Firestone vs Polyair Bags?

[Riding On Air Junior Member Find all posts View Profile Close Riding On Air]

Re: Firestone vs Polyair Bags?

Hi All,
As a supplier of this type of product I may be able to shed some light on this.
The general rule in the industry is that two filler points are used so that you can level a vehicle from side to side, but also to stop the air from transferring. The main reason is that air transfer results in a reduction in vehicle stability. Imagine driving up on to a side slope, only to have the suspension on the low side compresses dramatically as the air transfers...get ready for the roll over! You can actually feel this effect when going around a large roundabout so I would suggest you do not join them unless you had only towball loads on the vehicle, but even then I would use caution as you may notice a reduction in stability if things get messy.
Regards,
Brett.

[vh_ofc Lurker Find all posts View Profile Close vh_ofc]

Re: Firestone vs Polyair Bags?

Fair enough, I was not particularly thinking of it in relation to off road use but more towing on black top.
Cheers
Mike

[charlie Junior Member Find all posts View Profile Close charlie]

Re: Firestone vs Polyair Bags?

Just joining in the one valve/two valve discussion. I'm a one valve PP'er!
But I'm now reconsidering after riding on air's post.

The general rule in the industry is that two filler points are used so that you can level a vehicle from side to side, but also to stop the air from transferring. The main reason is that air transfer results in a reduction in vehicle stability. Imagine driving up on to a side slope, only to have the suspension on the low side compresses dramatically as the air transfers...get ready for the roll over! You can actually feel this effect when going around a large roundabout

The advantage of the tee system is both bags adjust to the same pressure. Driving slowly on rough tracks, articulation of the axle is probably increased by allowing the air to flow from the compressed bag to the less compressed bag. The penalty for that is reduced stability.
With two valves, if one bag deflates due to damage, the balance of the axle is lost until the other bag is deflated.

The airlift manual says
"Tee airline installation is best for vehicles that are loaded evenly side to side. The dual airline should only be used if the vehicle will have considerably more load on the left side than the right or vice versa."
I hope that the tee air line probably doesn't present significant risk, if that is the manufacures recommendation.
( That's my rationalisation for being too idle to change my setup.)
Best summed up as "opinion is divided...I reckon one valve is better, everyone else says two"

[MickL Addicted PP Member Find all posts View Profile Close MickL]

Re: Firestone vs Polyair Bags?

I reckon one valve is better, everyone else says two

Or you could add an inline isolation valve and have the option of both.


Mick

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Re: Firestone vs Polyair Bags?

I only have one valve, haven't noticed any stability problems. I do tend to think that it helps with getting a bit more articulation. If you were running full air bags with no springs i can see how it would be a problem, but with air bags generally just to give you a bit of tuning for different loads i doubt that the air bag would make that much difference, after all the springs are still doing the bulk of the work.

Cheers Andrew

[Racer Junior Member Find all posts View Profile Close Racer]

So have we come to the conclusion if one is better than the other or are they both fine?

I tow a camper van which makes the 150 sag, I have ordered Polyairs via the local 4WD shop however I've had a few conflicting comments regarding the Polyairs stating the Firestones are a much stronger bag........?????????

[yowie Advanced Member Find all posts View Profile Close yowie]

Have towed with Poly Airs for nearly 2 years with a van, no problems. Loaded an 80 series Cruiser with Poly Airs for 17 years, no van but a lot of camping gear, no problems there either.

[Racer Junior Member Find all posts View Profile Close Racer]

Good to hear Yowie...cheers