Report on Air Bag Suspension

Submitted: Saturday, Nov 13, 2004 at 22:58
ThreadID: 121585 Views:4630 Replies:3 FollowUps:3
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We took delivery of our 20ft BT 2 September 2004 and this was the first or one of the first vans with air bag suspension. For those folk considering this option here are my comments after 8,000 kilometres.
Cost was $3,500 which is more likely to go up than down. Because of the space the air bags take two water tanks are smaller at 60 litres rather than the normal 80.
There is evidently a slight reduction in weight as compared to normal leaf springs.
There are two main reasons for air bags. Side to side levelling is soooo easy. It obviously has limits but it really is a terrific feature. The other reason is that you can adjust the ride the van is experiencing according to the weight you are carrying and to the road conditions. I have no comments about the latter but at 50psi with an empty van it was about right and 70 psi with a full van seems about right. I now know I have more to learn in regard to this.
Levelling the air bags after a night spent on sloping ground is another task to add to the check-list before leaving in the morning. After my secret got out I must now admit to heading off down the road one morning with a very lopsided van. Luckily I had another ‘Bogger’ behind me so only went about a 100 metres before stopping and correcting my oversight.
That’s about it really. I would re-iterate though the enormous benefit of levelling. It is great. We never considered loss of air via puncture or similar as a problem any more than a broken leaf spring. Coaches and trucks have been using this technology for years with no more than normal problems.

Any queries I will try to answer,
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Reply By: Noosa Fox - Sunday, Nov 14, 2004 at 00:51

Sunday, Nov 14, 2004 at 00:51
I noticed that when you were camped on our front lawn you were able to level the van with the air bags, but when others have had their van there we have had to put about 150mm of timber on the low side to level up their vans.

Also for younger BOGgers like Anthony, who once said he was active in certain matromonial duties, your van doesn't have any spings to squeek. {cheeky smile}

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AnswerID: 565334

Reply By: Pixellator - Sunday, Nov 14, 2004 at 01:27

Sunday, Nov 14, 2004 at 01:27
Thanks Ivan for your comments re the AirBag suspension.
As you know, we have an 18 ft BT for delivery in February, and we have opted for the Airbag Suspension.
The weight saving appealed to me. To use Toyota IFS wheels to match the tow vehicle (using the leaf spring suspension) would necessitate using spacers on the van wheels, with a bit of a weight penalty. This is overcome with the AirBag suspension.
How fast is the height adjustment process?
Do you have any comments on the possibility of suspension alignment?- I understand that there isn't any easy adjustment facility.
Would the van travel better on the black stuff if it was set on its lowest level, with regard to drag/fuel economy/stability?
All these queries are from a novice's point of view. I am mastering my 7 foot box trailer!
AnswerID: 565335

Follow Up By: Bushtracker Buck & Babe - Monday, Nov 15, 2004 at 04:53

Monday, Nov 15, 2004 at 04:53
Hi Bob,
You have caught me way out of my depth here mate. About all I can comment on with authority is that the time it takes to do a levelling job when stopped is aproximately 30 seconds. About the same to change the pressure in the bags. I suspect that it would still pay to adjust the air bags according to distance away from the rubber stoppers ie according to the weight you are carrying. Logic tells me that with more air pressure then there is less give so the van's ride would be harder when pressure was higher. That's my best for now. Am still learning and am currently most pleased in identifying the need to constantly adjust load levellers and overall weight distribution to ensure safe travelling at speed and on rough surfaces. Basic stuff I guess.
FollowupID: 844099

Follow Up By: Flipp'n Lorry - Monday, Nov 15, 2004 at 05:26

Monday, Nov 15, 2004 at 05:26
Bob, tell me more about how the airbags reduce wieght and overcome the need for spacers for matching Toyota ISF wheels. I understand the need for the spacers with the normal BT setup, but how do the airbags overcome this? And how do you get a weight saving?

We are planning our second BT and this is of great interest to us,

Thanks in advance,

FollowupID: 844100

Follow Up By: Pixellator - Monday, Nov 15, 2004 at 05:46

Monday, Nov 15, 2004 at 05:46
Hi Phil

As I understand it, the whole suspension assembly is about 50+ kg lighter than the leaf spring assembly, so this, along with no spacers (heavy mothers), should save 80-100kg.

I believe that the hubs on the AirBag suspension have more space around them, or they are further out, thus allowing the IFS wheels to be unobstructed.

Are you planning on a l a r g e r BT?

FollowupID: 844101

Reply By: Flipp'n Lorry - Monday, Nov 15, 2004 at 06:49

Monday, Nov 15, 2004 at 06:49
We currently have an 18'6" (which we really love!), but are planning on getting the 20' next time round, mainly for a extra kitchen bench and cupboard space. Given that I reckon that the 20' is going to be about 180kg heavier, this weight saving is well worth thinking about,

AnswerID: 565336

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