Outer Limits 4x4 Board

Gday, have lots of questions, about 3link rear suspension.
What id like to know is, should i go with a 80/100 (or gq/gu) geometry, maybe add 15% more lenght in all the arms, less the panhard, and A frame the top arms?
Or copy straight of range rover? I have read that nissans with 4"+lift pigroot up rocky climbs due to too much squat or not enough. Wich brings me to, what is squat and anti squat?

Intended uses for my 60 series cruiser will be, mainly bush use but its also my kind of week drive to work.
Itll run +-4"lift and 33" onroad, 35"offroad tyres.
80/100 rear coils in rear.

Will be useing 80series axles front and rear.
Front pretty much as in 80 just on 60chassis.

In simple what do yous recon would be a good set up, nothing over the top just simple.

http://www1.pirate4x4.com/forum/showthread.php?t=168577" onclick="window.open(this.href);return false; - read this. Should get you started. Suspension geometry is a huge huge field, and also varys greatly with the application and personal preference.


Layto....

lay80n wrote:http://www1.pirate4x4.com/forum/showthread.php?t=168577 - read this. Should get you started. Suspension geometry is a huge huge field, and also varys greatly with the application and personal preference.


Layto....

Very good read mate, thanks lots. That explains lots cool

12ht wrote:Gday, have lots of questions, about 3link rear suspension.
What id like to know is, should i go with a 80/100 (or gq/gu) geometry, maybe add 15% more lenght in all the arms, less the panhard, and A frame the top arms?
Or copy straight of range rover? I have read that nissans with 4"+lift pigroot up rocky climbs due to too much squat or not enough. Wich brings me to, what is squat and anti squat?

Intended uses for my 60 series cruiser will be, mainly bush use but its also my kind of week drive to work.
Itll run +-4"lift and 33" onroad, 35"offroad tyres.
80/100 rear coils in rear.

In simple what do yous recon would be a good set up, nothing over the top just simple.

For the rear:

I would copy the range rover and make the links longer, and the A frame longer.

Gotta get the links parallel and horizontal at ride height.

As well as all the other usual crap, that should see a REALLY good rear setup.

As for the front, if you want a factory style system:

80 series and 79 series have the best front radius arm setup (Plus bunderas from 1991+)

Rangies and patrols are the same, and are not as good.

bj on roids wrote:

12ht wrote:Gday, have lots of questions, about 3link rear suspension.
What id like to know is, should i go with a 80/100 (or gq/gu) geometry, maybe add 15% more lenght in all the arms, less the panhard, and A frame the top arms?
Or copy straight of range rover? I have read that nissans with 4"+lift pigroot up rocky climbs due to too much squat or not enough. Wich brings me to, what is squat and anti squat?

Intended uses for my 60 series cruiser will be, mainly bush use but its also my kind of week drive to work.
Itll run +-4"lift and 33" onroad, 35"offroad tyres.
80/100 rear coils in rear.

In simple what do yous recon would be a good set up, nothing over the top just simple.

For the rear:

I would copy the range rover and make the links longer, and the A frame longer.
cool thats what i was thinkin of, that or a 80 with same mod ie longer arms

Gotta get the links parallel and horizontal at ride height.
ahha another point

As well as all the other usual crap, that should see a REALLY good rear setup.

As for the front, if you want a factory style system:

80 series and 79 series have the best front radius arm setup (Plus bunderas from 1991+)

Rangies and patrols are the same, and are not as good.

yeah front will be 80 100 i like that better design arms and stuff

please explain why Toy radius arms are better than rover????

Serg

the bush vs pin arrangement at the chassis is the difference, you do not get the binding a rangie / patrol does

12ht wrote:Gday, have lots of questions, about 3link rear suspension.
What id like to know is, should i go with a 80/100 (or gq/gu) geometry, maybe add 15% more lenght in all the arms, less the panhard, and A frame the top arms?
Or copy straight of range rover? I have read that nissans with 4"+lift pigroot up rocky climbs due to too much squat or not enough. Wich brings me to, what is squat and anti squat?

Intended uses for my 60 series cruiser will be, mainly bush use but its also my kind of week drive to work.
Itll run +-4"lift and 33" onroad, 35"offroad tyres.
80/100 rear coils in rear.

In simple what do yous recon would be a good set up, nothing over the top just simple.

80/100 and gq/gu rear suspensions are 4 link plus panhard (or if you like 5 link). They have 2 lower and 2 upper links (control arms) and a panhard rod.

A 3 link rear suspension would have 2 lower and 1 upper links plus a panhard.

A brief description of squat and antisquat is:

When the vehicle accelerates (forward for describing squat/antisquat) there is a reaction in the opposite direction called inertia (in Physics this is one of Newton's laws of motion). The inertia force is mass x accel (another of Newton's laws) and the resultant of the inertia forces acts through the centre of gravity.

The effect is like taking weight from the front and adding it to the rear. This wants to compress the rear springs and is called squat (the rear of the vehicle appears to squat).

Now the tractive force between the road and rear tyres is transferred to the vehicle through the lower links in compression (pushing) during acceleration. The upper link/links/A-frame prevent the axle rotating so are in tension (pulling).

Now the geometry (angle) of the links can be arranged so that resultant of the compression and tension forces in the links provides a net vertical upward force on the chassis (as well as the net horizontal force to accelerate forward). This resultant force opposes the squat effect, so is called anti squat.

If the value of the anti is equal (but opposite direction) to the squat then you have what is referred to as 100% anti-squat (and the rear height of the vehicle won't change). The anti-squat can be less or greater than 100% - greater than 80% is not desirable.

With large (over 100%) anti-squat the rear lifts during acceleration and this changes the geometry of the links. If the geometry change results in greater anti-squat (often the case using stock links with raised suspension) then it wants to lift the rear of the vehicle further and results in terrible behaviour when climbing and worse when traction is changing.

Squat and anti squat is not normally given emphasis for front suspension as the tractive forces in front links/arms is much smaller than the rear.

Instead at the front we are more concerned with braking (deceleration). This is similar to squat/anti squat if accelerating in reverse. For braking it is called dive/anti-dive.

With suspension lifts, the geometry of the links are changed. By using longer links with a lift, the geometry can be made better.

With parallel rear lower links the roll axis is parallel to the links. Ideally the roll axis should be close to horizontal to avoid rear/bump steer. Triangulating the links is used to improve the roll axis, but is difficult with many vehicles.

uninformed wrote:please explain why Toy radius arms are better than rover????

Serg

Yeah, what bubs said.

I agree the rear bush of cruiser radius arms are different and better than rangie and patrols.

But don't agree with BJ that rangie arms are as bad as patrols. The crucial difference (as far as articulation goes) between rangie and patrol arms is the spacing between the bushes at the axle end. The patrol arms don't flex anywhere as well because the spacing is much greater - they do have more flex in each of the bushes though and this helps.

Edit: This argument is valid only for classic rangies. Later rangies (and discos) have radius arms with the same style of chassis bushes as cruisers.

80/100 and gq/gu rear suspensions are 4 link plus panhard (or if you like 5 link). They have 2 lower and 2 upper links (control arms) and a panhard rod.

A 3 link rear suspension would have 2 lower and 1 upper links plus a panhard.



Yeah was thinking of removeing the panhard rod and A frameing the uppers, much like a rangie.
I have seen bolt in A frames for GU patrols before thats what go me thinking, that out of the 3: rangie, 80/100 and gq/gu. That if you got rid of the panhard and a framed the uppers but left the lenght and positions same, what would have the best geometry.

And on top of that if it would be a good idea on any of the setups to say, extend some links, ie maybe uppers and lowers or only lowers? if space permits.

Good replies, keep em comeing.

[quote="Bush65"]I agree the rear bush of cruiser radius arms are different and better than rangie and patrols.

But don't agree with BJ that rangie arms are as bad as patrols. The crucial difference (as far as articulation goes) between rangie and patrol arms is the spacing between the bushes at the axle end. The patrol arms don't flex anywhere as well because the spacing is much greater - they do have more flex in each of the bushes though and this helps.

Edit: This argument is valid only for classic rangies. Later rangies (and discos) have radius arms with the same style of chassis bushes as cruisers.[/quote


Yeah i belive the same. That rangie arms are better than patrol arms, but ill still go with 80arms as ill be fiting coplete axle and all up front and dont realy want to change the, exept for maybe a Xlink.

not only bush seperation at axle end but overall length of RA plays a roll...btw if you flex a LR/RR arm with no axle case you will see that the chassis end bush/mount is not the limiting factor.....it is the binding of the axle bushes....

also remember there is a certaim amount of twisting of the arm going on during flex...LR/RR parrallel pin is better for this

JMO

Serg

ok what axles are you going to run?

if 60 from what I understand they are narrower than coil rovers??? how far out will the coils be mounted???

Id push the lower trailing arms out as far as possible...right out against the axle flange... keeping the chassis end in against chassis rail to give them a little triangulation...every bit helps. keep them as low as practical on the chassis and as level as possible....longer the better.

A frame should have an icluded angle NOT less than about 40 degrees when viewed from above....make it Fing strong. keep it parrallel with the TA's when viewd from the side.

keep minimum 8 inches vertical seperation at the axle end from upper and lower links

keep your A frame a bit shorter like maybe 75 % the lenght of TA, this will help keep AS down during axle droop....

run what ever RA up front you want....Superior make some good ones...keep the chassis end mount low to keep ARA down...

try and keep front roll center level or lower than rear.....

keep pahard and drag link parrallel...

make sure you set your castor up correctly.

DONT TRUST MY LIMITED KNOWLEDGE....JUST A WEB WHEELER

Serg

uninformed wrote:not only bush seperation at axle end but overall length of RA plays a roll...btw if you flex a LR/RR arm with no axle case you will see that the chassis end bush/mount is not the limiting factor.....it is the binding of the axle bushes....

also remember there is a certaim amount of twisting of the arm going on during flex...LR/RR parrallel pin is better for this

JMO

Serg

good point

uninformed wrote:ok what axles are you going to run?

if 60 from what I understand they are narrower than coil rovers??? how far out will the coils be mounted???

Id push the lower trailing arms out as far as possible...right out against the axle flange... keeping the chassis end in against chassis rail to give them a little triangulation...every bit helps. keep them as low as practical on the chassis and as level as possible....longer the better.

A frame should have an icluded angle NOT less than about 40 degrees when viewed from above....make it Fing strong. keep it parrallel with the TA's when viewd from the side.

keep minimum 8 inches vertical seperation at the axle end from upper and lower links

keep your A frame a bit shorter like maybe 75 % the lenght of TA, this will help keep AS down during axle droop....

run what ever RA up front you want....Superior make some good ones...keep the chassis end mount low to keep ARA down...

try and keep front roll center level or lower than rear.....

keep pahard and drag link parrallel...

make sure you set your castor up correctly.

DONT TRUST MY LIMITED KNOWLEDGE....JUST A WEB WHEELER

Serg

nah dude ill be runing 80series axles front and back.

so with the a frame say itll be 460-500mm long and the lowers 1060mm long wht do you think of that? The lowers can be any lenght realy its the uppers that cant realy be longer not enough space.

the greater the difference in length, the greater the pinion angle change during droop/bump/articulation.....be carefull of uni bind

get a piece of paper, pencil, rule and compass out and do some basic line drawings to see what happens

Great thread guys, I don't have much to add but this is good tech.

Cheers

12ht wrote:80/100 and gq/gu rear suspensions are 4 link plus panhard (or if you like 5 link). They have 2 lower and 2 upper links (control arms) and a panhard rod.

A 3 link rear suspension would have 2 lower and 1 upper links plus a panhard.



Yeah was thinking of removeing the panhard rod and A frameing the uppers, much like a rangie.
I have seen bolt in A frames for GU patrols before thats what go me thinking, that out of the 3: rangie, 80/100 and gq/gu. That if you got rid of the panhard and a framed the uppers but left the lenght and positions same, what would have the best geometry.

And on top of that if it would be a good idea on any of the setups to say, extend some links, ie maybe uppers and lowers or only lowers? if space permits.

Good replies, keep em comeing.

If you use an A-frame, then technically it will not be 3 link suspension (an A-frame isn't a link - to be a link it must be capable of carrying axial loads only). Nor is a radius arm a link - another common misconception.

Just being my normal pedantic bastard self.

i was under the impression any bar that joined the chassis to the diff was a link.

Bush65 wrote:

12ht wrote:80/100 and gq/gu rear suspensions are 4 link plus panhard (or if you like 5 link). They have 2 lower and 2 upper links (control arms) and a panhard rod.

A 3 link rear suspension would have 2 lower and 1 upper links plus a panhard.



Yeah was thinking of removeing the panhard rod and A frameing the uppers, much like a rangie.
I have seen bolt in A frames for GU patrols before thats what go me thinking, that out of the 3: rangie, 80/100 and gq/gu. That if you got rid of the panhard and a framed the uppers but left the lenght and positions same, what would have the best geometry.

And on top of that if it would be a good idea on any of the setups to say, extend some links, ie maybe uppers and lowers or only lowers? if space permits.

Good replies, keep em comeing.

If you use an A-frame, then technically it will not be 3 link suspension (an A-frame isn't a link - to be a link it must be capable of carrying axial loads only). Nor is a radius arm a link - another common misconception.

Just being my normal pedantic bastard self.

also if using an A frame it is calculated as a 4 link.... covergence point is the center of ball joint. Roll center height is center of ball joint.

Serg