing?

Side point, but why do you reference a 10,000 lb trailer? The OP has a trailer that is listed as 6400 lbs. Hard to imagine he has 3600 lbs of cargo in it, which would exceed max GVW by 1200 lbs or so.
__________________

__________________
jcl is offline  
Old 08-20-2015, 10:43 AM   #59
3 Rivet Member
 
Mountain View , California
Join Date: May 2015
Posts: 236
There is a huge difference between the European car market and the US car market. Trucks / pickups do not exist in Europe, there are almost none of such vehicles. Minivans are not that popular. People are towing the travel trailers with sedans, station wagons, SUVs. Sure, the TTs are usually lighter than in the US.

But maybe this is the answer to your question why the car manufacturer would build stronger car than needed cars in Europe are more all-purpose vehicles. The average family has one or two cars, where in the US it is 2-3 cars more. So SUV needs to be a car to go for a shopping and to tow a trailer for vacation.

I am not an engineer, so maybe I do not understand all of the issues, but as another user (Zeta Tre) mentioned on another forum:

"The rear longitudinal beam in the X5 that make up the undeformable barrier in the trunk and where the hitch mounts to have a strength (whether you look at yield or tensile, are very similar numbers) of right about 600MPa to 700MPa. Ram brags about their new frame to have a strength of 50KSI. The conversion of the two is straight forward and reveal the X5 is higher by a factor of 2. In the X6 those same two members are made of a steel titanium alloy called CP800 and are even stronger.

And if you look at the torsional stiffness test that both Ram, GMC and Ford continue to do in the frame of their pickups they are laughable; impressive for a frame vehicle which is structurally deficient in torsional rigidity regardless of what steel you throw at it, but laughable when compared to a unibody."

Additionally, he added some videos



I spoke to a couple of people who know much more about cars than I do. They all admitted that BMW X5 is overbuilt. I know that this means nothing for pickup fans. It means a lot for me tough


Quote:
Originally Posted by gmw photos View Post
Why would a car company build any vehicle ( unibody or body-on-frame ) to be "substantially stronger than necessary". In other words, why would GM build a unibody chassis heavier and stronger, to withstand loads imparted by towing, when the vehicle is going to be marketed as a passenger vehicle, and have a limited tow rating ? That makes no sense to me, to build something heavier ( which hurts fuel economy ) and stronger ( which costs more money for them to engineer and build ) when there is no added return for them.

Step the discussion up to pickup trucks: why would they build a class one truck that has class three capabilities ? Again, this makes no sense to me from an engineering or marketing perspective.

In my mind, it makes more sense for a car company to build vehicles targeted to specific market segments. Cars and minivans to haul people on a daily basis. Trucks to haul a load, or tow a trailer. The tradeoffs are fairly clear. For instance, a truck trades away some ride quality, and nimble handling to gain load capacity, higher pulling capacity, bigger cooling system, heavier duty brakes, axles, etc. It's a tradeoff the consumer willingly takes in order to have a vehicle that is more tailored to a specific task.

Why would we assume at the consumer level that it would make sense for us to "guess" that we know how all the decisions were made around the conference room table ? The table where engineering, marketing and legal all had their say.

In the end what we do know is that there is a specific limit stated by the manufacturer. It almost certainly passed muster with legal and engineering, and most likely also with marketing.

To take that to it's logical end, it's safe for us to say, if we operate the vehicle within the stated design limits, we are likely to have a greater likelihood of successful operation ( safety, reliability, durability ).
__________________
bono is offline  
Old 08-20-2015, 10:47 AM   #60
Rivet Master
 
Currently Looking...
Mission , Texas
Join Date: Jun 2015
Posts: 836
I wasn't questioning a unibody towing. The question stands as written. Rephrased - "How come frame construction can tow so much more than unibody?"
Maybe I missed something, all I saw was 31' AS. Look up the weight for a 31' AS and see what you get. I found a 2013 was 7,254# trailer weight, 805# tongue, 10,000# GVWR.
As you probably know, 7,254# is before options (AC, microwave, battery charger for example) and variable weights (tanks and water heater) - at least that's how AS explains it in 75. Add in food and personal belongings and ...
I chose the high weight on purpose to be safe. But maybe the OP only adds 446# to his when using it, maybe his AS actually weighs less.
But again the main point for me was exceeding the vehicle's capacity.
__________________
nrgtrakr is offline  
Old 08-20-2015, 11:28 AM   #61
Rivet Master
 
2016 30' Classic
Lorton , Virginia
Join Date: Jul 2015
Posts: 560
Quote:
Originally Posted by bono View Post
And if you look at the torsional stiffness test that both Ram, GMC and Ford continue to do in the frame of their pickups they are laughable; impressive for a frame vehicle which is structurally deficient in torsional rigidity regardless of what steel you throw at it, but laughable when compared to a unibody."
Quote:
Originally Posted by nrgtrakr View Post
I wasn't questioning a unibody towing. The question stands as written. Rephrased - "How come frame construction can tow so much more than unibody?"
Maybe I missed something, all I saw was 31' AS. Look up the weight for a 31' AS and see what you get. I found a 2013 was 7,254# trailer weight, 805# tongue, 10,000# GVWR.
As you probably know, 7,254# is before options (AC, microwave, battery charger for example) and variable weights (tanks and water heater) - at least that's how AS explains it in 75. Add in food and personal belongings and ...
I chose the high weight on purpose to be safe. But maybe the OP only adds 446# to his when using it, maybe his AS actually weighs less.
But again the main point for me was exceeding the vehicle's capacity.
Except for the uninformed, torsional stiffness is NOT what you want when designing a vehicle for heavy loads. Ever notice why semi trucks have huge ladder frames and while under load especially from a stop they twist and buck when accelerating? This is by design.

A uni-body pickup truck trying to carry/haul the loads of a body on frame pickup truck would simply snap spot welds, contort and would be destroyed.

Ford tried a uni-body pickup before and it was a disaster. Shortly after the trucks went on sale, buyers discovered that putting heavy cargo in the unibody trucks could cause the one-piece body to flex with interesting consequences. Stories percolating through the Internet tell of uni-body owners who would load their trucks, only to discover that the sills had distorted enough to jam the doors shut. Yet others tell tales of having a fully laden truck twist badly enough to pop a door open when crossing railroad tracks. Age and corrosion only exacerbated issues as the load-bearing bodies began to perforate and rust.

You just can't pile as much weight on it before it begins to twist the entire car body in odd ways. On a ladder frame, the weight is transmitted to the suspension and the wheels in a much more direct, controlled way. "Flex" isn't necessarily an issue, since only the frame is flexing and the body is decoupled and riding on rubber mounts. The HD versions of Ford and Ram's trucks (F350, etc) actually have C-channel frames instead of fully boxed frames, like the 1/2 tons do, because allowing a little flex in the frame actually helps carrying and towing capability.


Uni-body vehicles are fine when used within their design specs. Once you start talking about towing and loads thousands and thousands of pounds above that, I tend to disagree.
__________________
Zybane is offline  
Old 08-20-2015, 11:51 AM   #62
jcl
Rivet Master
 
Currently Looking...
Vancouver , British Columbia
Join Date: Oct 2012
Posts: 1,050
The OP wrote he has a 2015 30 foot.
__________________
jcl is offline  
Old 08-20-2015, 12:03 PM   #63
Rivet Master
 
tjdonahoe's Avatar
 
2013 31' Classic
billings , Montana
Join Date: Feb 2010
Posts: 1,845
I haven't seen many cars towing travel trailers in Mt., although I've been looking at my wife's Venza !!
__________________
tjdonahoe is offline  
Old 08-20-2015, 12:29 PM   #64
Rivet Master
 
switz's Avatar

 
2014 31' Classic
2015 23' International
2013 25' FB International
Apache Junction , Arizona
Join Date: Sep 2012
Posts: 4,799
Images: 8
So the printed weight numbers of the door post versus the scales report is the heart of this long conversation. Which numbers are the ones to fudge? I went across the scale in May with the truck and trailer loaded for camping and me and the wife as the people in the truck.

GAWF 5,500 scales 4,700
GAWR 6,010 scales 5,700

GVW 9,600 scales 10,300

GCW 20,000 scales 18,660

So while the GVW was exceeded, the axle and tire with wheel ratings were under the maximum. The maximum combined weight was under the limit and the trailer weight was less than the maximum. This is a truck which is designed to carry loads. Most states DOT officers are only concerned that tire, wheel and axle ratings are not exceeded and the license plate has the correct weight ticket for the load.

The togue weight of the trailer is now reduced to 1,200 pounds in this example, so the trailer typically weighs around 9,300 pounds unhitched loaded for camping.

For us, the truck is properly sized for the job at hand. We have removed a lot of heavy items after this trip that will probably not be carried any more which will reduce the rear axle load some more.

When we saw a used 34' Classic (last one officially built - #25 of 25), I pushed the numbers and my truck could have been easily overloaded with that trailer that had a GVW of 11,500 pounds. Thus we ordered the 31' Classic with a 10,000 pound GVW that was within the towing GCVW restrictions.
__________________
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC

TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell

2014 31' Classic model 30 twin beds, 50 amp service, 900 watt solar system, Centramatics, Dill TPMS, disc brakes, 16" tires & wheels
switz is offline  
Old 08-20-2015, 12:38 PM   #65
Rivet Master
 
Currently Looking...
Mission , Texas
Join Date: Jun 2015
Posts: 836
Quote:
Originally Posted by jcl View Post
The OP wrote he has a 2015 30 foot.

Okay ...
2013 - 30' AS 7,365# trailer weight, 773# tongue, 10,000# GVWR
Pick nits much?
__________________
nrgtrakr is offline  
Old 08-20-2015, 12:43 PM   #66
jcl
Rivet Master
 
Currently Looking...
Vancouver , British Columbia
Join Date: Oct 2012
Posts: 1,050
Quote:
Originally Posted by Zybane View Post

Uni-body vehicles are fine when used within their design specs. Once you start talking about towing and loads thousands and thousands of pounds above that, I tend to disagree.
I don't think the 60s unibody pickup is as relevant. An SUV doesn't have the roof profile of a pickup, it is more of a one box of two box design. A better example would be a Transit or Sprinter. Available up to one ton class ratings. Unibody. Current design. Designed to carry loads. What don't they know?
__________________
jcl is offline  
Old 08-20-2015, 12:50 PM   #67
Rivet Master
 
Vintage Kin Owner
N/A , N/A
Join Date: Sep 2012
Posts: 995
Images: 1
Quote:
Originally Posted by jcl View Post
I don't think the 60s unibody pickup is as relevant. An SUV doesn't have the roof profile of a pickup, it is more of a one box of two box design. A better example would be a Transit or Sprinter. Available up to one ton class ratings. Unibody. Current design. Designed to carry loads. What don't they know?

A 1 ton Sprinter has only a 5000 tow rating.

I have never seen a body on frame race car nor a unibody semi. They make different tools for different applications for a reason.
__________________
rostam is offline  
Old 08-20-2015, 01:31 PM   #68
Rivet Master
 
2016 30' Classic
Lorton , Virginia
Join Date: Jul 2015
Posts: 560
Quote:
Originally Posted by rostam View Post
A 1 ton Sprinter has only a 5000 tow rating.

I have never seen a body on frame race car nor a unibody semi. They make different tools for different applications for a reason.
Agreed.
__________________
Zybane is offline  
Old 08-20-2015, 01:50 PM   #69
Rivet Master
 
dkottum's Avatar
 
2012 25' Flying Cloud
Battle Lake , Minnesota
Join Date: Jun 2009
Posts: 7,716
The good thing is we see more folks like the Tino's Touareg/Airstream combo all the time who have taken their head out of the sand to understand their is more to safe, comfortable and efficient towing than manufacturer's ratings. Knowing these design characteristics can make all of us choose better tow vehicles, hitches, and Airstream components while still remaining within tow ratings. And for those who wish to push the parameters and do it safely.
__________________
Doug and Cheryl
2012 FC RB, Michelin 16, ProPride 1400
2016 Ram 1500 Laramie Crew Cab 4X4 Ecodiesel 3.92 axles

The Truth is More Important Than the Facts
dkottum is offline  
Old 08-20-2015, 02:12 PM   #70
Rivet Master
 
Currently Looking...
K.C. , Missouri
Join Date: Nov 2011
Posts: 585
Quote:
Originally Posted by rostam View Post
A 1 ton ( "unibody"....note added by me ) Sprinter has only a 5000 tow rating.

I have never seen a body on frame race car nor a unibody semi. They make different tools for different applications for a reason.

Correct. And in the "Sprinter class", if we look at a Nissan NV, it has a 8700 lb tow capacity. ......and...... a ladder frame. No unibody there.
__________________

__________________
gmw photos is offline  
Closed Thread


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
VW Touareg diesel Never2late Tow Vehicles 8 06-17-2014 02:22 PM
Touareg and the Hensley question adwriter73 Tow Vehicles 3 10-25-2010 09:31 PM
touareg, bambi and weight distribution hitch ericwarren Hitches, Couplers & Balls 2 10-02-2008 10:19 PM
First road trip with Touareg and CCD... Xray Our Community 35 09-15-2004 02:06 PM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 01:07 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.