Spring Lengths vs Wheel travel

[TUFRR]

I have a 5 link in the Front and Beefed up Rear in My Rangie at full droop front or Rear the springs are completely Dislocated.
the springs are around the 19- 20" free length and i am quite happy with the ride height and it handles quite well.
I am currently using relocating cones but i am sick of the springs clicking
when they reseat.

I have tried retaining them top and bottom but i seem to loose a fair amount of wheel travel.

I have read the 4x4 mag with Nigel's Landie and i found his solution quite interesting.

I was thinking of getting a new set of springs made at a similar rate but about 3" longer and retain them top and bottom what do you think?

Simon

[GRIMACE]

interesting

I never really thought it would limit wheel travel noticably when retaining a spring but i guess if the springs gotta stretch then it kinda make alot of sense hey

But in you saying you want to get the same rate springs but in a 3" longer length would it be correct in saying you will be riding 3" higher than you previous spring setup ? ? ?

eg current 2" lift will become 5" ? ? ?

[landy_man]

yes you will riding 3" higher and be very tipy and unstable...

having a wheel on the ground, just dangling with no weight on it is pretty pointless.. just because the wheel is touching the ground does not mean it is doing anything...it may as well be in the air...

what rate are you springs... how much lift in total... i.e body lift as well as spring.... what size tyres....

what have you done to the "beefed" up rear...

[daddylonglegs]

I don't agree that because a coil spring is dislocated, that the wheel on that corner doesn't still have some traction. Remember that you still have the crossaxle seesaw effect. where the compressed spring becomes a fulcrum and its wheel as it rises tends to push the opposite wheel down. Of course the closer together the springs are, the better seesaw effect.
Bill.

[GURU]

yes same rate 3" longer will give 3" more lift and will loose abit of up travel

Bill is correct in what he is saying, BUT you have very minimal traction with a wheel with no weight on it.

You would need to make up longer springs with a smaller diameter wire (lighter rate) so that they stayed trapped at full droop, give you same the uptravel (so same travle as you have now). The only problem you get from this is the softer springs will cause more body roll onroad, so you need good shocks (adjustable ones) to stiffen it up to be able to drive sensibly onroad

from what I have seen the Pro Comp Explorers are the best for that, and come in long travel, but rancho's should be fine.

I have been playing around with springs in my RR and have really soft springs in the rear with non adjustable shocks (OME), front has rancho's and the front is much better handlign than the back through corners, will be measuring up shocks for rear soon and fitting pro comps

[TUFRR]

Unforchantly i dont know the exact specs of the springs as they were supplied and fitted when i had the 5 link fitted.
I am running PowerDown shockies and they are brilliant!
Does anyone know of a good spring manufacturer in Perth?

[daddylonglegs]

I f you have that much articulation already you should beware of Rancho's, indeed beware of any aftermarket shocks that don't have rubber bushes at least as big as the standard Rangy ones, particularly at rear top. I have seen shocks and top rear mounts snap on the rear of coil sprung Rovers during articulation because the top mount is really at the wrong angle to cope with extra travel without flexing/bending the shock shaft. If you have a scrap shock, to see what I am talking about, cut the top outer mud shield off and fit it to the rear. Then go and find an obstacle that will give full rear articulation. You should notice the shock shaft has a nice bend in it. If it is a good quality one it will flex straight again as the vehicle levels out, but this can't be doing the internals much good and it certainly puts a lot of strain on that beefy looking top mount.
Unfortunately most aftermarket shocks, Koni, Bilstein etc that I have tried all had smaller than standard bushes and all failed prematurely.
Bill.

[GRIMACE]

so bill what shock do you reccomend ? ? ?
I am goin the Monroes in the rear like Sam (strange rover) is using, but i am customising both upper and lower mounts in the rear (will be eye to eye).
I will be retaining my springs upper and lower and report weather it is a major hindrance to articulation.


TuffRR my springs are about 23-24" (out of the vehicle) and I can unseat them buy about 2"
So i would say you have some pretty big relocating cones at the moment and retaining the springs would mean you have approx 5" of spring extension, I can easily see how you think/claim it limits wheel articulation.

If you are willing to sacrifice abit of onroad stability I think the longer free length springs with a lower spring rate and then retain em would be your best option. Even then you could get some stiffer shocks or run duels to help the onroad experience but more $$$ to be spent.



Anthony

[daddylonglegs]

Difficult to recommend any particular brand Anthony. I personally use
Koni adjustable replacements for GU nissan rears, but their top eye and bushes are smaller than standard so I cut two thirds off the eye and weld on a complete eye from an old scrap Landy shock.
Bill.

[daddylonglegs]

I assume that a coil springs rate is the same in tension as it is in compression. If negotiating a given obstacle, your springs dislocate 4 inches at full droop and say you have 180 lbs per inch spring rate. If your springs were retained top and bottom, does that mean you would have robbed that wheel of
720 lbs of potential traction on the same obstacle.?
Bill.

[DiscoDino]

Bill...I ASSume the same

that is why the rears are non retianed. However, for the front ones, I prefer keeping it all tight for the high-way driving.

[GURU]

Once a spring is at its full droop (not retained and not dislocated) there is no downward pressure helping the wheel gain traction so there is no point retaining a shorter spring than the travel available (shock limited) as stretching the spring is, in my opinion, causing the opposite effect. If the spring dislocates then the only thing helping the wheel at droop gain traction is the see-saw effect of the other side at full compression.

You really need a spring that is longer than the travel available to gain any traction advantage ontop of the see-saw effect as the spring will always want to return to its free height, hence putting downward pressure on that wheel.

With all that said the further the wheel drops from ride height the less downward pressure there is.

[HSV Rangie]

On a RR replace the bouge unit with a coil spring.
This will keep pressure on both sides and allow traction to both wheels.

I have not done this but keep thinking I should.

Michael.

[daddylonglegs]

I just did some rough calculations based on a Rangey weighing 2000kg's and having a weight distribution of 50/50 front to rear, which I think is pretty close to what an average one is anyway.
I have calculated the seesaw ratio by measuring the distance from the outside of the spring to outside of wheel on that corner and dividing that into the total width outside of tyre to outside of tyre. that gave a seesaw ratio of about 1:3.5. Now if you sit diagonally opposite wheels on ramps high enough to start dislocating the coils, the seesaw ratio can means that the wheels on the compressed corners can transfer up to
about 286 kg's or about 630 lbs of downforce to the wheels on the extended corners, so if the coils are retained both ends you will lose this considerable contribution to tractive effort particularly if you don't have difflocks.
BTW,I think the Boge load leveler if working, does the same job as the central coil spring, and certainly improves the seesaw effect. Bill.

[Jmcdonald]

High there,

I ran some very soft and very long coils in an 83 range rover I think around the 24" in the rear and 22" in the frount, due to the rate of these coils I did not fid they suffered my up travel at all! I was still able to put wheels to the tops of the gards no problems and that was with a two inch body lift, tha main problem was the rear arms on a range rover are no long enough when still retaing the top chassie rubber mount as it could not flex as far as the spring could travel. That is your limit until going custom rear, mind you it was alot of flex and I ran the longest Rancho's you could buy frount and rear with custom shock mounts:> There is a cool little mod for the frount making extra travel with short springs. it is done useing a motor bike sping that is is located to the top mount with a long bolt down the center and a rubber on the top. The motor bike sping sits on the inside of your normal coil spring, it is attached to the top of the top of your coil with a plate that hold the motor bike sping and coil spring together! The effect this has is it allows your normal spring to drop away from it's seat and extra 4" or more while still been attached to the car and it is able to reseat with out hick ups, I have photos of this some where if any one is intrested :>

[GRIMACE]

High there,

I ran some very soft and very long coils in an 83 range rover I think around the 24" in the rear and 22" in the frount, due to the rate of these coils I did not fid they suffered my up travel at all! I was still able to put wheels to the tops of the gards no problems and that was with a two inch body lift, tha main problem was the rear arms on a range rover are no long enough when still retaing the top chassie rubber mount as it could not flex as far as the spring could travel. That is your limit until going custom rear, mind you it was alot of flex and I ran the longest Rancho's you could buy frount and rear with custom shock mounts:> There is a cool little mod for the frount making extra travel with short springs. it is done useing a motor bike sping that is is located to the top mount with a long bolt down the center and a rubber on the top. The motor bike sping sits on the inside of your normal coil spring, it is attached to the top of the top of your coil with a plate that hold the motor bike sping and coil spring together! The effect this has is it allows your normal spring to drop away from it's seat and extra 4" or more while still been attached to the car and it is able to reseat with out hick ups, I have photos of this some where if any one is intrested :>

Hey dont I have your old springs I think i do

[landy_man]

check out this discussion about half way down the page...

http://www.pirate4x4.com/forum/showthre ... ng+springs

[daddylonglegs]

Maybe its because I am a little biased towards unrestrained springs, but the way I read that Pirate discussion Landyman, it seemed about 50% in favor ,50%against. If i can borrow the use of a 4 post hoist or forklift some time I will try to prepare some definative tests with suspension both locked and unlocked.
Bill.

[Gwagensteve]

I have had my G on a forklift at my work, but got some very worrying looks for the boss I think the real way to carry out htis experiment would be to measure balance, weight transfer and travel all at once by doing the articulation test with corner weight scales on all four wheels too.

My guess is that the car will have more articulation with the springs unrestrained, but will have less weight transfer and better balance with the springs restrained, as the "high" wheel, (lets assume the front) will be loaded harder with the springs retained. When climbing this will result in less front end picking up and more front end traction.

I still reckon the bset way to measure balance is to compare the side angle of the body with the angle of the front axle to the ground. The body angle should be about 1/2 the alxe angle.

Jim Allen did some experimentation with this some years ago inthe US comparing a large number of D90 suspensions.

Cheers, steve

[daddylonglegs]

Yes Steve, I vaguely remember something in the US called" Defender twist off" where they compared vehicles with standard and modified suspensions over a series of tests and obstacles. I think they attached safety straps to each vehicle that people could pull on to prevent rollovers.
Some vehicles required the strap, one or two didn't.
Bill.

[Gwagensteve]

Yes, That's the one. Safari Gard premiered their Series 3 kit which I think is pretty similar to what you are running on the front of your car. they had some problems when the new front link broke under hard braking and roled the car!

I don't think that the safari gard kit did naything to really reduce the roll stiffness in the rear, but substantially reduced the roll stiffness in the front by elimitnating the cast radius arms and soinf to a three link+radius arm.

I seem to recall that the safari gard spring retainers have a small spring in them to perhaps soften the transition.

I feel that there will always be a point with unrestrained springs when you will get unwanted movement - especially when on a very large compound angle - there will be a point where the car will sort of "flop" onto full droop, whereas if the spring was retained, it is likely that the car will stay more stable. My avatar picture is a spot where I would not have liked to have unretained springs and more droop!

[landy_man]

seek... and ye shall find http://www.yellowdefender.com/twist_off ... ff_result/

some interesting reading...

[Gwagensteve]

Nice work! This is far more in depth than the Four Wheeler article. The discussion towards the end is what I find most ineresting- It's a far more sophisiticated discussion of suspension behaviour than we tend to see/have generally.

If you don't mind I will pop this link in General 4X4 tech. so more can benefit from it.

Cheers, Steve

[daddylonglegs]

Yes that is some powerful reading LandyMan. I don't think the three link design as presented at that time could be regarded as giving a proper representation of the possible performance improvements of such a system.
Probably the best arrangement is a lockable super flexy system with dislocaters ,and knowing when to use them. Hmm ?
Bill.

[Gwagensteve]

Interesting. depending on how it was done, the lockable dislocators might also be able to be used to lock suspension out on a particular wheel or to preload one side for a particular obstacle. Perhaps they could be fitted to the radius arms so they were going though a much shorter range of motion?

I am thinking of some sort of rod with holes in it every inch or so mounted to the radius arm and a collar with a solenoid or somesuch on the chassis. the hard limit to droop could be achieved with a simple pin through the rod, and preloading or locking travel out could be done on the with the solenoid.

I am sure there is a better way of doing this, but its only an idea.

In the current 4wd&Sport Utility mag, a Jeep built by SunRay Engineering inthe US has a very interesting way of preventing front axle wrap. I will try and post a photo of it. this system could be adapted to do this too.

Oops - my wife has the digital camera and she is out today. the photo will have to wait.

I starting thinking that this was off the topic, but now I'm not so sure.

[daddylonglegs]

Yes Steve, I have been thinking roughly along the same lines, and possibly locking hydraulically. I will kick the idea around in my head for a while and see what comes out.
Some more food for thought. My current shorty Landy has a 3link plus panhard rod front end with quite stiff short travel coil springs on drop away arms directly under the frame rails and an "A" frame/tripod located rear end with quite stiff single leaf parabolic springs that are shackled both ends.The rear shackles are made from old 2 stage hydraulic jacks and can extend several inches. This vehicle will drive right over a 22 degree articulation ramp and it is still very stable at the top.If you used the formula for calculating RTI scores it ramps 1760 out of a possible 1000 .It also exhibits very little body roll on the road or side slopes. My theory is that on a side slope the stiff compression rate of the springs provides good support for the low side, and the short free travel in extension means that the high side springs stop pushing the chassis up fairly early, thereby maintaining stability. The downside is that the ride is quite firm to harsh, but some of that may be a result of the substantially increased unsprung mass of having portal drop boxes.
Any comments on the short stiff springs with drop away concept?
Bill.

[Gwagensteve]

The more I kick this around, the more complex it becomes. I think in a pure sideslope situation, short/stiff springs as described will be superior to a softer longer travel setup. Certainly, in my experience, the softer the spring and the more compression travel the system has, the spookier it feels on big side angles, however, in general use, it might not be that clearcut.

I'm betting that your car has highish roll stiffness too - an effect of a light body, low COG and stiffish springs, and that this works in your application becuse you are getting lift out of your portal boxes. The added sprung mass of the boxes will help load the wheel, providing good traction even when the springs are dislocated. Additionally, with your springs mounted under the chassis rails rahter than outboard, you will be applying plenty of leverage to the drooped wheel, even if the spring is no longer assisting traction.

Many coilover applications have tender springs of very low rate to set rideheight whilst still providing some spring rate at full droop. I wonder if this is applicable to your application, and if you would see any benefit.

I think that your sprung mass and balanced front to rear roll stiffness probably go a long way to eliminate the "flopping" that I see with cars with unretained springs on high compound angles. (As would the forced articulation system) Many of the cars I see with unretained rear springs also have highish front roll stiffness, so when on a high compound angle, the car stops articulating in the front, only makong things sooo much worse, however, in a straight sideslope test, they do fine as they are propped up by the front roll stiffness being so high.

How does your car do reversing up a ramp?

It has also just occurred to me that there has to be sensible limits to "uncontrolled" travel. I'm not sure if there is a golden rule here, but I have seen plenty of cars with uncontrolled rear travel taken to the point where rear suspension geometry has gone out the window and, on a ramp, the high side front wheel is no longer being loaded. In these situations, it looks to me like the car would benefit greatly from retaining the rear spring, as it might force the front end to start contributing to the action.

See the attached photo's for a comparison. It is quite possible that the safari guard unloads its rear springs too, but I reckon that it is a moot point with the front working that hard, an I am suspscious this is how your car looks on a ramp Bill.

I wish I could type at the same speed I can think! ( and that's no boast about how fast I can think!)

[Gwagensteve]

Rather than like this: *eeeurghh *

[daddylonglegs]

Yes Steve it looks a bit like that, but only when the front wheel is another metre or so up the ramp. BTW my own Landy doesn,t have forced articulation. That is on the hybrid I built for Nigel. It also has outboard springs. My inboard springs were a hangover from the days when I ran smaller extra wheels inboard of the existing 35's. In order to keep the inner wheel track narrow and still have good articulation I couldn't have any projections outboard of the chassis rails. The suspension has served me well and although the ride is not brilliant, its not as bad as a Bj40 Cruiser I had, or an early Fourrunner I once had the dubious pleasure of riding in. one ton Navaras are pretty orrible too.
Bill.