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Author Topic: Question about Air Springs  (Read 7649 times)

b_smitty

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Question about Air Springs
« on: March 11, 2006, 07:57:26 PM »
One of the features on the Pleasure-Way Plateau (and Sprinter vans in general) is what are called "Ride Rite" air springs.  They are installed on the rear axel between the chassis frame and the leaf springs.  An optional air suspension compressor kit allows you to adjust the pressure in the air springs from within the vehicle.  I know that these springs are normally used to compensate for varying load conditions.   For example, when towing a boat or snowmobile trailer, one can pump air into the springs to level the vehicle if it is sagging under the tongue's weight.  Are there other benefits to having this feature?  Can one use it to level the vehicle at the camp site?  How is the ride affected by the air pressure setting?
Smitty

Gary RV_Wizard

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Re: Question about Air Springs
« Reply #1 on: March 12, 2006, 09:05:15 AM »
Your air springs might raise the rear an inch or two to help level the rig, but both will rise the same amount. You often need to adjust the sides differently, so they would not be of much help then.

The air springs generally stiffen the ride, taking some of the flex out of the springs. They are most useful in controlling side sway.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

b_smitty

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Re: Question about Air Springs
« Reply #2 on: March 12, 2006, 11:12:06 AM »
On the P-W, air springs are standard equipment but the compressor is a $550 option.  That tells me that most owners keep the springs inflated to some appropriate constant pressure.  If air springs are not a practical means to level the vehicle at the camp site, I don't see how one can justify the extra cost of the compressor, unless you are towing and have to frequently adjust the air springs to compensate for changes in backend loading.  Am I understanding this correctly?  Are there other circumstances in which you would want to change the pressure using the on-board compressor?   ???
Thanks for the help.
Smitty

Gary RV_Wizard

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Re: Question about Air Springs
« Reply #3 on: March 13, 2006, 10:10:09 AM »
Quote
I don't see how one can justify the extra cost of the compressor, unless you are towing and have to frequently adjust the air springs to compensate for changes in backend loading.  Am I understanding this correctly?  Are there other circumstances in which you would want to change the pressure using the on-board compressor?   Huh

I think you are probably right.  Most people will not find sufficient reasons to change the air pressure to do it as a routine thing.  And you can always make adjutments via an external air compressor if your loading changes significantly.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Jeff

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Re: Question about Air Springs
« Reply #4 on: March 13, 2006, 02:13:59 PM »
On our 83 Pace Arrow I had installed a set of helper bage on the rear axle that were not very effective but did come with a compressor and remote cockpit control. After a few months we installed Air Ox rear air bags/levelers  in place of the springs and used the first compressor and controls to inflate the front GM OEM air bags. Made a great combo when dring on crowned roads or in stiff crosswinds. I could tip the m/h until it tracked straight.

b_smitty

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Re: Question about Air Springs
« Reply #5 on: March 14, 2006, 04:25:27 PM »
Thanks, guys.  Jeff, since you have experience in this area, maybe you could comment further.  RV Roamer mentioned that air springs stiffen the suspension and help to lessen sway.  I'm thinking that a compressor would allow on-the-fly pressure adjustments to counter the affects of strong cross winds on vehicle handling due to excessive sway.  Increasing the pressure should stiffen the suspension and stabilize the coach.  The tradeoff would be a harsher ride, but that might be preferable to otherwise degraded drivability.  When the crosswinds diminish, the pressure can be lowered again to make the ride more comfortable.  Does this reasoning square with your experience?
Smitty

Jeff

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Re: Question about Air Springs
« Reply #6 on: March 14, 2006, 05:28:04 PM »
The air bags improved the ride and handling. If you were on a rough road lowering the pressure softened the ride and on one with dips stiffening them up would improve the handling. Changing the pressure (between 40-90 PSI were the allowable limits from one side to the other would remove the pulling from crowned roads or cross winds.

Before we replaced the rear springs with the Air Ox System crossing a RR track would throw the kids into the air off the rear beds. After installing it you could place a glass of water on the bedstand and it would not spill which was part of their advertising. Great system!

That system was built by Kelderman Manufacturing in Oskaloosa, Ia and was fairly expensive in the mid-late eighties when we purchased it but really helped the ride and handling of the overloaded, long overhang P-30 chassis that the Pace Arrow was built on back then.


The control system for the front air bags came from Firestone: http://www.pplmotorhomes.com/parts/rv-wheel-covers/firestone-ride-rite-kit.htm
« Last Edit: March 14, 2006, 11:03:42 PM by Jeff /Washington »

John From Detroit

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Re: Question about Air Springs
« Reply #7 on: March 14, 2006, 05:32:57 PM »
One thing I note is there are air spring systems and there are air spring systems.

For example.. My towed has air springs on the rear, helper springs at least, made by a company in Lansing,  The materials used in consturction are fairly inexpensive and the adjustment range is fairly small, but it's exactly what that ride needed.

The same company makes a kit for my Workhorse custom chassis,  It's fairly low price

Workhorse has an "Approved" set for the same chassis..... About 5x the price of the Air-Lift system

The question is: Is it worth it? (Since I have no expiernce with the more expensive system, or for that matter theless expensive on the workhorse chassis, I truly do not know)
Nothing adds excitement like something that is none of your business
My Home is where I park it.

King

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Re: Question about Air Springs
« Reply #8 on: March 26, 2006, 07:20:01 AM »
I have a 98 Pleasureway excell.  The air boosters came from the factory.  The original Dodge maxivan rear springs are a compromise between ride and load handling capacity.  Since the van is always fully loaded (7500 #), if you didn't have the air bags, you would be hitting bottom almost with every bump.  The lift from 0# air to 90# air is about 6 inches.  I add air until the lift is 3 inches (45#).  I maintain it as with the tire pressure for ride and handling.

b_smitty

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Re: Question about Air Springs
« Reply #9 on: April 02, 2006, 07:54:10 PM »
King, how often do you need to add air to the springs?  Do you change the air pressure on occasion to improve the ride/wind stability?
Smitty

King

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Re: Question about Air Springs
« Reply #10 on: April 03, 2006, 06:46:56 PM »
I only add air before starting on a trip.    I do check it occasionally, but not as often as the tires.

b_smitty

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Re: Question about Air Springs
« Reply #11 on: May 07, 2006, 09:51:56 PM »
Took delivery on our new P-W Plateau and have already camped three nights to shake out any latent defects (found none).  We ended up getting the on-board air spring compressor in the price negotiating process.  It allows the right and left rear air spring pressure to be adjusted independently from the cockpit.  What I found was that if the front wheels are level, side-to-side, there is often enough range of motion in the air springs to level the van front-to-back using the on-board compressor, all without getting out of the MH.  Only if I can't find a level spot for the front wheels, or if the campsite is otherwise significantly sloped, do to I need to use the leveling blocks.  Not bad!   :D
Smitty

 

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