LXI SUSPENSION ISSUE

[al perna]

guys I continue to have a issue with my leveling . On a hard R turn she will drop hard L side . On the L turn she drops R side .

all air bags are new
ride height is 8"+-3/16
replaced panhard rod
replaced all HCV

the folks at Josams said they have no idea what the issue is .

all thought and ideas will be appreciated

[dentmac]

For discussion purposes... I think the solid axle coaches have a three pt leveling system. The 450 had 4 pt until BB changed the Hadley system.
Are the front bags plumbed together somehow? The rear sensors only, are responsible for side to side leveling. If air can flow unrestricted between the front bags,tipping would be severe. The LXI perhsps has an anti sway nar. The 450 changed dramatically when the bags were plumbed together .

(10-18-2014 18:07)al perna Wrote:  guys I continue to have a issue with my leveling . On a hard R turn she will drop hard L side . On the L turn she drops R side .

all air bags are new
ride height is 8"+-3/16
replaced panhard rod
replaced all HCV

the folks at Josams said they have no idea what the issue is .

all thought and ideas will be appreciated

[al perna]

Ross, There was a anti sway bar , I removed the bar to increase ride quality some 70,000 miles ago. I can not say the issue surfaced upon removal , but it is worth noting . thank you

[GregOConnor]

I start problem solving with an assumption that something I repaired or modified is the issue. If there is electric involved it sounds like a diode issue. I have an equipment trailer with antilock brakes that gets some signals from bag pressure the trailer antilock works on any tractor even if the tractor has no antilock. Dot put a small blue light on the side so inspectors can see that the computer is working. Chp inspector told me there was a small window of time when these systems were installed. wonder if the problem is that complex

[davidbrady]

I agree Greg, problems tend to be a result of something that recently changed. In this case I'd have my eyes on the Panhard rod and the HCV's. Al, tell us about the panhard. I think you fabbed your own at some point but then you bought a new replacement bar from Ridewell. Is this true? What parts are new, what came with the new bar? Ends, bushings, and bolts? I'd also check all the attachment points for the bar. Check for cracks at the frame hanger and also at the top of the Rockwell diff cover; look for a dusting of rust powder which usually accompanies cracks. Since the behavior is symmetrical: leans to the left post right turn and leans to the right post left turn, I think an HCV issue is less likely. The cause needs to be associated with something that comes into play on both left and right turns and that would be the panhard rod or the tag axle. The tag axle does offer a degree of anti-roll; on my fixed tag axle LXi, the air springs are plumbed together like they are on the steer axle. If the tag is shifting this could also be a cause, again all attachment points, bushings, and welds need to be checked. Does anyone have an air diagram for a steerable tag axle? Here's a schematic for the fixed tag LXi suspension.

WanderlodgeGurus->Document Library->Models->LXi->LXi Print Package->LXiPrintPackage#4.pdf (Page 4).

Al, what does your tag air pressure gauge read as you enter and leave a turn?

[al perna]

the Pan rod is new . I was able to inspect , but only looked to find a bent or broken rod. I do wonder about weight , Randy mentioned the Honda Gold wing ( heaviest of all bikes ) hanging on the rear . The only problem with this is she has been there for over 20,000 miles or so . I will have her weighed and report the weights next week when we roll south .

Greg, I also agree that a most recent change is most likely the cause. This all points to the pan hard rod and its measurement . My question is why would the frame line up on a straight line but shift while in a turn ? There is approximately a 2" shift from Left to Right . I wonder if it needs to be tightened up a bit ? this would invove removing one side , use a jack or suck to raise the axle to allow the bolt to realign . You can see this should be left to those with the equipment and expertise " Not I " . so the next question is to find a shop who unlike Josams won t run thru the issue so they can get the next one on the rack .

[davidbrady]

Al,

Does it still lean out of a turn without the bike on the back, or does this odd behavior only manifest with the bike on the carrier?

[davidbrady]

Hey Al,

I did some quick back-of-the-envelop scribbling. Here's what I have:

1) LXi w/o bike on carrier: 50,000lb.
Steer: 16K
Drive: 21K
Tag: 13K
Center of gravity: 15' 4" behind steer axle

2) LXi with 1500 lb bike on carrier: 51,500 lb.
Steer: 14.7K
Drive: 23.8K
Tag: 13K
Center of gravity: 16' behind steer axle

Remember, the tag axle is pressure regulated and is set to a specific and unchanging pressure regardless of whether the bike is present. This means the tag load doesn't change whether the bike is there or not. (Unless you physically get under the coach and turn the regulator knob).

Ridewell tells me your drive axle is rated at 25K lbs so your okay there. None of the other axles are overloaded either. 23.8K lb on the drive air bags (divided by four airs springs) is 5950 lb per air spring which is well within the limits of the air spring. According to my charts, to achieve this load at design height the air springs require around 85 psi, again well within spec.

There's no reason for me to believe that the bus isn't capable of coming up to full ride height whether stationary or exiting a turn. You're well within specs. It's something else: either faulty or incorrect height control valves or problems with the steer or drive axle panhard rods.

[GregOConnor]

I'm not up on the dynamics but maybe it reacts as designed in the turn to keep the bus from rolling like a class c .... but is slow to return to level after the turn? could it be a valve problem or kink in a bag air supply line. My 94 wb bags air up and down slow. For my air-up question ?? is my bus slow to air??. I often wondered what a comparable bus air-up is. maybe a good benchmark to learn at a bluebird rally. My Komatsu excavator owners manual has a list of reaction times for each cylinder, and ground speed per rmp. I added temps and would like to add db levels some day.

I am sorry to ask continual questions I see that you are researching on a social forum I am censored off of but I have learned a bunch from your issue.

I also wonder if a steerable tag (what ever that is ;dynamic turn or ;caster follow??) Is there a function unique to steerable tags with leveling? a schematic in comparison to Davids fixed will reveal. also the steerable tags had issues and maybe the po had a hack done to correct it?
Thanks for working this out publicly I am in the market for a like vintage bus

[davidbrady]

Hi Greg

I've spent a little time with Al's coach and noticed that the steer tag air pressure does run significantly higher than the fixed tag; it's a passive caster steer by the way. Turns out there's a mechanical advantage that the fixed tag air springs enjoy. In the fixed variety the springs are mounted aft of the axle bolt on location; whereas, with the steer the air springs are mounted between the axle bolt up locations and the frame torque arm mounts. My fixed tag LXi ran 55 psi of air pressure at the tag; Al's runs closer to 100.

Al, something you may want to check is your air compressor governor cycle pressures. The air compressor should cut in at 100 and out at 125 psi. Since your tag pressures are so close to your lower cut in pressure it'd be wise to make sure that your compressor and governor stuff are performing properly - your tag axle air pressures don't give you a lot of wiggle room.