Thread: School me on EAS Airbag Replacement?

Originally Posted by airbagman

Some good info on the above replys, just to add the parts from us are from the same source as the original OE parts (Dunlop UK), so we have a fair bit of info on the lengths. With the Classic bags they do not have much scope to allow a longer bellows, without causing other issues, but a small increase can be had by using our standard listing for the front and a P38 rear bellows.
If anyone would like more info on these please let us know.
Regards,
Brett.

How do I get a quote from you? Email? I couldn't see pricing or part numbers on the website.

Originally Posted by DoubleChevron

they didn't know how to do hydraulics then .... think of a hydraulic ram ... the articulation will be the travel of the ram.... My 1963 Citroen DS will self level to perfection every single time regardless of the load.

When it is hydraulic over spring, the travel of the hydraulics is limited to the preload that can be put on a spring without it binding before the axle hits the bump-stop.
So that's your practical limit on self-levelling stroke. The springs themselves are limited by what fits between the chassis and the axle. Sure you could make a hydraulic system with a foot of levelling potential. But the spring towers would extend to the roof. Not at all practical.

If you put 7 adults into a stock 100 series, it cannot apply enough levelling to the rear springs so has to lower the front to get close to level.
Then, when everyone gets out, the back end is about 5 inches higher than normal. Meaning a low height car-park can result in serious problems.

The air suspension in such circumstances can use the whole stroke and is limited in force by the pressure and area of the bags. It has a far greater operating range in force and stroke than the hydraulic/spring setups do. It also bleeds off as soon as it overextends. So when unloading a heavy car it doesn't keep getting higher and higher.
On top of that, the spring rate is variable and can be tuned to increase when at lower heights and decrease at higher. When levelling to higher loads, the rate is automatically increased to keep the natural frequency of the suspension constant.
With a hydraulic over coil system the natural frequency gets lower and lower as more weight is added.

I'm pretty sure your citroen wouldn't have over half a ton of adults and cargo in it, several hundred kg of trailer ball weight and be expected to level. But 4wd's do.

I'm afraid your other examples (kinetic and forklifts) aren't relevant. I'm a mechanical engineer, I've done a fair bit with hydraulics and I understand their limitations well. Including when it's far better to use pneumatics.
On the flip side, I'm well aware of the limitations of pneumatics and when hydraulics are more suitable.

You are aware right, that the citroen type suspension is in fact pneumatic?

Dragging us back to the (relatively) boring topic... (I am a great admirer of the DS, 'everything' about it. - When I win Lotto.....)

I bought my '95 Classic with OEM bags, but bypassed due to stuffed compressor, "repaired" by a non-landrover mechanic. Enough said. All bags looked like the OP's pic, but none leaked...
Shrt story is I replaced them with the latest ARNOTTS complete units (2011) and eventually got the compressor working etc.

- As for comparitive ride, OEM vs ARNOTTS, I have no idea.
- I bought the ARNOTTS before I got the EAS system working perfectly, so never really had the car at the 'correct' height to experience the 100% original ride/handling. My own feeling is that the '89 on steel springs was softer on bumps / speed humps than my '95 Vogue, but the '89 rolled & wandered like a drunken sailor when pushed around the bendy bits... - and that was just in the car-park!

I went for the ARNOTTS simply 'cos I'm a little obsessive about 'improving' in any and every possible way if and when I can, and they were presented as being better riding (?) and could go a bit higher. - This 4WD idiot needs every possible advantage....
Cost differance at that time was'nt an issue.

Today, with the benefit of hindsight (and how I've subsequently used the car) I'd just go for bellows replacements.
Reasons, two actually:- Initial Co$t is now important these days and the the pease of carrying a couple of bellows on board and field replacement. - ARNOTTS are complete units, rubber is 'fixed'. - If they ever leaked, I'd go back to OEM bellows, just for $$$ reasons.
Or coily springy thingies...

Anyway, what are the best prices on OEM-quality bellows?

Originally Posted by Dougal

You are aware right, that the citroen type suspension is in fact pneumatic?

Um .... ok .... if you insist

I'm going away now .... I'm messing up this perfectly good thread with something totally unrelated

seeya
Shane L.
PS: No .... no pneumatics anywhere, unless you mean the 1000+psi of nitrogen in the suspension spheres. there is also no springs ... I'm not sure why you think hydraulics suspension would need crappy springs.... those things were obsolete in 1955 .... yeah you just found a passion of mine .... shi+ty old hydraulic cars DoubleChevron
PPS: Here's the one I'm doing up at the moment. If you can find a suspension spring anywhere, I'll give you the car !! Is this the best project car you have ever seen?

That is an epic Citroen thread!! There must be 1000 photos in it.

Hell of a project

Originally Posted by superquag

Anyway, what are the best prices on OEM-quality bellows?

That is the question. Ebay has some: http://cgi.ebay.com/ws/eBayISAPI.dll...tchlink:top:en

Originally Posted by DoubleChevron

PS: No .... no pneumatics anywhere, unless you mean the 1000+psi of nitrogen in the suspension spheres. there is also no springs ... I'm not sure why you think hydraulics suspension would need crappy springs....

Those high pressure nitrogen spheres are the springs. ~1000psi of nitrogen or 100psi of air. They are both pneumatic springs.

Originally Posted by Dougal

That is the question. Ebay has some: Range Rover Classic Front Air Spring Replacement Bag | eBay

Gee's there cheap. They probably don't want just the bare bag over there ... so it's not as easy to sell. I have owned pommy imports. The damage there salt does to cars in just unbelievable..... it really is staggering.... Take a perfect looking car, put it on a hoist and you'll find it's belly is completely gone.

Note: it states in the advert you "will need the original spring ends" .... I bet these corrode/rust away to nothing in the UK, so the replacement bags are useless without new ends.

Those high pressure nitrogen spheres are the springs. ~1000psi of nitrogen or 100psi of air. They are both pneumatic springs.

Sort of.... I just mentioned hydraulics in passing, not meaning to side track this thread. Basically, there is a pump and accumulator keeping the high pressure system running at several thousand psi. each axle has a very lightweight anti-roll bar. There is a clamp on this that runs back to a very simple spool valve (height corrector). If you add weight, the car will sink rapidly (the suspension is *very* soft). This will rotate the rollbar slightly ... which opens the spool valve..... and adds more pressure to the suspension circuit..... Bingo, self levelling that never fails.

The suspension itself it just hydraulic rams... when the wheel hits a bump it pushes the hydraulic ram up the cylinder. At the top of the ram is a "sphere/accumulator". This contains a diaphram with 1000+psi of nitrogen one side, and the hydraulic fluid the other. The trickery is the small valve that restricts the flow of fluid into and out of the accumulator. This is both the shocker and the spring. It's a true hydraulic car, not an "addon" leveling system for springs..... The plus side of this is ... Hydropneumatic is naturally a progressive spring-rate suspension.

it gets more simple, the brake pedal is actually just a spool valve .... a "button" ... touching the brakes just allows pressure from the main hydraulics into the braking circuit. How this for smart ?? The rear suspension feeds the rear brakes. No weight on the back of the car .... the back brakes barely work. I drop my loaded car trailer on the back.... There is HUGE pressure in the rear suspension to bring it back level ...... so then HUGE pressure available to the rear brakes.

The more I work on these old cars... the more I'm amazed they were ever built in the first place.

seeya,
Shane L.

Originally Posted by DoubleChevron

Blah blah hydropneumatic blah

While it's obvious you're in love with old french cars. It's less than obvious why you keep banging on about them in a completely unrelated thread.

They sell replacement bags because rubber items have a limited life.