air suspension question

[2_door]

quick question about the air bag suspension on the D3

1. is it self leveling when towing/loaded

2. is it manually adjustable by the driver

3. or does it auto adjust dependant on TR setting / vehicle speed / and when parked does it lower itself automatically :D

thanks in advance

[Ashes]

Yep,self leveling. Even the weight of a passenger can change it.
Can normally be adjusted by the driver to only to different heights, access, normal, extended.
Apparently there is a high speed height as well:twisted:

[rmp]

Search this forum for much more on the settings, it's a faq.

Answers not recently covered include:

1. yes it does auto-lower over time, wakes up every 6 hours to level itself.

2. TR does not auto-adjust the height, but the car will recommend raising in at least Grass Gravel, and will not engage Rock Crawl unless already raised

3. the adjustment by the driver is only height, not rake (difference front/rear)

4. yes it does drop by 20mm over 160kmph or something like that.

[CaverD3]

And drops autmatically from off road height to normal at 40kph.:mad:

[Desert Traveller]

It bongs at 40 and drops at 50 km/hr.

[2_door]

It bongs at 40 and drops at 50 km/hr.


umm, would that be inappropriate in some circumstances....can that be over ridden before you dump 2 tonnes of metal moving at 50klm/hr on its belly:(

I know that certain tracks can have a fairly high centre and the last thing you want is this happening :(

[CaverD3]

Sorry, bushwanderer is right I think.

No, drops just as you reach the base of the dune you need momentum to get up.

Also drops on deeply rutted tracks and damages the underside. :mad:

Nanny steps in because she thinks she knows what is best for you. :angel:

[2_door]

Sorry, bushwanderer is right I think.

No, drops just as you reach the base of the dune you need momentum to get up.

Also drops on deeply rutted tracks and damages the underside. :mad:

Nanny steps in because she thinks she knows what is best for you. :angel:

bugger :mad: not sure I want that happening :eek:

[dobbo]

It bongs at 40 and drops at 50 km/hr.

That sounds like an old Cypress Hill song

[2_door]

okay, so I dont want a D3 that has a mind of its own when it comes to dumping itself on its belly at undetermined/inconvenient times......:(

so, I am thinking a coiler would be the only option but do they come with all the goodies of TR????

[rmp]

okay, so I dont want a D3 that has a mind of its own when it comes to dumping itself on its belly at undetermined/inconvenient times......:(

so, I am thinking a coiler would be the only option but do they come with all the goodies of TR????

Need air suspension for TR. It's not all that bad, you can live with it, but it's just an annoyance that doesn't need to exist.

[CaverD3]

Coilers are slightly higher than the air suspension in normal height and lower than off road height.
Go for the air suspension as it is better generally off road and the handling and comfort so much better. Only in some situatios is it better.
Some have fitted longer springs on the coilers but it is not that much higher, I am sure some will give you a better idea.

[Ashes]

In the dune example though I would think off road vs normal height would generally be an issue. Wouldn't the D3 have more than enough clearance for sand/dunes at normal road height?

[Graeme]

From what I've seen, D3s don't need any run-up to get over dunes. I watched one do a standing start from the base of Big Red and fly over the top, once sand mode and DSC off were set at the same time.

[2_door]

In the dune example though I would think off road vs normal height would generally be an issue. Wouldn't the D3 have more than enough clearance for sand/dunes at normal road height?

has anyone got the under vehicle measurements for each height setting.

I know the trails around here as well as the inland tracks on Fraser have some decent size wheel ruts....and thats only a few places I have been :(

[CaverD3]

The air suspension is only too low where higher speeds are needed for momentum or where distances to be covered on deeply rutted tracks are too great to be done at 40-45kph (with the vehicle bonging at you, otherwise you need to keep it below 40kph:mad:).
At off road height as said is higher than coilers (and most other 4x4s) at speeds below the 50kph.
Also with the air the springs are cross linked and imitate the wheel travel of a fixed axle.

[wardh]

G/day 2 Door

If you check back to page 5 you will find some heights under the thread "How high is your D3"

I have the D3s tdv6 coiler and for me it does every thing I require of it now that it has had an after market lift (240mm clearence now. 185mm before). I wouldnt question the ability of the air suspension D3 and accept it has bells and whistles and credentials off road that the coiler hasn't got and could not match in some areas, but the improvement gained in the lift has taken it from very ordinary to more than acceptable and it is now a very competent off roader.

Sand driving before the lift was pretty hopeless, 185mm of clearence saw the D3 pushing sand and grading the tracks much to the pleasure of following drivers. The positives for me are,

The vehicle stays at 240mm regardless of speed. I personaly don't need TR for sand driving or any other form of driving for that matter. After 40 years of 4x4 driving both for leasure and occupation I still rather and can without TR make most of the terrain choices manually closely matching the Air D3, apart from heights and throttle response. But as I said before that suits the conditions that my vehicle is used for and my needs.

Sand I turn off DSC and I make the choice of what range/Hi/Low/auto or manual select the gear for the given conditions. Appropriate tyre pressures and gear choice selections also apply to other conditions. The point I am making is they are all available even without TR. Rock crawl! well I don't have TR to change the throttle response but Low range, first gear and steady as she goes gets me places that some people wouldnt even attempt. I still have hill decent and the traction control works just the same when I lift a wheel.

Other things! well the plough is no longer an issue (again for me) the tow ball is now the perfect hight for the boat trailer and I carn't see any issue for the future caravan at this point.

I don't have to worry about suspension pump failure. Don't need access height as we are all tall. Wheel alignments are more straight forward, gee what else? ah the ride, well it was pretty darn good before but it has also improved but I will not draw any comparison to the air as it is a while since I last drove one. The D3 coiler ride is streets ahead of anything else apart from the D3 air and the quiet smooth ride is the first thing people comment on when traveling with me.

Conclusion? well given the chance! I would probably have an air suspension D3 tomorrow, but then for my needs I would be faced with different issues for my circumstances.

Am I happy with what I have. Yes! but then each to his own opinion and view and D3 air suspension owners will be able to point out the good and the bad points for them

Cheers

[CaverD3]

:BigThumb: wardh


Good write up of your experience.

[gghaggis]

I run training courses for D3 owners over here in the West, so I've both driven and visually compared both coilers (std and lifted) and air D3's over the same obstacles.

In sand, there is little difference between the lifted coiler and the EAS vehicles, although as you can't turn the traction control off in a coiler, it can kick in when you don't want it. Another exception is when you're bogged. The ability of the EAS to be raised and the traction control to be aggressively set will get you out where the coiler won't. On the other hand, the coiler won't lower itself at speeds above 50kph. For EAS vehicles, fitting shortened height sensor rods can overcome this problem.

In muddy terrain, or rock climbing, the EAS does everything easier, and in extreme conditions it'll pull through where the coiler won't. Two reasons for this - firstly, as CaverD3 mentioned, the EAS models are designed to mimic a live axle car when in low range. This gives you a lot more wheel articulation than any independently sprung coiler can achieve. Secondly the TR programs can vary the sensitivity of the traction control, so for instance in "rock crawl', you have virtually instant suppression of wheel spin. The traction control in the coiler is set to approximately that of the 'mud/ruts' TR setting in an EAS car.

Towing and heavy haulage is an area where the EAS cars really shine, due to the self-levelling. The coiler is still competent, but will obviously sag more than the EAS car.

Reliability vs complexity would at first sight favour the coiler, but in all the trips we've done, with 5 ~ 7 D3's on each, we've never had an EAS failure. In extreme conditions (competition, mud drags etc) I've only seen direct air failures related to physically hitting the compressor on rocks etc (we make a protection plate for this). There are unrelated errors that can cause the car to lower (wheel speed sensors, height sensors, EPB module failure), but it is possible to overcome most of these with some basic spares or splicing directly into the air lines and using an external compressor.

Note too that in a lifted coiler, you are running permanently at 240+mm. This _will_ prematurely wear the CV joints, and increases your fuel consumption by a noticible amount.

Hope this helps,

Gordon

[2_door]

thanks guys, thats an excellent write up.

Now I am swaying back to EAS with TR :p decisions decisions :(

I am checking out a EAS TDV6 tomorrow so I will fill you all in on my conclusion then.

I had a look at a nice D2a this afternoon (smally4.6) and he picked up a bargain.....so many choices :confused::confused::confused::confused:

[wardh]

The issue of premature CV joint failure due to lifting a D3 coiler is interesting and was a concern that worried me until a few things were pointed out by a suspension specialist. Now I am no expert but it made sense to me and I am now comfortable with the modifications that I made and I will try to explain why (hopefully the drawings will open)

The measurements in the drawings are taken from my 2006 D3 S Coiler after the spring lift and as far as any dramatic angle changes to the drive shafts and CV joints you can see they appear to be minimal or in fact do not change angles or increase angles on the CVs that already existed prior to the lift.

The vehicle was parked on a very level garage floor. Measurements were taken using a long straight edge, set square, large callipers, plumb line and tape. Vertical centres were transferred to the floor and measured.

The front wheel axis (centre of the wheel) whether air suspension or coil is approx 40mm in front of the centre or axis of the differential so the drive shaft is constantly spinning at an angle via the CV joints to the wheel and diff. See (Fig 1) below. This is when driving straight ahead. When turning these angles at the wheels change dramatically.
As can be seen the rear axle configuration is similar but the rear wheels are approx 28mm behind the diff. (I state approx but the measurements below would be well within + or – 3mm)

Fig 1
18880


Now if we compare the angle of the drive shaft from a plane as viewed from the front or rear of the vehicle and compare the measurements below (Fig 2) against the ones above they are about the same. Now unless I am missing something, in the case of the front diff, the parallel wheel in front of diff distance was 40mm the lift has created 35mm parallel difference and a down angle which is still less of an angle on the CV than the forward one, are you still with me?
If you place a 30cm ruler end to end between the palms of your hands then move one hand in front of the other, then lift one hand you will see what I mean.
Fig 2
18881
If we consider that the lift in my case gave me an increase in height of 60mm in the rear of the vehicle then another scenario becomes apparent. Let’s look at the rear diff above and take away the 60mm from the 28mm, we now have minus 32mm of opposite angle which is standard height and similar to the standard height of the air suspension as well.

The air D3 has far greater articulation and height range than the coiler therefore creating more acute angles on the CVs. I am more than comfortable that the spring lift within the range that I have applied will not unduly cause premature wear in the CV joints. Regular off road 4x4 work will contribute more to wear and tear on drive and suspension components than day to day black top driving but I guess time will tell.

Briefly the other point raised was economy and to date the spring lift has made no noticeable difference in this respect.

The other issue was tow ball load and self levelling. I agree the air D3 is superb in this respect. My solution, the rear springs I have are heavy duty and I think without going back through paper work were 30% heavier rated. Testing it I put the boat on the vehicle which I know is a measured heavy 90kgs on the ball, I then put 5 x 20kg bags of stock feed on the A frame over the ball and the vehicle was about level. From memory the back went down about 3cm. When the caravan arrives because I have coil springs I will be fitting a Hayman Reese WDH and I think that is all that should be said as this has been well discussed in the past.

Cheers

[gghaggis]

Hi WardH,

Nice explanation and diagrams! But I'm still unsure of some of the things you're saying:

If you measure the angle from the point of view of the outer CV joint (at the front), it still increases wear on the outer ring as the wheel drops (as the ring is circular), regardless of any pre-existing angle in the horizontal plane. The point may be that this regularly happens when cornering or off-road, but these happen at low speed. Continuous running at open-road speeds will take their toll. When mine went (towing a caravan to the Pilbara and back at 240mm height), it was only noticeable as a slight 'click' when at extreme articulation.

[edit] Of course, I can't say definitively that in this instance running at off-road height caused the CV failure. But it was this event that made me consider an alternative to permanently fitting shortened height sensor rods, to reduce the possibility of it happening again.

Regarding fuel consumption, I can only say that when I run my EAS car around at normal height, and then do the same day-to-day travel at off-road height (via the use of shortened HS rods), the trip computer registers the fuel consumption as having increased by 0.2 to 0.5 l/100 - I know the trip computer is lousy at absolute values, but for a relative comparison I have no reason to doubt it. I can't see why a lifted coiler would be any different? Now consider why the consumption has increased. No doubt some of it could be attributed to air resistance. But around town I wouldn't have thought this would be a major contributor. I suspect that a slight increase in the drag within the CV joints also plays a part.

You're saying that you measure a 4cm frontal offset for the front CV-to-diff. I don't see anything like that on mine at normal height (I haven't mesured it at off-road height). Are you sure that the coil lift itself hasn't contributed to this?

Cheers,

Gordon

[gghaggis]

Sorry, just thought I should point out:

We're only talking small increases in risk here. If I had a coil D3, I wouldn't hesitate fitting longer coils. The std height coil D3 isn't really adequate for any serious off-road travel.

If I was in the lucky position to choose between a lifted coiler and an EAS car, I'd take the EAS car, not because of any slight decrease in wear, but well, because of the air + TR. It makes it that much more versitile.

Cheers,

Gordon

[wardh]

G'Day Gordon how's things in the west?

You would think I could find better things to do than measure my D3 but thats what happens when you mix retirement and owning a Land Rover.

Had I had the option I would have preferred an EAS vehicle also, but there was none available at the time and looking at what we required the coiler fitted the bill in many ways.

The geometry of the vehicle is quite interesting and during taking the measurements several thing were noted. In the case of the rear suspension the 2 lower arm pivots (near the diff) are at very different heights. This can be seen when looking at it from the front and the first thing you think is "thats going to hit the ground first trip off road"

The effect of lowering the vehicle or when the suspension is compressed is to increase the length of the wheel base, we are not talking huge amounts but over the full range of the suspension travel it would be several mm, so the measured 28mm axle off set at 240mm height is going to increase when at normal height in a EAS or standard coiler. You can also see this when looking at the spring through the wheel arch, it has a pronounced rear leaning angle.

The front spring also has this rear lean but is nowhere near as pronounced and the 2 lower diff side suspension arm pivots appear to be about the same height (I have not measured them)
Where the shock absorber is pivoted/bolted to the bottom arm it is at a slight angle indicating that the wheel under load will also move rearwards. This on a standard height coiler or EAS at standard setting would shorten the 40mm off set that I measured, but if compared to the rear suspension only slightly, but could account for why yours is different.

On the coiler one major short coming is the amount of articulation travel on the front suspension with very little droop and upward travel even under heavy compression. If you jack the whole front end up with both wheels off the ground it looks pretty good the wheels hang down quite well, I did this to see if this put undue stress on the CVs but the shocks limit the travel before this happens. If you then take out the lower shock bolts and lift the front end again the wheels drop even further before binding the CVs so there is room for error but in my view it also means you will never see long travel shocks for coilers as the geometry as it stands will not allow it.

The main problem for the lack of front articulation and why you do not get the same droop that you think you should get when you lift the whole front up is the very strong anti roll bar, as you apply pressure to one wheel say over a large hump or rock and we all like to see that wheel travel up into the wheel arch, the bar is also then applying upward pressure to the opp wheel. (oh how I miss my old disco! not realy) And this is where the EAS via its valveing can replicate a beam axle.

The rear articulation is quite acceptable the anti roll bar is set up quite differently and allows more twisting, the shocks still limit travel well before the point where the CVs are nearing the outer ring

Anyhow because of limited articulation (unless totaly air born and dropped wheels pull the stops out of the shocks Gee I guess some people will do that) I am not worried unduly about my CVs. Rear CVs have over 14000 Ks in lifted height no problems or wear detectable yet. fronts have about 2000Ks. Front and rear lifts were done at different times.

The increase in fuel consumpsion still haven't noticed any and I dont think it would be caused by the slight angle increase on CVs, that being the case extra fuel used means energy burnt, =friction=heat=quickly stuffed CVs. The amount you are indicating via your computer is within the range of averages that I work out when filling up, I dont have a computer. so maybe it has not become apparent yet, Any increase is more likely drag.

Cheers

Howard.

[gghaggis]

I'm trying to find the link on YouTube, but there is a very nice little video of the rear (and front) suspension in action (they fitted a web-cam to the underside of the car), where you can see the various angles and movements. Worth a look.

Cheers,

Gordon