Calling all MoHomers with air suspension. (1 Viewer)

Trikeman

Free Member
Aug 22, 2012
1,649
3,095
Wilds of Ceredigion.
Funster No
22,516
MH
AT 634 Apache.
Exp
Since 2011.
Hi All,
as I finished my air suspension install yesterday I am reaching out to owners with rear air suspension to find out what pressures you run for 'normal' loaded usage.
:thumb:

My intention is to experiment over the long term, I also understand that differing imposed rear axle loads affect settings (most of us are on the limits so we are all within a few kilos) :whatthe: however, I am interested in finding out what the 'average pressure' is, for a starting point.

Yesterday on road test I set pressures at 35, 45 and then 60psi and did the same route and not too much noticeable difference, other than a few cm's height and 'yaw' stability differences. If I get to the 'optimum' pressure, this is what I aim to maintain from there on in. For the greatest part of our usage our Autotrail is nearing the upper weight limits.
:Blush:

Your thoughts and recommendations, as always, will be greatly appreciated.

Regards,

Trikeman. :winky:
 

Armytwowheels

LIFE MEMBER
Aug 10, 2012
6,446
14,775
Market Harborough
Funster No
22,346
MH
Carthago S Plus - Iveco
Exp
Since 2011
Colin says - we run ours at 55psi. Ours is quite and old system and was installed quite a few years ago. Not sure if the age of the system makes any difference.

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Nov 13, 2013
488
431
Bideford, Devon
Funster No
29,004
MH
Benimar Tessora 487
Exp
since 2011
Air Suspension

That's a coincidence Phil from Rhino installs is here on Tuesday to fit a system on my Laika. Hope all goes well as on Plymouth Roscoff 10pm sailing! Will then join the debate!
 
Jan 19, 2012
628
612
Leicester
Funster No
19,488
MH
Coachbuilt
Exp
Since 2012
Interesting. We have an Autocruise Starseeker with recently-fitted rear air. Manual tells us to set at 1.5 bar [21 psi]. Fitter said to run it at 2.5 to 3.5 bar [35 - 50 psi]. Can honestly say I've noticed little or no difference in ride at any level! I leave it at just under 3 bar [48psi]. Rear axle loading is 1800kg, give or take 100 or so. You'd think there would be a chart somewhere to show pressure required for a given axle weight, since presumably there are no other determinants?

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Printermick

Free Member
Dec 13, 2013
58
41
peterborough
Funster No
29,357
MH
a class
Exp
just started
On Hymer B544

My gauges are in bar readings and I run at 2.5 or 3 (30 to 40 psi.)
Really only notice improvement on rough roads and being overtaken by fast coaches and trucks. Handy for more clearance on ferry ramps.

Like anything try different settings and see what feels right.
 
Mar 26, 2009
8,130
11,168
Yr Wyddgrug
Funster No
6,057
MH
Hymer B678DL
Exp
Since 2009
I use
Running light 35 psi
Medium load 45 psi
[HI]And when overloaded 70 psi just to keep head lights on road[/HI]

I run exactly the same pressures as Peter & Elaine. But, because I would never do anything remotely wrong I don't need the highlighted bit :winky:
 
Jan 22, 2013
1,245
58,350
London SE
Funster No
24,385
MH
A class Adria vision I707
Exp
since 1971
I normally run mine at 2 bar for all normal use and only put it up to 3.5 bar for the ferry, then lower to 2 bar when on the other side,
The main reason for fitting it was the enhance stability on corners and overtaking coaches,
trucks aren't a problem I am normally going quicker than them::bigsmile:

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DP+JAY

LIFE MEMBER
Mar 17, 2010
2,526
14,773
Dalbeattie
Funster No
10,674
MH
Laika 5009
Exp
since 2007, 25 years tuggin before that.
25psi max fully loaded (4000kg) Any more than that & the shocks keep topping out, but put it up to 50 for loading on ferries etc. to stop the tow bar grounding.
 

Wilderbeast

Free Member
Jan 20, 2012
92
85
Stockton on tees
Funster No
19,508
MH
"Hymer duomobil" B634 SL
Exp
Since 2011
As air suspension

The suspension assistance fitted on our Aviano is the one supplied and fitted by AS the instructions state minimum setting of 2 bar to maintain air bag shape with a Max of 7 bar but not to be used at this pressure for running, only manuvering purposes ferry etc:
I run at approx 3 bar and it seems okay.:Smile:

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autoswan

Free Member
Apr 3, 2012
776
4,649
Swansea
Funster No
20,381
MH
coach built
Exp
i`m a newbie
I have the air ride set at 35 psi on my auto trail, itfeels ok but not sure what best pressures are for load so had to judge it myself.
 

Techno

LIFE MEMBER
Deceased RIP
Jul 28, 2010
15,475
20,752
Leeds the one up North
Funster No
12,905
MH
Rapido 7090F 3 litre 160
Exp
May 2010
On my Starspirit I eventually settled on 3.5 bar for normal running and 5 to 7 bar fully laden.
Adjustments for on site leveling being the exception.
 

davejen

Free Member
Aug 21, 2008
1,861
1,235
Preston
Funster No
3,770
MH
Given up travelling
Exp
Since 1992
Inoted the replies, but do you feel the system is a benefit? if so in what way, or is it a waste of money?
Cheers, Dave:thumb:

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Apr 13, 2012
5,502
18,588
Funster No
20,541
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Mobilvetta Euroyacht
Exp
1996, then break 'til 2011
My 04 plate van was fitted with air suspension soon after I bought it 2 years ago - had new rear shocks fitted at the same time - not a lot more to do as I figured they would be shot after 8 years

Noticed a big difference, cornering and particularly on roundabouts - much more stable - and less scary - well worth the money



 

Millibobs

Free Member
Oct 27, 2013
101
21
Sax Alicante area Spain
Funster No
28,762
MH
Overcab
Exp
Since 2004
Hi All,
as I finished my air suspension install yesterday I am reaching out to owners with rear air suspension to find out what pressures you run for 'normal' loaded usage.
:thumb:

My intention is to experiment over the long term, I also understand that differing imposed rear axle loads affect settings (most of us are on the limits so we are all within a few kilos) :whatthe: however, I am interested in finding out what the 'average pressure' is, for a starting point.

Yesterday on road test I set pressures at 35, 45 and then 60psi and did the same route and not too much noticeable difference, other than a few cm's height and 'yaw' stability differences. If I get to the 'optimum' pressure, this is what I aim to maintain from there on in. For the greatest part of our usage our Autotrail is nearing the upper weight limits.
:Blush:

Your thoughts and recommendations, as always, will be greatly appreciated.

Regards,

Trikeman. :winky:
Hola :BigGrin
tend to always have mine on 3 to 3.5. Barr normally and 4 if very windy. We have Overcab which catches the wind. Blowing up to full certainly helps stability when on the autovias.
 
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Trikeman

Trikeman

Free Member
Aug 22, 2012
1,649
3,095
Wilds of Ceredigion.
Funster No
22,516
MH
AT 634 Apache.
Exp
Since 2011.
Inoted the replies, but do you feel the system is a benefit? if so in what way, or is it a waste of money?
Cheers, Dave:thumb:

Dave, early days yet but for sure it has transformed my MoHo as far as driving stability is concerned. Cornering, especially roundabouts is like night and day in comparison, I was always, sort of gripping the seat with my butt cheeks on long slow roundabouts, but on my tests yesterday and today that has disappeared. Wind buffet and drift has almost gone and coach over takes are a different world - straight line stability is superb.

The ride itself is different too, less roll and bumps seem to be 'softer'. Bad bits of roads around where we live have always given us a jolt but it now seems instead of a sharp jolt, the bump seems more 'rounded', if that makes sense. It is the best upgrade I have done and wished I had done it ages ago. Not so much internal rattling either.

Hope this helps,

Trikeman. :winky:

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pneumatician

Free Member
Feb 22, 2009
102
15
Burntwood Staffs
Funster No
5,708
MH
La Strada,
Exp
since 2000
Without motorbike in the boot approx 1.5bar with bike in the boot upto approx 2.5 bar.
Inflate too much and the ride is too hard.
Main reason for installation was so I could take islands at speed :)
 

swanseajack13

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Aug 19, 2013
983
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Swansea
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27,612
MH
A class
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3 years
swanseajack13

hi hope this helps your installer should have told you the correct pressure and also told you to let the pressure down if your mh is not used for a long time

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Trikeman

Trikeman

Free Member
Aug 22, 2012
1,649
3,095
Wilds of Ceredigion.
Funster No
22,516
MH
AT 634 Apache.
Exp
Since 2011.
hi hope this helps your installer should have told you the correct pressure and also told you to let the pressure down if your mh is not used for a long time

Hi Swanseajack,

I was the installer - I fitted a Dunlop kit and the pressures are mentioned as min & max pressures of the system. As there are an unlimited amount of variables involved (differences in load distributions etc) there is no 'fixed' pressure as such. Pressure can be calculated at one weight, eg the max weight you run at and then extrapolated to other weights, however its not an exact science - auto levelling valves and a reserve air tank could be the answer,,,,,,,, but all adds more weight.
Yes, letting the pressure down when parked up was within the manual.

Regards,

Trikeman. :winky:
 
Jan 19, 2012
628
612
Leicester
Funster No
19,488
MH
Coachbuilt
Exp
Since 2012
As there are an unlimited amount of variables involved (differences in load distributions etc) there is no 'fixed' pressure as such.

Don't understand that. The differences in load distribution will simply result in the weight acting on the rear axle increasing or decreasing? What are the other variables? Surely as far as the two air bags are concerned, all they care about is the weight pressing down on them? Which leads me back to my earlier point: regardless of model, surely the optimum pressure for the bags could be given as a table, linked to axle weight?
 
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Trikeman

Trikeman

Free Member
Aug 22, 2012
1,649
3,095
Wilds of Ceredigion.
Funster No
22,516
MH
AT 634 Apache.
Exp
Since 2011.
Don't understand that. The differences in load distribution will simply result in the weight acting on the rear axle increasing or decreasing? What are the other variables? Surely as far as the two air bags are concerned, all they care about is the weight pressing down on them? Which leads me back to my earlier point: regardless of model, surely the optimum pressure for the bags could be given as a table, linked to axle weight?

Correct, it will result in weight on the rear axle differences and a general corresponding scale.
However, there are variables with different types of suspension already on the MoHo's, the air bags are assistance, not the main/only source of suspension. Static axle weights can and are dynamically affected by things like overhangs, fore and aft load distributions, changes under braking, cornering, height and dynamic weight shifts (eg high/differing CofG) can affect the responses of the suspension.
There are lists given for specific axle loads/optimum pressures, however they are guidelines and although using them as a yardstick my initial question was what pressures are other MoHomers using. A good example of what I was looking at was the difference between low and high bodied pressures that affect 'yaw' stability, length variations, dynamic cornering where static imposed weight on axles change dramatically. Just a sort of survey really. What may be a very good pressure just standing there may not be the optimum for cornering or high CofG vehicles.

Regards,

Trikeman. :winky:

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Jul 4, 2010
1,194
804
Essex / central France
Funster No
12,437
MH
Hymer Star Line 680
Exp
9 years
As pointed out there are almost unlimited variables inputted into vehicle suspension, therefore every vehicle suspension setting is ultimately a compromise.

Other motor homers have given the pressures they use as a very rough guide for you to start your own experiments Trikeman (as you have), although the range of pressures do appear to range from one extreme to another.

Is the conclusion that, even the same MH just loaded differently will require different pressures dependant on a single factor of load alone, that there will never be a 'perfect' pressure without individual experimentation to suit your own personal circumstances?
 

DP+JAY

LIFE MEMBER
Mar 17, 2010
2,526
14,773
Dalbeattie
Funster No
10,674
MH
Laika 5009
Exp
since 2007, 25 years tuggin before that.
Correct, it will result in weight on the rear axle differences and a general corresponding scale.
However, there are variables with different types of suspension already on the MoHo's, the air bags are assistance, not the main/only source of suspension. Static axle weights can and are dynamically affected by things like overhangs, fore and aft load distributions, changes under braking, cornering, height and dynamic weight shifts (eg high/differing CofG) can affect the responses of the suspension.
There are lists given for specific axle loads/optimum pressures, however they are guidelines and although using them as a yardstick my initial question was what pressures are other MoHomers using. A good example of what I was looking at was the difference between low and high bodied pressures that affect 'yaw' stability, length variations, dynamic cornering where static imposed weight on axles change dramatically. Just a sort of survey really. What may be a very good pressure just standing there may not be the optimum for cornering or high CofG vehicles.

Regards,

Trikeman. :winky:

It will depend more on the rating & condition of the original suspension.
A newer vehicle with stiffer springs will need less pressure than one with softer or tired springs. Mine was originally designed as a 4000kg chassis & so needs less pressure than one which has been "uprated" from say 3500kg.
 
Nov 13, 2013
488
431
Bideford, Devon
Funster No
29,004
MH
Benimar Tessora 487
Exp
since 2011
Air Suspension

Well Phil's arrived good strong cuppa and he's under the van fixing the Dunlop Air Suspension will let you know what he thinks later.
IMG_2655.jpg

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Jan 27, 2013
1,334
871
Stamford
Funster No
24,452
MH
Benimar Mileo 282
Exp
Seven plus years
Inoted the replies, but do you feel the system is a benefit? if so in what way, or is it a waste of money?
Cheers, Dave:thumb:

Do you know that's just what I was thinking. I'm not adverse to spending cash on my MH :Blush:

In truth the handling on my old Kontiki 600 (04) was scary on bends and on the autoroute when buffeted by passing coaches, lorries, Dutch motorhomes, RVs, or driving over bridges, viaducts, etc etc ...

On my current MH the handling is spot on and can't see how it will be improved aside from giving a few inches extra ride height if I used the ferries (which I don't).

Both use the Al-Ko chassis, perhaps the shock absorbers on torsion bars suspensions need replacing more often?
 
Last edited:
Mar 26, 2009
8,130
11,168
Yr Wyddgrug
Funster No
6,057
MH
Hymer B678DL
Exp
Since 2009
Air assistance comes into its own when the leaf springs are "tired" and almost sitting on their bump stops. You have the option of replacing the springs with new or fitting air assistance. I chose the latter because it gave me the additional facility of being able to lift the rear of the vehicle for ferry embarkation. Prior to fitting, the handling on roundabouts was abysmal. So in my opinion it was definitely not a waste of money.

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