Thread: Polyair with a differance, opinions please

Originally Posted by twr7cx

I would assume what happens is you inflate the poly bag prior to putting the load on.
Due to the inflation, the bag expands and bulges out through the gaps in the spring.
You now have the bulged air bag between the spring coils.
Put the load on, and the spring has resistance stopping it's ability to compress.
The resistance is the bulged part of the air bag between the spring coils.

Polyair Springs air bag suspension lift kits

Originally Posted by joel0407

I haven't red this anywhere. I believe the increased rate comes from the air pressure. The spring mearly contains the bag.

Happy Days.

It isn't that simple.

Polyair specifically says not to use the air bags to lift the vehicle.

GENERAL MAINTENANCE TIPS: After fitting kits and/or extension leads, inflate air bags to 175 KPA / 25 lbs and test for air leaks by applying a liquid soapy solution to all valve cores, fittings and connections.


Caution - Do not inflate air springs while vehicle is on frame hoist. Vehicle must be standing on its wheels before bags are inflated.

• Maintain at least 35 KPA / 5 PSI of air pressure in the Air Lift Bags to prevent chaffing.
• Inflate your Air Bags before loading your vehicle to maximum pressure indicated on fitting instructions.
• Do not attempt to raise a loaded vehicle by inflating Air Bags. If loaded, jack up body until level, then inflate.
• It is recommended that tyre pressure be increased by 14 KPA (2 lbs) above normal for each 45 kg / 100 lbs total overload on the axle.
• POLYAIR SPRINGS recommends that the kits be used to support loads which are within the vehicle manufacturer's rated GVW

(My emphasis)

Polyair Springs - Airbag World | Air Bag Suspension Specialists

It isn't just the pressure that helps carry the load.

As the numerous and relevant SLS threads have apparently been read and given what others have already said. And you still think this path may be an option
My opinion..... Don't waste your time and money on this.

Cheers

I reckon you're 'over thinking the problem', if indeed there is one.

Does the vehicle sit well, is the rear sagging with normal load/use and with say 5 psi in the polyairs ? If so all OK so far.

With the vehicle loaded and 25 psi in the poly airs does the vehicle still sit and drive OK ? If so you haven't got a problem so why all the worry ?

Don't even think about 100 psi in your polyairs , you are correct that 25 psi is tops.

Another benefit with your polyairs is that as load increases and the springs compress, say when driving over rough ground, the polyairs become harder to compress with load giving a 'variable rate' effect. This means you don't bottom out and the strain/load on the vehicle its occupants and suspension is minimised.

Do you have std. springs ? It is important to have the correct length of polyair for the springs fitted. There should be little or no space above/below the airbag with the vehicle unloaded, a plastic spacer is often installed under the airbag to achieve this.

I've had polyairs on the RRC for 15 years now and on the D2a for about 8 years and have towed caravans and a camping trailer for many miles around Oz with no problems. The boys now use the RRC for bush driving and pump up the polyairs for a bit more lift and stiffness in the rear.

With quality heavy duty shockers I reckon you could be good to go with what you've got.

Deano

Originally Posted by vnx205

It isn't that simple.

Polyair specifically says not to use the air bags to lift the vehicle.

• Inflate your Air Bags before loading your vehicle to maximum pressure indicated on fitting instructions.
• Do not attempt to raise a loaded vehicle by inflating Air Bags. If loaded, jack up body until level, then inflate.

It isn't just the pressure that helps carry the load.

Ok. Now I am being convinced to restore the SLS with LR air bags.

Thanks for the link. Id been getting most of my info from here Polyair Springs air bag suspension lift kits and it's limited what info there is here.

What I'm getting from this is it is a bad thing to be changing the pressure in the polyairs

Originally Posted by DeanoH

I reckon you're 'over thinking the problem', if indeed there is one.

Does the vehicle sit well, is the rear sagging with normal load/use and with say 5 psi in the polyairs ? If so all OK so far.

With the vehicle loaded and 25 psi in the poly airs does the vehicle still sit and drive OK ? If so you haven't got a problem so why all the worry ?

Don't even think about 100 psi in your polyairs , you are correct that 25 psi is tops.

Another benefit with your polyairs is that as load increases and the springs compress, say when driving over rough ground, the polyairs become harder to compress with load giving a 'variable rate' effect. This means you don't bottom out and the strain/load on the vehicle its occupants and suspension is minimised.

Do you have std. springs ? It is important to have the correct length of polyair for the springs fitted. There should be little or no space above/below the airbag with the vehicle unloaded, a plastic spacer is often installed under the airbag to achieve this.

With quality heavy duty shockers I reckon you could be good to go with what you've got.

Deano

Yeah, I think the current coils and polyairs are all set up correctly. I only bought the vehicle last week.

The main reason for playing around with this stuff is to improve it. I currently dont have any intention of towing anything or carrying anything too heavy so as it is I have no use for the polyairs.

All the original SLS stuff is there and to hook it up to the polyairs would only take a little bit of plumbing. I dont know if it's still in working order or whats wrong with it.

The vehicle will be on a transporter to Darwin tomorrow and then I'll be there with no tool until I find a home to rent and get moved in.

The SLS valves seem to be clicking in an attempt to get the vehicle to where it wants it, not where it is. This apparently (from previous owner) flatens the battery. I have since learned I can disable this with Nanocom. The fuse is already pulled and it still clicks. Either the springs dont allow it to go low enought for the SLS or I dont have the polyair pumped up high enough.

My options were

1. Leave it as it is with the SLS stuff and polyairs being wasted. (Free)
2. Restore the original SLS. (Expensive)
3. Combine the 2 and get the best of both. (Cheap for a couple of coils)

1. Boring.
2. Best option but not going to happen too soon due to cost
3. Now starting to seem as it wont work.

Happy days.

Originally Posted by joel0407

What I'm getting from this is it is a bad thing to be changing the pressure in the polyairs

No, changing pressures in the polyairs is perfectly normal. I do it, in fact I did it on the weekend. What you mustn't do is inflate the polyairs to try to lift the vehicle back up after the load is applied.

I had a trailer with a small tractor behind my RRC on the weekend. Once I had loaded it I looked at how much the vehicle had sagged. Then I put a trolley jack under the rear crossmember and jacked it back up to the correct ride height. Then I increased the pressure in the airbags.

As an alternative I could have increased the airbag pressure prior to hooking the trailer up, but I forgot .

Originally Posted by BigJon

No, changing pressures in the polyairs is perfectly normal. I do it, in fact I did it on the weekend. What you mustn't do is inflate the polyairs to try to lift the vehicle back up after the load is applied.

I had a trailer with a small tractor behind my RRC on the weekend. Once I had loaded it I looked at how much the vehicle had sagged. Then I put a trolley jack under the rear crossmember and jacked it back up to the correct ride height. Then I increased the pressure in the airbags.

As an alternative I could have increased the airbag pressure prior to hooking the trailer up, but I forgot .

Yes of course. Changing pressure is normal, I'm just confusing changing pressure with changing height.

Happy Days.

I recieved a call from Polyair this afternoon as I had asked a question through the "Contact us" on their web page.

The answer was: Poly Air, in coil air bags cant be used to lift a vehcile because they grip the insides of the springs and cant expand up. He gave me an example of a person he had sold a set to, installed them and then measured the rear of his vehicle with the trailer on, inflated the poly air bags and found no change in height so requested a refund. Poly Air being the good guys they are refund the guy even though he wasn't following the instuctions.

Poly Air said that should have the guy driven up the road a little the bags would have moved with the spring movement and settled heigher. This all makes sense to me now.

Next problem he suggested is the SLS system can provide far more pressure then the Poly Air bags can handle and left to it's own devices it could just pop a bag. This also made sense as the SLS system would realise the vehicle is sitting too low with under rated springs and start providing pressure. Intead of the vehicle rising, it would simply push the bags out against the spring as stated above, then it would continue to apply pressure until the pressure was so high it pushed an end out of a bag and pop.

Anyway that idea is out the window now and it looks like once I'm settled in Darwin, I'll be restoring the LR SLS the way it was designed to be and maybe with a new set on shocks all the way around.

Happy Days.

Thanks for your help and ideas fellas.