air suspension leak

Rick 74 MC-8 · December 09, 2012, 09:33:23 AM

Hey guys I have an air leak on the front of my MC-8. I'm pretty sure its the air beam I'm thinking of retrofitting rolling lobe bags with block off plates. My question how high do I need to lift the front as to replace the bags. Is there enough room to raise with the suspension above ride height and block the body Or does it need to be higher to replace the bags.
Thanks in advance

Rick 74MC-8
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Lin · December 09, 2012, 10:07:18 AM

I have only done this once, but it seemed to make the job easy. Air up the bus. Then jack it from the jack points under the bags to as high as you want. Put substantial blocks under those heavy structural pillars at the raised end of the radius arms. Let the air out of the bags. Then let your jack down as much as necessary to have the air bag completely extended. It should come out and go back in easily. I found using bicycle tire tools good for removing and replacing the air bag collar.

I did this on the rear, which is already plated. My front still has the air beams. Finding a leak in the beam may be a challenge, but it may be worth it if it is patchable. There are others here that will know better. Also remember that the bolts for a plated bag are longer. I had gotten my stuff from Luke. He knows exactly what you need and you get it right the first time.

Sam 4106 · December 09, 2012, 11:20:11 AM

Our MC 8 already had block off plates when we got it but the suspension still leaked down. Corrosion between the the original bag mounts and the aluminum block off plates has caused enough force that the block off plates were cracked along the holes that let the air into the bags. My solution was to replace the aluminum block off plates with 3/8" steel plates that I made myself. I had to weld a piece of 3/4" X 3/4" bar to the edge of the 3/8" plates to have enough thickness to drill and tap for the 1/8" air line fittings. I cut the circles out of 3/8" plate with circle cutting attachment on my torch. Then I laid out and drilled the bolt holes. The horizontal hole for the air supply was the most challenging so I used my Shop Smith as a horizontal drill press for that. New aluminum front block off plates were $65 each and I thought they would eventually corrode again so I made my own steel ones for $12 each. I cleaned and painted the original steel bag mounts and the block off plates. When I reassembled the block off plates to the mounts I put a thin layer of caulk between them to slow down any future corrosion. It's been more than three years now and the air leveling system that was on the bus when we got it, keeps the bus at whatever height I set it for weeks.

When I did that job I raised the air bags as high as they would go, placed 3" heavy wall tubing spacers with a 1/2" plate on one end, between the axle and the rubber bumper. Then I jacked up the bus and removed the tires. That gave me good access from both the pit and the floor.

I soaked the bolts and nuts with PB Blaster for a couple of days and used a rotary wire brush in my Dremel tool to clean the threads. Another soaking and I was able to remove the bolts easily. That may not work if the bolts are original to the bus.

Good luck, Sam

Chopper Scott · December 09, 2012, 01:48:55 PM

Actually you don't have to jack the body up so much higher but enough that you can remove the tires and drop the axle down. I have a welding shop so blocking up the body wasn't much of a problem. Just make sure you are safe under there. One more piece of advice I would give is invest in new shocks while you are in there. I had to remove them to allow the axle to drop enough anyways and now have to remove the tires again and change them some day. Not as hard a job as one would think. Removing the old bolts is about the only occasion I found myself speaking French.

Dave5Cs · December 09, 2012, 01:57:38 PM

If you run her up on ramps first then fill your bags up block your jacking points, jack your axle up just a little to get your tires off the ramp to take them off, now start letting air out of bags.

Dave5Cs

robertglines1 · December 09, 2012, 04:36:03 PM

FWIW: most shocks are under $50 each.

Rick 74 MC-8 · December 10, 2012, 06:21:19 AM

Got it at ride height block the body let the air out of the bags and get the tires off. There's definitely a leak in the air beam. I will fix the leak but still go to rolling lobes and block off plates. Next take a ride to Mohawk and MCI and see who hasit a better price. When I pulled the inner wheel well off to get a better look at the top of the air beam. I was pleasantly surprised how good everything looked except for the top of the air beam. There was a small gap at the inner portion of the inner wheel well. I'll try to clean that area the best I can painted with some good zero rust paint spray some undercoating on and seal it up very good. this coach was undercoated when it was new it sure helped.

Rick 74 MC-8

Rick 74 MC-8 · December 14, 2012, 06:19:45 PM

Picked up the new rolling lobe bags and blockoff plates today.
Mohawk supply great people very helpful very friendly.

Rick 74 MC-8

John316 · December 14, 2012, 06:43:41 PM

Quote from: Chopper Scott on December 09, 2012, 01:48:55 PM
Actually you don't have to jack the body up so much higher but enough that you can remove the tires and drop the axle down. I have a welding shop so blocking up the body wasn't much of a problem. Just make sure you are safe under there. One more piece of advice I would give is invest in new shocks while you are in there. I had to remove them to allow the axle to drop enough anyways and now have to remove the tires again and change them some day. Not as hard a job as one would think. Removing the old bolts is about the only occasion I found myself speaking French.

Scott,

Glad to see you back around. Some of us missed you. Don't forget to drop on over to mcibustalk.com also. Good to have you back.

John