Thread: Self Levelling Unit for RR Classic

Originally Posted by Vern

Out of curiousity, why did Land Rover remove the boge unit if it was so good?

hmmm...how long is a peice of string??? IMO and its just my opinion, there are a few reasons: #1 we must remember that it was used on RR classics and 110 county's (remember county is a trim level/delux version, they were actually called 90's 110's and 127's in the uk with the different options, here in OZ because 95% of them were county spec they just got referred to as county's) when the Disco 1 came along, even though it was built on the same chassis as a RR it could not be upto the same spec,or why would someone fork out the extra $$$ for a RR. #2 new models require changes, just for the sake of them being new, or people loose interest...#3 the super soft ride of the RR was a love/hate thing, that is people either loved it or the hated it and it made them motion sick...I think they moved away to a middle ground and of course they were going to Air bag suspension anyway....#4 many MANY times LR has changed things for the worse: example wheel bearings being moved closer together at the hub...this would have required new tooling for that part and would have cost them set up to produce....but they intern knew the $$$ would be made back

of course I could be way off the mark.......

IMHO they were convinced that the self levelling air suspension was a "World first" and a great USP, which nobody else had, while several US and European makes eg BMW, Ford GM, were by then using versions of Hydromats.

The big advantage of using light springs and Hydromat is that the speed of chassis movement was reduced giving a smooth luxury ride. They achieved this with air suspension and ability to raise and lower for better road handling. (at considerable reputation cost)

Just about every innovation in suspension of 4WDs has been to make them "more car like" and a "Jack of all trades".
It was also the advent of ABS and the ability to program ETC from the hardware and software that led them to independent suspension with poor articulation, again for on road performance.
Lets face it , what percentage of owners actually go off road anyway? And who bothers that they replaced simple beam axles with a few wearing parts with independent suspension with zillions of moving and wear parts ,eg D3 front ball joints.
Regards Philip A

Serg,I don't know if much of the following information is of any use to you There was a hold up with the chores I was going to do today, so I had a play with the Rangey on the articulation ramp.
I disconnected the right side rear damper and drove up the ramp until it wouldn't go further. These are the measurements I took.
Distance from bottom of right front tyre to ground = 82cm
Vertical distance between right rear coil spring seats on axle and chassis = 50.5 cm
Free length of coil spring = 43 cm
Compressed length of spring on left rear = 15.5 cm
Lateral angular displacement of rear axle relative to chassis = 21 degrees
Angular displacement of right trailing arm relative to chassis =24 degrees
Distance between upper and lower mounting points for right rear damper = 70cm
compressed length of left rear damper = 36.5 cm
Shaft protrusion on boge unit =10 cm.
Shaft protrusion on disconnected Boge unit =12 cm

Observations.
Further articulation was hindered because the horn of the Boge mounting bracket on the A frame fouled on a web of the Rover diff. The web could be ground for clearance, but the 29'' dia left rear tyre fouled heavily on the top of the wheel arch tub, so much so that the vehice could not be pushed back down off the 20 degree ramp, and had to be driven down.
The chassis bushing on the non cranked right side trailing arm was maxed out. The A frame ball joint appeared to be close to its angular limit,although I thought they would articulate a bit more than 21 degrees

I had hoped that the Boge unit was still in working order to determin how much weight the right side wheel was supporting just at the point of spring dislocation, with and without the Boge disconnected, but unfortunately it was dead, and the fouling tyre and A frame horn would have precluded accurate measurement anyway
But to answer your original question, it does appear that the Boge unit has sufficient shaft stroke to cope with 12'' stroke dampers
Wagoo..

Thanks Bill, awesome work. If using light coils and retaining them, would they stretch the 7.5cm?

Originally Posted by uninformed

Thanks Bill, awesome work. If using light coils and retaining them, would they stretch the 7.5cm?

Serg,7.5 cm is near enough to 3''. The spring rate of a coil spring I believe is the same in tension as compression. So to stretch say a 124 lb inch coil 3'' would apply a lifting force of just over 370bs to the axle.That would equal less traction in the ramp scenario..

BTW, does anyone have a working boge unit lying around in their shed that they can measure how far the shaft protrudes from the units body? I'm reasonably sure it should be greater than the 12cm I measured on the dead one.I vaguely recall in the past having to disconnect both rear dampers and jacking the chassis up to the max and even put a bottle jack between the axle and the chassis to relieve enough load on the shaft to remove the unit from the vehicle
Wagoo

Are there any differences between a range rover and 110 boge unit?

There are differences, I think the 110 units have a higher load capacity and a longer shaft, and can be identified by a globular shaped chamber on the side of the Boges housing, with a canvas strap to keep the globe facing downwards.
I don't know what the globe contains. Extra gas perhaps?
Wagoo.

I'll measure my working Boge unit (110 version) tomorrow.
I am doing something similar to what Serg is talking about, standard height springs (starting with 180lb rear as per factory spec), Boge, raised shock towers and longer shocks. I won't be dislocating springs. Will take a few months before its all installed...Open to any advice on the topic...
The globe is the same as the canister on a remote-reservoir shock absorber as I understand it.


EDIT: I am somewhat concerned about body roll, I'd rather not run a rear sway bar but do want to be able to drive close to the speed limit with a lightweight roof top tent or kayaks up top.