edmck

Using Front Jacks To Reduce Body Flex - True Or False

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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.

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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.:P

Herman 

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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.

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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.

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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. :o

Bill

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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. 

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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?:lol:

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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.

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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.

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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?

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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.

 

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