Getting more flex from the front?

[FridgeFreezer]

It's really simple - two small round spacers slip in between the two halves and a bolt goes through each one. The upper plate has threaded holes, visible on the front edge of the plate in my photo.

[discomikey]

very simple, the way things should be!

[FridgeFreezer]

They need to be simpler, I always forget to unlock them!

[ToyRoverlander]

Leave them unlocked . Or does (on road) handling suffer badly when you do that?

[bill van snorkle]

Leave them unlocked . Or does (on road) handling suffer badly when you do that?

Roll stiffness when cornering would likely be reduced. It would be interesting to calculate the roll centre height with them locked/unlocked, although my minds eye sees little difference.

[Jamie_grieve]

It's easy to theorise etc but the fact is by simply moving the top damper mount you can get more travel than a stock coiler.

Here's the proof:

In this instance the front shackles are extended military or one ton ones but otherwise standard one ton geometry with no extended bump stops.

I always use multileaf springs for this very reason. Try this with a parabolic and even a good one will snap. I use soft poly bushes and greased bolts. 15 years on the road with this setup and no dramas at all. The rear flex was more than the front at around 35deg. The leaf springs being mounted much narrower don't need to move as far as outboard coils to achieve the same level of articulation.

Mine simply has a bit of angle iron welded to the side of the chassis rail with an end on it for the pin of the damper. The eye type lower damper mount on the series needs binned in favour of the pin type too.

Fridge, I like your setup, have you a flex pic of the way it is now?

[ToyRoverlander]

Roll stiffness when cornering would likely be reduced. It would be interesting to calculate the roll centre height with them locked/unlocked, although my minds eye sees little difference.

That's what I thought, but I don't know how noticable it would be in real life. As the roll centre lies on the imaginary line drawn between the fixed end of the leafspring and the shackle mount, where it crosses the vertical line from the axle, the roll centre height doesn't change.

[FridgeFreezer]

ToyRoverLander - which book is that picture from? We've tried to find any decent tech on leaf spring suspension design but of course modern books are all about coils & independent suspension.

Jamie, I couldn't say it's 100% flexed out but this is the best I've got - tyres are 37's for reference:

My shackles are standard, not extended, and ride height is standard. All the lift is in the portals.

[ToyRoverlander]

I found it over on Pirate when I was looking for info on anti-squat and roll centre on leafsprings ages ago. Here's the pic with some info

Here's the link to the thread on Pirate: http://www.pirate4x4.com/forum/general-4x4-discussion/639360-leaf-springs-anti-squat-whats-relation.html

[Michele]

It says "Chevrolet power service manual"...

Although the first drawing is familiar.

[FridgeFreezer]

Ah, it's from a book I've already looked at - "Race Car Vehicle Dynamics". I won't say I read it 'cos it's really rather thorough, and the section on leaf springs is quite brief, but it seems to be considered as the bible of suspension design (with a price to match!).

[Michele]

That's why it looked familiar, I have the book on my shelf

Quite a brick and tough to swallow (unless you're an engineer or you cut your teeth in a shop for your whole life).

[ToyRoverlander]

Would be a nice book to have, with lots of usefull information, I'll go and google it see what it costs.

[Bowie69]

About £60(!)

[ToyRoverlander]

That's quite steep for just a book....

[bill van snorkle]

A million years ago when mine was standard-ish, TIC parabolics & standard length ProComps:

.

My front shocks are actually in coiler shock towers which work quite nicely - weld the coiler spring mount on and then it's your choice of off-the-shelf shock turrets in any length!

It should be pointed out that Fridge's Volvo axles are some 9" wider than standard leaf spring axles, so the tyres would foul on these coil spring/shock mounts if used with the narrower axles. Also, I'm guessing these mounts, and the shocks have been fitted forward of the axle centreline , so that the shocks can provide at least some degree of axle tramp/wrap control, which is generally even worse with parabolics than with standard multi leaf springs. Fridges vehicle is also fitted with an antiwrap bar .

Further to the important subject of axle tramp. All the articulation in the world is worth SFA if traction from the drooping wheel cannot be properly transferred to the chassis, particularly in situations when that single wheel is the only one of the 4 that has any grip. I have mentioned it before , that I watched a mates front/rear difflock equipped Stage One v8 attempting to climb a steep hill with loose football size boulders once, when it wound its front springs up so severely that when they released all that energy, the front of the truck leapt sideways 6 feet, breaking both springs, destroying both shocks and snapping the expensive double cardan propshaft . Once the damage was repaired, a simple control arm made from a shortened Rangerover rear trailing arm, fitted to the centre/top of the axle housing and running forward to the bumper bar totally transformed the cross country performance of that truck.

A short flexible leaf spring bent into an arch is not a particularly ideal medium for tranferring torque from the axle housing to for/aft thrust to the chassis, unless backed up by some type of link to eliminate or reduce the horrible and destructive axle wrap,hop, skip and jump that the designers built into the front of leaf sprung Landrovers.

[deep]

It should be pointed out that Fridge's Volvo axles are some 9" wider than standard leaf spring axles, so the tyres would foul on these coil spring/shock mounts if used with the narrower axles. Also, I'm guessing these mounts, and the shocks have been fitted forward of the axle centreline , so that the shocks can provide at least some degree of axle tramp/wrap control, which is generally even worse with parabolics than with standard multi leaf springs. Fridges vehicle is also fitted with an antiwrap bar .

Further to the important subject of axle tramp. All the articulation in the world is worth SFA if traction from the drooping wheel cannot be properly transferred to the chassis, particularly in situations when that single wheel is the only one of the 4 that has any grip. I have mentioned it before , that I watched a mates front/rear difflock equipped Stage One v8 attempting to climb a steep hill with loose football size boulders once, when it wound its front springs up so severely that when they released all that energy, the front of the truck leapt sideways 6 feet, breaking both springs, destroying both shocks and snapping the expensive double cardan propshaft . Once the damage was repaired, a simple control arm made from a shortened Rangerover rear trailing arm, fitted to the centre/top of the axle housing and running forward to the bumper bar totally transformed the cross country performance of that truck.

A short flexible leaf spring bent into an arch is not a particularly ideal medium for tranferring torque from the axle housing to for/aft thrust to the chassis, unless backed up by some type of link to eliminate or reduce the horrible and destructive axle wrap,hop, skip and jump that the designers built into the front of leaf sprung Landrovers.

I've noticed a less extreme form of that behaviour with my Stage One. Very disconcerting! However, I have used leaf sprung Land Rovers off road for decades and not struck it before. Was I just lucky or is it because I now have real power and tyres with decent grip, as opposed to old 750 cross-plies? My driving style is very much "back-off and don't break stuff" (there's usually another way to approach something) so I'm not overly worried, just interested.

Anyhow, your explanation makes sense and I am grateful. The solution you outline, however, has to go in the queue behind making the brakes work for more than a day at a time and making the steering effort less heroic but probably ahead of fitting a diff-lock...

[FridgeFreezer]

Bill - welcome along, always good to have your input on suspension threads!

deep - I suspect things are worse these days as people have more power, parabolic springs, bigger tyres, and seemingly less mechanical sympathy!

Edit to add: yes my axles are wider than Series but by definition coiler-width axles would clear a coiler shock tower, so it's likely that Series with a bit of offset in the wheels would manage OK too.

[ToyRoverlander]

I was wondering. Would this problem be more evident when the front springs have lots or arch in them compared to a spring that's flat? I think it is. So it would be less on a sprung over vehicle with flat springs than on a lifted sprung under vehicle. What's a 101 like in this respect?

[bill van snorkle]

I was wondering. Would this problem be more evident when the front springs have lots or arch in them compared to a spring that's flat? I think it is. So it would be less on a sprung over vehicle with flat springs than on a lifted sprung under vehicle. What's a 101 like in this respect?

101's have very little articulation, and a mate who owns one fitted with a rear difflock tells me that their front axles also tramp and hop around badly on steep, difficult rocky climbs.

One really needs to look at why it was that most of the leading brands of leaf sprung 4wds were designed with their shackles at the front of the front springs, and why it was that these vehicles generally performed much better on steep difficult terrain than leaf sprung Landrovers. Those other brands don't tramp /wrap to anywhere near the degree that Landy's do .

[Gazzar]

Weren't the first LRs fitted with front shackles?

I suppose the rear shackle reflects the prioritisation given to road manners over off-road ability.

The Rover Cars market aspirations in the 1950's being a bit more upmarket.

G.

[bill van snorkle]

Weren't the first LRs fitted with front shackles?

I suppose the rear shackle reflects the prioritisation given to road manners over off-road ability.

The Rover Cars market aspirations in the 1950's being a bit more upmarket.

G.

Yes they were, and I once owned 2 80" Landys, one with front shackles and the other with rear shackles.The front shackled vehicle was a more capable climber, whilst the rear shackled truck rode slightly better at speed over rough terrain.

[Gazzar]

That's what I thought - and sort of confirms my belief that the ethos (if there was one) in the minds of the 50's Rover engineers for the LR, was as a light utility with 50:50 on road:off road ability, rather than a true mountain goat.

Of course in the 60's and 70's it all went to hell with nationalisation/unions etc, and only came back when Spen came up with the coil chassis.

G.

[Jamie_grieve]

I have to say I'm not convinced about all the talk of front wheel hop on vehicles with rear mounted shackles on the front. I'm not saying it doesn't happen but rather that it is enough of a problem to make the change from rear to front mounted shackles.

Take both your 80" vehicles, the one with the rear mounted shackles will climb an 18" high vertical step. The one with the front mounted shackles wont. Try it. Or try reversing up the same vertical step. Should be easier with longer travel rears... yet it isn't, why not?

Another test, hit a railway sleeper at 30mph with front and rear mounted shackles and see which one drives away.

On a hill so steep as to allow the front wheels to hop there is so little weight on them they aren't really contributing grip. A 2wd tractor will climb until it flips backwards.

I've seen more wheel hop on vehicles with no suspension at all like equal wheel tractors.

Do an emergency stop from 70mph with front mounted shackles on leafs with a large free camber and tell me how it went.

The Austin Gipsy uses Land Rover springs with the addition of anti wrap bars mounted just above the front springs. I've owned a few of these and can't honestly say there was any difference in climbing ability due to the suspension.

I do agree on high torque, high traction surfaces the wrap bars have their merits

I'd be the first to agree the front leaf spring suspension on a Land Rover is not the best but I'd also argue the better approach angle it offers far outweighs any loss in articulation compared to say a 40 series Cruiser which is about all it's fair to compare it to. I've owned two 40 series Cruisers and maybe they were better vehicles but the design of the front suspension on them would not be one of the things to make them so. Likewise the CJ jeeps which again might be a better vehicle than a Series Landy are again not exactly wonderful in the suspension department.

The wheel hop described only happens with short travel stiff springs and worn dampers or damper bushes. I'd say for the degree of windup described in the climbing stage one then there was a driveline problem rather than a grip and releasing one. I'd say the front uj bound up due to the diff housing rotating backwards. I'd guess the sideways shift was the truck standing on the front driveshaft rather than the springs breaking perhaps due to the sudden unload the snapped prop caused.

[FridgeFreezer]

I don't want to question Bill as he's undoubtedly got the knowledge and experience (and is something of an engineering hero of mine), however I do feel it's something of a pet peeve of Bill's that's not as big an issue (for most people) as perhaps it is to Bill - but there are a few few reasons;

I think the style of off-roading, the terrain (dry grippy rock or loose rocky climbs seem to be common) and comparisons with other vehicles which happen to have front-mounted shackles are perhaps skewing the data slightly. Over here we don't really have much if any rock-crawling / climbing and it's usually wet/muddy, even if the rock is dry your tyres tend to be wet & muddy by the time you arrive at the rock.

I don't think that makes anyone "right" or "wrong" on the subject, everything is a collection of compromises and the closer you get on the compromises the less difference these things will make. Comparing a Series failing a climb Vs a Toyota going up may seem to give a greater difference in performance than if you took the series, swapped shackles around and tried again.

I've posted before on this subject an article from a US mag where they showed people how to convert their front-shackled vehicles to rear-shackles for various reasons, real or imaginary, so it cuts both ways.