Air bags in rear springs

[Mattonpatrol]

Hey all, I'm doing a 3" lift on my GU wagon this weekend.. Now I know the GU's have a good tendency to sag on the ass end because they are heavy on the back, and I herd that I should be puting in air bags in to compensate for that extra weight on them, & especially since I have a draw system In it and will be soon putting on a rear bar on to... The new springs I have are ment for extra weight on them anyways but, my main concern is.... Is it really worth installing air bags in my 3" lift? Just for the fact that I don't want to have to buy a new set of sprins 6 months down the track & also my other question Is, do air bags reduce the flex on sprins or anything like that? When on full flex?.. Has anyone experienced this before?

[mudski]

Keen to see the experts input on this. I will say though I have read that using air bags will put undue stress on the spring hats and they may break from the chassis. To overcome this there is a special plate that runs from left to right ontop of the hats which equalizes the load. If I were to use airbags I would be putting this in. Plus using air bags has been on the back of my mind for a while now as i will be taking delivery of our new camper in a few weeks. Just wondering how much my troll will sag in the rear. Maybe new some OME springs might be in order.

[BigRAWesty]

YES... They are a great setup. They allow a nice soft ride when empty but they keep the car level when loaded.
They do restrict flex a little, but no big deal..
On a serious note though, the extra weight could cause issues with the rear top tower supports. If you can try fit a brace kit for piece of mind, but it's up to you..

Also try and aim the spring rate to include future mods like the bar. It'll be a little rougher until fitted but saves forking out twice..
You basically want the springs to carry the everyday weight. The rear bar, draw system, batteries if in the rear, and then the bags aid with the rest of the added gear for camping..

[MudRunnerTD]

The use of airbags in your rear springs are to allow you to set your car up for daily use and for heavy Towing. You have not mentioned towing in your original post so I would not be fitting them.

Yes, when in use (inflated to 30psi) they will restrict your flex for sure.

Yes the GU are a Heavy car, they should Not sag if they have been set up using the appropriate springs for your setup. A quality spring will consider your weight including the car, rear drawers, long range tank, rear bar, spare wheel hanging off the back, etc, etc, etc.

If you have plans to add more things then tell your supplier what you want and what you will be using the car for and they should be able to supply the correct weight springs for the car.

I have a 3" Old Man Emu Comp Spec lift in my GUIV (anything over 2" from OME is classed as 'Comp Spec' and only come in 1 spring weight) I also fitted airbags for when towing the camper and I was worried about it sagging too.

Since the lift a I have fitted black widow rear drawers, a Kaymar rear Bar and a 147lt long range tank and done 80,000kms since I installed it and the back Still sits higher than the front! The airbags are deflated and if I could be othered I would take them out. Love my Old Man Emu 3" lift!!!

So the primary roll of the Polyair air bags is to allow you to hook on a very heavy load occasionally but run lighter the rest of the time. If you use your car for a consistent use with similar load constantly then Airbags are pointless and you need the correct spring weight.

Highly recommend the Spring Tower Bracing from Superior Engineering the the other guys have mentioned above.

My2c. Cheers MR

[BigRAWesty]

There is a fair bit of weight added from an everyday car to a 2 week tour but. That's when mine kick in.
Even if you get springs matched for all the accessories there is a fair bit of weight in all the camping gear, food and people..

[MudRunnerTD]

Yeah there is Merritt in that Kallen but a decent spring should be able to handle that too or we need to rethink what we pack.

The pic below is at the start of my Madigan Line trip and the GUIV is as Loaded as it will Ever be!

Drawers are full, the back is Full, 60lt of water in the back, 60lt fuel on the roof, oz tent, extra spare on the roof, 147lt fuel under the back and NO air in the bags mate.

34530

34531

Sits pretty well on the Old Man Emu with about 65,000kms on it then.


Sent from my iPhone using Motorculture mobile app

[BigRAWesty]

Yea, well setup.
As you say a 3" lift doesn't have different spring rates, so what weight rating do they use for "comp" spec??

From my experience with the 2" lifts I feel my bro has fitted too higher a spring rate and it is a harsh ride. OME kit, but he can't remember what rate he went..
I'd love to stick stock rates back in as in reality I've only fitted a dual battery up front and draws in the rear. Both about the 40kg each..

I guess it comes down to the age old question. What are you going to use it for??

And I guess you can always add bags later if your not happy with the way the weight affects the car..

[taslucas]

A mate of mine runs ONLY air bags in the rear of his 98 GU. No rear springs. He uses it as a work vehicle and has a big drawer system to accommodate all his builders tools. He has the air valves run up next to the fuel filler cap to keep them out of sight and clean. He has had this set up for over 3 years and has not had any problems with it at all.

[MudRunnerTD]

A mate of mine runs ONLY air bags in the rear of his 98 GU. No rear springs. He uses it as a work vehicle and has a big drawer system to accommodate all his builders tools. He has the air valves run up next to the fuel filler cap to keep them out of sight and clean. He has had this set up for over 3 years and has not had any problems with it at all.

Yes this is a very different setup to the Polyair assistant bags that go inside the springs. I have heard mixed results for the airbag replacement system but if your mate happy then all good.

Thinking about this thread today. What Westy noted above has some merit. If you want a good touring setup then its not unreasonable to add poly airs for touring. As stated your flex will be reduced but I don't expect you to need a lot of flex when touring anyway. They really are an assistant only those.

[threedogs]

might want to think about strengthening the rear spring towers too.

[janderson]

might want to think about strengthening the rear spring towers too.
I'll 2nd that

[Mattonpatrol]

Yeah there is Merritt in that Kallen but a decent spring should be able to handle that too or we need to rethink what we pack.

The pic below is at the start of my Madigan Line trip and the GUIV is as Loaded as it will Ever be!

Drawers are full, the back is Full, 60lt of water in the back, 60lt fuel on the roof, oz tent, extra spare on the roof, 147lt fuel under the back and NO air in the bags mate.

34530

34531

Sits pretty well on the Old Man Emu with about 65,000kms on it then.


Sent from my iPhone using Motorculture mobile app


Thanks for the help boys!!! Yeah well look as you've have mentioned the king springs that I have baught are already rated for my draws& rear bar so I think I'm set..... At the end of the day, my troll is more of a 4wd then a toorer so I think I might leave the air bags out for now and see how I go... I want as much flex as possible lol

[BigRAWesty]

'
Thanks for the help boys!!! Yeah well look as you've have mentioned the king springs that I have baught are already rated for my draws& rear bar so I think I'm set..... At the end of the day, my troll is more of a 4wd then a toorer so I think I might leave the air bags out for now and see how I go... I want as much flex as possible lol

You can always add them later if your not happy..
I didn't notice a huge flex loss with bags..
Check out my build. The pics are all with poly air sprigs fitted, 2" ome kit and the factory rear sway bar disconnected
http://www.nissanpatrol.com.au/forums/showthread.php?p=292347