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Replacing Air Bags

June 25, 2012, 02:10:47 pm

Looks like I need to replace the air bags. The right rear is leaking air and the other 3 rears look like they should be replaced.
Will replace the fronts at the same time.

I sure someone has replaced the bags.
Any helpful hints?
Brand, Part # and cost?
Best place to purchased?

1999 U320 with 117,000 miles

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Re: Replacing Air Bags

Reply #1 – June 25, 2012, 03:14:42 pm

I replaced the rear airbags on my 1996 U320 about six months ago when I noticed two layers of cords exposed on one bag.
 
Firestone W01-358-9448 (complete assembly).

Just the bellows (Firestone 1T15L-2) are available and it would not be difficult to attached the bellows to the old puck. I could not find a source for just bellows and bought assemblies from SDTRUCKSPRINGS.COM for $148 each including shipping.
Check their coupons on the home page. I ordered two at a time to get maximum discount because they did not respond when I requested info on applying two coupons to one order. I could not find these airbags available on eBay.

I will replace the front airbags this winter when I will be in California.

Jon Twork submitted a step by step description which is available on Foreforums. Jon removed the panels covering the wheels but I managed to complete the replacement without removing those panels. I also installed a brass "T" with a shrader valve for each pair of airbags.

I plan to install an access panel in front of the driver front tire in the genset fan housing to allow easy access to the airbag fittings on that side. I may have to remove the panel covering the passenger front tire to get access to the passenger front airbag fittings but may put an access door in the entry step well.

By the way, the pressure in the front airbags when traveling is about 45 psi while rear airbags require about 75 psi.

I used Wrenches as follows: 1 1/8 for large nut on hollow air input bolt, 3/4 for nuts, 5/8 for air hose nut, 9/16 for brass fittings.

On the rear suspension: I was able to remove the front airbags between the tire and the wheel cover panel with the safety blocks in place. The rear airbags required addition lift using a hydraulic jack to provide room between tire and wheel cover panel. 

Airbag replacement is awkward but doable.

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Re: Replacing Air Bags

Reply #2 – June 25, 2012, 03:16:17 pm

Dick,

See my post today under "Air Ride Replacement Number". Carl Sandel initiated the thread.  All of the information is listed there.  Model no, source and cost.

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Re: Replacing Air Bags

Reply #3 – June 25, 2012, 03:27:43 pm

Dick,
      I just replaced my 2 left rear ones this morning on the road in the campground. Start to finish was 1 1/2 hrs. On my coach I did not have to remove the side panel. First thing I started doing about 2weeks ago was to soak all the bolts with PB Blaster. Did this every other day then cracked all of the nuts free before attempting the complete job. Being on the road I did not want to start in the campground unless I knew all the bolts would come off. Extended the coach to the max height and put my 11" safety blocks in place all around. Then dump the air. The only socket that I did not have was a deep 1 1/8 with 1/2" drive, best if this is 2 1/2" long but I was able to use 3" with the breaker bar. As it turned out I would not have needed it because the nut broke free with a cresent wrench. 3/4" box wrench, 8" long and a 5/8" combination wrench along with about 18" of extensions for your 1/2" drive will make getting the lower nuts off a bit easier. You will need some pipe thread sealant for the air fitting. When reinstalling the air line I use a light film of silicone paste.
Air spring Part no. W01-358-9448
Bought air bags at Truck Parts, Trailer Parts, Bilstein Shocks, Firestone Air Bags, Timbren out of MI $156.00 free shipping
Good luck, if you have more questions feel free to ask, not sure how different your coach is from my.

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Re: Replacing Air Bags

Reply #4 – June 25, 2012, 04:42:46 pm

Rick, Thanks for the great detail instructions.
I just ordered 4 airbags (all they had in stock) from, Truck Springs inc., Saginaw, Mi. and they'll be here tomorrow.
Same price as everyone else, $155.71 * tax and free shipping.

Will tackle the fronts later on this summer.

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Re: Replacing Air Bags---Update

Reply #5 – June 29, 2012, 07:49:15 am

The new bags were delivered Tue afternoon ($660.21, free shipping). Once I verified they were the correct replacements, they were are installed Wed. Not a hard job, just very hot outside. A short 1/2' offset ratchet really helped on the front upper nuts.

Will do the front 4 later on this fall once the temperatures cool off. Not looking forward to removing the front fenders. May do what Wyatt Sabourin suggested (June 25, 2012, 12:14:42 PM) and  put in a access port in the stair well and generator well.

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Re: Replacing Air Bags

Reply #6 – June 29, 2012, 12:54:48 pm

I had to jack our U300 up with a 10 ton jack to install the new airbag. I was concerned about the jack possibly slipping off with me underneath, especially since I had to jack it up pretty high. I welded up a couple of simple tools to slip between the frame members and adjusted them up after every 20 pumps on the jack handle. I am going to weld on a couple of tabs to better locate the safety at right angles and in the middle of the frame tubing. In case of jack failure, there is no danger to life or limb.

The other photo shows the hardware store adapters I bought to cap off the air hose to drive it. In practice, I just used the brass cap at the end of the U300 90 degree fitting.

Note: after an airbag failure, even capping the hose may not allow the coach to be driven. You have to check carefully the clearance between the top of the tires and the wheel well.

Pierce

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Re: Replacing Air Bags

Reply #7 – June 29, 2012, 02:49:03 pm

I had a set of safety jacks fabricated in December, 2010. I used them last November while searching for an air leak that was a "show stopper." The coach would inflate the air bags, but would not build pressure beyond 70 psi. Having the jacks with us allowed me to crawl under the coach with relatively safety while searching for the leak. I found the leak, fixed the problem with "percussive adjustment," removed the jacks, and we were on our way.

It's interesting to see implementations of the safety jacks. Here a description of our jacks: Safety Jacks The design has served our purposes so far. I recommend using Acme threads rather than the conventional threads that we used.

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Re: Replacing Air Bags

Reply #8 – June 29, 2012, 04:43:31 pm

Agree on the Acme Threads, much stronger.
Another method I have seen, A friend with a Eagle 01, designed, had built and installed 4 hydraulic jacks that would lift the bus 36" off the ground. Measeured at bottom of tire, with the hydraulic locks, wonderful, expensive, PIA. but worked.
Again, with a welder, grinder, mill, lathe, drill press, moxie, you can make anything.
Dave M

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Re: Replacing Air Bags

Reply #9 – June 29, 2012, 07:20:09 pm

"Again, with a welder, grinder, mill, lathe, drill press, moxie, you can make anything." Also enough money. A bit of knowledge also helps.

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Re: Replacing Air Bags

Reply #10 – January 14, 2013, 11:33:33 am

Keeping the info together. When replacing the air bags it is possible that one of the 90* brass elbows will break or be damaged. I suggest having a couple of new 90* assemblies on hand. These are available at the local truck parts shop. Also when reassembling the 90* fitting into the air bag use an anearobic pipe sealant to avoid leaks. Because you need to have the 90* fitting properly aligned you may not be able to tighten the fitting enough to avoid leaks and get the correct alignment.
Rick

http://www.useloctite.com/filephotos/documents/Thread_Sealing_101_Tech_article.pdf

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