How high is too high

[Laura & Charles]

We find ourselves in a very unlevel site, nose up. We’ve chocked the front tires very good and have added blocks under the rear jacks. All six rear tires are off the ground. I’ve read here that’s a bad idea but always the reason given is those are the parking brakes. As said, front tires are seriously chocked so that’s not my concern. But I am concerned about the weight of the drive and tag axles just hanging back there. Should that be a concern?

 

[A Traveler]

No.

 

[John From Detroit]

I bought out a lumber yard (Seriously I did of at least one size) and used 3-sections of 2x12 as a service rack, They were cross stacked for maximum stability and it worked very well. Once the engine replacement was done I put as many of 'em as I could in my towed and that's how I begain leveling so the wheels though often not "On the ground" in the literal sense were on the 2x12 which WERE on the ground. and thus safe. Recommend same for others. Still have a pile of 2x12 I plan to haul up to a local campground "Free Firewood"

Oh one other thing I did was some Steps

Three 2x12's glued together like this

1Foot
2 Feet long
A full three feet long

Now if I were to re-do them I might add a small block (say 4x4) and at the end of the 1' section and make each seciton 4" longer to allow for the 4x4 parking stop but I managed to never over drive it.

 

[FunSteak]

This is an interesting question. Our friends just purchased a class A gasser, around 30 feet, that includes leveling jacks. Their dealer told them never to lift the wheels off the ground.

I've seen plenty of rigs with some air beneath a tire or two. Is this bad practice? Are there known issues with jack failure or something? In my eye, it seems fine to jack up and place some support blocks under any unsupported wheels, then lower a bit to put the load on the blocks. Is this what others do, or is this not really a concern.

We have a class C with no jacks, so I don't have experience with this issue.

 

[Robert K]

Just stretching (I presume) your airbags for extended time. My airbags are after market that I added. They are not as heavey duty as they are only for some extra stabalizing.
I don't let my axels hang for long term.

All of your parking brake is on the rears

 

[Utclmjmpr]

If you look closely at today's suspension systems you will see various stops ,,retainers,,and stop designs that prevent the bags from "hanging" or damaging the bags.>>>Dan

 

[Skookum]

I think the concern is legitimate, but can be mitigated by not being an idiot about it.

The idea is that with the wheels still on the ground, the weight of the RV is better distributed and supported. The suspension has many contact points with the frame whereas the jack only has a single point of contact. A parking-braked wheel also has more holding power than a piece of smooth steel jack base, or a jack supported by a bunch of blocks. The jacks are inside the wheelbase so don't produce as much lateral stability as having the wheels touching the ground as well. If one is parked on a steep slope, that's also a lot of stress to be placing on jacks laterally. I have no idea of how much force can be applied to them non-vertically but the concern would be busting the mounts or bending the jacks.

The other thing is, most of our jacks don't have safety mechanisms. If pressure fails, down it goes. if you've got a foot of blocks under there, that's a long way for the rig to fall and it's probably going to mess up some other stuff too--and hope you're not holding a drink walking around inside!

It's less of a concern for the suspension being unweighted or fully extended. While it is designed to carry load and not be dangling, there should be both stops and good engineering to prevent airbags from ripping apart or shocks from being damaged by supporting axle weight.

 

[Gary RV_Wizard]

There is some history involved here, so bear with me.

A couple decades ago, the front cap assemblies of many gas motorhomes (and a few diesel pushers as well) were not well designed and the coach chassis were not very rigid. When the front wheels came off the ground, the direction of force on the chassis changed )from push-up to pull-down) and the front ends moved in ways the coach builders never anticipated. Windshields popped out or cracked, molded fiberglass caps broke, and the cap seam at the roof opened up. The wheels didn't have to fully come off the ground for this to happen either. From the mid-90's thru early 2000's, this was a common complaint and another piece of conventional, popular wisdom was born, i.e. "Never lift the wheels off the ground". But at the same time the chassis were getting stronger and more rigid, e.g. the 2001 Workhorse W-series chassis with 50,000 psi steel) and the coach makers learned they had to make stronger front cap assemblies, so the problem went away in newer coaches. The coventional wisdom remained, however, if only because there were still a lot of coaches around with the structurally weak designs.

If you own a coach on a Workhorse Wxx chassis or a 2006 or later Ford F53 chassis, odds are you will have no chassis problem with wheels off the ground. Ditto for most any diesel pusher using a Spartan, Freightliner, Roadmaster, Peak, Dynomax or Gillig chassis.

The park brake thing also needs a bit more insight. It's true the PARK brake is rear wheels only, so lifting the rear wheels defeat that. But lifting the chassis on hydraulic jacks places a really strong anchor onto the ground, arguably a better parking brake than the rear wheels. As long as the jacks don't physically fail, anyway. But some coaches had knee-action jacks that sometimes suddenly folded under severe side-pressures, and some coaches had undersized jacks that failed for the same reason. So again, conventional wisdom was reinforced.

And of course, many RV owners are almost clueless about the mechanical equipment type or capability on their coach, so they they are best-advised to follow some simple rules to avoid any possible mistakes. "Don't do it" is about as simple as a rule can be!

 

[Larry N.]

I'd add one thought to Gary's excellent summary: if there is the slightest side load (left/right/fore/aft bending motion) on the jacks, then you have to wonder how much leeway was built into the way the jacks are mounted to have sufficient strength for anything off of perfectly level, especially with the heavier weight in the rear. It may be OK, but I'd consider it.

 

[Gary RV_Wizard]

Good point, Larry. RV builders are notorious for cutting corners by using minimally acceptable components. My own high end coach came equipped with barely adequate jacks that sometimes groaned or shuddered when parked. The manufacturer voluntarily replaced them with a heavier duty system when I complained, but they only did that if the owner raised the issue. No general notification to owners and no recall.