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Roadmaster RR8 chassis airbag replacement

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I recently replaced all 8 airbags on my 98 Dynasty with the Roadmaster RR8 chassis, and figured I'd let someone else learn from my mistakes.  Below is a quick tutorial, which is from memory but hits all the high points.  I also did all 8 shocks, but that is quite simple - it's just difficult to compress the new shocks to stab the bolts.  

Make sure you wear safety glasses.  If you don’t start with them on, you’ll put them on later after washing crap out of your eyes.

This post covers only the front airbags.  The rears use essentially the same process, just using two leveling jacks.  And, the rear bags are much larger and heavier, and two of those bags have two air hoses each as opposed to the one on the front bags. 

1.       Remove the top nuts on either side (passenger or driver) front airbags

a.       ¾” or 19MM deep socket.   A shallow socket won’t reach the nuts.  You’ll be getting like 1 or 2 clicks at a time.  Your arms will fall off, and your neck will hurt for hours afterward.

2.       Extend front jack until the extension rate slows (have someone run the switch while you watch – you don’t want to over-extend).

3.       Measure between the front H frame and bottom of main frame rails.  Cut a 4x4 or 4x6 block about 1/8” shorter than this, and scoot/smack into place.  Ensure that the block will not impede removal of the airbag, or prevent your arms from reaching the top nuts and air lines. 

4.       Have your helper retract the front jack until the wood is pinched into place, then stop – you still want the jack taking much of the weight.

5.       Remove the air line on top of whichever bag you’re starting with – the air will blow dirt all over you.  I think this was a 9/16” wrench (it’s been a minute).  You can ziptie a sandwich bag over the end of the hose to keep it clean.

6.       Since you’ve already removed the top nuts (I hope, or else you’ll be pulling the blocks, dropping the jack, and then removing the nuts), all that remains are the bottom bolts which come out easily.  Removing the front bags is easy, as long as you placed the block in a good spot.  If not…

7.       Remove the fitting from the old bag, and USE LOCTITE 545 or 565 on the new threads.  I failed to do this and had to spend about 8 hours chasing leaks all through the system – ended up removing two rear bag fittings, pulling off the Teflon tape (I know…) and doping the threads with the proper Loctite.  This fixed the leaks.  Do. Not. Skip. This. Step.

8.       Here is the tricky part: the new airbag, when fresh out of the box, is too tall to fit into place.  The air fitting that you better have put Loctite on should have a small “nipple” that protects the end of the hose and provides a solid connection.  Tear off like 1” of “heavy” Teflon tape – the stuff you DID NOT USE on the fitting's threads (there are different grades of tape, this stuff feels noticeably thicker) and get it ready.  Push down on the airbag until it bottoms out, then while holding it down (I did it alone, but you might need your helper) you press the tape against the nipple, then let go.  The bag should stay compressed, as the rubber tried to expand and pull air in – it can’t, because the tape is blocking the hole.  Carefully get it up into place, and you’ll see why you needed to compress it - without being compressed, it will never fit.  Ensure that the bolt holes in the bag’s bottom plate are centered in the holes in the brackets, then carefully remove the Teflon tape.  The bag will inflate quickly, and the studs should go up through the top plate holes.  If you aren’t lined up, you might have only one stud go through, and the air line nipple can hit the top plate and get damaged.  If this happens, just use a mallet to align the bag’s top plate and once the studs come through the holes, remove the fitting and get a new nipple (NAPA has them, I forgot to record the part number).  I just took in another fitting with a good nipple so they could match it.

9.       Now you just reattach the air line, and bolt the new airbag in.  I replaced all hardware, as some of it wasn’t in great shape.  I used Nylock nuts in place of the stock standard nuts.

10.  Once all 4 bags are in place, nuts/bolts torqued (or PFT'd), and all air lines reconnected, extend the leveling jack until the wood is loose, take it out, and of course get out from under the coach if using a helper to run the leveling system.  Then, lower the front and run the engine until the air system reaches operating pressure.  This way you're checking for leaks on the front while starting on the rear.  Again, I didn't use jackstands.  Same concept of course applies - and they're easier to not forget, as your wood blocks are tucked up underneath mostly out of sight.

I hope this helps someone.

Edited by theturbinedoctor
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Thanks for this, but your 98 Dynasty is not an RR8S (Raised Rail 8 Bag Side Radiator).  It has a S-Series Chassis meaning Semi-Monocoque Chassis steel chassis with integral welded steel body framework.   It doesn't likely make any difference (besides possibly the bag part numbers) in your write-up.

  - Rick N 

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I blew an air spring in Colorado last year had one overnight and installed by a mobile mechanic. when I got home I replaced the other 7 also All 8 shocks not a bad job I bought two 20 jacks from Amazon about $50 each raised the coach as far as I could then inserted jacks . I drilled a hole in bag then used a sawzall and cut the bags in half makes removing very simple . Total cost for shocks ,springs and fittings less then $2000 labor would been over $2000 great savings if you can do yourself and I was 83 years old at the time .

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