Air Suspension for Defender

[Top90]

Thinking of converting a 90 to air suspension. To be able to raise/lower side to side and back to front.

I know it has been done by others, but where do you get the bits from?

I have not heard of 'Ogden Air' recently who used to do a kit but seem to have vanished, and I wanted heavy duty air spings that can take more abuse than a P38 air bag. Like something from a kneeling bus etc..

Any suggestions?

Cheers

Richard

[SteveG]

if it's just for side to side I wouldn't bother, just stick with coils. If you want it for on-road handling or for on-road height reduction to fit in a garage etc then it's worth it.

The truck airbags can be puctured just as easily. Only way to protect against this is to put a hard surround outside the air spring to take the knocks. On the p38 I never had a puncture in 4 years of off-roading as theyare faily well protected. Simonr has been using air suspension for a few years on his 90 and has had a few punctures on his firestone truck springs.

Cheers

Steve

[maverick]

if its just a valve block your afetr then look at air ride products state side and buy direct but you can get the same over here from suppliers like thorite

[Top90]

Basically want it for challenge use to go with my portal axles.

That way I can lean it over on to punches, raise the rear for driving off large rocks etc...

Was hoping to find a kit in the UK, otherwise I may have to look over in the USA.

I was not that worried about punctures. Just thought truck air bags would be longer and give more suspension travel.

How long can a P38 air bag extend to? And how much can it compress to?

Thanks

Richard

[BogMonster]

SimonR's setup is brilliant, I expect he'll be along shortly but it can do all sorts of party tricks and the amount of travel is enormous - in Wales last year he did a series of photos with the vehicle right up/right down/20 degrees of bank, very cool

[simonr]

Thought I could feel my ears burning!

Have a look at www.sproklegrommet.co.uk

You might have to wait a while as both the PSU's in the server seem to be cutting out occasionally. I'm re-building everything on another machine though.

It gives details of the bags I'm using inc part numbers. I bought mine from Automint and they are intended for DAF trucks. They have about 13 inches of travel (compared to about 9 on a +2" spring). I don't need to use any kind of dislocates, even with +4" shocks and I still have about an inch of travel in the spring at full extension.

I have had three punctures and fixed one with 'safety-seal'. One was when one of my shocks snapped and the rod went through the bag. One was when I pulled the shock mounting off the top of the axle and it damaged the bag and one was a splinter of wood from a broken branch.

For valve blocks, the air-ride ones are fairly expensive at about £700 a set. I made mine from individual valves x 8 @ £15 each (10mm port poppet valves). If I were doing it again, I'd buy one of these:

http://www.showtimehydraulics.com/air.htm

They come in around £250 for a complete set inc shipping to the UK.

You have to fabricate your own mountings - but it's pretty easy. I just used the bottom spring mounting cups bolted to the top of the air bag and a 1/2" UNC bolt welded to the bottom spring mount (which screws in to the bottom of the bag).

You need to relocate the front shocks using turrets intended for mounting a second shock. I would use Bearmach BA 2157 which loads of people can source and they are good value.

I plumbed mine in 10mm nylon hose and push-fit connectors (from AirTechnics in Tonbridge). The bags have 1/4 BSP threads, but most of the valve blocks use 1/4 NPT - but you can get fittings & adaptors easily enough.

I use an air-con pump as a compressor (common in Jeep circles) and I'm looking at supplying a conversion kit with all the plumbing, oiler, filter and hard to find fittings to go on the compressor.

Failing that, the bore of the outlet pipe on a LR air-con pump is the right size to tap as 1/4 BSP - which makes it pretty easy. Make sure the first meter or two of pipe out of the compressor is copper. The air coming out is very hot and makes the nylon tube burst - with a very frightening bang!

The copper pipe is just enough to cool the air and it can continue as Nylon.

To lubricate the pump, you have two options. Either use an oil-mister on the inlet and an oil separator on the outlet (best solution) or replace the oil inside the pump with high temperature grease. Very little makes it out of the outlet.

I used my cage as a reservoir, but you can get good value ViAir ones from Matt Savage.

That's about all there is to it!

Si

[ibexman]

Basically want it for challenge use to go with my portal axles.

That way I can lean it over on to punches, raise the rear for driving off large rocks etc...

Was hoping to find a kit in the UK, otherwise I may have to look over in the USA.

I was not that worried about punctures. Just thought truck air bags would be longer and give more suspension travel.

How long can a P38 air bag extend to? And how much can it compress to?

Thanks

Richard

I have a fitting kit for Automint air springs if youre interested

[Top90]

Simonr thanks for the info, it has given me a lot to think about.

This is definately the way I want to go.

Thanks again.

Richard

[nicksmelly]

Valve block on Ebay

[MogLite]

That seems quite a sweet install there Simon - well done that man

MogLite will hopefully one day be running on air-bags. Probably the same as Simons'.

I don't have the electronics knowledge (or desire) to do self leveling.

But I hope to go fully manual, using pneumatic switches, and maybe a set of digital pressure gauges.

There are a lot of trick bits stateside, from the low-rider scene.

But first I've got to get it running on coils.......

[dollythelw]

I found a good source for air reservoirs was disposable party balloon bottles, they weigh 3kgs, hold around 20ltrs, have a safety blowout disc and they're free

[simonr]

I found a good source for air reservoirs was disposable party balloon bottles, they weigh 3kgs, hold around 20ltrs, have a safety blowout disc and they're free

I've used Air-Con gas bottles before now. I suspect they are similar.

Andy, before you go down the air route - I have a better option which I'm considering at the moment. Should be dead simple, easy to make, ideal for manual control and it keeps your original springs so if the whole thing fails - it returns to being a regular coil-sprung LR.

Si

[DF1]

I've used Air-Con gas bottles before now. I suspect they are similar.

Andy, before you go down the air route - I have a better option which I'm considering at the moment. Should be dead simple, easy to make, ideal for manual control and it keeps your original springs so if the whole thing fails - it returns to being a regular coil-sprung LR.

Si

Sorry to rehash an old topic but what is the other option.

I just heard the other day of bags that can be placed inside the coil springs but

at a set pressure with no adjustment.

[simonr]

Sorry to rehash an old topic but what is the other option.

I just heard the other day of bags that can be placed inside the coil springs but

at a set pressure with no adjustment.

It is what lead to X-Springs The original idea was to place a small hydraulic ram (or electric linear actuator) inside a 'top hat' inside the top of a regular coil spring.

Then you can raise and lower the top of the coil spring - and if it breaks - it just leaves your truck sitting on a coil spring without the height adjust.

I built a setup with -1" springs (giving about 1" between the axle and bump stop) and used a ram with 12" travel so I could go between -1" and +11" height on either side.

My goal was something that automatically adapted to terrain and self-leveled the vehicle where possible. This used a lot of power - and didn't really react fast enough to drive at more than about 5mph. The X-Springs achieved much of the same thing (in terms of keeping wheels on ground) without using any power and with no (practical) upper limit on speed.

I used the same kind of idea here:

This uses an electric linear actuator more commonly used for positioning satellite dishes. It's capable of lifting 6000lbs (all be it fairly slowly!)

Si

[Clive]

Si,

I have been thinking along the same lines for use on my RRC. The idea being that I can have 3 'fixed' positions;- standard height, -2" for fast road and +2" for laning, etc. and use standard coils. There would be no self levelling just manual selection.

However, there may be space problems for the actuator on the rear spring mountings!

Then I just need switchable anti-roll bars and we're away!!!!

Alternatively I might just use the standard RRC Air Springs set up, modify the ECU and add Arnott Gen III springs. Only problem is you can't get the Arnott springs anymore.

Clive

[mad_pete]

Alternatively I might just use the standard RRC Air Springs set up, modify the ECU and add Arnott Gen III springs. Only problem is you can't get the Arnott springs anymore.

Clive

Won't Arnott ship em out ? I spoke to them fairly recently and they said they would it would just cost flippin loads.

And just for amusement How to manaully take a P38a to the max

[Escape]

Alternatively I might just use the standard RRC Air Springs set up, modify the ECU and add Arnott Gen III springs. Only problem is you can't get the Arnott springs anymore.

Clive

This place still sells Arnot Bags, ordered a set end of 2008, quite cheap and very fast delivery!

Mainly P38a stuff, but they have goodies for Classic and L322 as well.

[mad_pete]

Yeah I spoke to them they don't do the RRC classic arnotts though :-( only P38a

[geoffbeaumont]

And just for amusement How to manaully take a P38a to the max

Take note of the warning at the end though - if the ECU decides to go into real extended mode on top of this you're likely to pop an air spring, especially if you're cross axled at the time. Aside from working on the vehicle (and if you can use a jack and axle stands it's probably not worth messing with the electrics for that), you've most likely to want to use this mod in exactly the situations that extended mode might be triggered in.

Don't know how easy it is to get a P38a into extended mode, but parking on a rough side slope will do it with a classic!

[Daan]

I personally am not a fan of airbags as a spring for reasons that Simon mentioned (they can go wrong). However, has anyone tried airshocks in this application? I am sure they need a much higher pressure, but in theory, it should work just as well.

daan

[Al x 4]

I was flicking through some of my old man's old LRe mags and saw the write up they did on the Ogden Defender in 2003, prompting me to give it a search

I'm after a challenge solution for my 90 and was thinking air was the way to go after what I read. What kind of ball park cost is there for the entire system? I'm relatively handy with electronics so that's not really an issue either.

Is it reliable enough to use on the challenge spec truck I'm building, as I know there is a lot of mistrust surrounding their use on vehicles.

Cheers,

Al

[Kev Baldwin]

FWIW, the Ogden Air kit used custom mounts but all of the 'air' kit was off the shelf stuff from http://www.ridetech.com/index2.html in the US.

I did once have a ride (on-road only) in an air suspension equipped 90 and have to say it was without doubt the worst riding vehicle I have ever sat in! Proof that there's more to it than just replacing the springs wwith air bags.

[nicks90]

i've never understood why someone would put air suspension on a 90. Theres a chap in our club who has and he does very well in trials - but no idea if thats just cos he`s a bloomin good driver...

From my understanding, when you want to drive it on the road you lower the suspension. That means there is less pressure in the bags and therefore ride height goes down. But doesnt that make the bags softer and therefore all wibblywobbly?

And vice versa, offroad you pump them up to raise the suspension. That will make it really stiff? Seems the opposite to what you actually want!