Thread: So how do I increase my tyre size without reducing articulation?

Originally Posted by Bush65

No where have I said that I was getting 14" travel out of shockies that have a stroke of 10".

I have not misrepresented any facts or posted information based on conjecture or flawed theories

So what shocks give you the 14 inches of axle movement you claim.
Seeing that you do not know the specs of your landcruiser springs on the disco, do you know any specs of the springs on your Rangie or Bushie. How exactly did you determine that they have 12 inches and 14 inches of travel. You seem to be very vague about what you have. Do you even understand what the compression rate means. It is simple, it means the amount of weight that has to be applied to compress the spring 1 inch. So to compress a 200 lb per inch spring by 14 inches, you would have to apply 2,800 lb of weight on that spring. That is over 2/3rds of the total weight of a rangie on 1 wheel. If they are reasonably common 250 lb per inch springs you would have to put 3,500 lb of weight or over 80% of the total vehicle weight on 1 wheel

Originally Posted by r.over

So what shocks give you the 14 inches of axle movement you claim.
Seeing that you do not know the specs of your landcruiser springs on the disco, do you know any specs of the springs on your Rangie or Bushie. How exactly did you determine that they have 12 inches and 14 inches of travel. You seem to be very vague about what you have. Do you even understand what the compression rate means. It is simple, it means the amount of weight that has to be applied to compress the spring 1 inch. So to compress a 200 lb per inch spring by 14 inches, you would have to apply 2,800 lb of weight on that spring. That is over 2/3rds of the total weight of a rangie on 1 wheel. If they are reasonably common 250 lb per inch springs you would have to put 3,500 lb of weight or over 80% of the total vehicle weight on 1 wheel

Oh please... Rather than accept that there are other people on here who may disagree with you - BASED ON THEIR OWN FIRST HAND EXPERIENCE. You start casting aspersions on their knowledge or abilities.

You really have put your foot in it by picking on John's abilities at suspension/engineering though.

As he said. Why does it matter that he doesn't know the rate??? I am sure the numbers he has posted were obtained from measuring the articulation offroad. If you care about the spring rates, call Kings. If they won't tell you, measure a spring and calculate it, it isn't hard.

e.g. - in my case, I know the spring rates of one of my vehicles, but have NFI about the spring rates of the other (it has King Springs...), but I know how much wheel travel they each get.

Originally Posted by r.over

Do you even understand what the compression rate means.


So to compress a 200 lb per inch spring by 14 inches, you would have to apply 2,800 lb of weight on that spring. That is over 2/3rds of the total weight of a rangie on 1 wheel. If they are reasonably common 250 lb per inch springs you would have to put 3,500 lb of weight or over 80% of the total vehicle weight on 1 wheel

I could ask the same question of you. If I understand Johns post - he said he has 14" of axle travel at the springs.

So that means (approx) 7" compression on one side and 7" extension on the other.

So, to use your 200lb example = 7x200 = 1400lb total load, plus the force required to extend the other side (if retained top and bottom), AND the resistance caused by bushes, etc...

I think YOU need do some more reading on how suspension works before opening your mouth (keyboard) any further.

Originally Posted by isuzurover

I think YOU need do some more reading on how suspension works before opening your mouth (keyboard) any further.

I am not sure why you post such comments, but I think you need to do a little reading yourself.

If one side was fully extended ( 7 inches down in your case) and the other side had only 1400 lb applied to it, the other side would only be 7 inches up from the bottom or 7 inches different to the opposite side, not 14 inches. For the other side to be 7 inches up on standard position, it would have to be 14 inches up from the bottom and have 2,800 lb sitting on it with 200lb springs.

I am not sure why people never bother to work out the basics of how suspension works. It is further surprising that they want to have a go at people armed with this limited knowledge.

You can set up your suspension quite well if you understand compression rates and spring length. I am just attempting to explain it to help people looking at making mods. But it would appear that there are a few in the forum that just like to attack others and this is a little disappointing.

Originally Posted by isuzurover

Oh please... Rather than accept that there are other people on here who may disagree with you - BASED ON THEIR OWN FIRST HAND EXPERIENCE. You start casting aspersions on their knowledge or abilities.

You really have put your foot in it by picking on John's abilities at suspension/engineering though.

As he said. Why does it matter that he doesn't know the rate??? I am sure the numbers he has posted were obtained from measuring the articulation offroad. If you care about the spring rates, call Kings. If they won't tell you, measure a spring and calculate it, it isn't hard.

e.g. - in my case, I know the spring rates of one of my vehicles, but have NFI about the spring rates of the other (it has King Springs...), but I know how much wheel travel they each get.

It is very easy for people to make claims on the internet. The suspension travel is very easy to back up as it is largely just a mathematical calculation. All I keep on asking for him to provide some basic information on his set-up. How is this having a go at someone. If he is an engineer, and has designed his own suspension system, he would have had to know the spring data to do it.

If someone has got 14 inches of travel out of their suspension, I am REALLY, HONESTLY, GENUINELY, interested in how they have achieved it. So I am not asking these questions to put him down, I am asking it for information. It therefore becomes frustrating when he cannot as it then appears that what he posted is just claims and are not real.

Originally Posted by r.over

I am not sure why you post such comments, but I think you need to do a little reading yourself.

If one side was fully extended ( 7 inches down in your case) and the other side had only 1400 lb applied to it, the other side would only be 7 inches up from the bottom or 7 inches different to the opposite side, not 14 inches. For the other side to be 7 inches up on standard position, it would have to be 14 inches up from the bottom and have 2,800 lb sitting on it with 200lb springs.

I am not sure why people never bother to work out the basics of how suspension works. It is further surprising that they want to have a go at people armed with this limited knowledge.

You can set up your suspension quite well if you understand compression rates and spring length. I am just attempting to explain it to help people looking at making mods. But it would appear that there are a few in the forum that just like to attack others and this is a little disappointing.

Pot calling the kettle???

OK, you are right, I typed that before thinking it through. However, from static ride height, one compresses and the other extends as weight is transferred. However, your example is far too simplistic, and here's why:

Let's assume we have an RRC that weights 4600lbs and the weight is evenly distributed over each axle. 2300lbs per axle. In a cross axle situation, that would be sufficient to provide 11.5" of (theoretical) spring travel IF the force was being applied directly at the spring (and no other forces etc...). HOWEVER, the force is applied at least 6" further out, so it isn't as simple as you make out. For this reason, wider track will increase wheel travel, as will moving the springs inboard.

FYI, I have designed and built my own (leaf) spring suspension system, using the SAE design manual.


EDIT:

Originally Posted by r.over

The suspension travel is very easy to back up as it is largely just a mathematical calculation. All I keep on asking for him to provide some basic information on his set-up. How is this having a go at someone.

Oh please... You have challenged just about everyone who has disagreed with your viewpoint on here. If you think wheel travel is just a "mathematical calculation" then you have a lot to learn - so maybe my post was justified.

John said he didn't know the spring rate (several times IRC). If you doubt his claims about wheel travel, perhaps have a read through his other posts. If you do, I am sure you will find lots of great tech on LR suspension, and many other related subjects.

e.g.

Originally Posted by Bush65

...


The geometry of the 4 link and the details of the mounts will affect the comparison.

Technically, a link is a member that can only resist axial load (tension or compression) and neither end will resist rotation in any direction. So A-frames and front radius arms are not links. It is misleading to call Land Rover rear or front suspension 3 link.

The Land Rover rear suspension, with parallel lower links and upper A-frame performs much like a 4 link with parallel lower and triangulated upper links. But articulation is ultimately limited by the chassis mounts for the lower links, the ball joint and bushes for the A-frame.

So called heim/rose/rod-end joints are not road legal in Australia, so we have rubber or polyurethane bushings.

Ive got a credit card that lets me get the people who know what they are talking about do the calculations, I dont need to understand it my self, I just need to pay the money and say if it is what I was expecting or not.

So far it is what I was expecting so Im happy.

The stroke of the shockies limit the articulation on all of my vehicles.

My bushie has 14" Swayaway RaceRunners. Coil springs are Eibach. Eibach have them on their shelf in Sydney - they are not custom springs.

Spring calculations based on static load deflections do not tell the whole story of off road suspension travel.