Remove leveling valves - install manual system

[sledhead]

like Daves system I put 1/4 " lines 1 per corner no splices to the gauge control and 1 air in line with 5 air gauges .simple air only push to add and pull to let air out . I ended up removing the original leveling system as I never used it after I installed the leveling system . before you start measure all 4 corners in height so you can adjust the pressure to that when you drive the coach

Dave

[Dave5Cs]

The Daves agree, LOL

Dan don't know about your coach but our MCI 5C bags according to Goodyear our double convoluted bags can handle 110 lbs safely. We have had them to 100 more than a few times with no problems. I keep them between 60 and 90 depending on how rough a road is. And I would never go back to leveling valves. Our bags stay up where we put them for as long as we want them too.

Richard there are 4 needles in two valves so there is a needle for each corner independently.

Jim they are air valves.

[richard5933]

Hang on... roll out of bed?
Is this levelling problem while driving, or after the air has bled down while parked?...
Buswarrior

Our air doesn't bleed down. When we park, it will hold that height for months. I parked the bus for winter at the start of December. When I started it the next time in mid-March the height was exactly where we left it. So, at least that part we have - the bus will stay up. For whatever it's worth, at the moment we have no air leaks in the suspension system. The auxiliary tank will bleed down overnight, I think because the wiper switches bleeding air, but the suspension holds itself up.

What I'm talking about is how the bus is in relationship to the road. Assuming a perfectly level parking area, usually we'll pull in to park and the bus will be level side-to-side, as it should since the pavement is level. Occasionally however, it will list to one side - perhaps an inch lower on one side than the other - in spite of a level parking area. This is what I mean by rolling out of bed. When it acts up, it will act up going down the road as well - not maintaining the bus parallel to the road.

Am I correct in assuming that when driving on level/flat pavement the bus should maintain itself parallel to the pavement? And the job of the leveling valves is to maintain the bus parallel to the pavement as the weight load changes inside the bus?

One other question after seeing what you guys have done to manually adjust the height...

The GM has only three leveling valves from the factory - two in the rear for side-to-side adjustment and one in the front for front to rear adjustment. Could your system be configured to maintain the tripod setup that we've got now? If so, then it sounds like I'd need to do is run two airlines from each leveling valve to the new control panel and then use the adjustment valves/gauges like you have in place of the leveling valve. Or do scrap the existing airline feeding the leveling valves and install one master feed line to the new control panel, and then run a single line to supply air to each of the three locations where the leveling valves are now?

[buswarrior]

Your suspension bellows and levelling valves maintain air pressure integrity when parked, their air source does not.

That's the set-up for the irregular exhausting I described.

Yes, the levelling valve's simple job is to maintain the distance between body and axle at their mounting points.

If weight in the chassis is uneven, the valves care not. Whichever side is trying to be lower or higher will have air put in or taken out to return the body to axle distances.

Put the bus on banking, the body will take on the same angle as the axles.

They lead as busy a life as what a shock absorber does, pretty much in constant motion due to road imperfections. They often develop seepage leaks that trigger the sinking while parked seen on some buses.

The last commercial operator is not going to be fixing air leaks, as they flog the last bit of life out of the coach, so we busnuts inherit a common problem, and levelling valves get a bad name in our hobby.

Happy coaching!
Buswarrior

[chessie4905]

You are ready to change your leveling system before you get it figured out? Thousands of air ride coaches with the same system that work fine....keep digging. Is there still air pressure in tank below driver when this happens? If not, think about an auxilliarry air compressor. See post previous on air compressors. You could, at least try one to help in diagnostics. Leaking bag or fitting?

[richard5933]

You are ready to change your leveling system before you get it figured out? Thousands of air ride coaches with the same system that work fine....keep digging.

Any suggestions where to look? New leveling valves (x2) from Luke. Two different shops have tried to keep her balanced. I'm out of ideas.

[Dave5Cs]

Interesting discussion. Roads are normally not level. They are canted from the center to drain at 2 to 4 degrees or from one side to the other. So if you are driving a bus lets say down that road and it turns around a corner the bus liens one way or the other so it is not at any time the same measurement between the body of the bus and the road unless you are parked on a perfectly level pad.

Going around a clover leaf the bus will after 2 seconds change to level itself or go to its level. Meaning that bus may have been set to out of level like most buses in service are so that the passengers are comfortable on those out of level road.
 
So if its measurement stayed the same between the body and the axle then it would not be functioning correctly.

If it is less of a lean and then back to level because of the preset and time delay it will not react at all if it is within those original perimeters.

[richard5933]

Interesting discussion. Roads are normally not level. ...
If it is less of a lean and then back to level because of the preset and time delay it will not react at all if it is within those original perimeters.

Using this most recent visit to the shop as an example: The bus was pulled into the shop - parked in a level bay. Driver's side was about 1" lower than the curbside. Ride height was set so that the bus was withing 1/8" side-to-side. Held overnight at same height. Bus went out for a test drive, returned to same bay. Now the driver's side is 1" too high. Ride height was set again, going back to where things were when this all started, but this time the bus sits level.

What's confusing is why it seems to randomly change the side-to-side height settings. It can return to that same level bay half a dozen times and sit perfectly level, and then on the 7th trip out and back it sits off to one side (and may stay there for a few more test trips).

When it was at US Coach last fall, Bill kept setting the ride height. Then he'd dump the air and see if it would come back to the proper height. Each time he did this it seemed to come to a different amount of tilt to one side.

Seems to me like something is sticking, but other than the ride height valves what moving parts are there that could stick?

[dtcerrato]

As far as manufacturer recommendations for air bellows psi - it would differ between the manufacturer of the bag (Goodyear, Firestone, etc.) & the manufacturer of the bus (GM, MCI, etc.) I'm thinking when da 4104 "GM" book says 75 psi max. they're not referring to what the max pressure is that the bag will hold, but are setting the design parameters of what the engineers designed the coach's preferred ride height to be at which in the case of our bus it states to maintain a measurement of 3-1/2" to 3-3/4" distance between the axle & rubber bumper which probably corresponds to the 75 psi air bag. Going a step further than that - would be the ideal relationship of the drive train angles (drive shaft, u-joints, etc.) because they change with height...

We have the capability to manually level our tripod to level out the bus in an uneven campsite or to lean the coach for assisted more efficient dumping of the holding tanks, etc. We didn't change the function of the leveling valves just added tees with 12 vdc activated solenoids between the leveling valve & the air beam. also have a solenoid that will let air expel out of the auxiliary air tank. Taking advantage of the pressure regulator valve we bring the air down to 65 psi - at that point the regulator valve won't feed air to the suspension system so once the bus is manually leveled or leaned to dump using the 3 tripod solenoids it will stay w/o building back up. Being a nickel squeezer (penny pincher) the system cost under $50 and took a whole day to install!

[Dave5Cs]

Dan don't know what to tell you but it works fine for us. The reference to the 110 was not that I fill them to that it was just that was what you don't want to go over according to them. Yes I know that keeping it close to 3-1/2 " in height at the bump stops is pretty close to what it is at. We like the ride at 85- 80 better than at 65-75.
I also know you like to keep your coach original. That is something I don't always do. I like to upgrade when possible. Your engine is transverse and ours is a T drive which are slightly out of phase but not much with drop box so not a problem.

So anyway Richard wonder if they cleaned the bag filters right at the end that connects to the bags if they are similar to MCI's. Seems that if it is leaning to the right side that it would definitely be the rear valves.

[chessie4905]

Check the leveling valve links that connect to the body. If they are too tight, they could cause valve to bind. They should have rubber grommet at each end with a metal sleeve through the grommet, where the bolt attaches. Sleeve missing or worn grommet can cause slop causing your problem.

[richard5933]

Check the leveling valve links that connect to the body. If they are too tight, they could cause valve to bind. They should have rubber grommet at each end with a metal sleeve through the grommet, where the bolt attaches. Sleeve missing or worn grommet can cause slop causing your problem.

Thanks - it's now on my list of things to check.

Regarding air pressure - from the Service Manual for our 4108: ..Normal system minimum pressure is 102 psi and maximum pressure is 115-131 psi...

System apparently begins to once the pressure gets to 65 psi.

[sledhead]

if it was me I would remove the old system and install 4 new lines one to each corner . then you can adjust the height at any time . I have even adjusted the side to side adjustment when I was driving in a wicked side wind .

dave

[richard5933]

if it was me I would remove the old system and install 4 new lines one to each corner . then you can adjust the height at any time . I have even adjusted the side to side adjustment when I was driving in a wicked side wind .

dave

I've read that using 4-corner adjustment on a GM doesn't always end well - something about torquing the body if the adjustments are done wrong and result in a twisting.

Perhaps like you said but with 3 new lines? (Two for rear and one for front)

[daddysgirl]

Your suspension bellows and levelling valves maintain air pressure integrity when parked, their air source does not.

That's the set-up for the irregular exhausting I described.

Yes, the levelling valve's simple job is to maintain the distance between body and axle at their mounting points.

If weight in the chassis is uneven, the valves care not. Whichever side is trying to be lower or higher will have air put in or taken out to return the body to axle distances.

Put the bus on banking, the body will take on the same angle as the axles.

They lead as busy a life as what a shock absorber does, pretty much in constant motion due to road imperfections. They often develop seepage leaks that trigger the sinking while parked seen on some buses.

The last commercial operator is not going to be fixing air leaks, as they flog the last bit of life out of the coach, so we busnuts inherit a common problem, and levelling valves get a bad name in our hobby.

Happy coaching!
Buswarrior

I understand the single front valve and dual rear valves automatically maintain the proper level. I suppose weight couldn't matter unless all four corners are independent?
I always try to understand what improvements I should make...hence my interest in this topic.
But overall...is a independent, manual system an improvement over the existing system or would it add another item to the long list of weekly checks?
Or, could it be beneficial to plum an accessible connector directly to the three existing valves and maintain the height with the existing levers?

Questions are part of my thought process...I don't expect answers, and I am grateful for the post.