Air bag suspension truth and facts...

[LVRVLUVR]

Originally Posted by NevadaNick

Cbilodeau, you say these air ride dp cant go outside of highways, i invite you to follow me some of the places i take mine.

have you jumped it?

[Gordon Dewald]

How fast are you guys attempting to drive your MH while off road? I tried taking my F450 off road and found slowing down made it ride a lot better - and it is on springs.

It does not jump worth a darn!!!

[NevadaNick]

Havent jumped any of my motorhomes but i did jump my moms car a few times and my first van which was a 1961 Ford and it usually landed on the front bumper.

[Scatterbrain]

Originally Posted by cbilodeau

You are a technician. You are not an engeneer but you worked with some.

In my province a technician is pre-university and they don't go in a university.

I have two University diploma, Science and Engeneering from the Royal Military College of Canada (I was an army Officer on my previous career and almost 90% of the Canadian officers at that time were engeneers) and also a Computer Science and Operational Research and this bachelor was obtain at the University of Montreal.

But I don't expect specialists here to have any University Bachelor. If you or the OP or any specialist here comes with a so very good expertise I am very satisfied. But I have a good eye to detect a real specialist.

I am the president of a IT and Engeneering company in Montreal. So I have worked and hired engeneers and computer specialists since the last 21 years. My offices are in the most prestigious tower in Montreal at the second last floor.

This does not make me a Suspension specialist. At least this very scientific career helps me understand specs and technical aspects of a project. As a president, you are the one that get the worst case on the desk all day long.

You may now understand why I am expecting and am used to tehcnical discussions without the emotions people are bringing here simply because they "bought" a DP.

My motorhome restoration project is a challenge I brought to my 12, 13 and 15 years old kids. They learned from me electronics, electricity, mechanic, plumbing, everything on this motorhome. My five kids do home schooling and the Motorhome project is a chance from them to become autonomous people. You can not manage people like I do when you can not do the job yourself.

Sorry for my many english mistakes, my life is in french and I speak english only on my trips in USA. I am learning english and with IRV2 I have improved a lot.

N.B.: Today the kids learned the very importance of good isolation for spark on high voltage coils. We changed the coils boots together.

Actually, I have a B.S. in business accounting. However, that's not germane to this discussion.

In the report you posted they were looking for the best suspension system for a fully loaded trailer. Not the trucks. Not the trailer when empty or partially full. As I have pointed out before, when springs are loaded to their specified weight the vehicle will ride just fine. If you are running a fleet of trailers that you know will always be full, then at that point air makes no sense. It costs more and is more likely to break. I won't say springs never break, because I've seen it happen, but it's pretty darn rare. Rare enough to not have to roll it into your ownership calculations, even for a trailer expected to cover 1 million miles or more. Besides, there is little point in worrying about the ride quality of an empty trailer, is there?

The problem you run into in RVs is that they tend to run on chassis built for service/delivery trucks. The chassis isn't RV specific. They are sprung to function at the chassis' max gross vehicle weight, not the weight of your specific RV. The springs also don't vary from side to side in rating to accommodate the off center loading of your RV. This is where air suspension shines. The airbags can be adjusted individually to counter shifts in weight, springs cannot. They can adjust to counter increased or decreased overall loads, steel springs cannot.

As I pointed out before, if you're not at or near fully loaded, chances are you're a bit over-sprung with steel springs. With air this isn't an issue. Why don't you see air as spec on gas coaches? Cost. The primary buyer for those chassis aren't RV manufacturers. They are people building delivery and service vehicles. For those customers the added expense of air ride is just that, an added expense. It's the same reason you don't see a rear engine gas chassis. Can you imagine a FedEx or UPS delivery truck with air ride and a rear engine? What an expensive pain that would be for them.

With all that said, no one is saying you can't get a decent ride from steel springs in an RV. Some builders pull it off quite well, some fail miserably. We spent a good deal of time looking at different gas coaches before settling on our current DP. All of the coaches we drove were empty (except for us and the tank of gas of course) and they were all a bit rough. Some were teeth rattling, but most were acceptable.

[vtwinwilly]

I just finished reading this entire thread and the whole thing is swirling in my head.

In fact, the only things I know for sure are:

1) LVRVLUVR missed his calling. He should have been a politician. He seems to be able to take multiple positions on the same subject (and amazingly can find someone to argue with no matter which position he takes).

2) cbilodeau is still working on English as a second language. Keep it up buddy, you'll get there!

And...

3) air suspension on a MOTORHOME rides better than leaf or coil springs on a motorhome in most cases! Lookup "Rolling Lobe".

[cbilodeau]

Originally Posted by Scatterbrain

In the report you posted they were looking for the best suspension system for a fully loaded trailer. Not the trucks. Not the trailer when empty or partially full.

...

You are totally wrong. The study was on partially, 3/4 loaded and fully loaded. This is 10000 load, 30000 load and 40000 load.

Originally Posted by Scatterbrain

If you are running a fleet of trailers that you know will always be full, then at that point air makes no sense. It costs more and is more likely to break.

...

You are totally wrong. The study was also for 1/4 load and 3/4 load. Not only full load. The conclusions I have reported are for 1/4, 3/4 and full load. You are misleading the readers and you have the report in hands.

Originally Posted by Scatterbrain

Besides, there is little point in worrying about the ride quality of an empty trailer, is there?

...

You are totally wrong. The study says that the ride quality of a near empty trailer is about the same for air and spring. See the two clear gray bars in the graph. The study also say: With limited light or less-than-truckload shipments, the perceived benefits of air ride are minimal at best.

Click on this image.

Originally Posted by Scatterbrain

As I pointed out before, if you're not at or near fully loaded, chances are you're a bit over-sprung with steel springs.

...

You are totally wrong. The study show clearly that there is no benefit at all with air when fully loaded and they show it on the graph with the two orange bars (the small orange bar IS AIR and the big orange bar is SPRING). When not fully loaded the benefits of air is minimal.

They talk about truck load. They do not center the load since the study was made with real trucks with real customers loads. They do not center the load.

Originally Posted by Scatterbrain

With all that said, no one is saying you can't get a decent ride from steel springs in an RV.

...

You are totally wrong. Many DP owners are saying the total opposite on this thread.

I don't think you are able to have a rational discussion.

I don't think either that you can read a technical report.

Finally, I think you are trying to mislead members on IRV2. I don't understand what is the motivation. The study is available for everybody to read anyway!!!

[Scatterbrain]

Originally Posted by cbilodeau

You are totally wrong. The study was on partially, 3/4 loaded and fully loaded. This is 10000 load, 30000 load and 40000 load.



You are totally wrong. The study was also for 1/4 load and 3/4 load. Not only full load. The conclusions I have reported are for 1/4, 3/4 and full load. You are misleading the readers and you have the report in hands.




You are totally wrong. The study says that the ride quality of a near empty trailer is about the same for air and spring. See the two clear gray bars in the graph. The study also say: With limited light or less-than-truckload shipments, the perceived benefits of air ride are minimal at best.

Click on this image.



You are totally wrong. The study show clearly that there is no benefit at all with air when fully loaded and they show it on the graph with the two orange bars (the small orange bar IS AIR and the big orange bar is SPRING). When not fully loaded the benefits of air is minimal.

They talk about truck load. They do not center the load since the study was made with real trucks with real customers loads. They do not center the load.




You are totally wrong. Many DP owners are saying the total opposite on this thread.

I don't think you are able to have a rational discussion.

I don't think either that you can read a technical report.

Finally, I think you are trying to mislead members on IRV2. I don't understand what is the motivation. The study is available for everybody to read anyway!!!

A few thoughts.
One, it's a marketing brochure.

Two, you're right, they did mention three weights, but we're still talking about trailers.

Three, I'd love to see where they say that they don't follow proper loading protocol for weight distribution. It's not in that pamphlet. You're not being dishonest here are you? Maybe assuming a bit?

You don't load the weight of a trailer right over the axle. The best ride comes between the axles, both in terms of smoothness for the cargo and balance for the trailer. I can't imagine they took the 10k load and placed it anywhere different than where proper loading practices would dictate,which would not be over the axles.


Four, for a more detailed breakdown you can look at XTRA. Herein lies the real reason for the push to springs in trailers (not trucks):

As is the age old aphorism : "follow the money".


Here's a few quotes from them:

These days there’s less potential for cargo
damage.
Product packaging has greatly improved.
Cargo can be better secured thanks to logistics
posts as a standard in van trailers. And shippers
have improved the configuration of pallets and are
optimizing the way cargo is packaged and loaded to
get optimal use from a trailer

Now driver retention is influenced more by
pay, technology and length of haul, than by the
suspension on the trailer they pull.
Long-haul
trucking is a difficult job. Many years ago, drivers
had to do a lot of bobtailing, and EMPTY spring-ride trailers do a lot of bouncing around. To retain
drivers, trucking companies tried to give them a
nice, smooth ride by putting air-ride suspension on
tractors and trailers.

This statement (from a company with over 65k trailers on the road) seems to directly contradict Schneider's position paper:

That said, not every product can or should be hauled
on a spring-ride suspension—some easily bruised
produce, for example. For that, XTRA Lease does
have air-ride trailers available. But the far more
versatile, simple, and proven spring-ride trailer
will continue to make up the majority of our fleet
purchases.

Why do you think something very easily damaged is recommended to be shipped on air ride would be?

Of course, all of this is tangential to the main discussion of RV suspension. When you're driving your RV you are directly over the front axle, not in the galley.

....and another thing. If you're going to accuse me of not being able to read a "report" (which that two page brochure is not) you should know how to read the legend of a bar graph. The different colors are for different weights. Both of the orange are for 40k lbs. The little orange bar is for air.

Meanwhile, nowhere does it clarify how the data is to be interpreted. Is it better to be higher or lower? They don't say. Does the y-axis correlate to the amount of goods damaged or the proximity to a perfect score (percentage or percentile)? They don't say. What's the margin of error for their study? Their graph is dealing with a difference range of 3 tenths total. What if the margin of error is greater than the differences shown? Was it a controlled study? They allude that it was yet you insist it wasn't. If it wasn't how reliable is the data to begin with? If the loads were just slapped in randomly by independent drivers then the whole study is moot. If the damage values were assessed and reported by independent drivers then the whole study is again moot. This kind of information is what marks the difference between an academic study and a marketing brochure.

[Scatterbrain]

Meanwhile, this entire discussion is academic anyhow, as the suspension in your RV is dictated by the size of the rig. If you want 40-45ft you're going to be getting a DP or a super C. In both cases it will be diesel and air ride. If you want 36 or under it will be gas. In which case you'll have steel springs. The real discussion should be about the variables you can control, such as whether to get IFS or beam axle in the front. What kind of shocks to install. Whether or not to add sway bars (if the chassis didn't come with them) steering stabilizer systems or air assist. Whether or not the rear end will need a panhard bar added to keep it centered. These are things that you can control when you buy a coach and they can make a big difference in it's performance.

[NevadaNick]

And then we can throw tire size as well as pressure into the equation about ride quality. You see its not all about spring versus air or gas versus dp. Then there is shocks and there role in ride quality. Weight bias from front to rear as well as side to side. Where would you like to start or stop the discussion ? Also i dont think that dp owners are saying you cant get an acceptable ride from springs, just that air is better in most instances.

[Gordon Dewald]

Originally Posted by cbilodeau

Finally, I think you are trying to mislead members on IRV2. I don't understand what is the motivation. The study is available for everybody to read anyway!!!

Hi Carl;
Would you be able to provide a link to the actual study and not just the results. Who was the study supervised by?

With 10,000 + vehicles Schneiders would have some vested interest in convincing the clients to use a less costly vehicle setup.

[NC25T]

Originally Posted by cbilodeau

I have no theory. Read what the expert LVRVLUVR wrote on the first posts: The air bags on most motorhome is the cheapest suspension system. It is bad when the road is not perfect and the travel of the wheel is not very long. This is technical.

If you want to be emotional you will continue to say that I said it is the diesel liquid that makes the suspension bad. This is 3rd grade strategy. You put words in my mouth and then you blame me for those words. How come you react like this? Are you trying to convince yourself you took good decisions with a DP?

I do not view him as a expert, far from it.... it's just someone who has enough money to buy lots of motorhomes and state he spent $50K plus on his RZR's...

Maybe I missed it but I see no technical data on suspension travel, how much each type of chassis has and/or a comparison with these different types off-road. It's just what your "expert" claims. For me typically the only time I am off-road in my RV is at a camping area thus suspension travel isn't a concern.

To me technical is X brand/style of suspension has 8in of wheel travel vs Y brand/style has 8.2in of wheel travel. Also X can tow .... Lbs while Y can tow .... Lbs. not someone just blowing opinions our way...

Also it would be nice to see costs of the different suspension setups. If you claim air bag on most is the cheapest then let's see those numbers vs a leaf spring setup. If air bags are so cheap I wonder why they aren't in entry level coaches?

Not putting words in your mouth just trying to understand what you are both stating.

I actually do not own a DP thus you are putting words in my mouth

As I stated earlier where in the keys can you park a coach on the beach? I want to go there!

[cbilodeau]

Originally Posted by NC25T

If air bags are so cheap I wonder why they aren't in entry level coaches?
....

A lot of the entry level coach are on the Ford F53.

The F53 is part of the F-Series like the F150, F250, F350, F450 and F550.

Like previously said air suspension would be more expensive on pickup trucks that have no air for the brakes. Like the Scheider study show air suspension breaks more and cost more to take care of and there is no real benenfits. But they also says that on a good road you get the feeling of a better ride. Actually everything Scheider study says is in phase with what the OP claim.

This is easy to understand.

On a low chassis built for a motorhome the wheel travel is so low that an air suspension is the cheapest solution like the OP said. You could get a better feeling with an air suspension if the road is good and if the builder did a good job and the OP says that most don't do a good job and that it is not better than what we see on Spring suspension.

In the Keys they have state park and they are on the beach. I been there at least three times last year. I have also talked to many DP owners in the private park where we went and they simply can not go in those state park most of them. You can reserve online and try it. In december it was always full but if you check the website each 30 minutes you will find a cancellation.

[FreedomDream]

Originally Posted by LVRVLUVR

and another thing... the only difference between a 16k ford chassis and a 18k chassis is the leaf springs....

where as if it was air bags it would be a lever adjustment

another thing that uper end coaches with the likes of spartan, roadmaster, gillig chassis found out real quick that they couldn't get the desired ride out of the common 4 bag chassis

and went to 8 bags....now you are talking real motorhome with a real chassis,,,

I do believe that there is more to the increase in GVWR that added leaf springs. Breaks, spindle size, axel rating, shocks and other things all would need to be beefed up to increase a rating of a ton,

[cbilodeau]

Originally Posted by Scatterbrain

Three, I'd love to see where they say that they don't follow proper loading protocol for weight distribution. It's not in that pamphlet. You're not being dishonest here are you? Maybe assuming a bit?

...

I have loaded trailers when I was a studen. We had load protocol but there was no "gravity center" mesure taken on the trailer. This is a rough weight distribution. But for sure we put the load between the two axle. I don't understand.

Originally Posted by Scatterbrain

...
you should know how to read the legend of a bar graph. The different colors are for different weights. Both of the orange are for 40k lbs. The little orange bar is for air.
...

It is you that don't know how to read the graph. The small orange bar is for Air meaning that on full load the air suspension get 52% acceptable ride conditions while spring get 70%. I recall readers that my motorhome is always fully loaded.

Even the text can help you understand the graph. They say: With limited light or less-than-truckload shipments, the perceived benefits of air ride are minimal at best. This is the gray bars, we see the AIR is better than spring when 1/4 loaded or 3/4 loaded but by only 2%.

I think you are playing a game here. I work with many engeneer and computer specialists and everybody would laugh about you playing with terms you don't understand. I will make some people laugh at the office on monday I think.

Originally Posted by Scatterbrain

...
As is the age old aphorism : "follow the money"

It is completly ridiculous that mix data like this. The leaser is talking about price of purchase + the maintenance cost.

But RV chassis builder don't pay for the maintenance cost, only the spring suspension initial cost. And like the OP said, they are cheaper on a truck that already has air for the brakes and that has a low travel for the wheels. IT IS THE DP OWNERS THAT PAY FOR THE MAINTENANCE OF THE AIR SUSPENSION.

Originally Posted by Scatterbrain

...
Meanwhile, nowhere does it clarify how the data is to be interpreted. Is it better to be higher or lower? They don't say. Does the y-axis correlate to the amount of goods damaged or the proximity to a perfect score (percentage or percentile)? They don't say. What's the margin of error for their study? Their graph is dealing with a difference range of 3 tenths total. What if the margin of error is greater than the differences shown? Was it a controlled study? They allude that it was yet you insist it wasn't. If it wasn't how reliable is the data to begin with? If the loads were just slapped in randomly by independent drivers then the whole study is moot. If the damage values were assessed and reported by independent drivers then the whole study is again moot. This kind of information is what marks the difference between an academic study and a marketing brochure.

You are bringing any technical expression you have found on the internet?

Margin of error? This is ridiculous. You don't know what you are talking about. They are not predicting. They take the data from their truck float data. This kind of study is made by almost all middle and large company in today's world.

If we want to talk about "margin of error" we would have to make a study on many company to predict with a certain margin of error what you should expect for your specific float of vehicule in your specific usage.

And I could continue with what you say "controlled study". This has nothing to do since the purpose of this study is not for publication in a scientific magasine but for intelligence purpose for Scheider and their customers.

Business Intelligence projects are not for scientific purpose but for business intelligence purpose. Every year the number of BI specialists in the IT world is increasing since businesses need more and more inputs to take decisions.