Rubber Torsion vs Leaf Spring Axles

[Ray Eklund]

Getting the 2019 Oliver Elite II ready for our first trip and I have time to think... in and outside this different Travel Trailer... makes my Neanderthal Brain... buzz.

Having a 2019 Airstream and now a 2019 Oliver, two kinds of suspensions.

Airstream Advertisement:

"Our Dexter rubber torsion axles have internal rubber cords that provide load carrying capacity verses leaf spring type axles. A rubber torsion axle mounts directly to the travel trailers frame and will resist torsion and create a suspension system that is an upgrade that comes standard compared to the typical leaf spring axle."

Someone may understand WHY a Rubber Torsion Axle and NOT Leaf Springs as all other Travel Trailers? Is is so the Airstream sits lower to the ground and the theory would be less Air Pressure pushing against the Front of the Trailer?

(SUV's and 1/2 Ton Pickups)

When a Torsion Axle flexes at the time the Weight Distribution part of a Towing System is attached... the front of the Trailer needs to be Lifted and then when it is lowered, the weight needed to be transferred to the Front of the Tow Vehicle can be completed... AND have also Sway Control friction and pressure against any hardware mounted to the Airstream Frame. (The Oliver has some similar system but further back and chains, versus Bars as with an Equalizer Hitch with various Bars to transfer weight to the front of the Tow Vehicle.

When the Airstream travels on level and flat roads... there is NO extra WD STRESS added to the Frame.

When the Airstream travels over uneven roads, or rocks left to right... There IS EXTRA STRESS from the WD part of the Equalizer, and no doubt other systems? As then the Sway Control has the friction it requires to be effective? Although may not be necessary... on some or most SUV's or 1/2 ton pickups. I do not know.

My wife rode several miles on the Interstate within our 27 foot International. She said it rode like a stiff suspension Tank, several years ago. Our F350 was smooth in comparison and a great alternative to the Airstream in Tow and hard ride.

We have not used the Oliver yet, having Leaf Springs on each axle. Double Axle, four sets of leaf springs. It will be interesting how it rides on a level highway with someone inside. Yet to be, discussed, of course.

Does a Rubber Torsion Axle show NO Mercy to the hard Ride VERSUS Leaf Spring Axles on all the other Travel Trailers? Why are Pickups using Leaf Springs and Coil Springs for suspension... and not Rubber Torsion Axles? Just curious. Probably not for good reason...?

I need to speak with owners with Leaf Spring suspension Travel Trailers, if their cabinets and hardware vibrate loose some of the time, all of the time, or NEVER. I want to know. Our Airstream had been All of the Time, but with 3 years of tweaking... not as much.

My friend with an Arctic Fox... loved his Leaf Sprung Trailer. So... what gives?

This may also be related to the Front Separation Issues and popping Buck Rivets and Rivets on the Front Bed 27 foot models. Maybe 25 FB's as well. Some have followed other Threads and have better memory than my selective memory.

1- Why Rubber Torsion Axles?

When WD is used for SUV's and 1/2 ton tow vehicles, you must raise the Front, so to swing the WD Bars onto the L brackets. This creates more tension by lifting, but the BACK AXLE is being compressed as the FRONT AXLE is being lifted.

Airstream JC seems to BLAME 3/4 and 1 Ton Tow Vehicles for the STIFF RIDE.

We can and do Tow On the Ball, often. No WD needed and to date NO Sway, at all.

The Oliver II is about a 23 foot Airstream. No WD. No Sway Control, either. The FRAME is also very well supported with cross members heavy alloyed aluminum. It is heavy for its size.

The Front BED Airstream with the Storage Compartment has a weakened front shell supporting system... for reasons... unknown to me and others.

Anything here seem to be on or off Target? Those owning the FB models need to know WHY and not have it kept quiet from those who engineered the trailers.

Torsion Double Axles? Would Leaf Springs FIX this? Leaf Spring Axles would get the clearance higher, so I would not needed to add 3 inch Lift Kit to get the trailer to clear more ground when traveling off flat paved roads.

This is difficult to put into writing. I can visualize the moving parts and Axle Stress... but transferring to the front, damaging the skin is just... not acceptable.

[John Ware]

I have been wondering where you have been, Ray. I thought maybe your toilet was broken and you weren't getting any new inspirations. Just joking, for I always enjoy your comments. The rubber torsion system AS uses is just another kind of spring system. VW used torsion bars on their cars for years. One system isn't any better than the other, just different. They both require shock absorbers to tame them down.

[AlbertF]

Rubber torsion axles are independent and provide better handling, at least in theory.

When your wife rode in the trailer in the interest of science, what tires was it riding on and what was the pressure?

[Ray Eklund]

Airstream 27FBQ: Michelin 16 inch tires. 72psi. Today... 69psi... lower since last use. Before using, I will take it up to 72psi before using next trip. Nitrogen.

Oliver: Michelin 16 inch tires. 72 psi. Filled for Trip leaving next week.

Airstream JC 2008 for warranty work... "My 2006 23 foot Safari has leaky Shock Absorbers, do they need to be replaced?"

Response... "No, they don't do anything." Under Warranty while at JC.

(Do I look like I make this stuff up? I am not that bright. I am not a Human Bean mechanic.)

[Ray Eklund]

Originally Posted by John Ware

I have been wondering where you have been, Ray. I thought maybe your toilet was broken and you weren't getting any new inspirations. Just joking, for I always enjoy your comments. The rubber torsion system AS uses is just another kind of spring system. VW used torsion bars on their cars for years. One system isn't any better than the other, just different. They both require shock absorbers to tame them down.

******
Had a 1956 VW and a 1964 VW... they rode very well. Great off the road, as well with the rear wheel drive and an engine for added weight. Short wheel base and very tight bodies and door fit. Tires were 15 inch just like my 2019 27 foot long FBQ.... "tell me it isn't true ToTo... asked Dorthy".

New VW's have 16, 17 and 18 inch... naw... cannot be true?

Unlike my Airstreams... The 23 foot Safari with 14 inch C rated tires on my 2006... needed tires often. ... and a steel rim that did not match, since it looked bad when I had use it as a spare tire.

A VW Bug would float longer than an Airstream in a Lake, I have heard as the fit is so tight. Never tried floating the VW's, but my teen years I could afford to drive them and carried very few tools, as well.

Does any other Travel Trailer use Rubber Torsion Axles?

If Yes... which? If No... why not?

I have watched Airstreams making tight turns, making their Rubber Torsion Axles twist, change angles and leave rubber. I have watched straight axle trailers leave rubber on a tight turn... but the axle is straight.

Next time we are camped near a Straight Axle... I will inquire about the interior cabinets and hardware.

I will also report about our used 2019 Oliver and how it reacts, with factory 16 inch Michelins.

[John Ware]

My 16' Stock trailer has the rubber torsion axles without shocks. I haven't heard any of my cows complain, but usually they're on a one way trip. I think I've owned
around a dozen VWs of one kind or another.

[Ray Eklund]

Originally Posted by John Ware

My 16' Stock trailer has the rubber torsion axles without shocks. I haven't heard any of my cows complain, but usually they're on a one way trip. I think I've ownedaround a dozen VWs of one kind or another.

******

"If you spend too much time on the internet, you’ll see some die-hards that believe a double or tandem axle camper is safer than a single axle model. This simply isn’t true. Travel trailers with one axle are made the same way as their larger counterparts, using the same types of construction materials. So long as you don’t over pack and exceed the GVWR, and you keep up with your tire maintenance (including making sure the tires are properly inflated), a single axle camper is perfectly safe to tow. And for the record, you can’t overpack or ignore the tires on a dual axle rig either."

Bowlus Road Chief advetisement: "The Axle and the Wheel"

"The axle is a simple machine that’s been around almost since the dawn of time. In basic terms, it’s a rod with a wheel on each end. While some improvements have been made since the fourth millennium BCE when the wheeled cart was the hottest tech going, it’s the same basic design that you’ll find on your RV today. The axle’s rod runs underneath your camper and allows the connected tires to rotate as you move on down the road."

Reading the Bowlus web site: "Two Axles Aren't Better than One"

Appears to me the Bowlus has a Straight Axle... because it is better... or cheaper? Hmmmm. Let me think... this hurts the Rubber Torsion argument, if they use a straight axle.

www.bowlusroadchief.com

Been there. Saw them... not for Off the Grid Boondocking, but artwork in Aluminum!

Any Bowlus popping Rivets? Front end separation? Just curious...

[Ray Eklund]

Check it out. Cannot miss it. Ask for Aubree... leave a good tip.

[PatLee]

Regarding front end side dimpling: It doesn't help that there is a very large, oblong, horizontal storage door cut out in the front center of our trailers. This void provides no support against the flexing of travel on uneven roads.
I was at JC this week for work and there was a couple there who had their trailer in to get the dimpling fixed under warranty. Their AS tech came out to show them what they were going to install to reinforce that area on either side of the storage door. I wished I'd taken a photo but it was a right trianglular-shaped piece of metal that would be attached behind the skin, on either side of the door. The tech said the couple would never know anything had been added but it would fix the problem.

[John Ware]

Ray, I had a 22'Sport for 4 yrs and the only thing I didn't like about it was that it had a single axle. I traded it in for a 22' FC with more or less the same floor plan but has 2 axles.

[DCPAS]

https://askthervengineer.com/whats-t...xles-on-an-rv/

[Ray Eklund]

DCPAS... thanks. The curious will have some outside reading.

I finished the article and noticed "Up To 5,000 # for Rubber Torsion Suspension" trailers, unless my memory failed me.

Horse and Cattle Hauling trailers may or may not use conventional options. Never looked... will this travel season.

I also did a Cut and Paste that caught my Neanderthal attention:

"For larger campers (and anything with double axles), I’d instead favor equalized sprung axles with shocks. I wouldn’t say no to double torsion axles, though."

The Oliver has Dexter Leaf Springs with 5 Leafs to the Spring Set. Between the Leaf Sprung Axles are some independent moving heavy duty hardware that acts like Independent Suspension with a Large Rubber 'dampner' as the shock absorber? No shocks.

The Oliver is engineered so well for the Fiber Glass and the accessories, they would have spent plenty of time, if any?, considering Rubber Torsion systems. I personally like Leaf Springs and these qualify, but have an extra engineered system between the two axles.. maybe a dampner and the axles are independent from one another.

I use to work with 1963 to 1967 Corvettes when they were cheaper, used cars. They had ONE Sprung rear suspension running Left to Right. Maybe 5 Leafs... this was in the mid 1970s. It rode like a Tank and they all SAGGED in the rear. Some added more spring to sprung... kind of changes. Nice cars... too light in the 'rear end'. Especially the Big Blocks. All weight up front and no traction. Got old and drove a new 1978 Chevrolet pickup which began rusting the first year and bad valves, the first year and... missing part of the throw out bearing transmission system from the factory... Went to Toyota pickups and today, love the 2016 F350 Diesel almost as much as all of my full sized Tundras.

Now Trailers. I am going to get a real lesson next week with the Oliver System.

The Clearance of the Oliver is within ONE INCH of MY Airstream WITH a three inch Lift and 16 inch Michelin tires. And Olivers come with 16 inch Michelins as stock. Anyone who says it cannot be ture... can come and take a look. Was I surprised? You... betcha I was. But happy about not knowing any better.

The bumper is solid and even has a shank for attaching a Bicycle and a large open storage platform on the front for a Generator.

We measured the front tire edge to rear tire edge and they are within an Inch or less the same from our 27 foot and the Oliver II. I am going to measure the length of the Ball Coupler to the front tire and center... just for the Neanderthal curious nature I am stuck with.

Thanks. This author might write tough comparisons or nice comparisons... if you want to sell an article... you have to work with whom is paying. How do I know? Been there and would not do it for anyone... but that is how it goes.

This reminds me of buying the 2006 23 foot Safari. ALL Airstreams at the time had 15 inch Tires... ONLY the 23 foot had 14 inch Marathons. Dumbest thing I did as these tires were C rated and never dependable. The salesman did not mention it and I was a first time buyer... loved the trailer... but went through many brands of tires. No Goodyears for me. Michelin. So when you learn... you make improvements.

So... Airstream does things that did not make sense in tires at one time... maybe Axles deserve some close attention. Those of you reading this may have some thoughts or ideas, lets hear some.

[uwe]

Both systems work well. Neither are perfect. But...the torsion suspension offers the following advantages for use in Airstream trailers - there are a pair of massive steel tubes connecting both frame rails side to side. This gives tremendous support to the Airstream frame, which is intentionally undersized because of the semi-monocoque design of the shell/floor.frame. Also, the unsprung weight is substantially lower than 2 solid axles with leaf springs. The suspension can react to road imperfetions much quicker, and with less "shudder" than leaf springs and solid axles. Brake and cornering forces are better controlled, and Wheel position doesn't change very much when loading/unloading the entire suspension. Shocks on torsion axles are not really important, in my opinion mostly decorative, and that from experience towing with/without. Rubber torsion axles are self dampening, according to Dexter engineering dept. Shocks do make sense on a heavy leaf spring suspension. Another factor is that you have a truly 4-wheel independent suspension on your airstream. All that said, I have converted many leaf spring Airstream trailers to rubber torsion suspension, and have always felt a more solid towing experience afterwards. But not by a huge margin, and in rare cases on very small trailers, the leaf springs of the old days felt better, sorry to say. In part because they used very long springs back in the 50's, which give a nicer ride than the short ones used nowadays. All in all, if there was a choice, I would always opt for the rubber torsion suspension for the reasons mentioned above; lower unsprung weight and an overall more solid towing experience. Thats all I know...hope this helps.

[Ray Eklund]

uwe... first hand knowledge by doing. Thank you.

The days before starting our Boondocking Off the Grid Trips, they start with shutting down everything we were doing... and not start anything new, half done or misplaced.
I am tired of pulling small weeds and trimming branches of bushes.

*******
Airstream: My 27 FBQ 28 feet 6 inches (length from coupler to back rear bumper) and has 12.5 inches clearance to the center of the Axle. (3 inch Dexter Lift Kit and 16 inch Michelins now on trailer.)

Oliver: My 23 foot 9 inch Oliver (length from coupler to back rear bumper) and has 12.5 inches clearance to the center of the Axle. (Stock, naked.)

The 27 FBQ has 127 inches from coupler to the front edge of the Michelin Tire, front axle.

The Oliver Elite II has 157.5 inches from coupler to the front edge of the Michelin Tire, front axle.

Airstream 27 foot FBQ weighs, 5,923 pounds. Airstream quotes 28 feet long.

Oliver Elite II weighs, empty, 4,900 pounds. Oliver quotes 23.5 feet in length.
*******

These measurements are being listed as if they become of some value later, I would not have displaced my notes, scribbled onto a piece of note paper. I misplace things all of the time...

These numbers are as found on the Internet and, of course, if you have one AC or two AC's... numbers change, but this is not a scientific study paid with public money.

There are many Airforum Members who are curious, but staying on the side lines. If you do not stand in front of an out of control 44 foot RV... you cannot describe how terrifying the experience would have been.

That is this Thread... not Life and Death, but sure interesting. But make it a 44+ foot RV Diesel Freightliner... and now you need video.

I have always believed the International 27 foot and the International 28 foot were the same length, which would be 28.5 feet depending on how you are measuring. The 27 foot must have not added the storage compartment bumper.

[Coloradobus]

John Ware
Smaller airstreams like our 2006 16ft Bambi Quik Silver do not have shocks even being an International trim level. Ive fought with Airstream about shocks. They dont care. So we dont use the Quik Silver. Owned since Nov 2005, used three time. (We own other airstreams to use) It bounces like a baby buggie wildly. Plus the axle is underrated at 3500 lbs.On the scale our Bambi tips in at 3,480 lbs. remember its an International trim with all options, TV, spare tire, A/C awning pkg, TV antenna. If our trailer had been destined for Canadian retail market, CSA would have required a 4200 lbs axle

[rmkrum]

Interestingly, our 2007 22’ International CCD also does not have shock absorbers from the factory. With a properly set up ProPride hitch and weight distribution dialed in for the loading it follows us like an obedient puppy when we tow it with our 2012 4WD Toyota Tacoma. O bouncing, no sway, no porpoising up front in the TV.

Not saying it’s perfect. Could use more horsepower for the long clinbs, but heck, I’m retired and have lots of patience. We just wave at the big rigs passing us on the hills…



The angle of this shot makes the AS look huge, doesn’t it?

[John Ware]

Coloradobus,
The 22'Sport didn't have shocks either and would bounce like a basketball. I thought I was going to lose it once on a rough part of IH40 in Arizona. That's one of the reasons I switched to the 23'FC. Oh, and it wiggled ever so slightly going down the road like it was out of alignment or something. The FC tracts perfectly.

[AlbertF]

Originally Posted by Ray Eklund

Airstream 27FBQ: Michelin 16 inch tires. 72psi. Today... 69psi... lower since last use. Before using, I will take it up to 72psi before using next trip. Nitrogen.

Oliver: Michelin 16 inch tires. 72 psi. Filled for Trip leaving next week.

Airstream JC 2008 for warranty work... "My 2006 23 foot Safari has leaky Shock Absorbers, do they need to be replaced?"

Response... "No, they don't do anything." Under Warranty while at JC.

(Do I look like I make this stuff up? I am not that bright. I am not a Human Bean mechanic.)

I believe the GVWR of your trailer is 7600. Maybe 8000 lbs. With 16" tires (LT235/80/16?) 45 psi might be sufficient, and that would help the ride. You might not be comfortable with that. There are definitely opposing views. I run 55 psi with our single axle 22 - axle has been weighed at 3900 lbs loaded for a trip, with full water.

I've noted (actually, complained about) the lack of shock absorbers on the 22 previously. When the axle has 3900 lbs or more on it, the trailer rides quite well. When it has less, e.g. 3500 or so when we are just going away for a couple of nights (we travel light), it bounces. My solution (for now) is to ask my wife to bring more stuff. I think that's a good problem to have.

When we purchased our 1975 over 15 years ago, it had new axles but no shocks. I bought new shocks, and was quite surprised by the difference they made. While that trailer never bounced, it was definitely more controlled and rode better with the shocks.

The tandem axle 22 from the mid-2000s was a different animal. No shock absorbers, and if I'm not mistaken it came with 14" wheels and 12v heaters for the tanks - no ducting from the furnace.

[AlbertF]

Originally Posted by Coloradobus

John Ware
Smaller airstreams like our 2006 16ft Bambi Quik Silver do not have shocks even being an International trim level. Ive fought with Airstream about shocks. They dont care. So we dont use the Quik Silver. Owned since Nov 2005, used three time. (We own other airstreams to use) It bounces like a baby buggie wildly. Plus the axle is underrated at 3500 lbs.On the scale our Bambi tips in at 3,480 lbs. remember its an International trim with all options, TV, spare tire, A/C awning pkg, TV antenna. If our trailer had been destined for Canadian retail market, CSA would have required a 4200 lbs axle

Interesting comment about the axle. Our 22FB has a GVWR of 4500 - and the axle itself has a 4500 lb sticker on it. Obviously a bit of overkill; I didn't know it was a Canadian market requirement.

[Coloradobus]

John Ware
Our Quik Silver tracks fine. You dont notice how its riding behind our Sprinter passenger van. But following from behind you see see how it bounces wildly vertically on rough roads. Items in the rear shelves needs to be strapped down. Even the pillows end up on the floor. Yes I-40: in Arizona is very rough. We dont speed over 60. Those 14 inch tires are sppinning fast. We use Equalizer brand hitch