Air Bag Aging & the 10 Year Plan

[truk4u]

Just in case you really don't buy Jon's suggestion to change out your bags at 10 years, the proof is in the picture! Mine are original 1996 and although I wasn't having any bag or loss of air issues, I decided to change them out as a PM item along with all the norgren valves. I'm doing the shocks as well, what a deal, they're 42.00 each at Prevost.

So don't let those bags go too long boys, after 15 years, mine were looking pretty bad. Remember, if you blow a bag on the road, your going to get towed or hauled and it's not going to be cheap.

9045
9046
9047

[phorner]

Lookin' real good, Tom!

When I did mine, I also replaced all the air tank drain valves too. I had a couple that were starting to seep a little air past them and it was never gonna be easier to get to 'em!

A job I wanted to do only once if at all possible....

[BoaterAl]

Tom, we were actually waiting for the pictures of Nancy in some smok'en hot coveralls as you had promised. The air bag pictures are nice....but

[Woody]

Going to Prevost Jax for service Monday AM. Curious as to what $ I should expect for drive axle bags. My others are fairly new but the drive look like Tom's before pics.

[truk4u]

Al - You really believed that stuff!:p

Woody - The drive bags are 630104 and are 146.03 each.

[travelite]

Tom,

Do you have the Goodyear part number? I think 630104 is the Prevost part number, correct?

Thanks,

[Jon Wehrenberg]

Woody,

Shop prices. If the air bags cost $150 (round numbers) the drive axle uses 4 so you have $600 in parts and the labor to install should be 4 to 6 hours so on the high side you should expect to pay around $1350 total for the job. Get a firm quote.

In FL you can get a quote from Coach Worx also and my guess is the price will be very much in line with the actual cost of labor and materials. Changing air bags is something that provides a huge benefit relative to the cost. Failure to do so with the result being a blown or failed air bag results in a very expensive trailering or tow job, plus you still have the cost to replace them.

[phorner]

Woody,

Take Jon's advice to heart. It's about a days worth of work. The single decision determining the length of time is figuring out where to "stop".

When I did mine, in addition to the air bags proper, I replaced fittings, some of the air lines, and the tank reservoir drain valves too.

But, it also made sense to do all the Norgren valves and the ride height valves while we were under there.

And, of course, if I was going to all that trouble I might as well change the air dryer filter. Luckily, the shocks had already been changed!

You get the idea....

[Jon Wehrenberg]

Tom,

Do you have the Goodyear part number? I think 630104 is the Prevost part number, correct?

Thanks,

David,

I have the trade number for my steer and tag, and my drive axle (630104 is correct), but when I attempted to cross them with a generic air bag I could not. They are proprietary to Prevost unless you want to spend 50% more than what Prevost charges. For the last 15 years there has been nobody on the planet that could beat Prevost air bag prices.

[GDeen]

Good work Trukster!

[travelite]

David,

I have the trade number for my steer and tag, and my drive axle (630104 is correct), but when I attempted to cross them with a generic air bag I could not. They are proprietary to Prevost unless you want to spend 50% more than what Prevost charges. For the last 15 years there has been nobody on the planet that could beat Prevost air bag prices.

Thanks Jon,

I'm kind of a chassis and suspension nut. I was hoping for the Goodyear numbers so that I could look up constant pressure curves, load at design height curves, spring rates, and other engineering data. I agree, the Prevost prices look very good.

[Jon Wehrenberg]

Steer and tag.........1R11-296 Prevost 630104

Drive.....................1R11-088 Prevost 630126 (I think superceded by 630259)

I tried in vain once to find a generic Firestone, BFG or Goodyear but couldn't.

[travelite]

Thanks Jon! :)

[truk4u]

Yoo Hoo Jon, you reversed the drive & steer/tag. Were you in the squeezins at 4:40 pm?

[Jon Wehrenberg]

Truk is right. That's the problem...........I hadn't had an adult beverage.

[Steve Bennett]

We are replacing a set on a 97 Marathon XL40 that is being purchased by the founder of CruiseAir. The parts are $1,112.00 from Prevost, and we are having ABC bus do the instal for $1,000 for all 8. The air bags on this coach look much better than the ones Tom pulled. I replaced all 8 on my 92 about 2 years ago, and the old ones looked great. I think that the environment the coach is in has a large impact on how the bags/rubber hold up. My guess is that cold weather is a big contributor to the rubber deteriorating.

[Woody]

9048GOOD advice. 4 new bags going on as i write.

[Jon Wehrenberg]

Air bgs may age more quickly due to a variety of factors. I have no clue what determines if an air bag or tire or the O rings in our Norgren valves ages more or less quickly, but another consideration is salt and corrosion. I have had a 10 year old air bag fail because the steel can on the bottom corroded, no doubt because of living in the snow belt and driving all year.

Whatever the reason for the failure of an air bag the bottom line is the bus will drop down and rest upon the bump stops which are internal and driving it will be dangerous because every bump and pot hole will send shocks right up through the bus frame, and the coach will be down at the lowest setting at the loacation of the failed bag making it unsafely close to the ground for driving.

Peace of mind is worth the cost of air bag replacement

[Liam]

When I bought my '92 this year I had my local "spring shop" do a "if this were your bus" safety check and did all the shocks and bags. Old bags looked ugly. Glad I did. New bags have plastic horns so no rust problem. Can't beat Prevost's parts price. Labor for 8 shocks, 8 bags, steering shocks, 2 air valves, and a bent trailing arm was $2,200. Will be our loss when old shops like this die.

BTW the arm was stupid. It was installed upside down so the adjusting bolt smashed against the frame when the suspension bottomed. Who knows how that happened and when.

[flyu2there]

Do not mean to introduce thread creep but, all this talk about air bags do not forget about the "mini bags" on the engine. I just replaced the one under the tensioner for the serpentine belt that drives the radiator cooling fan and drivers air conditioning compressor. Suffice to say if that bag is lost you can compromise your cooling, both engine and personal, as in the driver. I found the leak at the air inlet fitting portion of the bag that is perhaps the term is vulcanized into the rubber. I will not elaborate on the difficulty of the job, however if I ever find the party who last changed this bag and installed the fitting using Locktite Red............

[Woody]

9048GOOD advice. 4 new bags going on as i write.

May be my imagination but the coach now rides a bit higher, has no air loss over several days, rides better - I also changed the belt tensioner that had a diaphram leak - It's nice to have all this stuff working right.

Another year or so and I'll have a new bus.

[BillhymerMD]

We need to have all our air bags replaced...does anyone have any recommendations for this kind of work in Central Illinois?

[pcb50]

Michael, where in cent. Il. are you? I'm southeast of Springfield 20 miles. Paul.

[Larry W]

Last year it was time for new air bags on our coach. There is not a coach company close to our home. I did some searching for a well respected heavy truck repair shop. I was led to a local heavy truck and equipment shop. The owner was not only interested in my money but also how the bus works. I ordered the bags and valves from Prevost. When I got all the parts from Prevost we set up a time for the work. I instructed the shop owner how the level low operates. They did a great job. The shop would not replace the bags with only one nut on the top studs as Prevost did on our vintage bus.
Great service but I think the best part was a total labor charge under $600. See if you can find a respected shop then shearch POG for all the information about how to change the bags. I shared the POG information with the shop. Very well pleased and over 10,000 miles since the change with no problems.

[Larry W]

I made a goof, The labor was under $700.