Any tips on changing a rear air bag (MC-7)?

[BlakeWright]

A rear suspension air bag (bellows) on my MC-7 has not failed, but it is starting to de-laminate where grease from the u-joint has attached it.  It is easier to change it now at home instead of on the road.  It seems straight forward to change it, but not having done it before, I would appreciate any tips from those who have done it.  Do you put any sealant between the bag and the flanges?  Thanks, Blake

[Stormcloud]

I have done this. Several times. Normally sealant is not required, but make sure the steel plates are smooth....sand them to clean up the rust is a good idea.

Also, check the new bead ring to make sure it isn't bent or a poorly formed one. Set the ring on a flat surface (table) and check if it rocks, and if the clamping edge of the ring is at uniform height above the table so that it squeezes dowm evenly on the lip of the bag. The new bolts have a sloped top on them, and should only be installed one way. If the bolt head protrudes above the bead ring when installed, or leaves a sharp edge above the ring, it's installed wrong.

I did end up using green tire slime to stop a persistent leak in the bottom of one of my new rear bags, but that wouldn't normally be necessary.

Regards.

Mark

[Tenor]

It's not too bad of a job, depending on the condition of your bolts.  Have your beams been plated?  That makes a big difference.  Original MC7 buses used an air beam across the top from bag to bag to move air around for a smoother ride.  Those bags have a ring around the top and bottom with lots of bolts.  Plated bags have a metal plate across the top of the bag to block the air beam and an air fitting on the side of the plate.  The bag will have metal caps that are crimped to the bag itself.  Check the condition of the rest of your bags.  I was told not to use sealer.  Be sure to clean and perhaps repaint your mounting surfaces.  My MC7 bags came apart very easily with hand tools, however, I have heard that they can be a real bear to get the bolts out.  Often you can get a few turns on the nut to raise the head of the bolt enough to put vice grips on them.  Of course, be sure to have the bus properly supported before you start the job!  I got my bags from Mohawk for a very reasonable price and theirs came with all of the bolts and nuts in the kit.  Always good to ask though!  I believe they also carry the bags for plated systems.  Good luck!

Glenn

[uncle ned]

The best way I found to change air bags was to call David at Davids coach repair. Takes all the worry and sweat and aggravation out of it.  well worth the cost for a lazy old man.

uncle Ned

PS I am on my way to help Ed out.  worry about old people under those conditions

[BlakeWright]

No, the beams have not been plated.  Blake

[Melbo]

I found on my 8 that a mirror and dremel tool worked for a couple of the nuts that were hard to see.  I just cut down the side of the nut and then split it open to take it off. If I remember right a couple of them required a half turn and another cut.

HTH

YMMV

Melbo