How To Make RV Camper Leveling Airbags To Replace Leveling Blocks
- May 28
- 6 min read
Updated: 20 hours ago
Ever since I saw the FlatJacks, I've wanted a set for the Sprinter Van Camper and the Hybrid Rockwood Roo camper trailer with tandem axles. For a camper van, you will need at least 2 of these. For a tandem axle trailer, you will also need a pair of these, one under each wheel on side that needs to be raised up.
As usual, they are expensive, which makes me want to waste time building them instead. Here it goes.
This is the best tutorial and construction method I have found:
They are using 2ft of 8in diameter discharge hose. Using a lay flat discharge hose is genius because, since it's a large tube, only the ends need to be sealed.
AIRBAG MATERIAL
The material used for the airbag in the above video is 8in diameter discharge hose. 8in diameter hose has a lay flat width of 13.5in. The hose recommended in the video is sold by McMaster for $35.70 per foot. For a 2 ft leveling airbag, the hose will cost $70.
This has the same specs as Sun-Flow SF-50 8in hose, so that's probably what is being resold by
Although the tubing is 8in diameter, the max lifting limit using this is probably only about 4in. To lift higher, a larger diameter tube will be needed. Flat-Jacks measure about 26.6 inches in diameter when flat and can lift up to 7in. A 12in diameter hose should be able to lift about 6in.
Hose Color Indicator for Discharge Lay Flat Hoses
Blue lay flat hose is medium duty (lower pressure rating), and red lay flat hose is heavy duty (higher pressure rating and usually a thicker wall). Since we're going to be driving over these, a heavy-duty hose is preferable. At 10 inches and above, the blue medium-duty hose has a wall thickness equal to or greater than the 8in heavy duty. The 10in and above medium duty have a working pressure of about 35 psi with a burst pressure of 100 psi. It only takes about 20-25 psi
Discharge Lay Flat Hose Manufacturers and Links
Sun-Flow
Sun-FLow SF-50 High Pressure
Ponaflex
Ponaflat 50
Kuriyama
There are discharge hose diameters available ranging from 8 in to 16 in. Let's take a look at the flat width and lift height.
Manufacture/Retailer | Hose Diameter (in) | Flat Width (in) | Wall Thickness (in) | Lift Height (in) Should be able to lift half the diameter | Working Pressure PSI | Burst Pressure PSI |
McMaster (Sun-Flow SF-50) | 8 | 13.5 | 0.13 | 4 | 115 | |
8.15 | 13.5 | 0.118 | 5 | 100 | ||
10 | 15.7 | 0.111 | 5 | 35 | 100 | |
12 | 18.85 | 6 | ||||
14 | 22 | 7 | ||||
16 | 25.13 | 8 | ||||
Flat-Jacks | 26.6in flat diameter | 7 |
WHERE TO BUY 8" DIAMETER LAY FLAT HOSE
By far the best price that I found for 8in, heavy duty red lay flat hose is on JME ELLSWORTH website. AT $9.19 a foot, it is far cheaper than McMaster and other vendors. They caveat is that it has to be purchased in 25ft lengths. Considering that I need 5 ft for the 2 wheels of a tandem axle trailer, and that I want to make some others for the Sprinter camper van, I'll be making good use of the $25 ft.
I wasn't expecting how massive 25ft of heavy duty lay flat 8" house actually is until I received it.
I knew it was thick, but it's still impressive. Almost like the sidewall of a car tire.
For 8" diameters in shorter lengths, the best prices I've seen are from Rain-Flo Irrigation. Their 8" Ironsides Red Layflat is $12.25 per foot, minimum of 5 ft increments. That's 1/3 the cost of the McMaster equivalent. Too bad they don't carry larger diameters.
Austin Hose sells some red layflat hose at $14.89 per foot. Not sure what brand, but the Working pressure is 75 psi.
12in diameter discharge hose is the largest size where the price is still reasonable. I've seen 14in and 16in hoses, but they get very expensive per foot.
10 INCH DIAMETER HOSE
10in discharge hoses are still reasonably priced. The layflat width is ~16in.
The working pressure is 35psi, but the burst pressure is 100 psi. It only takes about 20 PSI to operate.
Sunflow SF-10
The wall thickness is 0.111 inches. That's almost 1/8 inch, so pretty thick.
WHERE TO BUY:
The high-pressure 10" discharge hose is stronger and thicker. It's also made of EPDM covered with polyurethane. Rubber cement solvent adhesive, or PVC adhesive, won't work for this material. Rubberized super glue is used to glue EPDM.
WHERE TO BUY:
12 INCH DIAMETER HOSE
12" discharge hose is even better than 10in, and not much more expensive. Although the manufacturer's website says that there is a high-pressure version, I can not find it for sale by the foot.
WHERE TO BUY:
Factory Direct Hose: 12" Discharge Hose - Purchase by the Foot
Sun-flow does have a heavier-duty version of the blue hose on their website, but I can not find it for sale by the foot.
Ponaflat 10 in the 10in and 12in diameters is not as suitable as other brand 10 and 12in hoses. It has a thinner wall (will get damaged easier), and a lower working pressure. Do not recommend using this hose.
Austin Hose 12" ID Black Layflat Discharge Hose
This hose is made from Nitrile rubber. Natural nitril doesn't have good UV resistance. There's no mention of these hoses' UV resistance or of UV additives to prevent outdoor degradation. This may not be a good choice for long term outdoor use. PVC and EPDM have better UV resistance.
AIRBAG CONNECTION (VALVE STEM)
VALVE STEM
In the video they use a screw in valve stem. They discard the rubber washers that come with it and replace them with larger diameter 3/8 ID washers. They apply rubber cement to all the surfaces that contact the PVC.
The screw-in stem they used in the video is a standard style Schrader valve. The valve core can be replaced, but if the stem gets damaged, you have to replace the whole unit. Once the airbag ends are glued together, it will not be possible to replace the whole valve stem. Therefore, I'm going to use a TR618A tractor tire valve stem. This stem has a fully replaceable core that replaces most of the valve body if the valve body is damaged. The lower part that attaches to the airbag is more robust and protected from damage.
VG 12 is a standard vehicle tire valve screw thread defined under the DIN 7756 specification. It is primarily used for large heavy-duty or industrial tire valves (such as those on trucks or agricultural vehicles) and is officially designated as Vg12 times 26
Technical Specifications
Major Diameter (External): 12.243mm (max) / 12.091 (min)
Core Diameter (Internal): 10.869mm (max) / 10.717 (min)
Thread Profile: V-thread with a 60° flank angle
Thread Count: 26 threads per inch (TPI)
WHERE TO BUY VALVE STEM
The washers that will fit over the thread of the valve stem need to be about 12mm ID. McMaster has some bronze washers that have a 0.50in ID (12.7mm) and a 1.125in OD. Bronze is corrosion-resistant and galvanically compatible with the brass of the valve stem, so corrosion should not be an issue.
WHERE TO BUY WASHER:
The rubber gasket that comes with the valve stem will be removed.
The hole for the valve stem will be punched smaller than the threaded body of the valve stem so that it goes in tight and secure and will be easy to seal.
This is what the valve stem assembly will look like with the rubber gasket removed and the 2 bronze washers added.
If additional reinforcement is required around the hole made in the PVC, then a rigid PVC washer can be solvent welded to the PVC.
WHERE TO BUY:
Affiliate Disclaimer
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The "engineerable" angle is spot-on — I've been eyeing FlatJacks for my Sprinter build too, but that price tag makes me want to CAD something myself. I've been using https://facefusion.pro