Shock Valving and Load Levellers

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Originally Posted by isuzutoo-eh

But I have the leveller, and I don't have a big pneumatic cylinder and I don't have the knowledge for working out just how big a pneumatic cylinder it should be nor what pressure it should be run at and where would I get a compressor that runs at high enough pressure, if the '000+psi of the Boge unit is anything to go by. Suppose could go air over hydraulic and use power steering hydro to get the pressure. A bridge too far.
Or maybe it is chasing 60s technology when I should be more concerned with air springs?

Back to the shocks...

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It must be getting hard to find a boge leveller in good working order. I think the one on my 85 is. But it's hard to know.
They run high internal pressure because of the limited area. If you run a bigger pneumatic cylinder then you get the same force for less pressure.

A 100mm cylinder at 6bar (~90psi) will give ~470kg of lift.
How do you set your working pressure? Really easy, line to an accessible point with a schrader valve and pump it up to level.

Airsprings have a lot of advantages. But there can be some handling issues with the three link rear suspension and just outboard springs. I think that's why the classic rangies didn't drop the leveller until they had sway bars.

Coils also ride better over medium size bumps and articulate better. So coils with a pneumatic leveller could ride a lot better than air-springs offroad.

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Originally Posted by Dougal

It must be getting hard to find a boge leveller in good working order. I think the one on my 85 is. But it's hard to know.
They run high internal pressure because of the limited area. If you run a bigger pneumatic cylinder then you get the same force for less pressure.

A 100mm cylinder at 6bar (~90psi) will give ~470kg of lift.
How do you set your working pressure? Really easy, line to an accessible point with a schrader valve and pump it up to level.

Airsprings have a lot of advantages. But there can be some handling issues with the three link rear suspension and just outboard springs. I think that's why the classic rangies didn't drop the leveller until they had sway bars.

Coils also ride better over medium size bumps and articulate better. So coils with a pneumatic leveller could ride a lot better than air-springs offroad.

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The LL is close to 100mm OD already. Are you saying 100mm ID and would you have to deduct the area of the shaft?

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Originally Posted by uninformed

The LL is close to 100mm OD already. Are you saying 100mm ID and would you have to deduct the area of the shaft?

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Yes that OD is, but I'm not sure how big the piston is internally. I don't want to cut mine open to find out.:angel:

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Originally Posted by Dougal

Yes that OD is, but I'm not sure how big the piston is internally. I don't want to cut mine open to find out.:angel:

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just drill a hole and peak inside :D

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Originally Posted by rick130

The spring rates are vastly different between an LL rear end and no LL, so the valving needs to be appropriate for the spring.

Roll/low speed control comes from the bleed/low speed circuit of the damper and there's two ways to go here, either prop up the loaded (out)side with lots of low speed bump (Bilstein or current theory in race cars with downforce, which makes for a jiggly ride and defeats the purpose of the LL and using soft springs IMO) or use lots of low speed rebound to tie down the inside of the chassis, but if you use too much you'll start to pull the inside wheel off the road. Highly unlikely in a road going car, but been there, done that in race cars.

Land Rover tuned the Rangie dampers for ride, without them being under-damped at all.
Personally I reckon they got it right, you just need to let the suspension roll and comply and the driver (and passengers) just need to get used to it :angel:

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would I be correct in saying that since Mark is going for a 2 inch lift, then it may not be ideal to have as much body roll as the early RRC. Since his COG will be higher, and more importantly, his front and rear axle roll axis now definite oversteer, that having that body roll controlled a little more/firmer may make handling a bit better than it would be. I realise it will loose some of that classic RR feel, but maybe nessecary?

You could start playing with roll centres to help compensate, (ie. raise it) but that will increase front bite more by loading the front end more during cornering (increasing oversteer) and if we raise the rear roll ctr we are increasing anti-squat and on it goes like a dog chasing its tail .....

I'd go more low speed rebound rather than bump to start with, just to maintain some ride quality, and an overdamped chassis always feels more comfortable (stable) to drivers and passengers. (rough rule of thumb: rebound controls the chassis, bump the unsprung mass)

I really must get some 7/8" shaft shocks one day and play.
200psi gas pressure equals 120lb lifting force, just to see how it alters the feel of the chassis with low ride rates.


Just getting OT a little, the hydraulic rebound bump stop in the 90 Series Konis was designed to protect air bags in trucks at full extension. ;)

front roll centre will be raisedd due to coil lift (panhard moves up at chassis end). rear could be rasied with a MD 1 inch extended ball joint..... But yes you are correct in saying the AS will shoot up even more so.

I have some info on the LL somewhere too, Boge had several systems from memory, Nivomat and Hydromat. One was incorporated into the cars dampers, (MB, Rover SD1, etc) the other a stand alone LL (Range Rover) and both obviously damped.

IIRC ZF/Sachs were offering a rebuild service in Europe on the old things from last year too.
Apparently the classic car restoration sector has spurred the rebuild service to be offered.

Does anyone have a parts list of the brackets to mount nthe LL on the A frame and the corresponding bracketry for the chassis please ?

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Originally Posted by rick130

I have some info on the LL somewhere too, Boge had several systems from memory, Nivomat and Hydromat. One was incorporated into the cars dampers, (MB, Rover SD1, etc) the other a stand alone LL (Range Rover) and both obviously damped.

IIRC ZF/Sachs were offering a rebuild service in Europe on the old things from last year too.
Apparently the classic car restoration sector has spurred the rebuild service to be offered.

Does anyone have a parts list of the brackets to mount nthe LL on the A frame and the corresponding bracketry for the chassis please ?

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Ill try and dig some stuff up for you tomorrow. There is not much to it.

G'day all,
I really appreciate the tech you blokes are able to write about, I think I have my head around it...but keep at it!