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.

The 63-0126 part # is now too no longer available. It has been replaced by part# 63-0259. I am not assuming that only the # has changed they may very well be using a bag that is configured differently too.

I will be out most of the day.

The trade # for this new part# is 1R11-244 if anyone can get dimensions and compare the two it would be something I would be interested in knowing.

We will continue this experiment stay tuned:confused::eek:

Joe & Jon,

Part number 630259 must have been around for awhile, Brain put one on the front of my Liberty on 4/07. The rears on mine are 630104.

Tom,

Will the front of your bus raise from the full down position to the full up position without lifting the tag?

Can you speculate and let us know what aux air pressure it takes to raise the front to ride height?

It sounds like you have the correct fronts. The number for the rears corresponds with the one on my drive axle only. The tag has 630126.

For those whose front air bags are part number 630260 it is possible that air bag is for a seated bus, and that is why you cannot get full up travel. Apparently that is the air bag number that will be supplied and it is not suitable for a motorhome which relies upon the level low system for leveling.

Well if Brian was given the 0259's then SOMEONE at prevo parts got it right.

Who was it?

I got a notion to put the 0260's on the front on ours we have a 11800 front end and I would like to know if they would lift a lighter load or if the travel is just not enough.

Jon,

It takes full shop air at 120 psi to move it very slowly with the tag down. I just took it off the stands/blocks and had to cycle the shop compressor to keep the pressure high or it wouldn't come off the stands.

If the bus is running, it takes high idle and all the air it can make to move it. The front end is at gross weight, 14,000 lbs. At Mobile, I had to dump the tag to get the front up.

100 lbs of air will not lift the front:(

Tom, yer a crybaby on this one. :(:( I doubt if 100 psi will lift the front of anyone's bus. It sure won't lift the Royale. In my short experience with the Prevost level lo system, the Liberty leveling system is far superior IMHO. Have you sorted out the Aux air problem you were having? With a leaking check valve you might not be getting enough volume to the airbags. Just a thought.

Hate to disagree with you guys, but 100 PSI will bring my front up to almost road height. I am carrying a little over 14,000 on the front. I know this for sure because those that have seen my driveway will understand I have to drop my front to get throught the overhead door, and raise the front once outside so the baffle under the generator doesn't get crushed on the crown of the driveway. So every time the bus goes into or out of the garage I have to run the front up and down throught its maximum range of travel.

My rears come to ride height with less than 100 PSI.

My old bus with about 13,200 on the front required full pressure and a lot of time to come up to the max height and 100 PSI (aux compressor cut out) would only bring it up if the tag was lifted.

I have 630126 (1R11 296) bags in the front. Now I am really curious about exactly what bags our coaches need to have. Since Tom's coach and mine are raising almost the same weight then it follows that our air bags are different because of the different pressures required. That leads me to conclude the 630259 is NOT a direct replacement for 630126.

The plot thickens. When Dr. Joe C. changes a set of fronts this coming weekend I hope he can get some measurements. Diameter when installed deflated (at full height), maximum extended height (mounting plate on bottom to mounting plate on top), pressure at ride height, pressure to fully extend.

Mole Man - The suspected check valve (if there is one) has nothing to do with this pressure issue. I would suspect the bus will go to road height at 100lbs given enough time, but beyond that, forget it. However, the rear bags seem to have no problem raising even at less than max air pressure.

The 40' Marathon I had experienced the same. It would not lift the front without dropping the tag. The CC on the other hand would come right up. The Marathon was also at max gross on the front end, same as the Liberty. The CC was about 2000 lbs under gross on the front.

Jon - Keep digging, with Joe's help, we may find there is a better alternative to the front bag issue. It appears to me the 259 bags just can't lift 14,000 lbs without help. Maybe that's just the way it is! Mine is still hooked to a 100 gallon shop compressor, so I can do a little experimenting if needed.

How often do air bags need to be replaced?? Is it ok for the bus to sit for a week or more with all of the air dumped? Or should some be left in the bags?


Jamie

Jamie,

That's always a good question to ask. It's probably fair to say that when not in use, the typical bus suspension will leak down in as little as 2 days and as long as a week. Consequently, many coaches sit for long periods of time with flat airbags and it doesn't seem to effect them much. However, if you look at them when flat they look pretty bad so a number of us have been using Jon's custom built stands (blocks will work) to support them when in storage. Over time the stands probably make the airbags last longer.

As to how long they last, it varies depending on a number of factors but atmospheric conditions and time in storage are probably the main considerations. Like all rubber components they deteriorate with time. I personally start looking at them and at rubber brake lines with suspicion after 5 years.

I have the Mae West bags on the front of our 92 40XL Marathon. The bags were replaced in 2000, and I do not have the part #'s. We also have the quick response ride height valves. Our coach will raise to ride height @ 100PSI on the front 13,700Lbs without lifting the tags. The coach can be raised to about 4" over ride height with the Prevost Level Low @ 120 PSI, tags down.

Jamie,

The Prevost position expressed in Branson was that they are OK as long as they are holding air.

I disagree and here is why. Several of us have had problems with air bags as they reached 10 years of age. I have gone through this twice now with two different coaches and when my bags were 10 years old I had one leak due to corrosion on the metal base, and all air bags showed signs of serious dry rot. If I am not mistaken there have been at least 4 other POG members that had issues with 10 year old bags.

The problem with waiting for an air bag problem before reacting is the serious nature of a leak, or worse a blowout of an air bag. You cannot drive a bus that has a failed airbag. It is literally sitting on the ground in the front or left or right rear. When one does fail such that your bus cannot produce enough air to overcome the leak you can get off the road, but you cannot travel. These are not something you can buy at the local truck parts house. In fact I cannot find anyone listing the trade numbers we use on the internet as stock items. So a leak or failure shuts you down until it is replaced.

There are guys here with 15 year old coaches that still have the original air bags. I think the condition of the air bags should be the deciding factor. For me, based on anecdotal evidence only I am going to replace mine every ten years. I don't think you are in need of replacements yet, but every time you are beneath the coach you should look closely at them. Look for cracking or dry rot around the bottom where they roll. That is where it shows up first.

Jamie there is a large rubber bumper attached the the inside of the top plate on the air bags. When you go all the way down it settles on that rubber block and absolutely no harm will come to doing that.

I have pulled 2 sets of bags off 91's and they were so cracked and dry it is amazing they even held air.

I have also pulled ones that were already replaced once so not too old, 7 & 8 yr and cracking was not bad but already beginning. Jons suggestion of 10 yr lifespan is a good call.

If the 0259 does not do any better that the 0260 I am going to be very upset.

I sent Orren a PM with the industry #s for the 630126 that original may wast bag and if he can cross it to another manufacture I will buy them and will put all 3 set of bags one at a time on our bus and note the results. Just maybe we can solve a large shortcoming that Prevo is aware of probably has been for some time and is unwilling to correct.

For those that have heard the expression "Mae West" air bags, they are (or were) 630126 (1R11 296 which is the manufacturer's trade number).

Steve's post is just more evidence which suggests those air bags will lift the front with out maximum pressure to the full height. I think the 259 bags Tom has are not suitable direct replacements for the "Mae Wests".

In the olden days we were instructed to leave some weight on our tires when parked to allow flexing during walking in the coach. Flexing kept the rubber alive. I think we need an expert opinion from the rubber engineers to solve the issue of taking all the weight off of the bags when parked. The rubber today is not the same as rubber of old.
Steve please explain what a Mae West air bag is as opposed to our stock bags. Yes I'm old enough to remember what her bags looked like but were talking rubber bags here. Thanks

OK, I was going to stay out of the windbag discussion, but it's more than I can do. Keeping quite, that is. First off, are the part numbers everyone is kicking around Prevost part numbers? I'm thinking they are since these numbers do not cross with Firestone or Goodyear numbers found on those websites. If Prevost is sending folks the wrong bags, why not order the correct bags from a truck supply company that either has the correct air bags or can have them dropped shipped to you? Is the manufacture part number not on the old bags?
Now, on my old Liberty, the PO replaced the bags all around in 2004. Liberty in Stewart, FL did the change along with a bunch of other work. The system works perfectly at this time, thank goodness. From what I'm reading here, replacing the bags is a crap shoot as far as getting the correct bags that don't leak even when new. What a PIA, to order a part from Prevost and be sent something that is not a direct replacement.
Now I know we all want to be safety conscious and not put ourselves and others at risk, but replacing all your air bags just because they have checking or cracking is overkill. We once had a fifteen year old Foretravel that we drove over 250,000 miles and I never replaced any air bags. The unit had eight Firestone bags. No leaks, lots of checking and typical cracks at the top and bottom but I never replaced them. And, while I'm sure it has happened, I have never read or heard of an air bag "blowing out" and putting a coach on the side of the road. If anyone here on POG has had it happen, I haven't read about it in the last two years.
But, back to the problem with Prevost parts. Screw the SOB's, call around and get the bags from someone who gives a damn about getting you exactly what you need so your coach will operate properly after you replace the bags ONCE.
Merry Christmas

Yes Ted I agree with much of what you said.

However those fronts that Stuart has put on yours are no longer available. It is my estimate that sometime in the last year and 1/2 that occurred.

Believe me if I can get another source for those fronts I will be all over it.

Sure Erik and Deb's bus probably could have gone a couple more years. They bought it used and from all the other poor service issues we found anyone buying used should not assume that previous repairs were done correctly. When we took them off we found 2 DIFFERENT BAGS. So what would you have done at that point. Put them back in? Ya call Prevo and then they send you a bag that does not do what the old ones did. Then what do you do?

After too many calls to keep track of I call Mr. Jenson and get a mix between a stonewall and a tongue lashing. I am at my wits end. Additionally, say I have others ask for help. Am I going to assume liability for suggesting that they go with a bag that is not called for by prevo or let them know to just leave them in there till they rot out and blow then put some in there that Prevo says, knowing they will not be able to lift it in level low in the front.

I kept one of the bags I took off a 91 for show and tell and I did not exaggerated as to its condition. I think those little cracks you saw on your foretravel were way further thru than you thought if they were 15 yrs old.

I have blown 2 air bags on trucks and know of many others too, don't have any miles on the bus.

Ted,

Air bags fail. There are at least 4 POG members that I know of including me that had an air bag leak within the last two or three years. A leak is not a big deal because a small leak is easily compensated for while driving, but it makes the compressor cycle a lot more than normal.

Prevost supports your position to drive the bus till they fail.

Speaking of the only leak I had, however, I made it into my garage by the skin of my teeth. We were about 1500 miles from home when I realized if I shut the bus off, within minutes the left rear went down. While enroute home I noticed the compressor cycling often, and then it stopped cycling. It was on all the time.

By the time I got home I was losing air so fast I could hear it and the bus was barely staying up. I had to be going highway speeds to build enough air to keep the rear up.

My point is that a leak, one started will never get better. If you or anyone is comfortable with the potential for having to park it and get a roadside air bag replacement that's fine. But they do blow out, they do leak over time, and they are not readily available.

The issue today however is we believe there are coaches out there that do not have sufficient height in the installed airbags to make the bus like it was when it was built and Prevost appears to be stonewalling its customers for reasons we do not understand. If any Prevost folks are reading this perhaps they want to respond. Joe and I have gotten pretty deep into this and we are puzzled as to what is going on and why.

There is the possibility that the bags, 630126, 1R11 296, you /we want are not available from Goodyear any longer and that Prevost is making an attempt on the consumers back to find the models Goodyear has to offer. It sounds as though someone other than engineering is making the decision of which bags to offer as replacements for the old part number that worked.

Awhile back someone made a comment such that Prevost was still the place to go for bags as direct to Goodyear or one of their sales agents resulted on slow delivery and higher prices. The discussion went something like, Prevost probably buys so many that they can offer them cheaper.

This would be an opportunity for someone to make an adaptor kit to use a bag designed for something else that is readily available and reasonable in price, or have aftermarket bags made in China. :eek:

JIM

Here is some web info on the Goodyear bags.

http://www.goodyearep.com/ProductsDetail.aspx?id=14832

The Q & A gives contact number and supply info.
Contact the plant that makes them and talk to quality control.1-800-869-0435

Contact 1-800-843-6181 for customer service on where to buy what you want.

Sign up with Goodyear resource center so you can utilize their product design and application information.http://www.goodyearep.com/UserLogin.aspx?fromLnkPg=1

http://www.goodyearep.com/BusinessFA...?folderid=1344

Contact them to see where the bag you want can be purchased if at all.

Click this site and call other vehicle suppliers to see if they use the bag you are trying to find. Such as MCI.
http://www.goodyearep.com/WorkArea/s....aspx?id=15676

Gotta quit now Santa is commin.;):):D

MEERY CHRISTMAAS TO ALL AND TO ALL A GOOD NIGHT!!!!!!!!!!!!!!1

JIM

Jim you are not the first one to conclude that engineering isn't making those decisions. Brian conveyed those same thoughts to me earlier today.

http://www.worldeaa.com/about.asp

They don't have anything now, but I bet if you sent them a bad bag and told them what you want/expected in reliability and quality they would respond.

JIM

Jim you are beautiful keep it up.

My phone will get a workout monday.