Purpose and benefit of rear air dump feature?

[BellaBee]

Hello,
We are just about to take ownership of an XL37RB (very excited). We're upgrading from an I5 for a few reasons.

I've been doing research and learning about the M2 chassis to help me understand what I've purchased and how to best use and maintain the rig.

I understand there is a rear air dump switch and would like to understand the purpose and benefit of this feature. The I5 (our first MH) did not have air suspension or air brakes so these features are very new to me. I get the braking system as I noticed a significant difference in stopping power between the two chassis. The I5, while nice from a power perspective, had me cringing at times to stop the rig when morons inevitably cut you off in some way.

So, is the rear air dump feature useful because while driving the rear air suspension is filled and when you park you want to relieve this pressure? If so, why is that important?

Or, is it useful to help lower the coach a bit when parked? or, is it something completely different?

Any knowledge and experience with this is much appreciated.

Thanks in advance.

[FOURWHL]

Can dump the rear air bags and lower the back end on a site that's tilted forward to reduce amount of leveling required. I find the majority to be tilted forward and really wish I had that functionality but haven't gotten. around to adding it myself

[Vansteenburg]

Also, if you don't dump and there's lift on the rear, the air suspension can drain the tank trying to re-level due to the lift. Hit the dump and release the pressure on the bags and drop the back a few inches.

Also, don't forget, you'll get air warning if either tank is below 70lbs, and brakes won't release if the primary tank(p) is below 70lbs. The secondary tank runs the suspension, seats, etc.

[BellaBee]

So is the rear air suspension system automatic or do you have control of the level and firmness you desire?

[Vansteenburg]

Its automatic. You can get it adjusted if the height seems out of balance or too low.

[Travler]

I don't think they all come with the air dump feature. We have a 2017 XL37RB and love it, but we do not have the air dump feature. I think I remember from post in the past that there were some issues with people forgetting to put air back into the bags and causing damage. So I think they stopped the option.

[bclemens]

We stopped the option, but then added it back in for the 2018 or 2019 models. It's a catch 22...but we would rather the function be there.

[RV Randy]

It is not intended to be used to adjust your rear suspension height while driving. You either dump all of the air or when you turn it off the rear suspension will automatically reinflate to the preset level. I only use it for 2 purposes: When I pull the rig into my RV garage I dump the rear air and it allows a couple more inches of clearance between the top of my AC units and the garage door. When I unhook my trailer I lower the trailer jack down until it is firm, undo the coupler and dump the rear air. The hitch lowers and the ball drops out of the trailer tongue so I can pull forward. Reverse the process to hook back up.

[BellaBee]

So is the feature on my coach that just left the factory? Midnight Sapphire XL37RB now in-route to DDRV in SoCal. Thx.

[bclemens]

If it is a 2019 or 2020 then it would be.

[FOURWHL]

Just gonna leave this one here. This is why rear air dump is/would be nice

[houstonstroker]

Mine does not have this feature but I'm a little confused. After leveling the coach the rear bags self deflate at least that's what I think the air loss sound is. Since the feet are already down is the coach rear lowering or not?

[Silver Arrow]

I heard the same hissing sound in my 2014 DX3 a couple of times when the leveling jacks were down & initially I thought one of the air bags had developed a leak. In the process of trying to figure out how I could lift the back end up so I could get it down my driveaway I saw how the air suspension worked. There's a pair of mechanically actuated air valves which controls air into or out of each airbag to maintain the set height. When you significantly lift the back end w/ the jacks, the leveling system thinks the vehicle is too high & it exhausts air from the bag(s). Since this is a purely mechanical system it works all the time as long as air is available. If you look at the rear axle you'll notice 2 quarter inch dia. rods going from the backside of the axle housing up to a lever arm on a valve mounted to the frame. These valves control the ride height. As these arms move up or down, the valves add or bleed air from the bags at a slow rate. The lever arms can be adjusted to change this height, but you probably shouldn't mess with them.

[FOURWHL]

Idea is to dump the air bags before leveling so the front doesn't have to compensate so much. Here that would've saved me several inches of blocking in the front.

[bclemens]

Originally Posted by FOURWHL

Idea is to dump the air bags before leveling so the front doesn't have to compensate so much. Here that would've saved me several inches of blocking in the front.

Where is this mod on the upgrade rank?

[FOURWHL]

After crawling under and disconnecting the air bags manually its rocketed up to near the top! Benefit being while I was under I think I have a pretty simple idea as to how to do it.

Originally Posted by bclemens

Where is this mod on the upgrade rank?

[Webefine]

Here you go!

[Rancher Rob]

My 2019 XL37BH rig has the rear air bag dump button. I just dump before leveling as that is what they told me to do at the PDI. I do know from experience leaving the dealership and hitting a speed bump, you definitely want to re-inflate them before driving!

[AWF1945]

So I'll ask..if you want the switch in the dash added, is it already plumbed in the back? Or do they have to add a bunch of stuff? Bclemens, did ya'll just have switch removed, or the whole system? Mines a 2015 37 RB .. thx.

[Vansteenburg]

I googled that question on adding an air dump valve, and the article in Overdrive appears to be the simplest. Need a Haldex air valve, some wiring and a switch. Pretty simple instructions.