Polyairs and suspension travel

Submitted: Thursday, Aug 21, 2003 at 11:36
ThreadID: 6720 Views:2329 Replies:5 FollowUps:2
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I am considering Polyairs for my Landcruiser 100 series as the back sits low when fully loaded. I don't particularly want to put new springs in and raise the whole lot as most of the time she lives in the city and is empty. Polyairs have a good name on the forum, but mainly from tourers etc.
I live in Melbourne and visit the High Country and are not sure what the Polyairs are like for 4wding where long wheel travel is necessary. I gather that the Polyairs are inserted into the centre of the spring and the bump stops are removed so that you have just the Airbag. What happens at full compression such as when you are going over ruts with one rear wheel high and the other drooping into the hole. If loaded up and the Polyairs pumped up, do they compress enough to allow still good wheel travel.
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Reply By: duncs - Thursday, Aug 21, 2003 at 12:00

Thursday, Aug 21, 2003 at 12:00

I had Polyairs fitted to my GQ and I reckon they are great. I used the vehicle mainly for touring and they always performed well.

Being Sydney based my old truck spent a fair bit of time in the Blue Mountains where it worked pretty hard andkept going long after most others had stopped.

The previous owner of the cr used it in the Nissan trials a couple of times where it won a number of different events.

I don't believe the Polyairs compromised the vehicle in any way

AnswerID: 28597

Reply By: Member - Karl - Thursday, Aug 21, 2003 at 12:56

Thursday, Aug 21, 2003 at 12:56
Same here. Used the Polyairs for towing the trailer etc and have had no problems when off road with them. A good bit of kit IMHO.

AnswerID: 28601

Reply By: joc45 - Thursday, Aug 21, 2003 at 14:02

Thursday, Aug 21, 2003 at 14:02
I too had them on my GQ, now my GU, and reckon they're great. Best part is that you can deflate them in the city and still get a good ride. Pumped up, they took the heaviest of loads and restored the height to normal. I did over 10 years on a set in the GQ, not a single problem, and that included Kimberleys, etc. No stone damage, no pinching, nothin'.
There are different lengths of bag, depending on the vehicle, and whether you have hi-lift springs. I had standard springs initially on the GQ, fitted polyairs, then later fitted a 50mm lift set of springs, and the spring mob fitted a hard rubber block to fill the gap under the polyair bag. No probs experienced with that, tho would suggest that you decide whether or not to go with lift, and then get polyairs to suit, so you don't have to use the spacer block.
AnswerID: 28604

Follow Up By: pathfinder - Thursday, Aug 21, 2003 at 17:23

Thursday, Aug 21, 2003 at 17:23
for most kits, the bag is the same for a particular vehicle model whether it is lifted or unlifted - they account for the lift with spacers so doesn't really make a diff if you get the bag before lift and then spacer after
FollowupID: 19892

Follow Up By: joc45 - Friday, Aug 22, 2003 at 15:15

Friday, Aug 22, 2003 at 15:15
Sorry - sounds like I misunderstood the dealer.
FollowupID: 19990

Reply By: Member - John- Friday, Aug 22, 2003 at 00:45

Friday, Aug 22, 2003 at 00:45
If you are more a tourer and want to keep the car level at GVM but keep the springs stock, then either Polyairs or Noble Suspension Supports are excellent solutions. The latter is simpler to install, has zero maintenance and have no effect when the vehicle empty. Refer www.noblesuspensionsupports.com

If you are more into having fun in the high country then I would put the standard ARB OME system in with modest lift (40-50mm) and a little heavier springs all round (Land Cruiser 100 springs are too soft anyway).

AnswerID: 28691

Reply By: Member - Rohan K - Friday, Aug 22, 2003 at 11:01

Friday, Aug 22, 2003 at 11:01
Andrew, I use them too, But I'm a tourer towing a trailer.

Despite claims to the contrary, they will actually reduce the vehicles 4x4 ability over the rough stuff when inflated, in exactly the same way that stiffer springs will. In rough terrain you want soft, supple springs and soft damper settings to maximise articulation and traction. When inflated, the bag effectively increases the spring rate. This makes it more difficult to compress. Therefore there is greater upward force on the vehicle that can reduce traction. Think about jacking up one of the rear corners with the jack under the axle. Watch what happens to the front on the same side as the jack pushes the rear wheel up. At first, as the rear spring compresses easily, nothing happens. Then, as the spring begins to resist and the actual rear of the vehicle starts to rise, so too does the front (albeit at a slower rate initially). As weight comes off the front, you reduce the friction and traction at that wheel. Stiffen the spring rate and the rear of the vehicle lifts sooner, reducing the traction sooner. In really rough going, the shifting of the weight up and onto the opposite side reduces traction at both the rear and front on the lifting side. Increased spring rates just cause this to happen sooner.

"Stiffer" springs are actually worse than using PolyAirs or similar because they also restrict/slow the downward (droop) articluation of the suspension whereas the add-ons don't.

Smile, you're on ExplorOz
Rohan (Sydney - on the QLD side of the Harbour Bridge)
AnswerID: 28718

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