Thread: Thoughts on BOSS airbags to replace original SLS

Every body will just tell you to buy some OEM style replacements, and then to buy the SLS spacer Kit.

Im not sure how U feel about going down that path, i think it actually works out cheaper, but I wasnt happy "spacing"my bags, and so after months of researching, went down the BOSS airbag route.


In terms of feel, I cant realy remember how the OEM bags felt, and I havnt driven in another D2 with bags in it to comment, the possibly feel a little stiffer perhaps, maybe firmer is a better word to use. However, I have a bit of a mish-mash of suspension components atm so its hard to comment.

In terms of the bags, they feel like a good solid, quality item, I went down the route of buying my own bags, and then fabbing my own mounts for them, worked out quite a bit cheaper for me. I think I paid around $300 (Trade) landed for 2 bags and end plates, and the mounts cost me zero to make, little more stuffing about tho.

I have one slight issue with them, and that is that they have a slight leak around the threads in the end plates, its only very slight, but it means I have to remove the whole assy and remove the plates, weld them, and then reassemble the whole lot. One Day...

Based on the measurements I got from Dave at Boss, their airbags are about 45mm longer then the OEM rover ones. This measurement was taken @ 100psi in the Boss bags, and the rover ones just stretched out. Because of the nature of the design, the triple convolute bags need pressure to achieve their extended length.
The rovers bags are, I believe, alot more fragile than the BOSS bag, the OEM bags dont like to be over stretched, or over compressed, whereas the boss' can be compressed fully with no issue, and, I was told, stretched and placed in tension, similar to a captivated coil spring that is being pulled longer than its free length.

I am running them with Bilstein 10" Short Body 7100 Series Remote Res Shocks.

Anyway, heres some pics!

So do Boss actually make a straight bolt in kit or only generic airbags that you have to make your own mounts for?

The billies measure 2" longer than a traditional 2"extended shock, thus making them 4" over standard with the same compressed length. Given the design of the BOSS bag, I highly doubt that whilst 4wding you would ever fully compress them as the pressure would be immense, I am yet to use this thing in anger so I cant comment.
I have it sitting at standard height currently, but will recalibrate 50mm higher when I lift the front, I feel that at that pressure, you would never reach full compression whilst offroad, if that it the case, then I may look at dropping shock mounts, or going for a 12" version for extra down travel.

In the pics, U can see I ran them for a while with standard (stuffed) shocks, then upgraded to the 7100s, also U will see that as they get loaded up and comress, they get quite close to the chassis rail, this could be misscalculation on my part with the upper mounts.

I have a few more high res pics, pm me and I can email them if required.

Hope this has been of some help!

Originally Posted by twr7cx

So do Boss actually make a straight bolt in kit or only generic airbags that you have to make your own mounts for?

Land Rover Discovery 2 Replacement Rear Airbags | Boss Air Suspension

I bought a set of the Boss bags from Baffle and haven't fitted them yet with the concern of them rubbing on the rail. Baffle had a set where through.

Interested in how the mount can be adjusted to bring them out from the rail.

I am also planning on the 7100s yet to come

Landrover Discovery 2 Airbag Replacement |Boss Air Suspension Shop

At $690.00 they are $190.00 more than getting OEM replacement SLS bags.

A bit concerning about the above mentioned issue of rubbing through the airbag when fitted.

According to them:

Need Extra height ? You can modify the height control arm on the leveling sensor usually just adding a bend in the right spot is enough.

I wonder how much additional height is achievable at at what PSI as they have a working range of up to 160psi, but also the more pressure will mean it will be harder (not necessarily a bad thing).

If they are harder would it restrict up travel?

Possibly, no more so than a stiff spring tho maybe.
U can't have suspension both ways, u either have soft flexy suspension that won't carry a load, or u have hard stiff suspension that will carry heaps of gear, but will be rough when empty.
I believe that the SLS system by design inhibits "flex", when a wheel is lifted up on an obstacle, the system thinks there is extra weight in the car, and try's to even this out by deflating the opposite side. Not a great idea when off roading, there has been talk of a linked system left to right, but this is also fraught with problems.

My bags sit close to the rail, but don't actually rub. Unless the bag was completely deflated, if u fab ur own mounts, u have the option of offsetting them outward to gain extra clearance from the chassis rail.
The convolute design bag is a little more flexible with it's mounting options, the OEM rolling sleeve bag needs the be kept quite straight for it to work correctly, whereas the boss style seems to have a bit of room for error.

In response to "bending" the sensor arm, the height values can be reset to whatever height u like with a nanocom or similar, or, Bruce Davis does a very neat bolt on adjuster bracket to give u a few different height options.