Axle mods

[FridgeFreezer]

LWB's have the rear springs outboard of the chassis, SWB's are directly under the chassis.

I think you just notice wrap on the front more as you can feel it through the steering, and the front is more often scrabbling for grip on a climb. It's certainly visible on normal Series with parabolics. Rear springs tend to have more leaves too, mine are 2L front / 4L rear so harder to wrap the back.

[bill van snorkle]

I am trying another approach to the anti-wrap bar and have fitted a short leaf above the springpack on my SOA setup. I'm hoping this will spread any twisting load on the pack. Why are rears not as susceptable to wrap as the fronts?

Unlike the forward shackle placement of many other makes of leaf sprung four wheel drive vehicles,LandRover spring shackles being located behind the front axle in a way cause the springs to behave like forward facing radius arms, albeit flexible ones,without any means to to dampen the rebound forces of this flexibity in all directions, which magnifies the problem.Example,when the front differential of a coil sprung Defender applies torque to drive forward, torque reaction causes the axle housing to want to rotate in the opposite direction (rearwards) The radius arms, each being attached at two points to the axle housing also want to rotate rearwards, so the chassis end of radius arm pulls in a downward direction, applying downward force to the chassis. This is called '' squat'' and keeps the front axle more firmly planted. If we redesign the front end to locate the chassis end of the radius arms forward, below the bumper bar, when the front differential applies torque the axle housing still wants to rotate rearwards, but the radius arms now being up front want to swing upwards at the chassis end. An upward force is therefore applied at the bumper which tends to lift the front sprung mass relative to the axle,thereby reducing weight and traction on the front wheels(antisquat) In low traction conditions the front wheels will slip causing the torque reaction force on the axle housing to relax momentarily, causing the front sprung mass to move downwards again. The momentum of this downward movement momentarily restores traction to the front wheels which in turn starts the torque reaction thing happening again.This grip,lift,slip and drop together with a lack of forward progress is what we experience as axle hop. This would be bad enough with radius arms but when you substitute radius arms for flexible leaf springs you compound the problem by introducing ''Axle Wrap',' which is the rotating force of the axle housing distorting the spring into a shallow horizontal S shape.The flexible bushings of radius arms also permit a degree of axle wrap, though not as bad as leafsprings.Leaf springs also induce other more subtle undesirable forces that I won't go into here. The vehicles dampers (shocks) are not positioned to control the rebound forces when wheel slip relaxes this type of spring distortion, so axle wrap combined with axle hop gives us that horrible, violent carnage inducing front end bouncing and pig rooting whenever you ask a leaf sprung LandRover to do anything a bit difficult.

Now that you are all convinced, check out Fridges simple and elegant solution to address the problem.

Bill.

[Gareth Dickens]

Unlike the forward shackle placement of many other makes of leaf sprung four wheel drive vehicles,LandRover spring shackles being located behind the front axle in a way cause the springs to behave like forward facing radius arms, albeit flexible ones,without any means to to dampen the rebound forces of this flexibity in all directions, which magnifies the problem.Example,when the front differential of a coil sprung Defender applies torque to drive forward, torque reaction causes the axle housing to want to rotate in the opposite direction (rearwards) The radius arms, each being attached at two points to the axle housing also want to rotate rearwards, so the chassis end of radius arm pulls in a downward direction, applying downward force to the chassis. This is called '' squat'' and keeps the front axle more firmly planted. If we redesign the front end to locate the chassis end of the radius arms forward, below the bumper bar, when the front differential applies torque the axle housing still wants to rotate rearwards, but the radius arms now being up front want to swing upwards at the chassis end. An upward force is therefore applied at the bumper which tends to lift the front sprung mass relative to the axle,thereby reducing weight and traction on the front wheels(antisquat) In low traction conditions the front wheels will slip causing the torque reaction force on the axle housing to relax momentarily, causing the front sprung mass to move downwards again. The momentum of this downward movement momentarily restores traction to the front wheels which in turn starts the torque reaction thing happening again.This grip,lift,slip and drop together with a lack of forward progress is what we experience as axle hop. This would be bad enough with radius arms but when you substitute radius arms for flexible leaf springs you compound the problem by introducing ''Axle Wrap',' which is the rotating force of the axle housing distorting the spring into a shallow horizontal S shape.The flexible bushings of radius arms also permit a degree of axle wrap, though not as bad as leafsprings.Leaf springs also induce other more subtle undesirable forces that I won't go into here. The vehicles dampers (shocks) are not positioned to control the rebound forces when wheel slip relaxes this type of spring distortion, so axle wrap combined with axle hop gives us that horrible, violent carnage inducing front end bouncing and pig rooting whenever you ask a leaf sprung LandRover to do anything a bit difficult.

Now that you are all convinced, check out Fridges simple and elegant solution to address the problem.

Bill.

So, would it help to move the spring mounts to the rear and the shackles to the front on a series landy?

[bill van snorkle]

So, would it help to move the spring mounts to the rear and the shackles to the front on a series landy?

Having compared leaf sprung Toyota LandCruisers, Jeeps etc to LandRovers on difficult offroad obstacles, I believe swapping the shackles around would help a lot. However that would involve a fair amount of unnecessary fabrication work when compared to the anti tramp anti wrap linkage that Fridge has employed.

Bill.

[Soren Frimodt]

Having compared leaf sprung Toyota LandCruisers, Jeeps etc to LandRovers on difficult offroad obstacles, I believe swapping the shackles around would help a lot. However that would involve a fair amount of unnecessary fabrication work when compared to the anti tramp anti wrap linkage that Fridge has employed.

Bill.

Hi.

I do understand the advantages of having the shackles at the front, but I must say that I would NEVER swap them around! You see the advantage of having them at the rear is that when your wheel has to go up an obstacle, say a hole, the wheel tend to go much easier up when the shackle is at the rear. Which is quite logic do to the shackle going upwards when the wheel moves upwards.

My experience with other 4x4 brands, with shackles at the front, tells me that they often shoot the front wheels off the ground when going up steep but short holes.

See the following video of a toyota:

A Land Rover would never do such "jumping around"

http://www.youtube.com/watch?v=H9J8Kcv6gw8

Just my opinion

[bill van snorkle]

Hi.

I do understand the advantages of having the shackles at the front, but I must say that I would NEVER swap them around! You see the advantage of having them at the rear is that when your wheel has to go up an obstacle, say a hole, the wheel tend to go much easier up when the shackle is at the rear. Which is quite logic do to the shackle going upwards when the wheel moves upwards.

My experience with other 4x4 brands, with shackles at the front, tells me that they often shoot the front wheels off the ground when going up steep but short holes.

See the following video of a toyota:

A Land Rover would never do such "jumping around"

http://www.youtube.com/watch?v=H9J8Kcv6gw8

Just my opinion

Welcome to the forum Soren.

Your Youtube link shows an 80 series Toyota LandCruiser, that doesn't have spring shackles, and I'd hazard aguess that any vehicle regardless of suspension design, driven with such gusto would be lifting wheels and bouncing around in a similar manner on that course.

The only advantage that rear mounted shackleon frontwould provide is that when the front wheels strike an obstacle, the natural tendency for the axle to move backwards is accomodated rather than inhibited by the rigid spring hanger, and I have seen one or two Landcruiser leaf springs broken as a result, but this occurrance is not common considering the many thousands of leafsprung LandCruisers operated by large mining concerns, cattle stations etc being regularly thrashed at relatively high speed over hundreds of miles of severely corrugated outback roads throughout Australia,Africa etc. The reason all those other manufacturers fitted their shackles up front, together with providing decent strong diffs/axles and other transmission components is that their designers went out into the field to find out what working 4wd vehicle operators want and expect from their trucks. Knowing what we do about Series LandRovers do we seriousely think that Solihulls designers did likewise ?

Bill.

[Soren Frimodt]

Hi

And thank you for the welcome, super forum!

Okay bad video example, it was a quick find!

But anyways, landrover also had shackles at the front on their series 1 prototype, but didn't put that into production, how come?

The front mounted shackle gives better comfort on road. But Land Rover being a more uncompromised 4wd than the japanese, apparently choose this setup for offroad ability. I simply won't believe that a factory like land rover whom ONLY make 4x4's havent done at least as much research as the japanese car manufactureres, who only make it as a sideline production.

[bill van snorkle]

Hi

And thank you for the welcome, super forum!

But anyways, landrover also had shackles at the front on their series 1 prototype, but didn't put that into production, how come?

About 25 odd years ago I rang the head of engineering at LandRover Australia to ask why Rover changed the shackles around after 1950 (the front shackles were actually in production for a couple of years) He told me it was so that a more constant castor angle was maintained throughout the life of the front springs .

About 10 years prior to that I happened to own 2 80'' Landrovers, a 48 model with front shackles and a 51 models with rear shackles. The 48 model was always better at mountain goat type clambering up and over obstacles than the 51, and when it did lose traction on rocky hillclimbs etc, it would do so relatively smoothly like Jeeps, Toys, Nissans etc without the front axle bucking, bouncing and leaping about antics that the 51 and later leafsprung Landrovers I have subsequently owned, hence the reason for the afore mentioned phone call, to find out why Rover would make a modification that actually decreased the marques crosscountry ability. I'll grant you that the rear shackles give a slightly smoother ride, but I've always been prepared to sacrifice ride quality for cross country ability.

Bill.

[Soren Frimodt]

About 25 odd years ago I rang the head of engineering at LandRover Australia to ask why Rover changed the shackles around after 1950 (the front shackles were actually in production for a couple of years) He told me it was so that a more constant castor angle was maintained throughout the life of the front springs .

About 10 years prior to that I happened to own 2 80'' Landrovers, a 48 model with front shackles and a 51 models with rear shackles. The 48 model was always better at mountain goat type clambering up and over obstacles than the 51, and when it did lose traction on rocky hillclimbs etc, it would do so relatively smoothly like Jeeps, Toys, Nissans etc without the front axle bucking, bouncing and leaping about antics that the 51 and later leafsprung Landrovers I have subsequently owned, hence the reason for the afore mentioned phone call, to find out why Rover would make a modification that actually decreased the marques crosscountry ability. I'll grant you that the rear shackles give a slightly smoother ride, but I've always been prepared to sacrifice ride quality for cross country ability.

Bill.

Hi

it seems like you really have put alot of thought into it. And I can only say that we must have very different opinions 'cause I really think jeeps toy nissan etc jumps ALOT!! But thats fair enough there are ofcourse advantages in both setups, otherwise they wouldn't have been used. Thanks for the stories and convincing words..

[Gareth Dickens]

Sorry to hog this thread but hopefully this helps someone else out there. I also have a problem that my leafs are resting under the chassis. Now I haven't even got the big V8 lump in it. When I jump on the front xmember only the tyres give and I have absolutely no up travel on my suspension. The landy always drove very hard even on tar roads until I fit the millitary shackles. I have now gone back to normal shackles as I have done the SOA conversion and want to lose some height in fear of falling over. Does anyone else have this problem? I think swapping the fixed leaf mounts to the front will sort this issue as well as help with the axle tramp.

[bill van snorkle]

Sorry to hog this thread but hopefully this helps someone else out there. I also have a problem that my leafs are resting under the chassis. Now I haven't even got the big V8 lump in it. When I jump on the front xmember only the tyres give and I have absolutely no up travel on my suspension. The landy always drove very hard even on tar roads until I fit the millitary shackles. I have now gone back to normal shackles as I have done the SOA conversion and want to lose some height in fear of falling over. Does anyone else have this problem? I think swapping the fixed leaf mounts to the front will sort this issue as well as help with the axle tramp.

If I understand you correctly the main and wrap leaf at the back end of the spring is rubbing on the bottom of the chassis rail ? If the main leaves of the spring still have some positive arch then yes the suspension will feel very hard because the shackle will still need to swing rearwards to allow the spring to flex. If however the spring leaves are flat or have some reverse arch then the shackle would need to swing forward for the spring to flex. If your spring bushings are in reasonable order and you have original specification springs, the only reasons I can think of for your springs fouling the chassis is that the vehicle has at some stage been incorrectly fitted with SWB or a pair of even shorter series 1 swb shackles. LWB chassis are deeper from the chassis bush to the bottom wall. Or maybe your truck has had a collision at one time and slightly shortened the front of the chassis.

Bill.

[Gareth Dickens]

If I understand you correctly the main and wrap leaf at the back end of the spring is rubbing on the bottom of the chassis rail ? If the main leaves of the spring still have some positive arch then yes the suspension will feel very hard because the shackle will still need to swing rearwards to allow the spring to flex. If however the spring leaves are flat or have some reverse arch then the shackle would need to swing forward for the spring to flex. If your spring bushings are in reasonable order and you have original specification springs, the only reasons I can think of for your springs fouling the chassis is that the vehicle has at some stage been incorrectly fitted with SWB or a pair of even shorter series 1 swb shackles. LWB chassis are deeper from the chassis bush to the bottom wall. Or maybe your truck has had a collision at one time and slightly shortened the front of the chassis.

Bill.

None of the above. I don't quite understand either. How long are lwb shackles supposed to be centre of one hole to centre of other?