Not sure that I agree with much of that, VB airbags are most certainly air suspension or the ones we have fitted are as we have no other springs and the wheels are not rubbing in the arches, OK many of these bags are just helpers to the springs but they are not there to help the shock absorbers or dampers as they are also known, as the name suggests they are there to "damp" excessive movement of the suspension they don't carry any of the load.
Just had air suspension fitted definitely improves ride, apparently Fiat Ducato vans used for motor homes are just a basic van designed for temporary loads. When all the stuff, oven fridge shower water heater etc are fitted before any water or other stuff loaded mine was sitting on the bump stops, a common set up made any bumps very hard ride. Cornering much better and ride height improved.
My theory is that motorhomes with older chassis have saggy leaf springs that in effect means they have no travel before hitting the bump stops. Hence my suggestion that air assist can mask the weaknesses of old suspension, but it won't address the fundamentals. In such cases I suggest owners first replace their worn springs, perhaps with heavier grade items, before considering supplementary air assist.
www.rosmia.co.uk
This post is about air assist, not full air, and can be supplied and fitted for £550.
Maybe best not to diss other peoples opinions and experiences. As I mentioned earlier we found a big difference and it was well worth the investment in our case. Interesting you didn’t.
Sorry can't agree our van had an incredibly hard ride with full air it's still hard but markably better certainly worth the money.
You mention improvements in handling (eg roundabouts) and ground clearance which are good, but may I ask if you sense a softer ride?
I've not really had much time to road test it yet, and to be a fair test I'd would need to load it up with all the kit we would normally travel with. My early impressions are though that empty, it doesn't crash over road imperfections as significantly as with static bump stops. The spanner in the works is the change of tyre to a 225/70 R15. Michelins. As I said, I will have to experiment with air bag pressures and tyre reach a compromise. It was worth doing in our case to get the extra payload. So,sorry I'm unable to give a definitive answer at the moment.
I did the same, but in stages where I fitted new 215 camping Tyres, and crashed about. Then fitted rear assist and played with pressures. Picking on 2.5bar as the standard, and having a much improved feel in harshness and stability. A few trips ago I swapped to 225 non camping tyres, and have an even softer less crashy ride, but now feel I need to run the bags firmer, so have now gone with 3bar as the standard.
These are very popular in the USA but I couldn’t find much information from UK users.This is true of the 2019 on chassis where significant weight has been added behind the rear axle such as water tanks and was the point of my previous comments about where the stress points are. The semi air should not be used to cater for a low ride height due to under sprung suspension. This should be sorted by having the correct spring rates. IF you do use the airbags to do this then you are bringing the stress point forward in the chassis ahead of the rear spring linkage which increases the effect that weight on the rear has on the chassis.
I only put the Sumo springs on the front and an extra leaf plus semi air on the rear as I wanted adjustability depending on weight on the rear. The same issue does not apply to the front as the rear due to where the sumo spring is placed. My sprinter is a 4x4 170 up plated to 4.05 tonnes. I thought the front was fine but wandered a little at higher speeds when fully loaded, a common complaint of the Sprinter.At last, someone who’s got Sumo Springs fitted.
Which ones did you get, and did you do the fitting yourself?
2014
I know this sounds a little preachy for which I apologies in advance. I should say that I am not an expert but my Son does know a thing or two about this stuff (he is an automotive design engineer). If you are set at 3 bar my very strong advice to you is that you are very under Sprung and are now placing pressure on the chassis where it was not designed to. Assuming the rear is leaf sprung, adding an extra leaf is neither hard or expensive.….hence why we got an extra leaf in our PVC.
For my greater understanding, did you replace the existing single leaf spring with one of increased capacity, or augment the single spring with an additional leaf to increase the weight carrying capacity?
The latter, the PVC on 3/4 load was sagging on the rear with only 1 inch gap between the bump stop. The weight of the van load on the rear axle was measured which showed that the stock spring was under sprung by x nm (can’t remember the amount) from which the correct extra leaf spring could be calculated….sounds complicated but was easy to resolve in reality. Stock leaf off the shelf as this is a fairly common exercise it appears. This restored the ride height to standard at 3/4 load. We also have semi air but this is more to stop sway at full load and provides a more positive higher speed directional stability.
You could well be right and thanks for the advice, however, the setting allows for a reasonable amount of travel in the suspension and removes the harsh ride and "crashing" over larger bumps. This crashing was caused by the lack of travel in the system when it hits the "bump stops". The local stress on the chassis when subjected to this "impact" loading is probably much greater than the even loading provided by the air bags. Adding an extra spring leaf, whilst loading the suspension in the correct place, could provide too much support leading to a hard and uncomfortable ride and or the ride height being too high. At least you get to adjust the air suspension to a point.
What pressure are you running with?
What pressure are you running with the air assist?
It’s an interesting point but in theory the bump stops which are pretty solid could be placing a lot more strain on the one chassis point that I think the additional air bags would. They are “air assist” not replacement for the springs. Now, if there were no bump stops and everything relied on the leaf springs then I could see his point. There are many manufactures producing air assist, fitted in the same place and thousands must have them. I haven’t heard of any problems.
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