Replacement Air Bags

[BrianE]

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.

[Steve Bennett]

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.

[Jon Wehrenberg]

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.

[Joe Cannarozzi]

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.

[Jon Wehrenberg]

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".

[hhoppe]

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

[tdelorme]

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

[Joe Cannarozzi]

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.

[Jon Wehrenberg]

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.

[JIM CHALOUPKA]

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.

JIM