[[email protected]]

So I have been thinking a bit about airbags especially the drive axle air bags. I noticed that my coach tends to lean and sway quite a bit and I think it’s also part of the reason the coach tends to wander when going down the road. I know there are other potential issues for wandering so do not want to get sidetracked on those for this discussion. 

So my thoughts are that the ping tanks with the large line going to the axle may be contributing to the excess lean. So my rationale is as follows, because the air is not limited to what is in the bag but also the volume in the tank, now you have more volume that can be compressed. I think this is allowing the coach to lean more by compressing the increased volume. Question I have is for those folks that have done away with the large line bags and have gone to the smaller line bags do they notice any lean difference?

Another factor that I am sure affects things is my coach is a hump back coach so the center of gravity may be higher. 

So I may end up doing an experiment by using some reducing fittings and running smaller lines to my drive axle air bags direct, get rid of the ping tanks and use the smaller fill line. See if this improves the lean and hopefully also improves it when driving down the road which would also help a bit with wander possibly. 

Just some musings to keep my mind busy while I have a thousand other things I am trying to get done.

[Gnawrocki1]

Does your coach have a rear sway bar? Mine does and I think it was added at Newell by the previous owner.

I do have the large air lines to the bag tanks and I feel as though the ride is very solid from a sway standpoint.

[[email protected]]

Does your coach have a rear sway bar?  Mine does and I think it was added at Newell by the previous owner.

I do have the large air lines to the bag tanks and I feel as though the ride is very solid from a sway standpoint.

Is yours the hump roof?

Yes, mine has a rear and front sway bars. They are both the same size, around 2” on the rear and front.

[Gnawrocki1]

Does your coach have a rear sway bar?  Mine does and I think it was added at Newell by the previous owner.

I do have the large air lines to the bag tanks and I feel as though the ride is very solid from a sway standpoint.

Is yours the hump roof?

Yes, mine has a rear and front sway bars. They are both the same size, around 2” on the rear and front.

Mine is not the hump roof.  I am not seeing that that additional height and the associated weight moment you mention would have any more than a very very small impact due to the roof line.  
At one point in time, one of my front shock absorber mounts broke at the weld.  I also did not notice any difference in ride.  When I mentioned that to Newell, they said I would not notice much as most of the ride is driven by the air bags and tanks being a part of the damping of the entire system. (as I recall).

Sorry I can't help more

[[email protected]]

Does your coach have a rear sway bar?  Mine does and I think it was added at Newell by the previous owner.

I do have the large air lines to the bag tanks and I feel as though the ride is very solid from a sway standpoint.

Is yours the hump roof?

Yes, mine has a rear and front sway bars. They are both the same size, around 2” on the rear and front.

Mine is not the hump roof.  I am not seeing that that additional height and the associated weight moment you mention would have any more than a very very small impact due to the roof line.  
At one point in time, one of my front shock absorber mounts broke at the weld.  I also did not notice any difference in ride.  When I mentioned that to Newell, they said I would not notice much as most of the ride is driven by the air bags and tanks being a part of the damping of the entire system. (as I recall).

Sorry I can't help more

Appreciate your input. I am not an engineer so I am not sure as to the affect the height has, but I suspect you are probably correct that the difference would be minimal but it is a difference none the less. At this point I am just running these things through my small mind and seeing if anyone else has any experiences to add to the discussion. 
I think at some point I will get under there and make the mods and see what if any effect it has. I may need to try to quantify this somehow. Maybe this is in my head, I may look into something that will track the movement of the coach and I can see how its actually moving or not.

[HoosierDaddy]

I’ve put a few miles on the coach since replacing the front bags. Since the ping tank is in great shape we just replumbed with the smaller 3/8” ? lines in place of the large O/E lines. There is not much difference in ride, maybe slightly harsher. We just replumbed the rear in the same way. I don’t have enough miles yet to tell any difference. What you are describing may be mostly a result of worn suspension bushings. Is your coach equipped with slow acting HCVs? I believe they are recommended. I’ve never felt that my coach swayed or leaned excessively.

[Richard]

Jeff,

Your intuition is right on. The ping tank with the large diameter connection line does increase the air volume which in terms of suspension decreases the spring rate. Going directly from the six pack to the air bags will in theory stiffen the spring rate.

[[email protected]]

I’ve put a few miles on the coach since replacing the front bags. Since the ping tank is in great shape we just replumbed  with the smaller 3/8” ? lines in place of the large O/E lines. There is not much difference in ride, maybe slightly harsher. We just replumbed the rear in the same way. I don’t have enough miles yet to tell any difference. What you are describing may be mostly a result of worn suspension bushings. Is your coach equipped with slow acting HCVs? I believe they are recommended. I’ve never felt that my coach swayed or leaned excessively.

Appreciate your input, I may be a little bit more sensitive to these things than others or like I said it might be in my mind. 

Not sure on the HCV’s I need to investigate those further. They appear to me to have some age to them and possibly could be original. I was going to take a look at them soon enough.

---

Jeff,

Your intuition is right on. The ping tank with the large diameter connection line does increase the air volume which in terms of suspension decreases the spring rate. Going directly from the six pack to the air bags will in theory stiffen the spring rate.

Appreciate the confirmation, understand the concept in my mind but do not have the proper terminology to convey it. I guess going to a smaller line to the ping tank may also be a compromise, I am thinking like a 1/2” line instead of using 1/4” line. Will have to see, not sure when I will be able to get to messing with that, have other fish to fry.

[encantotom]

the newells once they went to valid do not have ping tanks that i know off.

tom