Need rear 4link help. Please! What options for coil front?

[BlueSuzy]

Hi all.

Lwb sierra. Planning 4 link rear but need some advise, And then also need some ideas for the front.

Lux front, bundy rear. 35s.

What are the pro's and cons for radius arms ontop of the front diff instead of under as i have no clue atm. Or should i run a 5link?

Needs to be engineer friendly.

Any help would be great. Thanks.

[Gwagensteve]

No problem with radius arms on top (I'm planning it for mine as an engineer friendly solution) but it's going to get VERY tight, everywhere.

Obviously the arms can't run outside the chassis or your tyres will catch them. I'm anticipating running a new gearbox crossmember and running the arms off that and slightly wider at the axle than the chassis end so they'll be under the chassis at the axle. This will result in reduced compression travel (approximately equal to 2" bumpstop spacing) but room for coils and shocks between the chassis and the knuckle.

I'm looking to go to three link front ( two lower arms, one upper, using a vitara rear diff centre for it's a frame mount) with a panhard eventually, but I'm happy to start with the easier to build and engineer stock radius arms, but IMHO they have to be Rover arms and have to be flipped. I love the clearance of my flipped radius arm rear. A similar setup in the front with a shaved housing would be very sweet for victorian driving- all the clearance of SPOA with zero axlewrap and bumpsteer.



Steve.

PS off topic the very high antisquat of radius arm rears is an interesting thing. It seems counterintuitive to have the car lift under power, but golly, it generates traction. Of course a radius arm front squats under power (in 4WD) and that's a good thing as far as I can see.

[BlueSuzy]

I concur.

I have some Jimny rear trailing arms here, and they look ok to be used, but bushes are expensive and have heard jimnys like to twist arms like coilys..

Another con maybe that the bundera coil arm setup, the centre is high pinion and the (unsure tech name) Steering bar runs under the centre.

Now with these jimny arms, if i ran them upside down, one mount is on the back of the housing, and one will be on top. So like a 45° angle to each other... Which may come in contact with the Jimny arms. (yet to look) Unlike the straight radius arms, like rover arms for eg, where the mounts are almost inline with each other, and probably won't even come close to the steer bar.
And i was unsure about the pin setup as if they had to be run in a crap place, the mounts are not so slippery and would tend to dig into stuff.. The arms might have to be 1/2 mounted inboard like you said.

Jimnys are almost same as sierra's chassis width, and their mounts are all straight under the chassis, making clearance an issue. They are not a pin design. The top bushes are like the diff end bushes.

I am just throwing things up in the air for idea's at the moment.

Would you be able to give me some info on how to setup the rear 4link?

I have been playing with a 4link calc and one of the write ups. Been studying them hard lately trying to sort it out. Can be confusing..Do you have any idea what antisquat i should be trying to get? I seem to be working it around the 80-85% mark. I have hard thats ok, But there is also alot of variables and other terms i'm trying to work out.

Lowest part of chassis(under doors etc) will be about 22", so the highest point of the chassis will be about 33"

I think the rear long arms will have to be under 900mm/35.4" Damn i hate this imperial! I always use mm at work!

96" wheelbase as front diff will be 3" forward. (stock is 93")

I was also have trouble trying to get the arms to cross each other allowing the 45' angle for the top links. and still getting the long arms to line up to the centre of the front diff. Do they have to cross? (1 writeup said they should.)

I will take a srceen shot tomorrow for more info..

Thanks again Steve. Your a good help.

[11_evl]

check my build thread, i have just done 4 link rear.
ill update it soon with more link pics and measurement, but id rather wait till after i have tested incase im giving you a bumsteer

my front 4 link i aimed for about the 80-85% mark
rear i went lower to about 58% but i have other holes to go to 95% and 40% to play around with.

(rear)
my upper link is 730mm
my lower link is 800mm

running a 40" tyre i needed at least 10" seperation at the diff so thats what it got.
i have the same seperation at the chassis end as well

as for the width of the mounts, on the bundy diff im using the factory mounts - 950 apart
and bolted to the rear of sierra chassis 700 apart

and i come up with this, whateva that means??

Static Anti-Squat 70 %
Travel Anti-Squat: 70%
Roll Center Height 31 in
Travel Roll Center: 30.76
Roll Axis Angle 1 degrees (Roll Oversteer) Travel Roll Axis: 1.14°
Instant Center X-Axis 189 in
Pinion Change: 0.00°
Instant Center Z-Axis 43 in
Travel Amount: 0.00

[KiwiBacon]

PS off topic the very high antisquat of radius arm rears is an interesting thing. It seems counterintuitive to have the car lift under power, but golly, it generates traction. Of course a radius arm front squats under power (in 4WD) and that's a good thing as far as I can see.

Some can help, but too much antisquat and it'll start hopping as your tyres slip. Resulting in your wagon humping a hill instead of climbing it.

[BlueSuzy]

I will have to have a look see later. Thanks 11_evl

Your always one step ahead of me

[11_evl]

Haha
post some pics of where your at. Or what your working with.

[Guy]

No problem with radius arms on top (I'm planning it for mine as an engineer friendly solution) but it's going to get VERY tight, everywhere.

Obviously the arms can't run outside the chassis or your tyres will catch them. I'm anticipating running a new gearbox crossmember and running the arms off that and slightly wider at the axle than the chassis end so they'll be under the chassis at the axle. This will result in reduced compression travel (approximately equal to 2" bumpstop spacing) but room for coils and shocks between the chassis and the knuckle.

I'm looking to go to three link front ( two lower arms, one upper, using a vitara rear diff centre for it's a frame mount) with a panhard eventually, but I'm happy to start with the easier to build and engineer stock radius arms, but IMHO they have to be Rover arms and have to be flipped. I love the clearance of my flipped radius arm rear. A similar setup in the front with a shaved housing would be very sweet for victorian driving- all the clearance of SPOA with zero axlewrap and bumpsteer.



Steve.

PS off topic the very high antisquat of radius arm rears is an interesting thing. It seems counterintuitive to have the car lift under power, but golly, it generates traction. Of course a radius arm front squats under power (in 4WD) and that's a good thing as far as I can see.

Do you have any pics of the front mounts (for the rear arms)

[BlueSuzy]

Sorry about the bodgy resize cut all over the shop

This is just a prototype with what i've been playing. Fee free to change any weights etc that you may think is wrong. I went off tare weight on compliance plate. And wasnt too sure on diff weights and tyres. Final lengths of arms are yet unknown. 1000mm lower arms will look shithouse..(i think on that setup) as well as no where to put them and etc etc. I havent got definate measurements on chassis as the whole section tapers in towards the front.


I am now thinking of using the original bundy location as a guide. Then the whole setup will change again..

[RUFF]

Some can help, but too much antisquat and it'll start hopping as your tyres slip. Resulting in your wagon humping a hill instead of climbing it.

If you can learn how to drive through the hop. It can be a huge advantage. But you need the driveline components to handle the abuse. My old buggy had enough AS to hop real bad if you let it. The trick was to squeeze it on hard enough till it just started to hop and then roll off the throttle wait for it to stabilize and then punch it hard. Hated it to start with but once I got used to how to drive it I would never have changed it. Dave Camp Bought the car and in his new rebuild I beleive he has given it even more AS again.

[MART]

Considered A frame rear, Cheers Paul.

[BlueSuzy]

Considered A frame rear, Cheers Paul.

I have thought about it, But then i would be copying you!

It seems easier, but the 4 link is growing on me, plus the time working it out has been good for experience.

Which is better?

Did you make all your arms?

I have been studying your chassis height to your tyres, it seems inline with the top of your tyres.

You didnt cut the top of the guards like i will be, I will be doing virtual lift, 2" to delete tricky rust behind the WT flare retainers and floor corner sections, so then i can get the chassis lower.

[BlueSuzy]

Just an update, Been playing more with the calculator.

I have come up with this. More for 34.5"s as 35"s are normally undersize etc.

I can move the top arms up or down to adjust anti squat. atm its 83% A top bracket will be made for 20% intervals to 100ish% or 60ish%



What do you guys reckon?

[1MadEngineer]

What do you guys reckon?

50-80% is always going to be nice,
eg a 4-6" lifted nissan is around 120% (and they hop like a bitch)
we run around 32-35% in the lux and it will climb anything you point it at.

[BlueSuzy]

ok, So if i aim for 83% for the top hole, i can make 2 lower holes for lower squat if i want.

Will the arms be ok at those angles? Every pic i see the bottom arms are more separated on the chassis.

[uninformed]

remember AS increases as the axle moves away from the chassis look at it through the range of travel

[BlueSuzy]

How can i do that?

Also, that last pic may be a no go. Might have tailshaft drama's!

[lump_a_charcoal]

Timaay, If I can get a LWB chassis, I may have to help (copy) you with this project...

All I ask is that you document and take pics of everything, as they are invaluable!

[uninformed]

its in the 4 link calc your using....just look around for the different pages with travel etc..

[BlueSuzy]

Timaay, If I can get a LWB chassis, I may have to help (copy) you with this project...

All I ask is that you document and take pics of everything, as they are invaluable!

Hmm How Much $?

Still bloody cleaning the chassis! Check Auszookers in my buildup..

its in the 4 link calc your using....just look around for the different pages with travel etc..

I will have a looky.

[BlueSuzy]

Worked it out on another page, so 10" up travel is 60%

10" down is 80%

Static height is 60%something.

Does the % range sound ok?