Pump My Ride - Ninety on air

[landroversforever]

M8x1 would be fine pitch, so those would probably then be extra fine which is M8x0.75 if I remember correctly.

 

[elbekko]

12 hours ago, Turbocharger said:

The fitting it really needs (top of pic below) is 7.7mm OD across the male threads and 0.75mm pitch or some dark hex fraction of an inch equiv. Could be M8 fine pitch? (The bottom one is today's M8 Amazon delivery).

Could be M8 gas fittings? They're very fine pitch I think. Struggled with that stuff before for LPG...

Some drawings of the P38 chassis from RAVE:

Front end, you can see the spring mounts and shock turrets:

Rear, spring mount is under the naughty shaped hole in the crossmember. The springs poke through there.

[Bigj66]

Great thread, following with interest 👍

I think the custom car guys use kits to retrofit air suspension systems so that could be worth looking at if you’re still after non LR components.

Trying to imagine a Series 3 on air....🤔

[Turbocharger]

12 hours ago, WesBrooks said:

What are the rough figures for the usual draw for the compressor and solenoids? Curious to see if I could get it running from the bench on a 350W or 500W PSU. I would check, but the two spare 12V batteries I've got are goosed.

The P38 compressor runs through a 30A fuse (so it's less than 400W then). I've just bench tested mine from a battery and saw 2.5A (30W) but that's not running against any pressure, just motoring the piston up and down.

Thanks for the chassis info - it explains the strange shape of the P38 rear top cups, but I've got enough info to work up what I need. Like I said, modifying a new galv chassis isn't on the menu so it'll go back to coils if I can't make what I have fit.

[elbekko]

I think it should be fairly trivial to make an adapter plate, it'll all depend on if the hole in the rear spring perch of your chassis will be big enough to fit the top of the air spring through. Should be fine I think.

[WesBrooks]

I'm thinking if not a plate it should be achievable with something less than 25mm to 50mm tall. Ok, you loose some from the lower range of travel but not the end of the world.

[WesBrooks]

52 minutes ago, Turbocharger said:

The P38 compressor runs through a 30A fuse (so it's less than 400W then). I've just bench tested mine from a battery and saw 2.5A (30W) but that's not running against any pressure, just motoring the piston up and down.

Thanks. Got a few 350W 12V PSUs kicking around that should be fine then. The high peaks may be to account for starting up while there is compressed air in the cylinder, and are probably very short lived.

[FridgeFreezer]

I might've missed this but are we sure that mystery fitting isn't 1/8" BSP or NPT?

[Turbocharger]

12 minutes ago, FridgeFreezer said:

I might've missed this but are we sure that mystery fitting isn't 1/8" BSP or NPT?

No 🙄 I think they're too small - 1/8NPT would be 9.5mm OD across the male thread and ~0.9mm pitch, these are 7.7mm OD and 0.75mm pitch.

[elbekko]

I'd be tempted to just use the stock fittings (ANR6460 if you need new ones), and fit a pushfit connector a bit further up the line.

[mad_pete]

Looks like this system has an adapter so the spring fits in existing mounts 

 

[Turbocharger]

Yes - I think they've made a new upper housing complete - I expect I'll end up making something like this (but probably not as pretty). At present I'm fitting springs with bits of wood etc to better understand which springs will suit a softtop Ninety best - and to understand why.

[elbekko]

I have a feeling shock choice is going to be much more important than spring choice - I know it can make a huge difference on the P38.

[WesBrooks]

I realise a quick search could give me the answer, but are adjustable shocks getting more affordable? ...or even available for our application?

Edit: Electrically adjustable.

Edited April 3, 2020 by WesBrooks

[MECCANO]

 

Just realised this post is redundant. Wes has already overed it... but heres some more picks anyway

 

 EAS setup on a range rover class

 

 twin shock setups that would do similar in a bolt on fashion (personally not a fan of the bot on bracket)

 

Edited April 3, 2020 by MECCANO
my post is redundant.

[mad_pete]

i like pictures. I have the bottom kit as air suspension is on my literal wish list but I haven’t moved the shocks yet. Have you emailed some air spring companies ?

in theory it’s sprung  weight (25 % compression? ) so want the same for air spring ? Range rovers would be heavier but are they heavier enough to make a difference ?

[mad_pete]

Found some reading

http://lhtech.com/pdf/automation/pneumatic/Goodyear-Air-Spring-Data.pdf

I’ll give it a read through later no idea of it helps yet.

[MECCANO]

Turbo C,

So when you say they p38 springs are more like a commercial vehicle spring, could you fit a rear bag and piston to a front top hat?

[Badger110]

Will the airbags give a smoother ride overall?  A recent journey in the back of mine made me realise that the dogs feel everything when we travel and although they seem unaffected, if it’s a fairly straightforward swap down the line, I could be very interested in doing something similar.

[robertspark]

If I ever get my 90 finished (now have a chance + instruction from swmbo as furloughed over virus).

I have a set of RR classic front and rear air bags that will clip straight on to the bottom axle mount (just remove the old coil spring mount.

 

For the top of the classic mount I am using the normal shock mount retainer plate modified to accept the air spring clips for the RR classic.

And remote spring mounts with adjustable shocks all around (all parts to hand now... No excuse over time any more!)

All tubing is 4mm od to the rrclassic air springs.

I have a choice of valve blocks.... I have a RR classic valve and driver block (which will save the need for separate MOSFET drivers.... As they are contained in the resin filled driver block)

Or the use of some(4) 4 piloted 5 port 3 position 1/4" pneumatic valves 4v330C (although they are limited on air pressure rating read waffle below)... So the rrc valve block may be used in the end

Along with 2 proper air compressors           https://air-zenith.com/product/2nd-generation-200psi-ob2-compressor-black/

(feeding a 20l (or 25 I forget) receiver (given the LR eas air compressors seem to be a common point of failure.... Followed by valve block seals)

The one really good feature of the LR classic and P38 eas was the use of a regenerative dessicant air dryer..... In that when air was released from the airbags it was exhausted via the valve block and then through the air dryer which released any moisture from the dessicant air dryer and made sure that the air in the air bags was dry.... Given being the lowest point in the system without an air dryer you are likely to end up with condensation accumulating over time in the bottom of the air bags.... The receiver will only tap whatever condenses.

I am overcoming this by using a dual (as I have dual compressors) membrane dryer arrangement..... One problem with membrane dryers is they bleed air.... Another is air pressure.... They are limited to 8 bar.... Hence they will go downstream of my receiver and I may put a smaller receiver downstream of the dryers with an nrv on the inlet ... Or better would be a constant pressure valve because membrane dryers work best under a constant pressure downstream.

I mention all this waffle as maybe there are some nuggets to consider about dry air, valve blocks and compressors.

I have another use for the onboard air too hence I wanted some resilience in air compressors each with a 100% duty cycle. No not blowing up tyres...

 Eas controller via ATMega mini onto a custom PCB (I need a couple so have a standard 14 high current output BTS621 dual high side switch ICs (used in the wabco ABS to drive the abs modulator.... Have open circuit and short circuit protection and fault indication ) and a number of analog inputs.... The PCB is part designed schematic wise using https://easyeda.com/

 

The code.... I started and returned to the Arduino IDE several times... But have used Visuino     https://www.visuino.com/ which is really great visual programming software.... But when your sketches get very big and complex I struggled with the speed as it wa NTS to redraw the wires everytime you move add a wire.... You can turn off the auto wire ... But it just means that when your sketch gets even bigger it just grinds to a halt (I have one sketch which can take 20mins just to load.... )

I am now using XOD   https://xod.io/ which is very similar but much more programmer friendly but it only works with Arduino compatible boards (ie a chipset listed in the Arduino family...)

Where as Visuino has a vast microcontroller base.... They have also just kindly bumped up the fees for Visuino and launched a PRO version... At more cost that provides can bus interface (which I need) as I am hijacking some other sensors plus it's easier to send data around the network to multiple boards using 2 wire.

 

I'll stick with XOD for the moment.

But still gravitate to using the Arduino IDE as well.

 

For MOSFETs, the ir540 is a good (high current plus high voltage plus cheap and available) choice... Plus these are very cheap as a quad PCB module you may want to consider (from memory.... The RRC or P38 valve block is a 7 channel valve block so two of these will work nicely if you don't want to use the standard rrc or P38 resin driver block.

 

https://www.google.com/search?safe=strict&client=ms-android-xiaomi-rev2&sa=X&biw=360&bih=641&tbm=shop&sxsrf=ALeKk00QGM0vmoGnZmb-dX1k8arN6mkN8g%3A1586082169584&ei=ebGJXo7wIdKW8gKOvZ64Dw&q=mosfet+irf540+four&oq=mosfet+irf540+four&gs_l=mobile-sh-serp.3...8077.11096.0.11845.5.5.0.0.0.0.108.471.3j2.5.0....0...1c.1j4.64.mobile-sh-serp..0.2.212...0i30k1j30i10k1.0.ptdD6oa5hEk

 

Interested plus subscribed.

 

 

[FridgeFreezer]

1 hour ago, robertspark said:

given the LR eas air compressors seem to be a common point of failure.... Followed by valve block seals

I think they're a common failure but not a common cause - if there's a leak in the system, the compressor runs flat out and burns itself out and people blame the compressor rather than the 50p bit of pipe with a hole in it.

[elbekko]

Exactly. The compressor wears out because the rubber bits - valve block o rings and air springs - leak.

[robertspark]

True cannot argue with that analysis.

[robertspark]

Maybe they (landrover / wabco for the BCM) should have programmed a duty cycle into the EAS controller to limit the number of starts and continuous running cycle to save the very expensive compressor though and lock it out under fault if it cycled too often. Getting a bit offtrack but maybe it's something to consider adding to the microcontroller code.  

 

The best explanation of the RR EAS system was I think this one which is worth considering integrating into a microcontroller... Or at least similar... 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.landyzone.co.uk/attachments/eas-system-information-document-pdf.60384/&ved=2ahUKEwjD_dy1yNHoAhXObsAKHSOJArQQFjAAegQIARAB&usg=AOvVaw2YdciZpxmIGcLe9yNuiJSt

 

I have also got some pressure sensors (each corner) which I did consider may be useful to determine an off-road situation where one wheel may be loaded but then it's what you do with that information because it would probably be useful with more information such as a 9 axis gyro, accelerometer and magnetometer.... Speed sensor.... Steering angle.... And all of a sudden the code is very complex... and what you want to do with all this info .... Automatically by microcontroller....

 

[landy_andy]

I don't frequent here much these days as living in Canada now.. just happened to be browsing & thought you'd like to see these pics.... I made them way back in 2005.

They use commonly available HD Firestone bags... if you want more info drop me a PM.

Cheers,

Andy