Frame flex

[Actec]

I have seen a lot of videos on YouTube regarding frame flex.
Can this happen to class c units

[bikendan]

Moved thread from the General Community Discussion section to the General Motorhome Discussion section since the OP's question is specific to motorhomes.

[kenandterry]

Originally Posted by Actec

I have seen a lot of videos on YouTube regarding frame flex.
Can this happen to class c units

These YouTube videos…….were they showing this frame flex issue on anything other than trailers?

[Odyknuck]

Class "C"s are built on truck chassis that are made so much better than the tin plate frames on trailers.

[Reverse_snowbird]

Frame flex is less of an issue with class C's.
However, you need to level the same as a trailer.... raise one side or level front to back. You don't want to bend the frame. It's unlikely, but not impossible.

[NXR]

Originally Posted by Reverse_snowbird

However, you need to level the same as a trailer.... raise one side or level front to back. You don't want to bend the frame. It's unlikely, but not impossible.

Nailed it. The most common cause is using the jacks to lift a tire or tires off the ground and leaving the tire(s) dangling in the air instead of using blocks. And then a failure occurs.

My canned response on this subject:

While many people are comfortable with having a tire or tires off the ground, I am not because of that whole pesky "things break" problem.

I've worked on way too many hydraulic systems in one of my careers (aviation maintenance) to ever fully trust a hydraulic system, or any system, to never fail. As many redundancies as there are in a modern jet things still can and do break. RV's do not have system redundancies so about everything is a single point-of-failure.

A few ways a failure can cause collateral damage:

- Jack collapses with a tire off the ground and the frame gets twisted as that corner collapses to the ground while the other three are still elevated.

- Jack collapses with a tire off the ground and the windshield pops out and/or cracks.

- Raising the front tires off the ground also raises the entry step a lot higher. Even if a stepstool is used the risk of a fall by a person increases.

How can a jack "collapse"? With the LCI (Lippert) system pressure is applied to the orange hoses going to each jack to extend them. Each jack is plumbed separately. If one orange hose fails the hydraulic pressure holding that jack up, some 2,500 lbs PSI, goes to zero and the jack collapses from the weight of the corner. But the other three jacks are still pressurized so they stay extended.

Even people with brand new motorhomes have posted about how they had a massive hydraulic leak due to an improperly-routed line while others had age-related deterioration and failures.


I also worked a long time as a firefighter/paramedic. Our job began when people's decisions went bad or when things that "always worked" went and failed. In other words, "It's never a problem until it is."

While I'm not comfortable with having a tire off the ground I know many people are. We're all influenced by our training and life experiences.

Since I'm not paying your repair bill people certainly are welcome to do whatever they want. Please just do it when we're there so I can get more pics.

Just NEVER have the rear wheels off the ground ever because that's where the parking brake is (on a gasser anyways). And Park on the transmission.

The pic is what happened to one person who lifted their rear tires off the ground using Auto Level and the motorhome slipped.

FWIW.

Ray

[Sunseeker16]

Not only is there a risk of a twisted frame there is risk of putting a jack through the floor if the mounting point fails. Whe have seen pictures of less than stellar welds holding the jack mount to the frame.

[sherman12]

I joined this forum back in 2012, hence Sherman12. I was looking at new and used Georgetowns and I found the forum extremely useful on what to look for on GTs around that year. One huge problem GT had back then was bad orange hydraulic lines that had huge bubbles in them, appearing ready to burst. I was told this would happen when the hydraulic lines from GT's supplier left the lines stored outside and water would build up inside the lines and essentially rust them out inside out.

Well, when we went to the dealer to look at the used 2011 GT with only 4000 Florida miles on it I told the salesman I wanted to see the hydraulic lines under the entrance stairs. I thought the guys' eyeballs were gonna fall out when we looked and saw the orange lines ready to pop like a 9-month pregnant momma! He wouldn't even let me see if the hydraulic jacks worked he was so worried the lines would let go right then and there. So of course new lines installed became a condition of the sale. During our PDI I removed the stairs and saw new lines.

But, on our initial weekend outing with the rig our electric awning stopped working and the water heater didn't heat. For whatever reason then I crawled under the rig and saw they only replaced the orange lines that were visible under the stairs, not all of them. The orange lines operated the four leveling jacks and the three slide-outs so there were seven in total. They replaced two. I was livid. I called the dealer and got lip service from the service department. So, on our return home, I drove right to the dealership, parked my rig blocking the road to the service area, and went inside looking for the owner, who happened to be there. We went around and around a bit but to their credit, they called in a mobile truck repair company that replaced every line with much better quality NY DOT-mandated hydraulic lines.

A potential diaster and lawsuit averted.

[bubbles]

Originally Posted by sherman12

I joined this forum back in 2012, hence Sherman12. I was looking at new and used Georgetowns and I found the forum extremely useful on what to look for on GTs around that year. One huge problem GT had back then was bad orange hydraulic lines that had huge bubbles in them, appearing ready to burst. I was told this would happen when the hydraulic lines from GT's supplier left the lines stored outside and water would build up inside the lines and essentially rust them out inside out.

Well, when we went to the dealer to look at the used 2011 GT with only 4000 Florida miles on it I told the salesman I wanted to see the hydraulic lines under the entrance stairs. I thought the guys' eyeballs were gonna fall out when we looked and saw the orange lines ready to pop like a 9-month pregnant momma! He wouldn't even let me see if the hydraulic jacks worked he was so worried the lines would let go right then and there. So of course new lines installed became a condition of the sale. During our PDI I removed the stairs and saw new lines.

But, on our initial weekend outing with the rig our electric awning stopped working and the water heater didn't heat. For whatever reason then I crawled under the rig and saw they only replaced the orange lines that were visible under the stairs, not all of them. The orange lines operated the four leveling jacks and the three slide-outs so there were seven in total. They replaced two. I was livid. I called the dealer and got lip service from the service department. So, on our return home, I drove right to the dealership, parked my rig blocking the road to the service area, and went inside looking for the owner, who happened to be there. We went around and around a bit but to their credit, they called in a mobile truck repair company that replaced every line with much better quality NY DOT-mandated hydraulic lines.
A potential diaster and lawsuit averted.

My 2012 GT378 had the hydraulic orange line "bubble" issue soon after purchasing new. The issue on mine was the outer vinyl (I think it was vinyl) orange covering developed bubbles apparently due to poor connector terminations. The actual 3000psi rated tubing remained viable. I dealt directly with Lippert and they supplied and paid for all orange tubing shipping and replacement. Haven't had a problem with both front wheels occasionally being airborne for over 20 years.

[Twinboat]

A of this chatter about bending your chassis with levelers is just that chatter.

Haven't any of you ever entered a gas station entrance ramp with a steep apron ? Did it bend your chassis ?

How about picking up a wheel with levelers. If you get a flat, the tire sinks a bunch and then you need to lift it to change that flat. Is your chassis bent ?

When you operate the levelers, they level the chassis. If you manual adjust them to get a lifted wheel back on the ground, YOU are twisting the chassis.

The chassis can't flex enough to damage anything, because it's bolted to a ridged box, the body. Even if it does flex some, they design it to. That's why cross members are riveted or bolted in, not welded.

[Larry-NC]

Originally Posted by Twinboat

How about picking up a wheel with levelers. If you get a flat, the tire sinks a bunch and then you need to lift it to change that flat. Is your chassis bent ?

Help me understand. Your arguments are:

• If frames are so easy to bend, why is it that they don't bend when you have a flat?
• If frames are so easy to bend, why is it that they don't bend when you jack the vehicle up beyond normal level to get clearance (with spring drop) to install the repaired tire?

Those are pretty persuasive arguments that frames don't easily twist. Help me understand why anyone would contend otherwise.

[Sunseeker16]

No. Seems you have the answers.

[DavidMcCollum]

That is the only issue I have with using auto level. I normally do it manually so that I can get all the jacks to touch the ground first. Then level from there a little at a time.

[sherman12]

Originally Posted by DavidMcCollum

That is the only issue I have with using auto level. I normally do it manually so that I can get all the jacks to touch the ground first. Then level from there a little at a time.

That's what my DW and I do too. Touch down each jack, DW operating the jacks and the level inside the coach. Final test is if the bathroom door mid-ship will stay half way open then it's perfect.

[bubbles]

Originally Posted by sherman12

That's what my DW and I do too. Touch down each jack, DW operating the jacks and the level inside the coach. Final test is if the bathroom door mid-ship will stay half way open then it's perfect.

Interesting due to the fact that the Georgetown levelling system only extends/retracts jacks in pairs (2 front/2 rear/2 left/2 right) anyway and never individually. Bathroom door check good though.

[sherman12]

bubbles, you are correct and my post should have read we adjust each jack separately by pairs, both front, rear, curbside, roadside. Interestingly though our first motorhome, a 2000 Tiffin Allegro with HWH levelers we could operate each jack on the four corners individually.

Thanks for pointing out my mis-statement.

[BehindBars]

There were some comments in the thread that, to me, are suggesting that certain usage of leveling jacks or lifting wheels off the ground with leveling jack could result in motorhome frame twist.

Well, I don’t know about all motorhomes, but on my Sunseeker with 4-jack Lippert hydraulic jacks, the two rear jacks work independently, while the two front jacks are plumbed in series. There are only three valves. Side to side leveling is done with the rear, and the two front jacks will seek their own balance by shifting fluid between the two. It is nearly impossible to lift three corners and not have the fourth corner supported, therefore it’s unlikely you could ever twist the frame significantly. It’s almost like having a three legged stool, which can’t rock even if it has a short leg. Yet with this three valve leveling system I can accurately level the coach in most any situation that’s within the lifting range of the jacks.

My frame twist indicator on class Cs is the coach entry door alignment. If the truck frame twists, the door latch won’t line up. I have not had much trouble with this Sunseeker, although there was just enough frame twist going on that I slightly enlarged the slots in the door catch.

Another factor in the amount of class C frame twist would be the chassis wheelbase. The chassis upfitter’s materials and quality of work will impact to what degree the frame stiffness is retained after the wheelbase is stretched for the intended motorhome floorplan/model. I’m running a 182” wheelbase, but I would expect the longer ones, like 220”, would possibly be more prone to twisting.

[bubbles]

Originally Posted by sherman12

bubbles, you are correct and my post should have read we adjust each jack separately by pairs, both front, rear, curbside, roadside. Interestingly though our first motorhome, a 2000 Tiffin Allegro with HWH levelers we could operate each jack on the four corners individually.
Thanks for pointing out my mis-statement.

My 2000 Georgie Boy was the same but had a Big Foot system.

[DavidMcCollum]

I really wish mine had the Lippert system with the two front jacks on the same pump interconnected. That was the way my old Bounder was with Power Gear Jacks. I have the Big Foot system that is each jack independent with it's own pump and tank. It is a real pain to check each tank independently. The old Power Gear I had only had one tank and one pump. The two front ones were interconnected as mentioned above. It would be hard to twist a frame with that setup. With 4 independent jacks you can cause damage if you try.

[sherman12]

Camping friends of ours have 2012 Sunseeker with the dealer installed leveling system. They have mentioned a few times to me that if their rig isn't leveled just right their shower door doesn't work well, so much that a couple of trips together they used the CG showers instead of their own. I hadn't given it much thought then. but now it seems odd to me while on the subject.