Using Front Jacks To Reduce Body Flex - True Or False

[edmck]

Is it true that lowering the front jacks to the point where the weight is off the front wheels you will reduce body flex/torque when the rear jacks are deployed to level the coach? Just had some guy in our park tell me that as he watched me recaulking the top of the front cap on my coach because of body flexing.

[hermanmullins]

Ed,

In my opinion if you have an issue with your chassis flexing because you have leveled the coach, then you have raised the coach to a very unsafe level. Leveling jack are to level the coach and to keep you from getting sea sick from the swaying.

Herman 

[wolfe10]

edmck,

That is a riddle with no repeatable answer.

If the rear is enough higher that you need to raise the front until weight is off the suspension, YOU ARE LEVEL.

If the rear is not enough higher that you need to raise the front until weight is off the suspension, YOU ARE LEVEL.

[kaypsmith]

My common response to a remark like that is, "thanks, this is great to know", then continue working.

[desertdeals69]

Don't try to level the coach side to side if the air has been dumped.  If the ground is slanted and the coach is on the bump stops and you lift one side you will twist the body. The front jacks need to be down so that the body can tilt as needed.  The front jacks are plumbed together so even if they are down the front can tip.

[manholt]

edmck,

In the interest of Science...what year, make and model coach do you have?

[wildebill308]

I do know on my coach I  have to use the front jacks enough to allow the body to move. The rear jacks can be lowered individually but the front jacks are on one button. So you move the front up off the stops and use the rear jacks to level side to side. I have read some where in my documentation that not doing it this way can cause body twisting. 

Bill

[tbutler]

So many different systems, we need to know what year and model coach and what leveling system you have. 

Our first coach had a tripod system, one jack in the center front, two in the rear.  The front was a pivot point for side to side leveling, thus no twisting of the frame. 

Our present coach has air leveling only, HWH system.  So we don't have this problem.  But it is a totally different animal from the OP. 

[five]

23 hours ago, manholt said:

edmck,

In the interest of Science...what year, make and model coach do you have?

Got your slide rule out, Carl?

[rayin]

Wasn't preventing frame flex the very reason for the 3-jack system? HWH jacks work in pairs to prevent excessive frame flex, however when air bags are dumped this can allow the frame to flex on extremely unlevel ground; which is probably why Winnebago says to level the coach first then extend slides.

[redandsilver]

Here's my 2¢.

On my coach they may start out in pairs - like if the right side is low then the front and rear jacks on the right side will deploy.  Then when that is lifted it might show the front is now low,  so pushing the button to raise the front will then deploy the left front jack (by itself) until pressure is on that jack,  then right and left jacks will work in unison to raise the front up more. Then if the rear were to be showing low,  the left rear jack (one that hadn't been deploy yet) will start down and again when pressure is on that jack then the right and left rear jacks will work in unison like the front jacks did.  I believe that any adjustments after all 4 jacks are down would be 2 at a time whether it was the left side or right side, the rear or the front.

I have never heard of deploying the front jacks just to reduce body flex/torque when the rear jacks are deployed to level the coach.

Sometimes only the front needs to be raised to make my coach level - but I will usually deploy the rear jacks just so there is a little pressure on them to help stabilize the coach some, but not enough to raise it out of level.

My owner manual says to level first then extend the slides.  I have been pretty level and tried to extend the slides with the jacks up and they go out about 2-4 inches and then stop.  Once I deploy a set of jacks even a few inches (not touching the ground) then the slides will extend as normal, so there must be a switch that says if jacks are not down the slides don't work.  I have never tried raising all the jacks and then seeing it the slides will retract.  But with hydraulic slides I don't think you need to be perfectly level as sometimes after a rain I tip the coach down in the front so water runs off the slides before I retract them in and I don't have to re-level.

[rfsod48]

Do you all normally use manual level or auto level? When you do level isn’t it common practice to dump the air first?

[redandsilver]

On 10/3/2017 at 9:40 PM, rfsod48 said:

Do you all normally use manual level or auto level? When you do level isn’t it common practice to dump the air first?

In my case my system is totally Manual.  There are lights that show which side is low and then you raise that side up until that light goes out.

Then if another light lights up,  you level that area til that light goes out etc.

In most cases yes it is common practice to dump the air before you level.  However there have been times when I wanted the coach higher than normal because I planned to work under it so I put extra blocks under the jacks so they didn't have to extend all the way down and to coach was still higher then when a normal leveling job was done. But that's just how I do it when I might need to work under it and it's not something I would do when camping.

 

[rayin]

IF you have an HWH leveling/slideout system, This is their bible: http://www.hwhcorp.com/ml20673aafaq.html#SystemMaintenanceQuestions

Their jacks ALWAYS work in pairs, you cannot manually extend just one. Yes, one jack may reach the ground before the other in that pair, but when the system senses resistance it pauses until the other of that pair also reaches the ground, only then does leveling begin.

[manholt]

I have both air and jacks, can do it on manual (I prefer that) or auto.  The Jack portion, I can run one jack at a time.  Same with air after I dump air out of Tag axle.  System is Power Gear.   My 2011 Allegro Bus, had HWH Jacks only, but I could still go to Manual and do one jack at a time!  In 1987 I had a new Barth with HWH and those jacks operated as RAYIN said.

RedandSilver, never put blocks under your Jacks to work under coach unless you have a death wish!

[kaypsmith]

4 hours ago, manholt said:

RedandSilver, never put blocks under your Jacks to work under coach unless you have a death wish!

Never work under your coach on jacks, either on blocks or not without secondary jack stands or adequate blocking for safety sake. This is a rule that I have abided for fifty plus years, I have seen many needless injuries and deaths due to someone not following those warnings. Anything hydraulic or electric is probably safe 99.5% of the time, but never know when the unexpected will happen.

[redandsilver]

11 hours ago, manholt said:

 

RedandSilver, never put blocks under your Jacks to work under coach unless you have a death wish!

I have to use blocks to raise the coach up high enough to get my 12 ton jack stands under the coach.

I don't have a death wish and have worked in industry for 30 years which preached Safety Safety Safety so I know how to work safely.

But thanks for your concern.

[rayin]

On ‎10‎/‎3‎/‎2017 at 9:40 PM, rfsod48 said:

Do you all normally use manual level or auto level? When you do level isn’t it common practice to dump the air first?

I only  use the auto-level feature of the HWH system. It dump air bags first, then continues to deploy jacks until the electronics detect level. That sensor does need to be "tweaked" about once a year to match the bubble-level in the frig.

No reason to re-invent the wheel, or in this case how to level the MH.