Replacement Air Bags
A while back Roger and I replaced our air springs (air bags). It started out with Roger receiving a set of the wrong air bags. I opted to do mine at the same time, and since I was aware he received the wrong ones I spoke to the parts folks in Elgin, and while we were both looking at the same parts list on our respective computers he and I agreed on the part numbers and trade numbers. We received the correct air bags and both our buses could be raised or lowered through the entire range. Both would easily be raised to road height.
I recently became aware of a POG member getting a set of air bags for the front of his coach. After installing the set the coach could not be raised above ride height. Also, the coach at the air pressure settings could not reach ride height without raising the tag axle. An increase in system air pressure did not have an appreciable affect.
After a lot of research between some POG members who may post their findings on this thread it appears that this problem is not isolated to the bus in question, but may be a widespread problem. The front air springs supplied by Prevost, either direct to you the owner, or to the mechanic in the service center will not perform like the air spring it replaces.
What this means is that if you have recently had the front air springs replaced in your coach you may not be lifting the front to the full ride height. This of course will have an impact on road clearances and may affect your steering geometry. It will also limit your ability to level the coach on an uneven campsite because you likely have lost several inches of vertical travel.
The problem lies with Prevost changing part numbers. I cannot be sure of the part numbers required for IFS coaches, or even if they are affected, but on solid axle coaches the front air bags that work are old Prevost part number 630126, trade number 1R11 296. These are what has been known as the "Mae West" air springs.
If you are about to change air springs or already have your bus should be able to travel from the full down position to the full up position which is 3" or 4" above ride height, which is about 11.5" between the top and bottom mounting pads for the air bags. Anything less than that travel and your bus has had its leveling capabilities limited. If you think that is relatively unimportant think about the next time you need to raise the front to keep from scraping on a sharp upslope like a driveway.
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