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 > LevelAir Style Air Bags - Build Your Own Thread

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mike_mn

Twin Cities, MN

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Posted: 03/17/08 10:40am Link  |  Print  |  Notify Moderator

After spending a lot of time researching here, searching the archives and collecting information, I wanted to compile it in a step by step process of how and why I built my Leveling Air Bags the way I did. This doesn't mean your bags will turn out like mine or that yours will even hold air if you follow the way I built mine, but I am making this thread to explain the reasons for using the building techniques and materials that I chose to use.

A special thanks goes to dalehelman, symbasden, Gaffer222 and Chuck_S for posting their pictures, experiences and explanations on building and/or using these bags.

If you are considering building your own Air Bags, please note, they are not cheap. The set of 2 bags will cost you approximately $100 all inclusive to make them, more or less, depending on how many of the necessary items you have laying around your house or shop.

The next best homemade leveling option I have seen, which are cheaper, but take up more storage space are these made by prairie boy & gurl. Their measurements are here if you want to make some like them.

To start with, here is my all inclusive Materials List needed to make a set of bags:

--48 inches of 8 inch diameter red lay flat heavy duty discharge hose - extruded PVC over 3 ply poly yarn. The cost of 2-24 inch sections precut of hose from Spokane House of Hose - 800-541-6351 was $38.12, but the shipping was $23.85 for a total cost of $61.97 for the hose. If I knew how much shipping was gonna be(they didn't have a cost til they shipped it), I would have searched harder for a local hose supply company. The cost of this hose will determine how much over or under $100 these things cost to build. Choosing any other type of hose is an unknown and you can report back if you use a different material.

--1/4 inch x 1 inch x 12 ft Aluminum bar stock. Your local metal/aluminum stock yard should have this for around $15-20. Mine cost $16.30. This is more than you need, but they usually charge for each cut, so you might as well hang it out your side window on the way home and cut it for free. You will use approximately 105 inches of bar if you cut to my recommended length of 13 1/8 inches. The reason I chose to use the Aluminum is for 2 reasons. One, I don’t have to paint it and two, it is lighter than steel. There are some folks that are concerned with holding strength of 1/4 inch aluminum, but I had one of my mechanical engineers figure that with 5 - 1/4-20 bolts torqued to 15ft-lbs spaced evenly at 3 inches, the pressure holding the bars together is 18000lbs per side or 1384lbs force per inch(with a very small amount of deflection(< .010 inch) between the bolts) based on the aluminum material) holding the aluminum bars together. If there is 30PSI in the bag, that means there is 9450lbs force against the seams 13.125in*24in*30PSI=9450lbf. This is still a 2:1 ratio of holding force. Since most HTTs are <6000GVWR that means 1500lbs force on each bag(tire). As long as you keep to 30psi, which is what most people around here have recommended, there should be no leakage if sealed properly. So, all this to say, the key to being leak free is conservative and proper use of sealing the bags, the choice of 5 bolts and the aluminum bar are going to be leak free. It never hurts to add a few bolts for good measure if you feel the need. If you choose to inflate to 40psi, which won't get you much, if any, extra height, the pressure on the seams jumps to 12600lbs trying to peel apart the clamps. You should still be fine, but you are getting closer to the point in which leakage may occur based on the 18-20,000lbs clamping force with the 5 bolt setup.

--Qty 2 Bolt in valve stems. I was eager and went to the first auto parts store I could find to buy mine, so with tax I dropped $12.76 on these things. I think with some diligent shopping you could find them for more like a few bucks a piece.

--Rubber Cement. I purchased mine at a local True Value. This is the stuff that is used on an automotive tire when using the patching method of leak repairs. I bought 2 – 4oz tubes for a total of $4.24 with tax, but ended up only using 1 tube based on the way I sealed my bags. The bag material is extruded PVC, however I think that PVC pipe cement is not going to be as flexible as the rubber cement will remain indefinitely. I may be wrong and the PVC cement is a better option, but thus far the rubber cement has worked fine.

--Bolts, washers, lock washers and nuts. This is a large variable. Depending on the type of bolts and nuts you choose. Expect to pay approximately $10 total for std zinc coated or $20 total for stainless steel. I have a pretty good selection of misc nuts and bolts at my house, so I was able to get by with what I had. I used qty 20 each: ¼-20 x 1 1/4 inch bolts, ¼” flat washers, ¼” lock washers, and ¼-20 nuts.

--Inflation Device – This is at your discretion, but is a cost if you don’t already have something. I am planning to purchase a double piston bike pump for my system and am estimating it will be about $15 or so. You can find also find cheap 12v pumps for around $20-30.

--Deflation Device – Cheapest is just to hold the button to drain the bag, but that is a little tedious. A core puller is the quickest. I have one of these, another option is the core tool valve stem covers. That way you would be unlikely to forget them at home. One of these options is $1-5. A note here: Keep an extra valve core or 2 around your camper in the unfortunate circumstance that the valve core takes flight when you are trying to remove it and is lost in the grass.

My Cost breakdown: (costs are rounded to the nearest .25)
48 inches Discharge Hose(bags)-$62.00
12 ft Aluminum Bar Stock - $16.25
Bolt-In Valve Stems - $12.75
Rubber Cement - $2.00
Hardware – free, had what I needed
Inflation Device - $15.00 estimated
Deflation Device – free, had what I needed
My Total Cost - $108.00

Next I will go through my assembly steps with photos for building one bag. Keep in mind you will need 2 bags for a tandem axle trailer. You will also need to use in between the wheel chocks, as they are the only type that will lock the wheels in place when on the bags. In a few weeks I will be adding a Build Thread for my Binder Style Chocks. There is no tools needed and they cost about $20 for a set of them and lock in place as good or better than other home built in between the wheel chocks.

[image]

* This post was last edited 03/18/08 12:17pm by mike_mn *   View edit history


07 GMC Yukon XL 2500 6.0L 4:10-P3-Reese Dual Cam 1200
15 Puma 30DBSS
Me,Wife,02F,04M,06F,08M,10F.
My Leveling Air Bags Build Thread
My Tool-less Binder Chock Build Thread

SemperFiCop

USA

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Posted: 03/17/08 10:57am Link  |  Print  |  Notify Moderator

Mike,

This is one of the BEST, Most DETAILED and Well WRITTEN Instructions (with pictures) available!

Clearly, you guys spend many hours (with the help of dalehelman, symbasden, Gaffer222 and Chuck_S) compiling this information.

It is with great pleasure for others to "look & learn" from fellow RVers fine examples.

Thank you, very much...[emoticon]





mike_mn

Twin Cities, MN

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Posted: 03/17/08 11:01am Link  |  Print  |  Notify Moderator

This is a photo of all the items I used to make a bag. Not pictured are a table vice and a black sharpie marker.
[image]

Step 1 - Measure your bag and cut your bars. As you can see, the width of the bag is 13 1/8 inches. I cut the bars to this same width. The reason for this is it allows for even compression of the bag, also putting the maximum amount of pressure on the side corners. Clamping that overhangs could have the affect of lessening the pressure just inside the side corners, leaving a weaker location in the clamp. Clamping force is closest to equal over the whole bag this way.
[image]

Measure 13 1/8 inches and cut your first bar using the hack saw.
[image]

Take your first bar and use it as a guide to help make consistent cuts.
[image]

Use a file to bevel the edges.
[image]

Use sandpaper(I used 220 grit) to smooth the edges.
[image]

mike_mn

Twin Cities, MN

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Posted: 03/17/08 11:14am Link  |  Print  |  Notify Moderator

Step 2 - Measure, Punch, Pilot hole, Drill Hole, Chamfer.

Using a ruler or square and a pencil, find the center of the bar and mark it, then mark in 3 inch increments to both ends. Then mark the drill location using a center punch and hammer. Then drill a 1/8(.125) inch pilot hole. Using a small bit allows for more accurate placement of the hole when using an electric hand drill.
[image]

After you Measure, Punch and drill a 1/8 inch Pilot holes in your first bar, use is as a guide to make the holes line up on the other bars. This will make them look neat and fit together nicely when it is time to install them.
[image]

After you have drilled the pilot holes in all the bars, drill them out with a 9/32, this is a slightly oversized 1/4 inch bit to help with alignment. Make sure to chamfer the holes to get rid of the excess sharp spots left when drilling a hole. You can use a large drill bit if you don't have a countersink bit, but be careful not to drill out the hole with the bigger bit, you just need to touch it to smooth the edge. Also, make sure to match up the bars and mark them for thier location. I used T for top B for bottom, a number for the side and an arrow for the orientation.
[image]

Gaffer222

Northwestern CT

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Posted: 03/17/08 11:19am Link  |  Print  |  Notify Moderator

Great job making and documenting. You should be a book publisher if you are not already.


2007 Ford Expedition Limited w/Tow package & 3.73 Rear end
Equal-i-zer & Prodigy
2015 Keystone Outback Terrain 250TRS
DW, DD Circa 2002, DD Circa 2005


symbasden

WI

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Joined: 07/29/2003

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Posted: 03/17/08 11:22am Link  |  Print  |  Notify Moderator

Great job Mike! I seem to always forget to take pictures till I am done [emoticon] Glad to hear that you are making your own, they really are great. This thread looks to be a great resource for those that would like to make their own [emoticon]

The bags certainly aren't cheap and I am VERY cheap when it comes to camping, if I can build it, I will to save money to be able to camp more often. However, these bags have been the best investment that I have made in my camping pleasure. It is just so easy now!

Everyone, just remember to use an in between the wheel chock with any of these bags, there is no other type of chock that will chock your wheels securely when they are on bags..

* This post was edited 03/17/08 11:39am by symbasden *


Jeff

2009 Rockwood Signature Ultra Light 8317SS
2004 Dodge Ram 1500 QC LB Hemi
DW Kelly and DD



mike_mn

Twin Cities, MN

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Posted: 03/17/08 11:31am Link  |  Print  |  Notify Moderator

Step 3 - Mark, drill and test fit bars.

Place the top bar onto the side of the bag. I didn't take a picture, but make sure the cut was done evenly from the supplier. Top and Bottom edge should line up perfectly. If not, take a razor and make a better cut to line up the top and bottom flaps. When you are satisfied, place your bar on the top along the edge, allowing a small amount of hangover to trim off later. Take your sharpie and mark the center hole only.
[image]

Drill the bag at the spot marked with the 9/32 drill bit through both sides of the bag. No need for the 1/8 inch pilot hole here, it might make the cut worse actually. Install the top and bottom bar and the center bolt and tighten down. As you can see the bar is bending out from the center. This is good, it will compress well as we add more bolts.
[image]

Leaving the center bolt in, drill the next hole and insert a bolt and tighten, as you cut a hole, insert a bolt and tighten from the center to the edges. Note: The bolts will need to be hand screwed through the bag material. They wont be a slip fit through the bag.
[image]

Here we are will all 5 bolts installed.
[image]

And this is the side squish I have be talking about. We are squishing the edge off the side of the bar causing the clamping force to be even across the entire opening.
[image]

mike_mn

Twin Cities, MN

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Posted: 03/17/08 11:34am Link  |  Print  |  Notify Moderator

Thanks Gaffer and Jeff. I am happy you approve.

Thanks for the note on the need for the in-between wheel chocks.

I will be adding my Binder Style Chock build thread after I get my camper to verify the wheel spacing.

mike_mn

Twin Cities, MN

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Posted: 03/17/08 11:06am Link  |  Print  |  Notify Moderator

SemperFiCop wrote:

Mike,

This is one of the BEST, Most DETAILED and Well WRITTEN Instructions (with pictures) available!

Clearly, you guys spend many hours (with the help of dalehelman, symbasden, Gaffer222 and Chuck_S) compiling this information.

It is with great pleasure for others to "look & learn" from fellow RVers fine examples.

Thank you, very much...[emoticon]


Thanks SemperFiCop, so much is left to the imagination a lot of the time when dealing with mods and making stuff, since it is not that much more effort to add the small details, I figured I would just do it up right and give all the info I can.

mike_mn

Twin Cities, MN

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Posted: 03/17/08 12:01pm Link  |  Print  |  Notify Moderator

Step 4 - Install Bolt in valve stem

With the bag lying flat, on the top side identify the location of the valve stem. I used 1 inch from the side and 4 inches from the bar edge. On the first one I built I used 3 inches from the bar edge and was not real happy with the location. 4 inches seems to be a bit to far...so I would probably recommend 3.5 inches from the bar edge and 1 1/2 inches from the side if I did it again. After measuring remove the bar clamps. You will notice the markings you made on the bars will have transferred to the bag material and will be making sure you use the same bar for final assembly(as shown later).
[image]

!!!!IMPORTANT NOTE!!!!! Prior to drilling the hole for the valve stem, make certain you have a block of wood inside the bag to keep the drill bit from piercing through the other side of the bag.
[image]

Here is the stock valve stem. I tossed out the bushing and the washer.
[image]

Instead I used 2 - 1 1/2 inch diameter 3/8 inch washers. One goes on the inside of the bag and the other goes on the outside of the bag.
[image]

After drilling your 13/32 hole for the valve stem(this is based on your valve stem having a 3/8 thread on it). Install the valve with the bottom washer installed. Use your fingers to press around the edge of the threads. If there is any excess bag material trim it off with a razor blade. I wanted the 2 washers to clamp well and flat between the bag material.
[image]

Now you are ready for preping for the rubber cement. Use heavy grit sand paper(60 grit or so) or use a small wire brush like I used to rough up the area around the hole on both the inside and outside of the bag. Also rough up the washer sides that will be touching the bag material.
[image]

Before applying the rubber cement, clean the areas and remove any small debris. Use a dry cloth. Not sure about using something like alcohol for wiping it down, might be ok but not sure. When satisfied, apply the adhesive use your finger to spread a thin coat to the rubber on the valve stem and on the inside washer also on the outside washer and let them all dry. At the same time apply a thin coat in the inside around the hole and the outside around the hole using your finger to spread it out. Again let it dry. When the adhesive is dry or tacky to the touch, install the valve stem with the inside washer, install the outside washer and then tighten the bolt using a 9/16 wrench. I think it is metric, but 9/16 is close enough. Tighten the nut until the top washer starts trying to spin when you are turning the nut. After you complete the clamping bar assembly come back and tighten the valve nut one more time until the washer attempts to start spinning, this will be approximatly 1/4 to 1/2 turn. After doing this installation, the only risk of leakage that will come from this valve is the valve core being bad.
[image]

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