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Purchased 6 air bags from Prevost (On Sale this month) and installed. Used Joe's advice to compress the new air bags before installation and plug the bag before installation to make the process easier. Worked liked a charm, compressed bag to fit easily into it's space. Slowly loosen the plug and align the bag as it decompresses.
Thank you Joe
Chuck
I havent even met Joe (yet), and I will say he has been super helpful and am looking forward to retaining his services for my coach. . I've read through enough of his things going back over a decade here - that I've also made mistakes that I have read about his warnings against. . too bad I read it too late. I now do a search beforehand and read everything through before undertaking something rather than doing something and then coming here when I hit a roadblock. . inevitably you'll usually see a Gil or Joe post that provides some insightful information.
Hey Bus driver u must have another Joe. I never do that never not even once.
That's okay the publicity is wonderful.
Here's what you can do to facilitate easy installation of the airbags if you don't have the Brute Force to just compress them and put them in. you can really compressed those things down a long long way Chuck probably more than you realized but it's tough I'll give you that. When you've got the bus on the body supports and you've got your jack underthe drive axle for example will use that as an example. You got to take the outer duals off to change the airbags reasonably easy you don't have to take inners but if u r a novice pull both duels. When you set the jack to lift the rear axle up to pull the tires off set it so that there's a whole bunch of Ram extended out in order for you to get it high enough to get the tire off the ground. Do that on both sides so now you got the bus supported on stands and you've got the rear axle up on Jack's and tires are off and the Jacks Are way super extended. Now when you go loosen up all your airbag nuts you can back those jacks off and drop them way down You can't just do one side at a time cuz it'll get cocked and the bolts won't easily lineup so you drop both Jack down go back and forth couple timesalternating lowering Jack's and you can drop that suspension way way down out of the way and those air bags will just float in and out Chuck. Then you run the jack back up until the studs go through the holes.
Bada bing bada bang.
Thanks Joe, as always great advice.
I used the level low and raised the bus as high as it would go, put supports under the frame then dumped the air. That gave me the height I needed to get under the bus without removing any tires. Old bags came out without to much effort and by compressing the new bags and plugging them I had the reduced size needed to install the new bags with out struggling with them. I lined up the mounting holes, slowly unscrewed the plug in the top and guided the bolts into their mounting holes as the bag slowly grew in size as the air returned into the bags.
Chuck
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Easier way. Drop the cradle lift out the old drop in the new raise the cradle. On IFS front ends similar choice. Fight them in and out or take a very few short minutes and undolt the upper a arm from the frame.
Hey Joe, have you ever built a jig to air them up in and check for leaks before installing them?
That's very dangerous you better make sure it's one hell of a cage cuz if the bag escapes it could kill someone. There's really no reason to air up in advance.
With all the Leaky crimps on the new tag axle air bags that I've been getting that end in 2 5 9 I've been tempted to take one of them back off and shoot some green tire Slime into it I wonder how that it work I bet you it would work good. We need another test pilot.
Lol I recognize that green painted floor line in that picture! Learning so much this week!!!
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Hey Scott. Everyone, Scott has a 1 0f 4 Libertys ever produced without over the road ac. Now I've had my hands on 2 of them. its a 97 and Liberty put 4 togeather and Buddy Greg was where they were sent to be marketed.
Back to the reason for the post.
Clue these photos aren't of these components being put back together these are photos directly after disassembly.
What is wrong with these pictures.
Oh no...there's a disc brake rotor in the same picture as a grinder ;-)
And the grease looks fresh...
Looks like an oil-less oil bath hub.
Somebody took it upon themselves to take a hub that you're supposed to put 90 weight in and change it to grease. I've seen that done before I'm tag axles but it takes some nerve to do that on the steer axle on a bus.
Grease vs oil is a debate that's been going on in the trucking industry for many decades. They'll come from the factory with oil. If the manufacture says not to use grease, don't use it. I'll stick with oil in the hubs.
Oil depends on oil seals, as long as they're doing their job life is good. Let that seal fail and you're going to lose a hub and wheel.
Grease doesn't depend on an oil seal.
It's more of a preference. Regardless of which way you go, get in the habit of putting your hand on the hub center every time you stop. If it's hot you have a problem, call Joe.
Even though some circles accuse me of it I never use customers for test pilots I'd never do that on somebody else's bus. I'll tell you another good reason not to do Greece it's almost impossible to put it together without contaminating the bearings with having grit stick to them you got to have hey surgical type cleanliness around things to make sure that goes together clean and anybody who's seen me work knows that don't happen too often
Joe:
I thought it was just you that got dirty and parts stayed clean.
Chuck
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Happy Thanksgiving everybody. Eat drink and be merry.
There was a recent discussion on service intervals. Here is some more for u to add to the data banks.
These bags r original 2001 chassis IFS. They represent about average condition to age IMHO. Id also guess prob 5yr ago or so they started to more resemble these, than new ones. 15yr thats a good number for a still servicable airbag based on what I see and how I think i know u bus guys and what your comfortable with.
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While im on the subject there's some things I've been wanting to pass on.
The devels in the details listen up pay attention
The only way to pull the front bag on IFS. Unfastened the lower shock nut and swey bar end link. THEN WITH STANDS IN PLACE TAKE AN ADDITIONAL JACK HERE. Jak it up until the upper arm is square with the frame. Remove the 4 a arm nuts and bolts being sure to take away the bokts with the nuts thsts important. Getting the arm square is also vital to the since of a removal of the bolts. If they don't FREELY come make slight adjustment of the jack to make it so. Ok that dont take 10 min. Then slowly drop the jack till 1 end of the arm clears the pocket and u can push it up out of the way.
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On top of the bag opposite the fittings is a 3/4in nut first remove it. Before proceeding put a wedge atop the loose bag and wedge it down.
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This is why the wedge is important. With the wedge in place only then is there enough room to turn out that 90. Look at that. Oh I so love these buses.
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Ok continuing here is EVERYBODY'S stuff. Lot to show u there's 10 different potential M.I.F.s here let me show u. First the galvanized Street elbow if u look at the D shaped opening it has to go thru a brass street elbow dont fit so u have to use one.
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Here is how I get it out. Very simple. Uncle Leverage. Always always plug the female on removal and installation.
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Always use dope on both ends of the thread.
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Here is some input ull not get anywhere but here something I've learned and not ever seen addressed and its crucial to a good proper repair.
After u get this out of the street elbow and in your hand I mark where they stopped with the 90 and then I note the amount of force it takes to begin to unscrew it u will see why later. Im going to move to another post too many pictures for 1.
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This piece is quite a piece. I used to think they were all defective but have grown to decide they r designed correctly.
I'm talking about the male end and the way they threaded it. Normally with pipe threads after a turn or so u should begin to feel resistance but not with this piece. The photo with it threaded in,well, I did that by hand and look threads r gone u would think someone cut that thread too deep. No so, its done for strength because the piece is so darn heavy so it don't crack there. So now u know what your looking at.
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When reassembling it u first put the compression 90 in and here is where that notch comes in. Knowing that when u put it up into the galvanized elbow coming out of the top of the bag and u will be BOTTOMING OUT the extension u turn the coopression 90 fitting 1 turn short of tight. Stop at the notch 1 turn short of tight. This will give u wiggle room when u stick it up and not have to make difficult revolutions when its up.
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Then when u bottom out the extension uve only 1 revolution to go and there's enough meat on the 1/2by3/4 90° to redneck a couple of adjustable wrenches as shown.
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Here is how easy the bag goes in with the a arm out of the way and the female end of the elbow the extension bottoms out into after the new bags up and in. In these pics the arm has been completely removed but not nessessary, only the ends attatched to the frame need taken away. If there is 1 thing to take away its the weird extension what it is and how to manage it. If u get a leak at either end of the galvanized street elbow u have to pull the bag. 2nd most important point pull the a arm away get it square and its pulled back in 10 min.
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Zoom in on the bolts note shims.
1 last thing. Sometimes the upper arms r shimmed usually they r not. Important. If shimmed remove shims BEFORE u try to pull.out the bolts and replace the shims LAST thing before tightning nuts. Another tip that only someone who fought them out can completely appreciate.
Great info Joe!
What year did Prevost switch to IFS?
My 96 (95 chassis) is straight axle. I would guess 96 sometime. I've seen this question asked but haven't seen a definitive answer.
The Hs got it first. Happened over a few years either front axle could be had same year for a couple years. I never was a big fan. Consider this. A straight axle sits at ride height at about 65 psi. The ifs need 90 before it even begins to come up. What one would be softer??? In defense of IFS the oversize air bag ping tanks probably dampen the higher pressures more than adequately. So why not add them to the straight axles bet I'd be noticable.
As is Difference in ride is undetected by most accept on rough road and i think the straight axles r quieter on rough road. Less parts less money weight is probably close.
Hey Mike and another tidbit. In the entire rest of the universe u have king pins on straight axles and a arms and ball joints on IFS front ends.
Pier in all his wisdom has figured out how to have both at the same time. Prevo IFS also sports king pins along with its a arms. Why would u do that? LOL Im unaware of anything else like it.
Up to 84 the straight axle had 4 airbags those rode even softer but those axles sit under 96in wide chassis only.
Doesn't really apply here but interesting - saw posted on FB forum awhile ago that passenger/transit shells (Greyhound) kept the straight front axle setup until just a few years ago.
As stated, it depends on model and use. I think they are still making straight axle coaches. Keep in mind the IFS was not installed to improve ride. It was to increase weight carrying capacity and improve the turn radius.
Gill I think the straight axles r all gone. 96 or 97 Sawdust's H is the newest prevo I've ever seen with one. Getting in and out with my Xl was never an issue with the straight axle however overweight motorhomes with 18,000 plus on the steer axles can be an issue.
Joe, Prevost made X-3 commuter buses, and possible Greyhounds, that are straight axle. I think they still make straight axle coaches. The service manual I pulled was for 2012 model year.
Ok very interesting. I still think the motorhome cassis with them ended in around 96 or 97 but thats only based on my past jobs.
Joe, on an XL motorhome chassis, Prevost model year 1996 starting with VIN T-5873. Typically sold as a completed 97.