EAS - Harsh Ride - Calibration?

Ok, so having resolved several issues offline thanks to Rave, I've now met my match in my latest priority - curing the ridiculously harsh ride my P38 has.

In short, the EAS appears to work fine, changes height when it should, etc (despite dropping at the front over a few hours, for which I will fit new bags) but the ride itself is of very poor quality; crashing through pot holes and rattling along even seemingly smooth roads. I realise this could be duff shocks, but I'm going to start with the cheapest checks & fixes and work my way up. So I guess the first check is whether the EAS needs recalibrating (Keith, I'd like to buy a cable if you're listening)!

Armed with nothing but a tape measure and a notepad, I ventured out and found myself some level ground on which to take some measurements. Here are my findings.. Assume "access" height (bumps?) is zero, the car raised the following amounts at each setting;

Low: 3-4cm at the front, 2-3cm at the back
Std: 9cm at the front, 7-8cm at the back
High: 10-11cm at the front and back

There were often differences of 5-7mm left to right, but only between the rears. At access height (which I assume means it's sitting on its bump-stops) all four read the same.

Does that all look correct, or am I in dire need of recalibrating?

EDIT: I may have answered my own question, but wouldn't mind confirmation. Rave lists the following settings, which suggest my "Standard" setting is a bit too high;

Access: 0 cm
Low: 4 cm
Std: 6.5 cm
High: 10.5 cm

Valiante said:

Ok, so having resolved several issues offline thanks to Rave, I've now met my match in my latest priority - curing the ridiculously harsh ride my P38 has.

In short, the EAS appears to work fine, changes height when it should, etc (despite dropping at the front over a few hours, for which I will fit new bags) but the ride itself is of very poor quality; crashing through pot holes and rattling along even seemingly smooth roads. I realise this could be duff shocks, but I'm going to start with the cheapest checks & fixes and work my way up. So I guess the first check is whether the EAS needs recalibrating (Keith, I'd like to buy a cable if you're listening)!

Armed with nothing but a tape measure and a notepad, I ventured out and found myself some level ground on which to take some measurements. Here are my findings.. Assume "access" height (bumps?) is zero, the car raised the following amounts at each setting;

Low: 3-4cm at the front, 2-3cm at the back
Std: 9cm at the front, 7-8cm at the back
High: 10-11cm at the front and back

There were often differences of 5-7mm left to right, but only between the rears. At access height (which I assume means it's sitting on its bump-stops) all four read the same.

Does that all look correct, or am I in dire need of recalibrating?

EDIT: I may have answered my own question, but wouldn't mind confirmation. Rave lists the following settings, which suggest my "Standard" setting is a bit too high;

Access: 0 cm
Low: 4 cm
Std: 6.5 cm
High: 10.5 cm

Click to expand...

Set your EAS as below. All from centre of wheel to wheel arch lip.
Access 405mm.
Motorway 445mm.
Standard 470mm.
High 510mm.
Extra extended (not settable only used if chassis is grounded) 540mm.

wammers said:

Set your EAS as below. All from centre of wheel to wheel arch lip.
Access 405mm.
Motorway 445mm.
Standard 470mm.
High 510mm.
Extra extended (not settable only used if chassis is grounded) 540mm.

Click to expand...

Yep, that seems to comply with Rave exactly. Access is already spot on, so I'll need to adjust the others - mainly Standard ride height.

I just need the cable now - have PM'd Datatek.

Valiante said:

Yep, that seems to comply with Rave exactly. Access is already spot on, so I'll need to adjust the others - mainly Standard ride height.

I just need the cable now - have PM'd Datatek.

Click to expand...

Setting must be done on level ground with computer outside car.
Don't make the mistake that some do and set it sat in car then get out to take readings.

I got the cable a few weeks ago but haven't plugged it in yet as I didn't want to mess it up. My EAS works ok but I have similar issues to you with slight pot holes and the general ride quality should be better i think. I have had new shocks all round and a new steering damper which helped with tramlining but didn't make the ride much better.

I think I was put off plugging it after watching the RSW video that I think said don't recalibrate for the sake of it or something along those lines so i left it alone.

Goodfella said:

I think I was put off plugging it after watching the RSW video that I think said don't recalibrate for the sake of it or something along those lines so i left it alone.

Click to expand...

Whilst I agree you probably shouldn't dick about with the settings unnecessarily, you have an actual problem which doing so may resolve.

I'm certainly going to - I think as long as you're sensible and follow the guidelines you'll be fine.

Read all the existing settings and write them down before you change anything, then you can go back if you screw up.

Goodfella said:

I got the cable a few weeks ago but haven't plugged it in yet as I didn't want to mess it up. My EAS works ok but I have similar issues to you with slight pot holes and the general ride quality should be better i think. I have had new shocks all round and a new steering damper which helped with tramlining but didn't make the ride much better.

I think I was put off plugging it after watching the RSW video that I think said don't recalibrate for the sake of it or something along those lines so i left it alone.

Click to expand...

If your settings are as i listed above don't change them. If they are not, take the present sensor readings of each height listed on EASunlock. Note them. Measure heights to arch from wheel centre for each height setting to determine what if anything needs adjusting. Starting with access, adjust up or down in small increments until height from centre of wheel to arch is as listed on all four corners. Take sensor readings with EASunlock, note the new settings and write them to ECU. Do the same for each height setting that needs changing.

If you are suffering harsh ride on a p38a things to look st worn suspension joints
Is it Polly bushes as they do produce a rough ride
Are the shocks standard or aftermarket?
How old are the air bags any thing over 7 years will be hard and produce a poor ride
I usually recalibrate every two years as the sensors wear they corrupt and cause the uneven stance
Has the compressor or valve block been checked are the seals ok if it is sinking and the bag seals are good suspect valve block
Last point don't always go for the obvious on the was it is the simple things that are missed and usually people give up and fit coils major step backwards

Valiante said:

Ok, so having resolved several issues offline thanks to Rave, I've now met my match in my latest priority - curing the ridiculously harsh ride my P38 has.

In short, the EAS appears to work fine, changes height when it should, etc (despite dropping at the front over a few hours, for which I will fit new bags) but the ride itself is of very poor quality; crashing through pot holes and rattling along even seemingly smooth roads. I realise this could be duff shocks, but I'm going to start with the cheapest checks & fixes and work my way up. So I guess the first check is whether the EAS needs recalibrating (Keith, I'd like to buy a cable if you're listening)!

Armed with nothing but a tape measure and a notepad, I ventured out and found myself some level ground on which to take some measurements. Here are my findings.. Assume "access" height (bumps?) is zero, the car raised the following amounts at each setting;

Low: 3-4cm at the front, 2-3cm at the back
Std: 9cm at the front, 7-8cm at the back
High: 10-11cm at the front and back

There were often differences of 5-7mm left to right, but only between the rears. At access height (which I assume means it's sitting on its bump-stops) all four read the same.

Does that all look correct, or am I in dire need of recalibrating?

EDIT: I may have answered my own question, but wouldn't mind confirmation. Rave lists the following settings, which suggest my "Standard" setting is a bit too high;

Access: 0 cm
Low: 4 cm
Std: 6.5 cm
High: 10.5 cm

Click to expand...

Your standard height is actually higher than normal.I would expect this not to give a harsher ride.If I drive down the same road in Low mode the ride is harsher than when in Standard mode.The standard mode gives a better ride than the low mode,which I guess is why Land Rover designed it that way.I would suspect you have other suspension issues.

JohnP38 said:

Your standard height is actually higher than normal.I would expect this not to give a harsher ride.If I drive down the same road in Low mode the ride is harsher than when in Standard mode.The standard mode gives a better ride than the low mode,which I guess is why Land Rover designed it that way.I would suspect you have other suspension issues.

Click to expand...

The reason you get a harsher ride in motorway setting is there is less air pressure in bags and the travel is shorter. This causes the suspension to hit the bump stops over rough roads and give a percieved hard ride. The reason you get a harder ride if standard setting is too high is because there is more air pressure in bags than there should be and the suspension is that much harder.

wammers said:

The reason you get a harsher ride in motorway setting is there is less air pressure in bags and the travel is shorter. This causes the suspension to hit the bump stops over rough roads and give a percieved hard ride. The reason you get a harder ride if standard setting is too high is because there is more air pressure in bags than there should be and the suspension is that much harder.

Click to expand...

Good point about the higher pressure at the higher setting.I havent driven it on road at that setting.When I get a chance I will try it out and see what the ride is like.

Can't see how low air pressure can be an issue when land rover designed the system as I have offered as help have you looked at the other components of the suspension for wear and how old are the air bags would be more of a concern than air pressure as it will be down to a component at fault rather than the controller.
Also just as a point my classic runs constantly in the hi way mode without a ride issue compared to normal it is a lot smoother and hand els far better

vougese39 said:

Can't see how low air pressure can be an issue when land rover designed the system as I have offered as help have you looked at the other components of the suspension for wear and how old are the air bags would be more of a concern than air pressure as it will be down to a component at fault rather than the controller.
Also just as a point my classic runs constantly in the hi way mode without a ride issue compared to normal it is a lot smoother and hand els far better

Click to expand...

Because the airsprings are dependant on pressure. The more pressure you put in them the higher they go the less the lower they ride. You can have higher pressure at any ride height but only if the car is loaded. If the car is fully loaded there will be much higher pressure at standard height than if the car was light because the pressure has to be increased to maintain the height against the load. This happens at all ride settings.

I do understand that but in 15 years of playing with eas, i never had a problem with pressure always been old bags and duff bushes and shocks
Still think you are barking up the wrong tree sound more like old spring which have gone hard and lose the will to be supple on the cups
If the height setting are out then you need to look at the bags as it is these that move and when old become more reluctant to do so thus stick and the was tries to compensate.
On the classic when this happens it will usually keep Hightower over nite but have a flat battery as the system try's to self adjust but cannot due to stiff bags. But if it has just been driven some movement will be possible till the bags cool down then it stuck again
Does the vehicle in question jolt when rising? Is there a lack of movement at motorway speed drop not manual overide ecu control?

Wammers a Question:

Is the air pressure in the airbag increased to raise the vehicle or the volume of air contained increased (at the same pressure). The sprung weight of the vehicle doesn't change once the vehicle is moving, only the ride height???

zzr1200 said:

Question:

Is the air pressure in the airbag increased to raise the vehicle or the volume of air contained increased (at the same pressure). The sprung weight of the vehicle doesn't change once the vehicle is moving, only the ride height???

Click to expand...

OK get an air bag with no load applied to it and put 2 psi in. It will be fully extended. Now put a 1/4 ton weight on top of it and see how much air pressure you have to put in it for it to reach the same extended position. If the volume of air is increased the pressure within the bag also has to increase to extend it and carry the load. The higher the suspension is set the more air pressure is in it and the more resistant to compression it is. It is basically a infinatly variable rate spring. If you put 10 psi inside a football 10 inches in diameter and take it 200 feet under water it will be the size of an orange. You would have to inflate it to equal the water pressure at that depth to return it to it's normal size. Hypothetically, say you have 60 psi inside an air bag at standard ride height. If you then load the vehicle, the air pressure within the bag has to be increase to maintain the vehicle at that height. If no pressure was added it would sink as do coil springs. So the more weight that is added to the vehicle for a given height setting the more air pressure is required. That is why when you get out of the car and the suspension is unloaded you hear ticking, that is the valve block releasing air to return the suspension to the selected height setting.

vougese39 said:

I do understand that but in 15 years of playing with eas, i never had a problem with pressure always been old bags and duff bushes and shocks
Still think you are barking up the wrong tree sound more like old spring which have gone hard and lose the will to be supple on the cups
If the height setting are out then you need to look at the bags as it is these that move and when old become more reluctant to do so thus stick and the was tries to compensate.
On the classic when this happens it will usually keep Hightower over nite but have a flat battery as the system try's to self adjust but cannot due to stiff bags. But if it has just been driven some movement will be possible till the bags cool down then it stuck again
Does the vehicle in question jolt when rising? Is there a lack of movement at motorway speed drop not manual overide ecu control?

Click to expand...

The OP said he had a harsh ride, he also says the standard ride height is set too high. Whilst i agree that less resiliant rubber through ageing can have some effect. I think it is far more likely to be the ride height setting causing the harsh ride in this case. Go to a road with speed humps and drive along it in motorway mode, (lower pressure in bags less travel). Then at standard height, (higher pressure in bags more travel). Then in high mode, (more pressure in bags lots of travel). I think you know which is going to be more comfortable. The low mode is no good because it has low presuure and no travel so bottoms out. The high mode has higher pressure and lots of travel but cannot compress. Pretty obvious really.

wammers said:

OK get an air bag with no load applied to it and put 2 psi in. It will be fully extended. Now put a 1/4 ton weight on top of it and see how much air pressure you have to put in it for it to reach the same extended position. If the volume of air is increased the pressure within the bag also has to increase to extend it and carry the load. The higher the suspension is set the more air pressure is in it and the more resistant to compression it is. It is basically a infinatly variable rate spring. If you put 10 psi inside a football 10 inches in diameter and take it 200 feet under water it will be the size of an orange. You would have to inflate it to equal the water pressure at that depth to return it to it's normal size. Hypothetically, say you have 60 psi inside an air bag at standard ride height. If you then load the vehicle, the air pressure within the bag has to be increase to maintain the vehicle at that height. If no pressure was added it would sink as do coil springs. So the more weight that is added to the vehicle for a given height setting the more air pressure is required. That is why when you get out of the car and the suspension is unloaded you hear ticking, that is the valve block releasing air to return the suspension to the selected height setting.

Click to expand...

A good example of this is when you have a good heavy load in the trunk and begin to offload it. With the tailgate open the car will not adjust the height but as you begin to unload your cargo the back will get higher and higher due to pressure/weight/height ratios changing. As soon as you shut the tailgate the EAS will kick in and level things up again.

Hi guys. I wasn't going to post again until after I received the cable from Datatek, but I see this conversation is carrying on without me so I might as well have some input as it's my thread!

@JohnP38 & vougese39
I agree there could be faults with other suspension components causing the harsh ride, however these take more time/money to replace. That's not to say I won't go there, but I'm not going to look at these things first when I can calibrate the ride height for free, give or take a few quid for the serial cable. I'm not "barking up the wrong tree", I'm just focusing on the cheapest/simplest stuff first then I'll work upwards. Also, vouge, a little punctuation and a few line breaks would make your posts easier to read.

@wammers
I appreciate all your advice and whilst most of what you say is accurate (taking a football to high pressure ocean depths would certainly shrink it) - we're not talking about taking the Range Rover diving and altering external atmospheric pressure here. Also your references to weight change in the vehicle requiring greater pressure to maintain height are spot on, but again that's not relevant here - we're not drastically altering the load weight on the springs.

What I don't agree with is that it takes a greater pressure to raise the vehicle, and a lower pressure to drop it. A football or a tyre have a fixed volume, therefore more air means more pressure. Air springs have a variable volume and expand when more air is added, but the external forces acting on them remain the same, therefore the pressure of the air inside remains the same, give or take a few psi during inflation/deflation. What is increased/decreased to change ride height is simply the volume of air.

However, OEM Dunlop air springs have "interesting" variable spring rates and as they increase in size/height the firmer that spring rate becomes. The later Arnott Gen II & III bags don't suffer in this way and have been developed to have the best spring rate at Standard ride height.

So to all:
I fully appreciate and read each and every reply, but until I have the cable and a chance to recalibrate, there's really no use in debating this further. So thanks, and I'll let you know the outcome.