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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Larry O on April 11, 2006, 08:09:58 AM



Title: Air Beam Leak Repair
Post by: Larry O on April 11, 2006, 08:09:58 AM
I have a significant leak on my drivers rear side air beam.  I posted this on the "old" board and got a couple of replies.  The concensus is that it would be better to convert the air bags than to weld the air beam.  Unfortunately, I was not online for a few days and now the postings aren't available and I need a bit of clarification.
 
One of the posts advised to replace the air bags with "rolling lobe airbags".  Can someone shed some light on these types of airbags or preferrably on the whole process of bypassing the airbeam.  Also, any suggestions of suppliers of what I will need would be helpful.


Title: Re: Air Beam Leak Repair
Post by: plyonsMC9 on April 11, 2006, 09:28:36 AM
I have a significant leak on my drivers rear side air beam.  I posted this on the "old" board and got a couple of replies.  The concensus is that it would be better to convert the air bags than to weld the air beam.  Unfortunately, I was not online for a few days and now the postings aren't available and I need a bit of clarification.
 
One of the posts advised to replace the air bags with "rolling lobe airbags".  Can someone shed some light on these types of airbags or preferrably on the whole process of bypassing the airbeam.  Also, any suggestions of suppliers of what I will need would be helpful.


Hi believe Rich @ International Bus Parts carries the air bags.  He may even be supplying the air bags for my current air-bag replacements.  He is a good guy, and regular MAK advertiser.  His web site is : http://www.1800intlbus.com/

Phone is : 800-468-5287

Hope this helps,
Phil




Title: Re: Air Beam Leak Repair
Post by: JohnEd on April 11, 2006, 03:08:57 PM
Folks,

I have read a lot of posts on the air beam problem in the past couple of years. (I am NOT an expert.) What I keep hearing from the people that have deleted the beam is that the suspension then becomes harsh.  The guys that go to the rolling lobe have all said that it is "close" to being as good a ride as the "air beams".  One guy said that the inside of the air beam was rust free and required no work.  Apparently the things rust through from the outside top only and can only be repaired by welding a new piece of plate to the top of the beam and doing it with care.  They seem to rust through due to road dust and dirt collecting on the top of the beam.  From the pictures I have seen it is true that you can only get to the top by removing the floor above the beam.

Now for my question to the board:  Is it true that the air-beam ride is superior?  Can the top of the air-beam be accessed through a hole cut in the floor and can that hole be properly repaired?  Would it be prudent to coat the top of the air-beam with epoxy fiberglass while the thing is exposed during a floor ripout.  They all seem to get ripped out regardless and that is another question.

Thank You

John


Title: Re: Air Beam Leak Repair
Post by: Ross on April 11, 2006, 03:41:24 PM
Mine are plated with standard airbags.  I wouldnt say the ride is harse.  Maybe a little harder than the airbeam ride but not the night and day difference some people make it out to be.  On the interstate I doubt I'd even notice a difference.  If I ever replace the airbags, I'll replace them with rolling lobe, but I won't do it just to get a better ride.


Title: Re: Air Beam Leak Repair
Post by: LUKE at US COACH on April 11, 2006, 05:10:10 PM
Hi Larry & Folks:

If your air beam can be repaired, then I would suggest that you try it.

With regard to the newer air bellows to compensate for bad air beams, the experience in our shop is as follows:

We operated MCI 8's & 9's with bypass plates and the original bellows in commercial charter service.  Never a complaint from customers or our coach operators!!!

Now we have, over the years had several commercial operators come into our shop with MCI's, that had been converted to the newer bellows and asked us to Remove Them,and Add the Bypass Plates and go bag to the ariginal bellows!!!

Each customer responded that passsenger and driver discomfort went to Zero.

The key, when adding bypass plates, is that the ride height of the coach is properly set!!!  With any air ride coach, improper ride height as described in your maintenance manual, will produce an uncomfortable ride along with adding additional stress to the air suspension system along with the coach structure!!!

I Hope this HELPS!!!

Happy & SAFE! Bussin' to ALL.

LUKE at US COACH


Title: Re: Air Beam Leak Repair
Post by: edroelle on April 11, 2006, 05:56:18 PM
Now, what I am going to say is very dangerous in that I tend to disagree with Luke - who I consider an expert.

A fellow bus nut (I think he went by Luke Skywalker) had a professional welder repair his front air beams.  He continued to have air leakage such that he plated his air beams and installed rolling lobe bags.  The beams were so perforated with tiny holes, he could not get them closed-up.

I guess the key statement from Luke B.  is, "If your air beam can be repaired."

I thought the ride was somewhat harsh with my MCI 8, plated air beams, and standard air bags.

Ed Roelle
Flint, MI


Title: Re: Air Beam Leak Repair
Post by: Melbo on April 11, 2006, 05:59:09 PM
I just find it entertaining that LUKE is a newbie.

Melbo


Title: Re: Air Beam Leak Repair
Post by: Dallas on April 11, 2006, 06:44:06 PM
I just find it entertaining that LUKE is a newbie.

Melbo

I prefer to think of all of us as "FNG's........                                                    Fairly New Guys. LOL
[/b]

Dallas


Title: Re: Air Beam Leak Repair
Post by: DC_Bus_Nut on April 11, 2006, 09:56:21 PM
Let me guess Dallas, you were in the military...FNG.


Title: Re: Air Beam Leak Repair
Post by: DC_Bus_Nut on April 11, 2006, 09:59:04 PM
Additionally, MCI is (was as of 2 weeks ago) having a sale on Airbags. I numerous bags with all of the hardware for $74.oo+ each. A bargain. Installed at DC Trails Bus Repair & Towing here in Wash, DC for a reasonable price too.


Title: Re: Air Beam Leak Repair
Post by: Burgermeister on April 11, 2006, 10:48:08 PM
This is the reprise of a Post by Marc Bourget on Sat Jul 4 10:43:22 1998:
In Reply to: PD4104 airbeams replaceable? posted by Bill on Fri Jul 3
01:04:16 1998:

Gentlemen

The plenums are intended to reduce the "ramp up" or rate of rise in the bag pressure when responding to bump deflections.

The following is a quick attempt at calc'ing some numbers, ( please check my math, but the approach is valid)

Assuming the air bag is a cylinder 6" wide x 10" tall, each inch of air bag height occupies about 280 cubic inches volume. Hitting a bump which moves the axle up two inches would reduce the volume 20% or 56 cu.in. (if the bag didn't expand width-wise by stretching).
 
If a plenum is 8x8x30" (approximately, as just an example) the total system volume would be about 2200 cu.in. and a 2" displacement (the same 56 cu in) would be only 2.5% reduction in volume.

Back in high school chemistry, Boyle's Law taught us that Pressure and Volume are (inversely) proportional, (assuming Temperature remains the same) In the single bag situation (no plenum) in response to a 2" deflection, an initial pressure of 80 psi would raise to about 100 psi. In the plenum system the same bump would cause the pressure to rise to about 82 psi at the biggest deflection.

This may or may not be a problem. It will make the ride a bit harsher, but whether this is material depends on how youthful the lower back and posterior are as well as the quality of the roads travelled.

More significantly, what will 10 times greater pressure increase (20 psi vs. 2 psi) do to the useful life of the airbags? Personally, I don't know, but as much trouble as they went to to build in the plenum system, and considering the historically tight sphincters of the pencil pushers who control the $$ it is doubtful that the mfg's would have put the plenums in if they didn't have a good reason.

Again, the ol' adage rears its ugly head, you makes your choice and pays your price!

Marc.
Added on Date: 1/17/99


Title: Re: Air Beam Leak Repair
Post by: LUKE at US COACH on April 12, 2006, 07:41:03 AM
Hi Melbo & Folks:

That is "OLD"!!!! Newbie.

LUKE


Title: Re: Air Beam Leak Repair
Post by: Busted Knuckle on April 12, 2006, 08:07:27 AM
I just find it entertaining that LUKE is a newbie.

Melbo

I prefer to think of all of us as "FNG's........                                                    Fairly New Guys. LOL
[/b]

Dallas
Dallas fairly is not what it stood for last time I had someone screaming it at me! LOL and I never get lost either 'cause someone's always tell'n me where to go! LOL  ;DKnuckle ;D


Title: Re: Air Beam Leak Repair
Post by: Dallas on April 12, 2006, 08:24:23 AM
I just find it entertaining that LUKE is a newbie.

Melbo

I prefer to think of all of us as "FNG's........                                                    Fairly New Guys. LOL
[/b]

Dallas
Dallas fairly is not what it stood for last time I had someone screaming it at me! LOL and I never get lost either 'cause someone's always tell'n me where to go! LOL  ;DKnuckle ;D

Yeah, but I have to be nice 'cause it's a family board, and I use too many bad words as it is.
Besides, It's true, I believe ya'll are fairly nice guys, except when you don't agree with me, then you are obviously the reason this country is going to, unhh, unhh, Damn, I can't say that word!
To a bunch of GREAT GUYS:
Salut!
Dallas


Title: Re: Air Beam Leak Repair
Post by: rwc on April 16, 2006, 08:43:12 AM
I have never heard anyone talk about it but is it possible to get replacement airbeams?? Are the only options to repair the old one or plate and go with just the bellows?  :o


Title: Re: Air Beam Leak Repair
Post by: Burgermeister on April 16, 2006, 11:33:57 AM
You'll get a better appreciation of the task if you go to Gumpydog's site and look at the pictures.  The airbeams are rectangular tubes about 6x6 or 6x8 and 36-40" long  buried in the frame structure  below the floor and inside the wheels.

It can be done - anything can if you're determined enough!  but it's alot of work.   My "California" MCI-9 had a huge amount of fine silt all over this area that served as a "sponge"  making sure the corrosion continued long after the rain was gone.  Haven't "tested" for leaks yet,  but I'll let you know if any show and what I do to address the problem.


Title: Re: Air Beam Leak Repair
Post by: Melbo on April 16, 2006, 06:06:24 PM
Like the old expression goes

Given enough time and enough money you can fix anything

Not to say it is always worth it

Melbo