Information/opinions on Repairing MCI Air Beams

[oldmansax]

I was just reading the post by Belfort on his radiator woes. Ed said this was comparable to repairing MCI air beams & then having problems later. That led to this post.


Has anyone repaired air beams successfully? If so, how? How much improvement in ride do the air beams provide? Do they usually just deteriorate on top? Could the entire top plate be replaced? I have access to a complete machine shop so I could probably get the work done at a reasonable price.

Educate me please

[gus]

Tom,

My 4104 has about the same setup. I've done a lot of research on this subject on this and another forum. The general consensus, and I agree, is that the beams are not worth trying to repair.

The reason is that they usually have pinhole rust through from the top next to the floor. Once pinholes start there is not much point in trying to weld them closed because others will pop up. I tried this once on an air tank and it was a disaster. It would seem that the only way to patch a beam is to make a plate to fit the complete top of the beam. I'm not sure this is possible because of clearance problems but it will be major because the floor will have to come out. Maybe the beams can be removed from below but I don't think so. If so it is again a major job.

The easiest way, they way I'm going to go when the time comes, is to install plates between the two top air bags and the beam. These plates seal off the bags from the beam and have air inlets to the bags. This supposedly makes the ride a bit stiffer but I'm not completely happy with the ocean liner ride of my 4104 anyway.

[kyle4501]

The problem is corrosion thruout the entire air beam. Odd thing about corrosion is that the higher stressed the part is, the faster corrosion acts.

When you patch the leaks, you are reinforcing that area, & are creating stress risers in the part. Since it no longer leaks, you are also able to put more air pressure in the vessel. These are 2 of the reasons that the new leaks appear so quickly.

If one was determined to repair the air beams, the only way that is sure is to build new ones & totally replace the old ones. This will require major dissambly, so is best done prior to installing a nice interior.

My bus (092) has block off plates & rides GREAT! I really can't imagine a better ride & it has the double convoluted bellows. 092 also has holes in the side of the air beams big enough to stick your fingers in.

So if you like your interior, install block off plates & be happy. 

If you have no interior . . . . How long do you want to work on it before you use it?

[oldmansax]

Just to clarify, my '73 MC7 is already converted and I am mostly happy. I use it a lot. It already had the blockoff plates installed when I bought the bus so I have nothing to compare the ride to. I know MCI has come out with a rolling lode conversion kit but I did not know how that compared with the original setup either. This is why I am asking questions.

Thanks for the info so far.

[JohnEd]

Old,

I don't have one and never fixed one.  I have been an avid reader of this board for years and trust the "collective wisdom".  My read is that the "air beam ride" is superior to the Rolling Lobe or the plated off bellows on the stock system.  How much better?  Seems those that have gone both ways think it is a lot but the expense discourages many from doing the repair.  Nobody would rip up a finished interior.  The failure of the box is in the "top only" from what I have read in the past and this is the first day that I have ever heard of a "hole in the side big enuff to stick your finger through" and I don't deny anyones experience.

The repair involves installing a replacement top and welding it on.  You may be well advised, given the comment about the sides, to cutting the center out of the box and inspecting the interior to verify that you don't have badly carroded interior sides.  I would clean and paint the interior up to a couple inches of the top plate so the welding doesn burn paint.

The beams charge the collapsing outside bags in a turn and "help" keep the bus from leaning.  Sway bars do most of the work, however.  They also let the bags dump air pressure on a large compression(bump) and that gives you a better ride.

The "ocean liner" ride is corrected with "Really Good shocks".  Bilstien would be my choice if they make them for an MCI but I would ask the board before I made my purchase.  Maybe you could DOUBLE shock the entire bus...I think that would be wise...but I have never even heard that mentioned, that I recall.

Hope this helped, if even just a little.

John

[Ncbob]

Jack Conrad is our resident expert on changing over to 'rolling lobe' airbags...he's done it on his MC8 and has flexibility I didn't believe. When he grounded here in our park...he was able to 'overinflate' to the point where he raised the chassis and cleared the obstacle and pulled ahead.  Looks like a good system to me...but then I'm a newbie in contrast.

Chances are he'll have some input on this topic.....

Your turn, Jack......

NCbob

[NJT5047]

If your bus is converted, and you cannot remove the flooring over the bad air beam, or don't want to go to the trouble, air beam blockoffs are the only way to go. 
The ride will be slightly less cushy, but the handling may be improved.
Repairing air beams is major work.  Often they rust out on the top where settled road dirt and silt stays wet.  Rust from outside in.  Goes both ways though.  And, as Kyle states, once you fix one area, another leak may show up.   
My vote goes to blockoffs.  Kits are available with new style airbags and plates.  Definitely a good solution.   Mohawk, US Coach,  and Caylor's Supply could supply parts.   
Best, JR

[JohnEd]

JR,

Is it true that the rolling lobe has more travel than the stock bags?  Can the rolling lobe be used with the air beam to achieve a better ride. 

Thanks

John

[oldmansax]

As I said, mine already has the blockoff plates but I have just replaced one air bag & plate on the drive axle and was wondering about my options when I have to replace the rest.

If Jack can raise his bus on command enough to clear obstacles, that opens a whole 'nother  area of benefits to the rolling lobe option. How much travel (height) can you gain? If you combine lobes with a leveling system, would you have more leveling ability? I very seldom stay in campgrounds. I am usually at a friend or relatives house on sometimes VERY un-level ground. The lobe options appears to be something that would help a lot based on what NCBob said.

I am now waiting impatiently    for Jack to weigh in....

[JackConrad]

    Yes, I get about an additional 1"-1 1/2" total travel with the rolling lobe air bags.  If you install rolling lobe air bags, make sure you install new axle bumpers. If your OEM bumpers are compressed or missing, you can ruin a rolling lobe air bag when the bus settles.  MY rolling lobe air bags came from Mohawk Industries. I cannot comment on total travel of other manufacturers.
   Since our bus already had block-off plates on the rear air bags, I cannot compare the rolling lobe bags to the OEM bags with the air beams. But, I can tell you that the rolling loge bags are a much smoother ride than the OEM bags and block-off plates.
     We installed a leveling system that still uses the OEM leveling valves when driving and a manual over-ride for use when camping or manuevering the bus (such as at NCBob's place).  
      If changing to rolling lobe, do a complete axle, not just 1 bag or 1 side.  Jack

[oldmansax]

Thanks!

Looks like the rolling lobes are the way to go when I replace mine.

Now all we need is time & money....