Bus Conversions dot Com Bulletin Board
December 18, 2014, 01:27:37 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: If you had an Online Subscription: It will not get torn up or crushed if you back over it with your bus.
   Home   Help Forum Rules Search Calendar Login Register BCM Home Page Contact BCM  
Pages: 1 2 3 4 5 [6] 7   Go Down
  Print  
Author Topic: bus not level when air up  (Read 11387 times)
zubzub
Hero Member
*****
Offline Offline

Posts: 1168


'53 4104. Roadworthy but rough around the edges.


WWW

Ignore
« Reply #75 on: April 30, 2008, 06:38:14 AM »

I'm going to encourage you to work out your levellers and tag air supply.  I have read the whole thread, and while i don't know MCIs (or much about buses really) I do know that not working out how a system works is a good way of getting caught with your pants down later on (and besides your are on a concrete pad in your driveway, how much better could it get.   From what I can tell from this thread it is possible that your tags are not getting any air....when you air up the bus do you see/feel more tension in the tag bags?  If you don't you need to work that out before even deciding to go further.  Also remember soemtimes there are very simple solutions and online forums while well meaning can complicate simple problems...when all is said and done you are doing the diagnosis.  I just had another thought, you have different air bags L and R on the rear drives that may not be helping the levellers do their job either.  Like I said I don't know much, but from here it looks like there could be simple solutions (change/adjust the levellers etc..) and while buses are a bit of a bear to work on they really are just big cars that need big tools to do the job... Good luck with that.
p.s. I suggest a nice 3/4" impact driver , can't see how to work on a bus without one.
Logged

RJ
Former Giant Greenbrier Owner
Hero Member
*****
Offline Offline

Posts: 2878





Ignore
« Reply #76 on: April 30, 2008, 09:04:36 AM »


I do notice that if she's been sitting for a week or so and I take off as soon as the low air light flicks off (90 psi.) and I don't let it get up to 120 pounds pressure for a little bit... she's more prone to lean.





Chazwood -

Just because the light flicks off doesn't mean that the air system is full, that only happens when the governor pops off at around 120 psi. 

The reason you're seeing your coach still leaning more if you drive off that early is because the suspension is supplied air from the aux tank up front, under the driver - which also happens to be the very last tank in the system to be fully pressurized.

Another problem you might encounter by attempting to drive away when the low air light flicks off is that your parking brake won't disengage.  DD3s like to have plenty of air applied to them for release, and sometimes that additional 30 lbs of psi is the difference between driving away and getting frustrated.



On another note, if you're driving away when the air pressure light flickers off, it clues me into the fact you're not doing a proper pre-trip inspection before moving the coach.  Sorry, but for an old driver trainer, this is one thing that bugs me about most busnuts who haven't spent any real time in the transportation industry - their failure to do a proper pre-trip before driving a fifteen-ton vehicle.

If you don't know what a proper pre-trip entails, read this:

http://www.busnut.com/bbs/messages/12262/16203.html?1167072614



Sorry to hijack this thread somewhat, but the line quoted above caught my attention, and I had to respond, based on "What Price Safety???"

FWIW & HTH. . .

 Wink

Logged

RJ Long
PD4106-2784 No More
S13406 Now
Fresno CA
bowmaga
Betty Owner 1
Full Member
***
Offline Offline

Posts: 148


Super Betty




Ignore
« Reply #77 on: April 30, 2008, 10:20:02 AM »

uh...that last one goes in a different thread....I think.  But thanks.  I haven't driven it off since its gotten to my house!!

I am definitely getting air in the tag bags.  I'm getting air in all the bags, all the way around.  I can inflate and deflate the tag bags from the rear air valves...check.  The drive axle  bags on both sides are getting good air and i can't hear any leaks.  Right now...she's a lot better than what she was.  She is less than 2" out of level when aired up.  I think the rest of the unlevelness is just in the levelers.  As for the tag axle.  She is stuck, I assume from sitting and rusting fast.  I will take the shocks off and start working it over the next few days.  My situation has gotten a lot better from my intial cry out for help, a little better.  I think mostly airing it up and down has gotten things moving again and working better.  I will keep eveyone posted what happens if i get tag axles loose and working properly.  Thanks for all the input.  I always like to read up what people are thinking, cause i mostly don't know what to think.  3/4" impact...got it, it didn't do any good.  But local trucking company truck with monster air compressor worked just fine.
Logged

Greg Bowman
1979 MCI MC9
NJT5047
Hero Member
*****
Offline Offline

Posts: 1942





Ignore
« Reply #78 on: April 30, 2008, 11:35:47 AM »

You say i should be able to move the linkage, but i think thats impossible.  I can reach it, no problem,  but the valve arm is attached to a 3/8"  x 1" bar that is bolted to the axel.  unless that bar moves with the axel that valve isn't moving....or am I not understanding how this whole leveling valve actually works with the bus. 

As for the tag.  I think i'm just going to remove the shocks and replace them while I have the tires off.  I'll get those axle's to move up and down one way or another.  I don;t think I have the smarts or the know how at this point to unhook and hook up pressurized air to each tag bag.  I will try the hard way first...pry bar, blocking, grease, jacks, some cuss words, a little praying and some beer.....well a lot of beer.

Being the kind and supportive soul that I am  Wink, I'm going to actively assist your efforts by drinking some beer and offering up some choice cuss words to the bus'n gods.  I'll be happy to repeat this offering as required until satisfactory results are noted.  Tongue
Hope this helps!
BTW, the leveling valve linkage will have to be removed from the axle if you want to move it with a broomstick.  A good idea, but they may have to be readjusted when you hook back up.  Probably needs adjusting anyway.  Definitely will if you replace the leveling valves.  I recommend leveling valve replacement since you're so close to them anyway. 
Different airbags on opposite sides would not have negative effects on leveling.  If the leveling valve is adjusted correctly, it'll apply whatever is necessary to bring the bus up to level.  Each drive axle leveling valve is independent of the other side.
JR
Logged

JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
chazwood
Sr. Member
****
Offline Offline

Posts: 430



WWW

Ignore
« Reply #79 on: April 30, 2008, 06:14:50 PM »


I do notice that if she's been sitting for a week or so and I take off as soon as the low air light flicks off (90 psi.) and I don't let it get up to 120 pounds pressure for a little bit... she's more prone to lean.





Chazwood -

Just because the light flicks off doesn't mean that the air system is full, that only happens when the governor pops off at around 120 psi. 

The reason you're seeing your coach still leaning more if you drive off that early is because the suspension is supplied air from the aux tank up front, under the driver - which also happens to be the very last tank in the system to be fully pressurized.

Another problem you might encounter by attempting to drive away when the low air light flicks off is that your parking brake won't disengage.  DD3s like to have plenty of air applied to them for release, and sometimes that additional 30 lbs of psi is the difference between driving away and getting frustrated.



On another note, if you're driving away when the air pressure light flickers off, it clues me into the fact you're not doing a proper pre-trip inspection before moving the coach.  Sorry, but for an old driver trainer, this is one thing that bugs me about most busnuts who haven't spent any real time in the transportation industry - their failure to do a proper pre-trip before driving a fifteen-ton vehicle.

If you don't know what a proper pre-trip entails, read this:

http://http://www.busnut.com/bbs/messages/12262/16203.html?1167072614



Sorry to hijack this thread somewhat, but the line quoted above caught my attention, and I had to respond, based on "What Price Safety???"

FWIW & HTH. . .

 Wink




And here I thought I was doing a good job of pointing out that taking off too soon was a bad habit.  Grin

You know me....Mr. "What not to do"

Actually, what I find myself doing is (on the day of departure) about 4 or 5 hours before we leave, I start the bus and run down thru my checklist. I do this in case there is a problem. This way I still have time to fix it.

When departure time finally comes.......(remember, I have 8 people to get out'a dodge Tongue) I fire her up and take off.

Sitting around for half a day will bleed her air pressure down a little and I don't feel like waiting until she blows..... before we goes.

Thanks,
Chazwood.
« Last Edit: April 30, 2008, 06:40:48 PM by chazwood » Logged

1983 Eagle Bus Model 10
6V92
Thekempters.com
Tony LEE
Sr. Member
****
Offline Offline

Posts: 404



WWW

Ignore
« Reply #80 on: May 02, 2008, 10:24:54 AM »

"When the air bags are working normally, jacking the bus to remove wheels is easy.  Air it up, just set the jack under the jack point, extend so that it is against the jack point, and bleed the air out of the bus.  It'll give you 5" of jacking without any effort.  Don't jack on the axles unless the air is bled out and the bus body is jacked up.
JR"

I don't understand this.  Those jacking points are attached to the suspension below the airbags, so how can airing up and then putting the jacks under the jacking point  assist with raising the axle?

What I'm describing is airing up the bus to its normal ride height.  Then place a jack under each jack point and snug up the jacks.  No effort so far.
Now bleed the air from the suspension and you just essentially took the weight off the drive wheels and the bus is jacked up 5" higher than at rest with no air....even with the weight of the coach off the drive axle, the wheels are still on the ground, but all you need to remove the wheels is a small bottle jack under the suspension....only the weight of the axle (not the coach) is on the drive wheels. 
Jacking the axle up to remove the wheels only requires an inch or so of easy jacking. 
What this amounts to is saving the labor to jack the coach off the axle....I've done it from an un-aired
position, and used the aired up method.  Airing it up first is much easier.   
 

I can certainly see the logic of this if there are body jacking points, but my understanding is that the vehicle body shouldn't be jacked up anywhere except perhaps at the suspension connection points (meaning the air beam??) - and they are not easy to access with a normal jack.

What jacking points are you putting the jacks under once the bus is aired up to make it easier to raise the axle with a second jack. This point must take the weight of the body because once the air bags are deflated, the suspension is not holding the weight.

I am also curious why using two fully-rated jacks and having to provide adequate ground support for both jacks (because if one fails, the other must support the lot) and then releasing the air from the air bags (how do you do that without modifying the air system???) is really much less work or any safer than using one jack on one base and jacking three inches more on one jack.

Logged

NJT5047
Hero Member
*****
Offline Offline

Posts: 1942





Ignore
« Reply #81 on: May 02, 2008, 08:16:34 PM »


I can certainly see the logic of this if there are body jacking points, but my understanding is that the vehicle body shouldn't be jacked up anywhere except perhaps at the suspension connection points (meaning the air beam??) - and they are not easy to access with a normal jack.

What jacking points are you putting the jacks under once the bus is aired up to make it easier to raise the axle with a second jack. This point must take the weight of the body because once the air bags are deflated, the suspension is not holding the weight.

I am also curious why using two fully-rated jacks and having to provide adequate ground support for both jacks (because if one fails, the other must support the lot) and then releasing the air from the air bags (how do you do that without modifying the air system???) is really much less work or any safer than using one jack on one base and jacking three inches more on one jack.

On an MC9, the rear jack points are jacking up the body and 'sprung' weight of the suspension.  While the air beams are part of the 'sprung' weight, you're not jacking on the airbeams proper.   The airbeams  are hollow chambers that form the upper airbag mounts. 
When the bus is aired up, the rise gives you about 6" of movement.  Placing a jack under the proper jack points and snugging it up holds the body up about 6" higher than an un-aired bus. 
Keep in mind that the unsprung components of the suspension are still sitting on the ground. 
There's an air drain (line from the compressor trap) inside the LH service door near the tag axle dump valves.  The air is easily drained from that drain valve.    This point is also where you would want to air up an MC9 with shop air.
With the jack points held up, and the bus air vented off, the front air suspension drop will add another few inches to the rear of the bus too...good for working under the engine...changing filters etc.
Once the bus air is bled off, the unsprung weigh is easy to lift with a small bottle jack. 
It is contraindicated that the weight of the coach be lifted from any unsprung component. 
When I jack my MC9, I block the post behind the drive axles for safety.  I'm not sure that air-beam units have this post.  However, the jack post can be blocked next to the jack. 
Jacking up an MC9 high enough to remove the drive wheels, using only the jack point to lift a drive wheel, will require about 10" of jacking from an airless position.   It'll have to be jacked high enough for the shocks to lift the axle. 
I generally place a jack under both rear jack points when jacking the bus so's not to twist the crap out of the body.   I really don't know if this could damage the thing, but I'm not going to test it. 
I am able to have the drive axle off the floor sufficient to remove the drive wheels in less than 5 minutes and not a lot of work....with two manual 12 ton bottle jacks and two 2 ton jacks.  The second jack won't hold the weight of the bus, but it's blocked anyway, so not a problem. 
I offer this method for information...however one wishes jack their bus up to remove their wheels is cool by me!  Just be careful!  Smiley
As stated prior, jack failure isn't as much an issue as driveway failure.  Be very careful with the jacking substrate.   Residential driveways are not designed for jacking up buses.  Most aren't designed for the weight of a the bus on tires.
Bowmaga, hope you get that tag (s) lubed and cooperating.   We're going busing next week, so I'll miss the action...bummer.  I'm too cheap to buy one of those 'aircards'... Angry
We're heading over to Denton Farm Park in Denton, NC, for 5 days, then return home for a couple days...wash the bus and fire back down to Fayetteville, NC, to Gene and Darrells KOA bus'n rally.  Anyone in the area oughta mosey on down for a fun-filled weekend!    Grin Grin Grin Cheesy Roll Eyes Cool 
Cheers, JR

Logged

JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
Tony LEE
Sr. Member
****
Offline Offline

Posts: 404



WWW

Ignore
« Reply #82 on: May 03, 2008, 03:25:01 AM »

Sorry JR but that doesn't seem to apply to my MC8 so it must have quite a different suspension arrangement to yours. On mine, the jacking point - the square tube projecting below the front airbag just in front and inboard of the dual wheels is below the airbags so jacking there raises the part of the suspension directly connected to the axle. It maintains the same distance from the ground whether the airbags are inflated or not. Of course jacking there also raises the whole body too because that is supported off the axle via the airbags. As I said, I understand your technique, but first I would need to know where the approved body jacking point. Where is the jacking point that just raises the body (or holds it up when the airbags are deflated) and leaves the axle hanging (unloaded)?

As for letting air out of the airbags, I thought there were non-return valves just prior to each levelling valve. Wouldn't this prevent de-airing the suspension via the inlet in the engine compartment.
-----------------------------------------

Last time I got a new tyre, it was in a small country shop and the installer couldn't work out what was wrong with the jack. Lots of pumping and not much movement - and difficult to see what was going on because it was raining and he didn't want to get down and dirty.

Jack ended up embedded so far in the pavement that the handle couldn't move.  Was quite a job to get it out.
Logged

JackConrad
Orange Blossom Special II
Global Moderator
Hero Member
*****
Offline Offline

Posts: 4447


73' MC-8 8V71/HT740 Southwest Florida


WWW
« Reply #83 on: May 03, 2008, 06:10:16 AM »

On our MC-8, the body jacking point is behind the drive axle where the lower radius rod attaches. No "non-return" valves on our MC-8.  Jack
Logged

Growing Older Is Mandatory, Growing Up Is Optional
Arcadia, Florida, When we are home
http://s682.photobucket.com/albums/vv186/OBS-JC/
NJT5047
Hero Member
*****
Offline Offline

Posts: 1942





Ignore
« Reply #84 on: May 03, 2008, 11:09:45 AM »

Like Jack says, my MC9 will drop like a rock if the air is bled off.
And, as Tony says, an MC8 may be different from an MC9...an MC8 is definitely different from my MC9.   My bus doesn't have airbeams.   

I'm gonna post a picture of what I'm talking about.  That'll clear up what I'm jacking on.  Wink
JR
Logged

JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
Tony LEE
Sr. Member
****
Offline Offline

Posts: 404



WWW

Ignore
« Reply #85 on: May 03, 2008, 11:57:41 AM »

Ah, that explains it. Both the original poster and I have same vintage MCIs - but different models - so it is good to clear up any confusion. A bit like those with spring parking brakes advising those with DD3s - can cause injury or damage.
Logged

bowmaga
Betty Owner 1
Full Member
***
Offline Offline

Posts: 148


Super Betty




Ignore
« Reply #86 on: May 04, 2008, 05:31:08 PM »

well the original poster is back....good news bad news.  Good news is..we greased the hell out of everything and everything pretty much has grease to it.  10 tubes of grease pumped into the tag axle zirts.  Unbelievable.  Bad news....they are still stuck.  I don;t think they even moved.  We even went so far as to replace grease zirts and we also took the collar off the split washer and the flange key...I just don't know what those things do under that collar?  We were under the bus and greased the cross tub where we could and had grease coming out of the end of the axle where the arm assembly meets.  The collar wasn't taking grease on the bottom, so that made us dig in farther.  We did not take the split washer apart, it seem somewhat OK.  We know there is grease back in the bearing tube as it is called, but i think the damn thing is just rusted fast...its not busting loose and I don't know what else to do.   Those guys who pryed theirs down....are lucky.  No amount of prying will get these down.  The only other thing I can think of doing is unhooking the air line to the air bag, unbolting the bag, unbolting the collar again and try to pull it out of the bearing tube, as the manual says to do, manually grease it up and slide it back in and that would probably work....if we can get it out.  Then hopefully we could get the air bag hooked back up so it didn't leak.  Other than that, it was a beautiful day in northwest Ohio.  She is one big frustrating piece of steel.  She is a lot more level than she was....still at least an 1" or 2" out of level, but I think I will try to adjust the leveling valves next to see if i can get the rest out.  I think the girl has been sitting so long, leaning to that back left corner, she's kind of "grown" into that position.  Anyone else have any other ideas??  Other than a forsale sign...I've thought of that several hundred times myself.
Logged

Greg Bowman
1979 MCI MC9
Dallas
Guest

« Reply #87 on: May 04, 2008, 06:13:10 PM »

If you are gonna remove the airbags anyway, you might as well see about changing them out... just cheap insurance for later and a good way to keep from having leaks when reinstalling.

While you have the bags off, you might try putting a low profile 12 - 20 ton jack on the plates where the airbags were and try jacking the axle down.

I know this is probably a stupid question, but....
The tag axles aren't chained up are they?  Roll Eyes
Logged
bowmaga
Betty Owner 1
Full Member
***
Offline Offline

Posts: 148


Super Betty




Ignore
« Reply #88 on: May 05, 2008, 05:52:52 AM »

I wish they were chained up, but no, unfortunately they are not.  I figured as much.  Is there any place to get parts other than me calling MCI?  I just feel like i call them and i have no other options, they can charge me whatever.  I need to get new shocks for the tags anyway, i figured i might as well get new air bags and plates.  Do you think if i get the axle pulled out, I can get her parts broke loose, greased up and put back in so they will work?  I don't understand the bearing tube, what its all made of and/or how it works.  The manual simplifies everything to much.  Is the bearing tube made up of actual ball bearings?  Or is it just a tube that rotates within another tube?  I'm not even sure we will be able to get the darn thing out.  I'm pretty sure it's not going to just slide out of her spot.  I just can't believe its rusted fast so much that it won't break loose.  The worst part is they both aren't stuck in the same position.  The passenger side is almost down....and the drivers side is pretty much almost up, by what i can tell.  I need some help....I don't think I can afford to pay someone to spend a day trying to bus them loose.
Logged

Greg Bowman
1979 MCI MC9
bowmaga
Betty Owner 1
Full Member
***
Offline Offline

Posts: 148


Super Betty




Ignore
« Reply #89 on: May 06, 2008, 05:03:21 AM »

What happened to all the helpful advice???  Don't tell me you guys are stumped and I'm on my own......The more I think about this tag, the more it frustrates me.  If it can get grease into the axle and tubes where grease needs to be, I would think this thing should break loose.  Has anyone else out there had to actually replace a tag axle because it was stuck fast.  I hope I'm not the first.
Logged

Greg Bowman
1979 MCI MC9
Pages: 1 2 3 4 5 [6] 7   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!