LR air strut suspension

[roverrescue]

I'm in the planning phases of another Offroad trailer build.
This will be another boat trailer for 5m plate alloy boat
Always I start with the suspension and work up,
I'm a little bored of triangulated four links from the last two builds so have two competing designs.

Easy one is radius arms plus a panhard with thoughts to use an air strut.
I figure that LR have dialled in Offroad durability to their struts and the overweight D3/D4 with front axle weights approaching 2tonne should be perfect for this application.

Big question is what are the dimensions of a front strut or better still does anyone have a dead one kicking around???

Kind regards

Steve

[Stuart02]

Sounds like a very inconvenient and horribly expensive way to go, but good luck!!

[cjc_td5]

I think the main issue would be the fact that the strut sits vertically (or close to) whereas on a boat trailer you want a flat suspension setup that does not impinge on the boat envelope? Otherwise the struts are known to be robust and durable.

[roverrescue]

Thanks for thoughts
On most recent boat trailer with triangulated 4 link the dampers were defender fronts attached at top rear of guard down to axle ... 180lb/in springs at 300mm ride height. Plenty of room under a boat due to the deadrise
Easier to package suspension than in a camper or box trailer.

As long as the struts are in the 550mm or so range when at ride height and 200mm or so diameter fitting will be easy

Ride height adjustability and single package for damper/ spring is the benefit

If the LR option is too large I'll likely run a coil spring strut???

S

[Chilly]

I'm in the planning phases of another Offroad trailer build.
This will be another boat trailer for 5m plate alloy boat
Always I start with the suspension and work up,
I'm a little bored of triangulated four links from the last two builds so have two competing designs.

Easy one is radius arms plus a panhard with thoughts to use an air strut.
I figure that LR have dialled in Offroad durability to their struts and the overweight D3/D4 with front axle weights approaching 2tonne should be perfect for this application.

Big question is what are the dimensions of a front strut or better still does anyone have a dead one kicking around???

Kind regards

Steve

I have a front strut from my TDV8 Range Rover Sport sitting on the scrap pile. More than welcome to it.

[roverrescue]

And on the expense side at about $500 for a pair
Really not that Exe compared to buying a pair of air springs plus appropriate dampers?

If I wanted boring and cheap I'd build it with ****ty ALKO components and rebuild every 3 years

S

[rangieman]

I think your onto something here and i like your theory for a boat trailer with the ability to raise and lower the suspension for launching and retreaving aswell as ride and durability [thumbsupbig]
I like thinking out side the square it is all part of being a Real Landy owner[wink11]
Dont let the nay sayer`s put you off :bat:

[roverrescue]

Ta Chris - I think it solves a bunch of packaging dilemmas! And should be tough too.

Trailer will tilt to allow shallow launch retrieve also means axle and suspension can stay out of the water
Planning on building a frame over the tilt section with RTT on it. Frame will raise for launching and loading but lower to lock boat down to trailer. Thinking of swing out kitchen etc up front in space at bow with storage on other side??

Next step will be to dust off the CAD and start doodling hence wanting some dimensions...

On that note Chily I might take you up on your offer but first if not too much hassle just having extended and compressed lengths and max diameter will help planning if it's not too much to ask you to measure your dead strut????

Regards

Steve

[Graeme]

The front shocks don't have much travel - perhaps around 100mm whereas the rears, whilst fully extended are around 50mm longer than the front, have around 200mm of travel. I can get more accurate measurements tomorrow in daylight as I have a few sets of both in the shed.

[roverrescue]

That would be awesome Graeme

Thankyou

A single axle trailer doesn't need much travel
Articulation is largely at the hitch

As long as there is sufficient travel for high speed bump control
Limited down travel is actually advantageous to limit
Roll understeer in a linked suspension

Steve

[Pedro_The_Swift]

Cant wait to see the drawings,,[smilebigeye]

[p38arover]

Big question is what are the dimensions of a front strut or better still does anyone have a dead one kicking around???


I have two L322 front struts I replaced last Xmas but have not got around to throwing out. Too bad you're not closer, you could have them.

127946

[roverrescue]

Thanks for the offer Ron
The bottom mount of those looks a little more challenging to adapt
Seems the d3/4 is a simple eye mount lower with bolt plate upper
Should be pie to adapt to a axle/radius arm mounts

S

[p38arover]

This might be a better view of the lower mount:

127950

[Graeme]

D3/D4 shocks...lengths are bottom pin centre to top mounting plate.

front open 570mm, closed 530mm, closed without helper/bump block 490mm, max dia 140mm (top mount)
rear open 580mm, closed 440mm, closed without helper/bump block 430mm, max dia 180mm (top mount)

MY12 D4 rear shocks have same open length but a longer closed length of perhaps 30mm IIRC, presumably due to longer helper/bump block.

[roverrescue]

Graeme
Thanks a million for those dimensions - absolutely perfect and much more compact than I would have guessed!!! I'm sure I can make these work on a trailer

Now next question do the d3/4 have published axle loads at tare and GVM????
The 40mm of free travel of fronts will be insufficient but I fear the rears might have too much mojo if they have an axle load rating of 2800kg or so????

It goes to show how vital traction control is on the new discos though eh
40mm of total travel at front and 140mm at rear is pretty limited!

Steve

[cjc_td5]

40mm strut travel would be 100mm+ at wheel.

[Graeme]

Helper/bump stop compression is considered to be a practical part of the travel, but to what extent I cannot readily determine. Same applies for the fully-extended lengths with the internal bump-stops that don't get removed when removing the air-springs from the shocks.

[cjc_td5]

If you use a D3/4 strut you would have to run say a double wishbone setup, or a long transverse arm which would mean camber change as the wheel swung though its travel?

[roverrescue]

I have decided this thread is currently useless ;)

In order to improve its usefulness
And perhaps illustrate just how perfect a d3/4 strut is going to be
See images below (excuse the iPhone head tilt)

This is my old girl trailer running a 50mm axle with Landy stub axle flanges
On 235/85R16
Dampers are vertical
Tape tells the story - perfect length for Graeme's rear strut measurement

On the new build the lower eye will mount below axle tied in with radius arm mounts
Upper mount will be angled back at tangent of the arc scribed by radius arm
Upper mount will have to be adequately beefed - will likely build an inverted v style strut mount from chassis rail up to near hull bottom back down to keel support with lateral bracing to guard

Now I have some measurements it's CAD time

Steve127977127978127977127978127977127978

[roverrescue]

Hmmmm
How good are my image attachment skills
Uploaded those two images a few times just to really add in pics!!!

Mod feel free to edit if you think necessary

S

[roverrescue]

Chris
Why would you need a double wishbone geometry
If the strut can take the applied loads in double wishbone geometry it will be more than capable of the loads in a single arc of a radius arm

Depending on Offset range of bag might need to trick the upper mount a little but I doubt it

My only fear is the rear struts will be too heavily sprung for a 1500-2000kg trailer

Steve

[Chilly]

Hi,
Just caught up with this thread. I'll try to measure tomorrow. Might be interesting to see if. TDV8 RRS are the same or not!

[cjc_td5]

Chris
Why would you need a double wishbone geometry
If the strut can take the applied loads in double wishbone geometry it will be more than capable of the loads in a single arc of a radius arm

Depending on Offset range of bag might need to trick the upper mount a little but I doubt it

My only fear is the rear struts will be too heavily sprung for a 1500-2000kg trailer

Steve

I only asked as the D4 strut has a single pin at the bottom end, unlike the strut posted by p38rover that has two mounting points at its bottom end, which allows a rigid mount to a lower arm.

Could the "heaviness" of the ride be adjusted by varying the position of the strut fulcrum between the arm control pivot and the wheel?

Chris

[roverrescue]

Chris - understand now
Yeah agreed I would use d3/4 strut with the single eye mount lower to simplify geometry.
Ideally it would be awesome to find a pressure /load / height / spring rate graph for the d3/4 strut similar to what Is published for firestone bags.
With that everything would be clear.
As you say changing the geometry could be used to alter effective spring rate

My assumption is the relatively small air volume of the struts in question - with no rolling sleeve will mean they have a relatively narrow range of pressure / height / spring rate with a sharp rise in pressure (spring rate) as stroke increases... as opposed to a rolling sleeve spring which has a long linear portion of rate vs stroke.

Will do some looking around for info on them

S

[Graeme]

Both front and rear air-springs have a rolling fold. The rear springs are much larger diameter than the front.

[Chilly]

A few photos.
Well hopefully I have loaded them ok.

[rijidij]

I think your onto something here and i like your theory for a boat trailer with the ability to raise and lower the suspension for launching and retreaving aswell as ride and durability [thumbsupbig]
I like thinking out side the square it is all part of being a Real Landy owner[wink11]
Dont let the nay sayer`s put you off :bat:

I agree, if nobody thought outside the square we wouldn't have any technical advancement......go for it.

Cheers, Murray

[roverrescue]

I figure I may as well add stuff to this thread to keep my rambles in one place

2015 model Discovery -
max front axle mass 1450kg, rear axle 1855kg
My calculated tare masses
Tare front axle 1125kg, rear axle 1450kg

I then measured lower control arm pictures on the net with estimated distance from mount to strut to total arm length 70% front 75% rear
Then using beam calculator for applied force on cantilevered point
the following individual strut loads (converted to kg to keep simple)

Front at tare 810kg at GVM 1035kg
Rear at tare 960kg at GVM 1240kg

Now this is roughie roughie but essentially using a strut with no mechanical advantage as I propose on a 1500kg ish trailer the fronts are likely Suitable with
Trailer axle loads similar to tare loads of strut....

the rears likely a little to high a load rating
BUT considering the rear struts have much longer travel I'm thinking they could be run at lower pressure and thus length
BUT if they are rolling sleeve as indicated above by Graeme load rating will change little inspite of height - hmmmmmmmm

I think I need to get my hands on a strut!!!

More thinking
Steve

[roverrescue]

Couple more pics to put them all together
This a triangulated four link setup using defender front coils
Once again can see plenty of room in a boat trailer geometry for struts

Pics also show the tilting mechanism
This trailer was built for a smaller boat (not one on trailer)
But I'll use essentially the same design frame again

Will run radius arms from inside of rear frame with struts from radius arm axle mounts
Up to similar location as pictured...

CAD work starts this weekend

Steve128110128111128112

[Graeme]

BUT if they are rolling sleeve as indicated above by Graeme
No doubt that they have a rolling sleeve - had them apart several times and have a full set still assembled.

[roverrescue]

Sorry Graeme on re-reading my words they do seem to doubt you! Not my intention at all.
I see they are a rolling sleeve - that generally means the springbrate is pretty constant through
The stroke irrespective of height which might preclude the rears from my plan

I'm looking at a bunch of "air lift" PDF at moment
There seems to be quite o few options available through them

S

[Wheatie]

hi steve
I have a D4 and it uses and integrated airbag / strut
which are a challenged to maintain
have you considered a caravan air suspension system
My Trakmaster van rides on air and it has separate components that make maintenance a lot easier
mind you I haven't had to do anything with it
just a thought
Russ


I'm in the planning phases of another Offroad trailer build.
This will be another boat trailer for 5m plate alloy boat
Always I start with the suspension and work up,
I'm a little bored of triangulated four links from the last two builds so have two competing designs.

Easy one is radius arms plus a panhard with thoughts to use an air strut.
I figure that LR have dialled in Offroad durability to their struts and the overweight D3/D4 with front axle weights approaching 2tonne should be perfect for this application.

Big question is what are the dimensions of a front strut or better still does anyone have a dead one kicking around???

Kind regards

Steve

[roverrescue]

Thanks Russ
Been there done that
Last build used firestone airsprings and matched dampers

Something different this time!!!!

Seems there are some good air lift options that are packaged even
Nicer than LR units

S

[roverrescue]

So this weekend I was gonna light up the old Linux LibreCAD
But instead went with "Cutting And Dicking" around


Dragged old trailer into shed
It runs on rusty old hilux front leaves on a 50mm square solid axle
With flanges welded each end that bolt up to Landy stub axles

So I went for it and cut the old springs out , removed dampers
And think I've decided to make a MkI radius arm panhard rod air strut
Suspension on the old chassis

Photos are
-with it "slammed" teeheehee
128149

-At ride height
128150

Roughie strut length compressed
128151

-Then extended
128152

-arms at ride height
128153

-overview from rear
128154

-pure dumb luck and largely why I'm going with
MkI on this chassis - the front radius attachment
Lines up perfectly with one of the strongest parts
Of the chassis
128155

I have the Radius arms sitting on axle for setup but thinking about it this
geometry will keep bolts etc out of the salt - will run em high I reckon?

Will likely pair this setup with some air lift 82107 struts
Air Lift AirOver Shocks 82107 - Free Shipping on Orders Over $99 at Summit Racing (https://m.summitracing.com/parts/air-82107)

Obviously chassis will need some building bracing, front radius mounts
And panhard mounts. I'll likely lean the struts back at the tangent to radius swing but I can't
See any negatives other than the corrosion issue!!!!!
Will need to find a lanolin type product that is rubber safe.

Steve

[roverrescue]

Couple more hours at it today

First cut out some rusty bits with the plasma

I established what is needed for radius-chassis attachment
Thought one was to plasma off the mounts from a wrecker d1
But as my geometry will be top mount rather than side mount I think
I'll just go see my metal man and fabricate some.... the link mount is 70mm diameter slug of 25mm thick steel with 39mm centre hole and inner smooth radius'. I should be able turn these up....

Step two was to plasma out a pair of axle mounts.
These are 5mm thick cut out of some RHS. OEM axle mounts are 5mm
Boxed in and braced. So should be enough

128278

I also took a pic with a roughy old damper at "air lift 82107" ride height

128279

Top mount will be different - braced between centre and other chassis , but bottom mount I'm not sure whether to
Link into radius arm mount or just make a double shear lower mount onboard of the radius mounts....

128280

Final plan was to sort panhard - reckon illuse the old damper axle mount leading the axle

Sooooo now I'll just order some struts and make this happen!!!

S

[roverrescue]

Got some work done on the radius arm chassis mounts
Started with some 90mm round bar in saw

End up with a 25mm thick Slug turned to 80mm OD with 39mm ID for OEM bushes
Still need to chamfer and tidy it up but one side is close

Plan to then cut hole in 6mm ear shaped plates and weld slug in
Can then tinker it into something pretty

Slowly slowly

128404


128405

[W&KO]

Any updates....

[roverrescue]

I ended up finishing the rig
I thought I made a post about it?

Anyway in the end I used a pair of 80series radius arms
Length was good and the leading pin mount was easier to fab.
Used a landy panhard
Mounts welded to 50mm solid axle which runs landy stub axles (un braked)

In the end I bought a pair of double convoluted bags - it rides less softly than the previous 4 link I made which used rolling sleeves
(A bit of geometry plus spring rates in that)
But it still does the job
9L air tank bolted to frame which I fill via a shraider
Manual Paddle valves to control air in and out of bags
From memory 9L let’s me cycle up and down full stroke 4 times

Works well - rides smooth - height adjustable is awesome

Can post pix later

S