COMPLIANCE + Full Air Bag suspension for a GU

Submitted: Thursday, Nov 05, 2009 at 20:09

ThreadID: 73551 Views:7720 Replies:10 FollowUps:12

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Member - Roachie (SA)

I typed in "Air Suspension" in the search field and got 18,524 threads to look at. Then I tried typing in "Air+Suspension" and still got the same number of threads.

So, I'm not sure how to narrow down the parameters...(most of the ones I quickly looked at were about air compressors or air conditioning etc.

So, that leads me to starting a new thread.

I am considering junking my coils and fitting a set of AirBagman full suspension in their place.

Reason???

Well, basically I have had the wind put up me by a kindly gentleman wearing a blue uniform. This occurred last night at a meeting of a 4wd club I am in the process of joining (if they'll have me). The Police Officer (Paul Bryant) from Adelaide, did his usual presentation....as he has done to several 4wd clubs and other interested groups. Paul is a member of the patrol4x4 forum, (as am I) but last night was the first time I'd met him.

Paul's presentation was aimed at bringing to people's attention, various factual information relating to modifying their 4x4s (as well as other cars).

He didn't really tell us anything (as regards my own Patrol) that I didn't already know; with a couple of notable exceptions:

1). In SA (not sure about other states), it was recently made LAW, that you mustn't increase the diameter of the tyres your vehicle has, by more than 1.5% from the largest ones the manufacturer's tyre placard shows as being suitable. In the case of a GU Patrol (mine is a 2000 model), they were fitted with 265/70R16. Most owners of that model Patrol replace their tyres with 265/75R16 tyres which are (apparently, according to the info Paul presented) 2.6% larger and therefore (technically) illegal. Paul went on to admit that his patrol has 265/75R16 tyres too. NOTE: I just did my own calculation Site Link which shows the difference is actually 3.29%. Now, my Patrol is shod with 315/75R16, which are apparently 11.57% larger than the 265/70R16. So that's one thing I need to address if I don't want to cop a fine (pun intended) at some stage down the track.

2). Internal mirror..... I have a dual cab with a canopy that has no windows. Having no visual access out the back, I have removed my internal mirror and replaced it with a rear view camera. Apparently, it is illegal to drive a vehicle that does not have an internal mirror, even though it may be totally useless. NOTE: I will not be refitting the standard mirror....but I may buy and fit the smallest mirror I can find up beside the screen.

Other things noted are lift of more than 2" can be done, but must be engineered....this can cost upwards of $4,000-. A 2" lift is okay without engineering. I already knew this, but as mine has a 4" lift which has not been engineered for SA, I am considering fitting full airbag suspension. As I understand it, these can be adjusted (on the fly). So, I would be able to pump them up when I need to have more ground clearance under the body, but keep them at about 2" above standard when I'm on the road and subject to possible Police scrutiny.

So, after all that verbal diahreare (I know this is spelt wrong, but spell check couldn't give me any better suggestions), my question is does anybody have a GU Patrol with full air bag suspension. Please note: I'm not talking about Polyairs or Coil-Rights (which just slip inside the coil spring and help with heavy loads).

Of course, the other big issue that affects more 4x4 owners than anything else, is weight. You don't have to do much to your rig to be overweight. Paul related some of the horror stories he is aware of where seemingly "normal" 4 wheel drives have been involved in MVAs. If the owner is lucky, he gets away with his insurance company wiping him like a dirty backside. However, if someone is killed or seriously injured, the driver can be charged with negligence....not because of the way he drove (he may have actually been "in the right"), but if the vehicle exceeds the GVM, he could still be charged with manslughter or similar because he was driving an un-roadworthy vehicle (because it was over GVM)....... I've known all this stuff for some time, but when it's put to you by a Police Officer and he outlines the consequences...well, lets just say it kind of hit home in a big way with this little black duck.

Cheers

Roachie

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Reply By: Member - Lotzi (QLD) - Thursday, Nov 05, 2009 at 20:39

Thursday, Nov 05, 2009 at 20:39

Hi Roachie

Gee, I hope fellow forum members really read what you have written and digested what is said . . .

I am a firm believer in air bag suspension, as we were endeavouring to have Denning air bag 4x4 and 6x6 coaches built for tour work on Fraser Island in 1989, for your Roachmobile, it is possible, but in today's climate must be engineered, but done properly, you wont regret it.
I have used air bag suspension on just about all hi ways, including some that have only recently been sealed, just great.

The big thing that I got out of your thread is the fact of weight, insurance issues and liability, any time I have mentioned that some vehicles are over weight on this and other forums I have usually had a very clever verbal comment, of which I don't have the verbal ability are desire to respond to.

In the end, if forumites are going to let the world know how clever they are as far as weight issues go, just remember that there is a big world out there reading what you are publishing.

if you can get a decent air bag set up, go for it.

Cheers all

Lotzi

AnswerID: 390133

Reply By: Robin Miller - Thursday, Nov 05, 2009 at 21:21

Thursday, Nov 05, 2009 at 21:21

I cannot comment specifically on SA law Roachie , but I think you will find some short cuts in what you were told.

I have only bothered to have mine verified , but it essentially is this about the tyres.

For placard , in Victoria the law actually stated as largest tyre approved on that model car by manufacturer of which a local placard is but a derivative but not the same thing.

Hence My 2002 Patrol manual lists 245/85/16 tyres as an option in UAE I think.
which are significantly taller than 265/75/16 and then in vic you could go up on this 15mm making some but not all 33 inch tyres ok.

Air bag suspension wobbles - don't do it.

As for weight , I agree you should never overload these cars and mine is lighter than standard despite having winch lockers etc , this is why I steer away from things like bullbars and big dual batteries as a real cost benefit analysis does not show them in a good light.

Robin Miller

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Follow Up By: viz - Thursday, Nov 05, 2009 at 21:56

Thursday, Nov 05, 2009 at 21:56

"Air bag suspension wobbles - don't do it."

huh???

Why for you say that??

viz

FollowupID: 657908

Follow Up By: Robin Miller - Friday, Nov 06, 2009 at 06:52

Friday, Nov 06, 2009 at 06:52

Air Bag systems have fundamental issues because of a non-linear force/displacement ratio.

These short comings are designed around in commercial applications but generally inadequately addressed in after market installations.

Robin Miller

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Follow Up By: viz - Friday, Nov 06, 2009 at 14:50

Friday, Nov 06, 2009 at 14:50

Just quickly, 'cos I am bout to step out the door to go scuba diving... ;)

I have never felt or heard anything in 50,000 odd km of air bag driving in various terrain that could be attributed to "wobble". I understand of which you speak, but it does not manifest itself in my car in any form that I can detect.

And I am an anal retentive compulsive sort who has spent a small fortune on suspension to "get it right".

viz

FollowupID: 658009

Follow Up By: Robin Miller - Friday, Nov 06, 2009 at 17:41

Friday, Nov 06, 2009 at 17:41

Thats good Viz - you sound like you have yours sorted out well , but I hope it didn't really cost a small fortune.

Its not that it can't be done , just that it needs to be done very right with an understanding of the principles involved and by and large conversions are not done to the standard that factory engineered systems can be.

Robin Miller

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Reply By: Dave B ( BHQ NSW) - Thursday, Nov 05, 2009 at 21:51

Thursday, Nov 05, 2009 at 21:51

Bill, in regard to the internal mirror, hasn't the cheese got a lovely little mirror behind her sunvisor?

That's a fixed one in my opinion.

Dave

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AnswerID: 390148

Reply By: viz - Thursday, Nov 05, 2009 at 22:12

Thursday, Nov 05, 2009 at 22:12

Having had all sorts of suspension mods on various 4WD, and now airsprings on the Bruiser (rear only) I can say with great confidence, it is the best move I have ever made in suspension mods...

Just done 5000 km to the Red Centre and back (from Sydney) with the airsprings and a heavy load - drove like a Range Rover... Well the rear did anyway. The front is variable rate coil, 2" lift from Lovells - I am still thinking about that one - did not cope as well. I use Tough Dog adjustables - go well with the airsprings, not so good maybe with the coils. Tighten up for low and heavy, loosen off for high and light loads.

Upside - variable ride height - and when travelling on the tar, low is good; in the boonies - high takes all the pain out of the washouts, yumps and roller coasters. And I reckon it travels better on the horrugations.

Downside - bloody dear to buy; and you need a good compressor. I broke a bolt on the compressor mounts (I use an Endless Air 8 cfpm pump driven by the engine) and had to use a little Bushranger back-up pump - took about 10 minutes to pump up the bags to 80 psi. You also have to think long and hard about how you hook up the airbags to the air system and operate from inside the cockpit - the off-the-shelf item is a bank-breaker. Made my own.

Maintenance? Real real easy. I carry a spare for the bush, takes 20 minutes to change over - the missus could do it while you give advice and chug a beer...

The Patrol goes real well on Airsprings, due to its "primitive" suspension design. Cruiser 105 front needs some mods; Cruiser 100 IFS cannot do. Pity.

(Wonder if the 200 front could have them??)

viz

AnswerID: 390150

Follow Up By: Member - Tony S (WA) - Friday, Nov 06, 2009 at 00:38

Friday, Nov 06, 2009 at 00:38

The 7 seater Discovery has them on the rear - Brilliant. They automaticly level the vehicle.
The only problem with them is that you cannot raise and lower the suspension to compensate for the disconnecting of a 200kg ball weight of a c/van that has a Treg hitch.

Tony

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Follow Up By: viz - Friday, Nov 06, 2009 at 05:15

Friday, Nov 06, 2009 at 05:15

I saw someone do that the other day on a Disco with a KK trailer - did not seem to have a problem. When reconnecting he did something first to raise it - methinks it was to put it in low range? Not sure...

viz

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Follow Up By: Member - Roachie (SA) - Friday, Nov 06, 2009 at 10:09

Friday, Nov 06, 2009 at 10:09

Thanks for your feedback Viz.....

I'm somewhat confused by the whole thing.... You're talking from first hand experience that the ride is plush and very good, even with a heavy load on and going over tracks to the Red Centre.

Then I have Peter (Ozhumvee) below, re-counting his experiences with a vehicle they were travelling with where the whole thing turned to shiit in a hand basket.

I can understand the concept that Peter mentions (as some others) that when you pump the bags up to get lift, you also lose articulation and the "sponginess" you need to absorb the rough stuff. Also, with the bags let right down for corrogations etc, you lose ground clearance.

Hence, my confusion......

I guess I'm not likely to be doing any of (what I class as) the real hard core trips (CSR and the like), so that's why I'm thinking they may be okay for me, as they are for you.

I love the idea of being able to vary the height at will and I reckon that with the right type of shocky, they should be okay for 98% of the kilometers I do in my rig.

If I do go this way, I will probably import the bags/kit or whatever, direct from the USA and save myself some serious coin.

Thanks to everybody for your comments,

Roachie

FollowupID: 657961

Follow Up By: Member - Tony S (WA) - Friday, Nov 06, 2009 at 13:13

Friday, Nov 06, 2009 at 13:13

Hi Viz
You push a button in side to raise the rear suspension. What my problem is its the weight on the draw bar - 200kg. You can "centre" the coupling with the jockey wheel how ever some times you miss judge.
Tony

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Reply By: Member - John - Friday, Nov 06, 2009 at 06:41

Friday, Nov 06, 2009 at 06:41

Roachie, have seen the results on a GQ, worked, but to my mind it works in reverse to the way it should, when you want lots of flex and compliance in the suspension, ie, max ground clearance, the air bags are pumped to the max, limiting the suspension travel and when you lower the bags, lots of suspension flex which is what you don't want.............Hope that makes sense?

John and Jan

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Reply By: Ozhumvee - Friday, Nov 06, 2009 at 08:54

Friday, Nov 06, 2009 at 08:54

Roachie, don't go the airbag route, they work fine on the bitumen and good dirt but can't hack the work off road.
On our trip to the Geo centre of the Simpson last year we had a 79 turbo tray with airbags in the front and polyair type assist in the rear with the standard leaves. After a few days of very rough cross country going the RHS front bag had punctured due to insufficient clearance between the chassis and the airbag, we stuffed it full of sand but eventually cut up a floor mat to add to the bump stop to enable the vehicle to crawl the remainder of the distance to Birdsville.
There are a few problems with airbags, you can't maintain ride height and have suspension flex/compliance it is one or the other. You get drop but none or limited compression. When you let them down to restore some give in the suspension they then allow too much sideways movement and rub.
The mounts used to mount the bag to the diff are very light and not suited to extended off road use. The vehicle above eventually tore them off the diff housing. He did carry a spare airbag bellows but as the bottom mount had smashed (it is only alloy held to the diff housing with TWO little bolts) we were unable to repair it. He has since refitted the standard coil setup with aftermarket coils.
We also met a Nissan traytop on the CSR this year who was having problems in the rough corrugated conditions with the vehicle slowly breaking up. He found dropping the airbags to a pressure point to soften the ride meant it was virtually on the bumps stops which were then hammering the vehicle due to the lack of suspension travel. Pumping them up meant that it rode too hard again transmitting the road shocks to the vehicle and occupants. He freely admitted that he should have just gone the heavier spring route.
I've no doubt that there are thousands of heavy vehicles clocking up millions of k's on all sorts of roads but they all have limited suspension travel.
Unfortunately unless the vehicle is designed by the manufacturer to have the airbags as standard I'd leave it alone, the airbag sellers seem to want a shi!load of money for poorly designed and executed fitments.

AnswerID: 390194

Reply By: Willem - Friday, Nov 06, 2009 at 10:20

Friday, Nov 06, 2009 at 10:20

I was going to say something but have decided against it....hahahaha

Cheers

AnswerID: 390213

Follow Up By: Member - Roachie (SA) - Friday, Nov 06, 2009 at 13:53

Friday, Nov 06, 2009 at 13:53

Thanks for sparing me the agony ol' mate....hahaha

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Reply By: Squizzy - Friday, Nov 06, 2009 at 11:29

Friday, Nov 06, 2009 at 11:29

Hey Bill,

If you know Ken in our club, he has full air bag suspension in his GU fully controlled from the cab.

I will send you his contact number via email.

Geoff.

AnswerID: 390216

Follow Up By: Member - Roachie (SA) - Friday, Nov 06, 2009 at 13:50

Friday, Nov 06, 2009 at 13:50

Thanks GT....

FollowupID: 657988

Reply By: Nomadic Navara - Friday, Nov 06, 2009 at 13:10

Friday, Nov 06, 2009 at 13:10

Here is an interesting bit I OCRed from Australian Caravan +RV Oct/Nov page 61:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ESC VEHICLES AND THE LAW

ESC is mandated on all passenger-carrying vehicles sold in Australia from 2011. Because the programming relies on parameters such as engine and transmission performance, tyre specifications, steering systems, suspension type and performance characteristics, mass of the vehicle and weight distribution, Australia's transport lawmakers have recommended ESC vehicles not be modified in any of these areas.

The current edition of Vehicle Standards Bulletin 14, covering modifications to cars and 4WDs, has a critical clause (2.6) which states:

"Unless specifically permitted by the vehicle manufacturer, vehicles equipped with ESC as original equipment cannot be modified under the Modification Codes I contained in this Section of the National Code of Practice, as the current codes do not possess sufficient scope to account for all the parameters noted above.

"Similarly, vehicles equipped with electronic stability control (ESC) must not have the ESC control unit disconnected or modified."

The Australian Automotive Aftermarket Association is currently taking up this issue, which could affect common after-market vehicle changes, such as suspension upgrades and replacement wheels and tyres.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ESC = electronic stability control

I wonder if twin cabs will be included as "passenger carrying vehicles?"

PeterD

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Follow Up By: Robin Miller - Friday, Nov 06, 2009 at 17:47

Friday, Nov 06, 2009 at 17:47

That gives us a year to get a new car , but one without ESC.

I think that could be the end of thinking about a new Prado !

Robin Miller

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Reply By: Member - Bucky - Sunday, Nov 08, 2009 at 08:54

Sunday, Nov 08, 2009 at 08:54

Roachie

Not all seems to be right there,. Are you sure you got it right ?

Trucks have no Internal Mirror. See where I am coming from, and you have intended to make things safer by installing a camera. not too sure where that leaves people with caravans, and rear cameras too.

One area that concerns me with your 4B, is it's height above sea level. it's bloody high, and there would be some legal issues there.

Another area would definately be your weight, no not yours or Annette's, but the weight of the Patrol. It's bloody heavy, and one way which you may get it back to legal, would be to change the suspension, to suit it's rather heavyness. ( new word ! )
Dunno how you will ever be able to get an insurance claim, if you stack it..
Are you with Shannon's. ?
How many engineers do you know ?

Other than that ,,,,.... how are you ?

Cheers mate
Bucky

AnswerID: 390441

Follow Up By: Member - Roachie (SA) - Sunday, Nov 08, 2009 at 10:03

Sunday, Nov 08, 2009 at 10:03

G'day mate and thanks, we're all keeping well here.....

The height issue is one thing I need to address.....it can be easily measured.....the top of your headlights are not allowed to be more than 1200mm above the ground. I haven't measured mine, but am fairly sure they would exceed this.

As regards suspension, I already have a pretty good arrangement, which sees the beast sit level and ride pretty well; although she gets a bit of a roll happening on roundabouts.... hahahaha. Improving the suspension won't make it legal. If it tips the scales at more than the GVM then it's illegal; simple as that. Of course, it IS possible to get it engineered for a higher GVM, but apparently this can only be done when the vehicle is new and before it is registered for the 1st time.. What you need to do is buy the new rig, before you register it get it modded with regard to suspension and whatever else needs to be done (like strengthen spring towers, gusset the axle tubes etc), then get an engineer to sign-off on the increased GVM....then get it registered and insured.

The problem with that (assuming I was even in the market for a NEW rig, which I am NOT), is that you have to shell-out the money for the rig from the dealer and immediately hack into it with a gas axe (well, maybe not ACTUALLY a gas axe, but you get my drift) and other non-reversible modifications....all in the hope that the engineer will agree that what you've just done to this new truck is okay and that he will give you the extra 300kg (or whatever) of GVM for the paperwork. THEN you have to find an insurer that will cover your new rig. Hey! It ain't gunna happen!!! hahahaha

As regards my own rig.....when I cracked the chassis last year, I got it fixed under insurance. The assessor didn't question my over-size tyres or the weight of the rig. I'm insured through TCIS Ins Brokers (Lombard Insurance is the underwriter). They have a full list of the major modifications done to my rig.

Cheers to you and Lyn mate

Roachie

FollowupID: 658221