blocking for a 1975 4905

[Lonnie time to go]

I have two flat tires on one side of my bus.
I need to jack this up and get blocks in there.
Please i want  to do this the correct and safest way

[Cary and Don]

The safest way is a mobile truck tire repair service.  We had the same thing, and after watching the guy do the tire in our yard, it was worth every cent it cost. It takes a huge jack to lift the bus, the jacks have to be in the exact right spot,  the wheels are HEAVY, and the lugs are a bear to break loose. He pulled the tire, mounted a new tire, didn't drop the bus and everyone lived to tell the tale.

Don and Cary
GMC4107
Neoplan AN340

[Lonnie time to go]

I have looked at the post for MCI blocking. I assume it would be the same area to look for on GM 4905

[zubzub]

Jacking up a bus sucks if the ground is not solid but it can be done without a specialist.  You do not mention if the flats are the duellies in the back or  a front and a back.  1st things first try filling them with air unless they have seperated from the rim they should fill also sometimes flat tires just need refilling and then will hold air for a long time ,  use the bus air or a decent sized compressor.  
If you decide you need to change them if they hold air and you can safely drive to a truck tire shop just do that.
You can remove the wheels at home  if you like to (have to $) do your own service of bearings etc. If the bus will move run it up on some blocks, at least 4.5" high on the side that needs changing/wheel removal.  I like to loosen the lug nuts a little at this point a good 3/4"impact should do this (remember on some (all?) buses  the L side has reversed threads) then

chok the front and back of all the other wheels

(all chocked  is overkill but I prefer it to being killed).  Now that the bus is on a run up block  and choked you can safely get under there put down some wood as base  for your bottle jack and jack up the bus under a suitable bearing point.  I use an air assist jack because it is faster and a little safer  as I am not under the bus during the lift.  Once the bus is up enough to remove the wheel you can do so as long as
you are not going under the bus in any way, but if you are going to be sticking your head  (or anything else) under there or in the wheel wells now is the time to use some stacked lumber
under a suitable bearing point (bulkhead, suspension mount etc..).  Lower the bus on to your stacked lumber to make sure it securely holds the load.

 Never get under a bus that is being held up by a bottle jack alone they are not stable or secure enough by themselves)

All of this is suggested as advise only use it  at your own risk and remember to use professionals if you are not up to the task.

[buswarrior]

There is a mighty adventure in this, if you haven't removed your wheels before.

Call the tire service with your needs, unless...

You have the short jack to fit under there (this is your design criteria for choosing one, it has to fit under with a flat)

You only need blocking under the axle, as back-up for the lifting jack, as noted, let it down on the blocking, don't leave the weight on the jack.

You can get all the stuck wheel fasteners off. 6 feet of fence post sometimes isn't enough, if they have been on there forever.

You can get the rims to come away from the brake drum...how long since the wheels were last off? Another reason for annual re & re for inspection purposes. If left too long, the rims will not come away by way of any force you can apply, the bus has to be driven with the fasteners just finger loose and let the brakes and weight of the coach break them free, and you need tires for that...

You can deal with the 300+ pound flat tire/rim combination, and the flat repair.

There are some mountains better left to others to climb, and you fund the expedition!

happy coaching!
buswarrior

[Lonnie time to go]

    The two flats are on the duellies at the rear axle.  To add more they are both off the rim and not able to hold air.  If i can get the bus up and at least one tire and rim off then i can take it to a place for repair. I just want to be  safe and use suitable bearing points. 
Thanks for the help. 

[zubzub]

there is an old trick of digging a trough to change a tire.  Problem with a bus is the trough could end up getting you stuck.  In your case I would dig enough of a hole to get the jack under the bus somewhere and then lift it a bit get some blocking in there jack again etc... 
I cannot emphasize enough how easily a bus can fall off a bottle jack on unfirm ground.
until you have it high enough, at that point if you are feeling adventurous  you can pull the axle etc and remove the duelly as a unit and take it to the shop where they can loosen the lug nuts etc  and you can repack the bearing and one more maintenance item is done.  Really don't know your strengths (physical and mechanical) so this may be way off base.   I'm a big guy and I like to do everything so I can take care of things when I don't have the time or $ to get someone else to do it.  Good luck, and don't let the bus crush you.

[PP]

I don't know if this is relevant to your situation or not, but I air up the suspension, block the bus, air down so there isn't any weight on the axle, and then use a bottle jack to lift just the axle. But I guess if you're sitting too low due to the wheels sitting on the rims, this might not work. You might be able to get the flats off, but the bus would be setting too low to get inflated tires back on. If you plan on changing tires on the road in the future, you might want to invest in a 10 or 12:1 lug buster. They work fantastic Ask me how I know LOL Good luck, Will
BTW-I had my bus up on blocks for almost a week after crawling around under it looking for air leaks when it suddenly rolled off the blocking. It didn't go forward more than 18" because it stopped the minute the tires got traction, but I was under the thing at one point prior to this happening. THis is not good -now I do as ZubZub suggests and always block every wheel, even if they're not solidly on the ground. That was my wakeup call! My suspension holds air for more than a week now even if the brake system loses about 5# an hour. I know where the air leaks in the brake system are and they're not going to get fixed unless they get worse. Sorry, got off subject here.  

[buswarrior]

Thanks for the reminder, PP!

The missing advice in all these blocking threads is the critical first step:

You MUST lift the bus on a level surface.

If it won't sit relatively still with the parking brake released, pick another place.

Blocking the wheels is not sufficient to defend against the weight of the bus leaning on the jack/blocking, and you cannot trust that your wheel chocking efforts will be, or remain, sufficient.

The difference in the physics involved between lifting a car and the bus, using effectively the same jack footprint, is staggering to say the least.

happy coaching!
buswarrior