Firestone Air Spring Failure

[Toribk]

I was in Ashland, VA getting ready to depart the campground and the rear of the coach would not air up after retracting the jacks.

To make a long story short, when we re-leveled the coach, I noticed the right rear air spring was completely detached from the piston and obviously would not seal and hold air.

I subsequently had it, actually both, replaced on site by a local mobile diesel service via my extended warranty and contacted Firestone the next morning.

By my photos, their assessment is that the internal bolt the holds the retention ring that secures the bellows to the piston must have come loose or broke and the cause is usually attributed to an over-extension of the air spring.

Now, I bought my coach new five years ago and I know for a fact that the rear of the coach has never been lifted in a manner to allow the axle/suspension to drop in a manner that would over extend the air spring. In fact, I even check the level of my coach inside before I deploy my jacks to ensure shaft travel is kept to a minimum when leveling.

Additionally, looking at the Freightliner XCM chassis suspension drawings, it appears that the shock would be the stop limit for the axle and suspension range (including the jacks) of travel which, I would think, would be calculated in a manner not to exceed the maximum extension of the air springs.

My conclusion is that the air spring just failed....period. But, I don't have a lot of experience with air springs and suspension systems and thought I may get some feedback from those on the forum that do.

One good thing that did come out of this is that I now know how to replace the airsprings, which is not that difficult at all provided you carry the proper tools.

[BFlinn181]

Sometimes things happen. It might be a manufacturing defect or the result of a stretching of the bag you didn't recognize as an over-extension of suspension. My Spartan chassis has multiple large nylon straps that prevent the axle from hanging on the air bags when the frame is lifted.

[Navy80to04]

So I installed airbags on my RV do I need to dump the air out of my airbags before I jack it up and level

[BFlinn181]

Originally Posted by Navy80to04

So I installed airbags on my RV do I need to dump the air out of my airbags before I jack it up and level

Your air bags assist the original leaf or coil springs, I'd guess. Unless the RV is lifted up higher than normal ride height, I don't think there'd be any advantage to dumping air. An air suspension chassis dumps air to lower the RV 3-6 inches so the jacks don't have to extend as far.

[Navy80to04]

In the instructions, it said not to lift or hang the tires. So I may dump air then level rv. The jacks will pick tires off the ground. And rv instructions say not to do that.
Do I just touch the ground with them and then pick up the low side?
If I use auto, it picks the camper up off the ground.

[TQ60]

If insurance paid for replacement and you have the old ones then check warranty.

First see what voids the warranty...If lifting by frame to have tire clear that could be issue but checking with coach manufacturer to confirm if the shock would limit this.

We remember some county coach units having shock issues due to axle movements....

Ask the manufacturer to send you something indicating their design limits the axle movement to not allow the damage.

Take that then seek replacements from Firestone under warranty. ...for next time....

[spanny1212]

Toribk Sorry to hear you had an airspring failure. I worked for Firestone Industrial Products in Noblesville, IN from 1973 through 1978 as a Airspring Project engineer and in tech services. First of all they changed the design. The cup at the base of the rubber member was cured in place and had a blind hole from the bottom for mounting. That blind hole fitting also was the attaching point for the jounce bumper. Also there was an aircraft cable end welded to make a loop that was similar to a tire bead. That would not allow the small end of the rubber member to pass over the cup shape steel piece. Now it appears they do not cure the cup in place. I'm not sure if it has a stud attached to the bottom of the cup or a blind hole in it. If you still have the failed airpring I would check if the cable or wire broke. Not sure why that would happen unless weld broke. They could have changed the design to a solid ring which could be butt welded. Goodyear used this design. We were not crazy over that design. I have 2013 Winnebago Tour with Firestone's on the drive and tag. Rolling sleeve design just like yours. I'll bet that airspring is a Neway 1T15K1 or Firestone 1T15M4. Front is ZF. Also the shocks are what hold up the axles. Shocks are critical on air suspensions. The nylon straps might be a backup for broken shocks. These airsprings are extremely durable. I doubt if you have over 70 psig in them when loaded. I drove dump trucks during my college summers that had Neway pusher airlift axles. I had to manually adjust airspring pressure to 50 psig. We burst tested one once a year with water. Typically would go to 700 psig. Anyway I hope you have long life out of your new airsprings.

[Toribk]

Spanny1212

Thanks for sharing your insight as a former employee and engineer.

The airspring that failed was Firestone No. W01-358-8184 and I have attached a photo of the basic assembly diagram for you to review.

If I recall correctly, Firestone told me that there was a blind bolt and retention ring that held the bellow down to the piston and internal rubber stop. It was their opinion that the bolt somehow failed

Of course, for me, it's hard to tell by looking at the drawing, but perhaps you might have a better understanding of the lower assembly after reviewing it and render an opinion.

[spanny1212]

Looks like the lower bead is seated by air pressure, like a tubeless tire. The higher the pressure the tighter the seal. It could have lost its seal. Obvious this is a cost reduction design. I'll bet it could have been resealed with a fixture to hold the airspring height and lubricating the seal area and a blast of high pressure air. Like seating a tubeless tire. The are probably small sealing ribs on the inside diameter of the bead. Did you find a broken bolt? Not sure if bolt had anything to do with it. Overextending would probably pop the seal, but shock should prevent that. Mystery. I'd keep it and piston if rubber looks good with no weather checking. Regards