Ping tanks to improve ride

Topic: Ping tanks to improve ride (Read 2272 times) previous topic - next topic

Ping tanks to improve ride

January 26, 2025, 11:12:13 pm

This is probably just wishful thinking. I see that Foretravel has add a ride and handling feature for 2024 and on. This is using ping tanks connected to the front airbags. They act like a larger volume of air to soften the front suspension and allow more movement. Has anyone looked into retrofitting a system like this?

https://www.foretravel.com/img/pages/photo/1680200760_model_ih45_brochure_path.jpg

Re: Ping tanks to improve ride

Reply #1 – January 27, 2025, 12:10:52 am

Only works for independent front suspension which most of us don't have.

Re: Ping tanks to improve ride

Reply #2 – January 27, 2025, 06:00:29 am

Quote from: craneman – January 27, 2025, 12:10:52 am

Only works for independent front suspension which most of us don't have.

What would be the issue with trying to use it on a non IFS suspension? All the ping tank does is make the air bag volume larger and reduce the spring rate.

Re: Ping tanks to improve ride

Reply #3 – January 27, 2025, 07:21:39 am

This was brought up several years ago (like 10 or so) by a member that either had this type of system on a Blue Bird and was looking at the pros/cons of adding to a 320. We had a verry lively technical discussion about the snubber valves that may or may not fit or even needed on a strait axle. I will hunt the archives to see if I can find that thread and link it up later today as I am headed out to Dr. appointments.

Mike

Re: Ping tanks to improve ride

Reply #4 – January 27, 2025, 09:23:21 am

Quote from: Pamela & Mike – January 27, 2025, 07:21:39 am

This was brought up several years ago (like 10 or so) by a member that either had this type of system on a Blue Bird and was looking at the pros/cons of adding to a 320. We had a verry lively technical discussion about the snubber valves that may or may not fit or even needed on a strait axle. I will hunt the archives to see if I can find that thread and link it up later today as I am headed out to Dr. appointments.

Mike

Either of these? (I searched for "snubber" with you as post author)

Source Engineering Comfort Air Ride Valves

motion controls

ETA - Looks like you mentioned the main thread on it (discussion with member travelite who used to have a Blue Bird) in one of those posts:

Ping tanks

Re: Ping tanks to improve ride

Reply #5 – January 27, 2025, 11:46:21 am

Ping tanks can be added to any air suspension. The trick will be to have the correct volume. Softening the 'spring rate" too much can result in the suspension bottoming out on larger impacts. Snubber valves and other controls may also be helpful. As spring rate is changed the damping of the shock absorbers become more critical. Rasing the ride height will reduce bottoming out and may also help as an easy fix. Try raising the height an inch and see if that helps.

Re: Ping tanks to improve ride

Reply #6 – January 27, 2025, 12:01:58 pm

Quote from: Dennis H – January 27, 2025, 11:46:21 am

Try raising the height an inch and see if that helps.

I would absolutely NOT recommend changing ride height from factory spec!

Shocks have a max extended length, raising the ride height could easily have the shocks supporting the weight of the axle on dips as they reach max extension.

In the rear, the very short drive shaft angle is critical. Changing ride height by an inch changes that angle.

Re: Ping tanks to improve ride

Reply #7 – January 27, 2025, 01:03:41 pm

So much more to this than many understand. Years of offload suspension and trouble shooting improperly serviced aircraft struts has taught to me a lot. Increasing the air volume will increase travel by reducing the compression ratio to compensate movement. When you hit a bump in the road and the axle moves closer to the coach the pressure to hold the coach up increases till it either bottoms out on the frame or overcomes the load induced. On my U320 3610 I have installed end of travel switches on the front axle and have noticed on larger hi speed bumps that I have actually gotten to end of travel range. It only happens on hi speed large road bumps usually associated with construction that was not posted. In my opinion my standard setup is very close to what I would design into a system to start with. Variables could have been bigger or smaller bags also. Granted shocks play an equal part of this equation. They spoke of 3/4 inch lines and if you have changed airbags on a 320 you would know the current stock size lines are a pain to install. Also the port into the bag is restricted to about 7/16" diameter with a fitting inside of that. (Restriction) this in my world would not be possible to change. I personally like the response of our coached compared to other vehicles I driven in regards to ride and roll.
For the space available and the line restrictions internally within the stock airbag I think you would improve ride by going to better shocks. our shocks lower mounts are not double sheared and modification should be completed by all of us, and especially with higher compression and rebound requirement shocks. Tires also affect how your coach rides. I really didn't see a return to additional tanks and associated heartache to install. Basically we already have these additional tanks by having dual air bags per wheel??? Most only have a single airbag. Shocks and tires make more sense in my world.

Re: Ping tanks to improve ride

Reply #8 – January 27, 2025, 02:37:00 pm

With OEM shocks and H tires, we don't have a problem with ride. It's good unless you hit highways with lots of pot holes and uneven bridge approaches. Changing to G tires lowers the load rating and dropping pressure also lowers the load rating. As less and less $$ are spent on infrastructure, the RV ride is going to be worse overall. There should be a road rating app available.

RVs on rough roads must increase wear and tear with more shop time/expenses. Perhaps just one of the reasons big RVs are falling out of favor.

We drive over the same roads with a MBZ ML320 and a Lexus RX400h, both SUVs. The difference in ride is amazing. Shows what a more sophisticated suspension will do with the same tires/pressure. But don't think for a second that RV manufactures are going to be able to duplicate Toyota's engineering.

Pierce

Re: Ping tanks to improve ride

Reply #9 – January 28, 2025, 08:59:46 am

Quote from: wolfe10 – January 27, 2025, 12:01:58 pm

I would absolutely NOT recommend changing ride height from factory spec!

Shocks have a max extended length, raising the ride height could easily have the shocks supporting the weight of the axle on dips as they reach max extension.

In the rear, the very short drive shaft angle is critical. Changing ride height by an inch changes that angle.

Your point is well taken. As for rear driveline articulation the driveshaft design has to accommodate and work anywhere from full axle drop to full sitting on the bump stops. Chaning the ride set height slightly will not have any ill effect.
As for topping out the shocks, any change in suspension damping may also affect this That is why I mentioned that adding ping tanks may require different shock damping. I suggested the slight change in ride height as that in effect increases air bag volume and some of the road impact feel is from the suspension bottoming out. My suggestion is a minor tweak.

Re: Ping tanks to improve ride

Reply #10 – January 28, 2025, 10:11:26 am

You might want to reconsider the fact driveshaft design has to accommodate and work from full axle drop.

Ride height question

Re: Ping tanks to improve ride

Reply #11 – January 28, 2025, 10:28:14 am

While driveshaft angles may be much greater with full extended height, for long life and vibration free operation, for an RV the angles should be at least .5 degree to a maximum of 3 degrees. Easy to bring coach to normal ride height then raise it an inch and check the shaft angle. For angles greater than 3 degrees, here is a chart.

Pierce

Re: Ping tanks to improve ride

Reply #12 – January 29, 2025, 02:03:43 am

Suspension changes come with many unforeseen changes. Raising the rear of the coach will also effect the castor on the front suspension. You think the manufacturer didn't find the sweet spot? Again I repeat better shocks and tires before redesigning your coach. That being said if you do come up with an improvement I'll be first to follow but it has to work. Downside to a mushy suspension will be body roll in the turns and stability changes. Imagine having a blowout and causing damage to someone else because you deviate from factory design??? I'm not a lawyer but always fear what other may think. And yes I do deviate from original design so I probably should just keep my opinion to myself. Just saying.

Re: Ping tanks to improve ride

Reply #13 – January 29, 2025, 11:18:48 am

I figure Foretravel engineers knew what they were doing. After 265k miles on the coach- she rides just fine.

Re: Ping tanks to improve ride

Reply #14 – January 29, 2025, 11:49:59 am

Quote from: erniee – January 29, 2025, 11:18:48 am

I figure Foretravel engineers knew what they were doing. After 265k miles on the coach- she rides just fine.

I completely agree. 👍 👍

Re: Ping tanks to improve ride

Reply #15 – January 29, 2025, 08:39:27 pm

Thanks for all the replies. It would definitely require some re-enginering. I studied suspensions a little, way way back in school but nothing like this. The softer suspension could work but I think now that would require more travel. Like you all said, this change drives a lot of things. Too bad as the SW US highways are littered with potholes.

DSD. The new Foretravels also have the anti-roll bar needed for that soft front end. That front end must really soak up the bumps.

Re: Ping tanks to improve ride

Reply #16 – January 29, 2025, 10:22:07 pm

Quote from: AdventureSofie – January 29, 2025, 08:39:27 pm

DSD. The new Foretravels also have the anti-roll bar needed for that soft front end. That front end must really soak up the bumps.

Or they needed to add to overcome a deficiency. Personally on our old coaches I actually appreciate how the dual rear tires manage roll without a physical sway bar. While traveling down the road with large crosswinds the rear manages it well and both front tire handle the loads from steering only reducing the down wind tire loading our tires/wheels run the same temperature in a crosswind because both front tires are loaded equally. Pretty nifty IMO. had to add a huge sway bar to the rear of the bronco because roll was terrifying with over 20" of travel. It's all about tradeoffs and IMO Foretravel's drive so much better than single inboard airbag vehicles. Having outboard twin airbags is a great design.

Re: Ping tanks to improve ride

Reply #17 – January 30, 2025, 01:17:07 am

The MCI series of buses with their single inboard airbag leaned precariously at the hint of a corner. This may be the reason for your quote, " It's all about trade offs and IMO Foretravel's drive so much better than single inboard airbag vehicles. Having outboard twin airbags is a great design." GM's buses like my 4107 also had one inboard airbag but the air suspension design along with the full monologue construction gave them the reputation of being the sports cars of buses. In our u300, the bridge construction is only 13 feet of the length or 36 percent. This is why Foretravels flex and suffer windshield cracks or allow the windshields to move. Having owned both, as good as the U300 is, it's no match for the handling of the GM buses.

Pierce

Re: Ping tanks to improve ride

Reply #18 – February 02, 2025, 10:19:02 am

Giving this some thought a better solution would be to use a larger diameter air bag. This would increase the volume but also reduce the air pressure required to support a given load.

Re: Ping tanks to improve ride

Reply #19 – February 02, 2025, 10:26:29 am

Quote from: Dennis H – February 02, 2025, 10:19:02 am

Giving this some thought a better solution would be to use a larger diameter air bag. This would increase the volume but also reduce the air pressure required to support a given load.

Foretravel used a larger air bag then the Country Coach when I was comparing two different coaches a long time ago

Affiliate Notice