[jdkskyking]

Here’s another ZF Newell quandary…. 

While driving… the Steer Axle Airbags are overfilling and are not exhausting air to lower back down to “Travel Height”. The nose of the bus will riding high. The steering feels different. 

I’ve referred to it in the past as “feels like I’m driving on ice”. 

Like many things on my bus, I’ve been chasing many oddities for years. This condition has also existed for many years but is not consistent. I dive the bus for a while, park it, I get out and notice that the nose of the bus looks higher than it should. This year I finally found a shop in Columbia Missouri that was able to complete a three axle alignment and make my bus’s handling “Great Again”. This condition changes how it drives and pisses me off. 

This is after driving two hours from Bentonville Ar to Springfield Mo.
   


I lowered the suspension completely to allow the bus to “Air Up” to Travel Height.
   


This looks normal.
   


In December of 2021 when my “Handling” problems Began, I had the entire suspension inspected at the factory and it got a clean bill of health. But there was a question about how a HCV so I decide to replace all three and start over. That was my first introduction to the air ride suspension on my bus. 

Yesterday I took steps to correct the problem but this post deserves some background. 
Bus was built in 2004. 
In the past several years,I’ve completed an entire rebuild of the suspension. New ZF control arms, airbags, and HCV. My bus is responsible for the realization that the ZF RAS system hydraulic accumulator has a limited life span. 
I’ve fabricated custom rear HCV control arm for “fine tuning” the rear bag Travel Height. 

I’ll post what I considered using information from this site, internet searches, AI input… 

If you own one of this era units, here’s what my bus’s steer axle Height Control Valve installation looked like in October of 2021.
   
   

In my bus I have a forward hatch in the middle of the forward through bay to gain access.

[jdkskyking]

Here’s a few pics of what I did. Test drive today from Bentonville to Little Rock. 

                           

My intent is to increase HCV Control arm throw. 

HCV is mounted to frame of bus.

The HCV “Control Arm” is attached to the HCV control arm and to an arm welded to the center of the SWAY BAR. 

This is my first attempt to improve functionality of the steer axle HCV without completely re-engineering the system. I will say that the system operates differently than the rear HCV because of the control rod connect to the sway bar vs the rear control arm “hard point” in the rear.

[hypoxia]

1482 is similar but a little different.  The sway bar mount uses a muffler clamp instead of being welded.  I've had a couple of height control valves act similar to what you describe, replacing them cured the problem in my case.  Once the ride height tops off the air springs the ride is the same as having no suspension damping at all.  Even creeping down the road is awful.  On the Newell I have used Barksdale 52321-Q197.  I take the arm off of the valve and use the original arm, I don't even disconnect the arm from the coach.  That valve is plumbed the same as the Newell proprietary valve which makes the switch painless.  You could use a Hadley valve but that might require some adaptation.

I had not given any thought as to the sway bar mount location being an issue.

The access through a hole in the forwardmost bay sure beats other coaches that require getting under the coach.
       

Barksdale 52321 Drawing.pdf Size: 68.37 KB  Downloads: 6

   

[cwl1979]

In my 15 years of commercial experience, when the suspension is being "funny" something isn't working properly. Overextension of the airbags is most commonly caused from the control valve internals going out. buying a new one for 60 bucks is a cheap fix. It's such a common failure part that most commercial drivers up here in Alaska carry a spare. I used to carry one for the tractor and one for the trailer, as well as an airbag for each. If you're really looking for better components with more adjustment, order a Hadley valve.

https://daytonairsuspension.com/products...-h01501-k1

[afrench]

Wow learn something every day.
Didn’t know about the access hole behind the steer axle. Good to know, I think I’ve got a ride height that needs replaced there!

[Richard]

Jeff there is another scenario that can cause what you are seeing.

IF one of the raise solenoids for the front is leaking, then the front can rise like that. Both sides would rise because the front air bags are pneumatically connected when in travel mode.

When the front is raised, it will cause the tires to toe outward due to the design of the suspension. Towed out is evil handling, the coach will go from side to side on it's own.

[hypoxia]

HWH or Valid Levelling?

[jdkskyking]

Jeff there is another scenario that can cause what you are seeing.

IF one of the raise solenoids for the front is leaking, then the front can rise like that. Both sides would rise because the front air bags are pneumatically connected when in travel mode.

When the front is raised, it will cause the tires to toe outward due to the design of the suspension. Towed out is evil handling, the coach will go from side to side on it's own.

Hello Richard, Happy New Year!

Yes, that is on my list to investigate.

My Steer Six Pax is mounted on the forward side of the cab firewall exposed to the elements and very difficult to access. My end goal it to relocate the Six Pack to the left forward bay with my air compressors. I have a new Six Pack ready to go for that project. That will be a time consuming project. 

On my drive yesterday, I stopped at a rest area to check ride height. No change from when I departed the house which was encouraging. When I arrived at the LIT Downtown Riverside RV Park, the Travel Height was 1/4" higher than it should be. 

I will adjust the travel height again today and test drive it again. 

As always.... Thank You for the information !!
JK

---

HWH or Valid Levelling?

VALID

[jdkskyking]

Jeff there is another scenario that can cause what you are seeing.

IF one of the raise solenoids for the front is leaking, then the front can rise like that. Both sides would rise because the front air bags are pneumatically connected when in travel mode.

When the front is raised, it will cause the tires to toe outward due to the design of the suspension. Towed out is evil handling, the coach will go from side to side on it's own.

This is the location of my front six pack. Mounted on the outside/forward of the cabin firewall and aft of the front cap.

Not ideal when I have room in the forward bay where my Thomas air compressors are located. 


   

[hypoxia]

If a raise valve was leaking wouldn't the suspension ride height valve be constantly exhausting?  In travel mode the Valid 6 pack ride height valve should be open.  It is common for the Valid valves to get dirt/grit in them causing leakage.