Rear 4 link springs

[V.W.Dave]

Hey guys,
I am thinking about adding a 4 link rear end to my build just looking at all the costs and ideas out there. I will be using Patrol bushing and rings, thick walled black pipe, CNC cut hangers.
Anyway I know how to do the set up and have all the tooling just wondering what everyone out there has used for springs? I am running 60 sieries cruzer diffs on 35s, Ute chop swb Will be making it 100in wheelbase.
I am not 100% sure if I am going to do this yet just getting ideas right now. I just figure I have it all stripped down right now with the body off and planning on running twin transfers and I need more room for the drive line. I am just looking for a very forgiving spring. It will be driven very hard on most weekends. If you look at my build up so far I want the rear to have as much flex at the front.
Anyway let me know what you all have run and what you have replaced.

my build so far
http://www.outerlimits4x4.com/viewtopic ... 6&t=211462" onclick="window.open(this.href);return false;

[11_evl]

air shocks.

check my build for ideas if you want

[V.W.Dave]

Mate I would love to but I am building this on a very smallllll budget. its just going to be a test rig. in a few years I will build one like yours.


Ohh and yes I have read yours a few times very nice...

[Guy]

Vitara coils.

[BlueSuzy]

I will be using vit/jimnys

Then i may need to go aftermarket lifted ones, once everything is in place..

I didnt see the point in only coiling the rear..

Just run the same springs that are in the front, in the back, or longer, and make up a wrap bar to control the torque twist that Fcks the leafs.

[joeblow]

use aftermarket vit. don't use jimny ones in the front as she will be all over the road. working out your all-up weight would be a start to working out what springs you will need.

[BlueSuzy]

I have vit v6 lwb rear going into front.

Jimny rears into rear.( I have the jimny fronts, smaller coil diameter than the rest, and smaller height also, not using them)

Only setting up atm, not driving yet. Spring rates will be tested and adjusted to suit.

[V.W.Dave]

use aftermarket vit. don't use jimny ones in the front as she will be all over the road. working out your all-up weight would be a start to working out what springs you will need.

I am only doing the rear not front just yet that may be down the road a little. I have a set of springs out of a 94 JLX vitara will they be ok?
The over all weight of the sierra should be about 300kg to 350kg over factory but 90% of the extra weight is in the 60 sieries Diffs (unsprung weight) Over all the sprung wieght of the sierra it self will be very close to factory give of take 70-100kg with the spare and bigger trans/engine.

[V.W.Dave]

On my weekly rout I have 2 pedders and they have tons of used springs that I can use so it may be a trial and error.

[BlueSuzy]

use aftermarket vit. don't use jimny ones in the front as she will be all over the road. working out your all-up weight would be a start to working out what springs you will need.

I am only doing the rear not front just yet that may be down the road a little. I have a set of springs out of a 94 JLX vitara will they be ok?
The over all weight of the sierra should be about 300kg to 350kg over factory but 90% of the extra weight is in the 60 sieries Diffs (unsprung weight) Over all the sprung wieght of the sierra it self will be very close to factory give of take 70-100kg with the spare and bigger trans/engine.

Bar work will help fix it to the body weight of a vit. vit soft/hardtop swb and jimnys weights are very similar, lwb are heavier, well der..

[V.W.Dave]

use aftermarket vit. don't use jimny ones in the front as she will be all over the road. working out your all-up weight would be a start to working out what springs you will need.

Hey joe do you know off the top of your head the weight of the 1.3carby ,1.6efi, sierra 5speed, vitara 5 speed? or the weight of the W/T diffs? You normaly know crazy facts like that. If I can get all that info I could work out the weight.

[Gwagensteve]

Vitara SWB rear springs will be pretty close in rate. Mine are a little bit soft, some estate wagon or GV rears might be better (or aftermarket lift vitara rears)

Take careful measurements of the static height of a vitara spring in the car, and bumpstop clearance stock, then you can position your springs correctly.

There's plenty of travel (and more importantly, articulation) in vitara rear springs when used in a sierra, as they have to be much further inboard so roll stiffness will be lower, and wheel travel much higher per inch of spring movement than in a sierra.

You'll wish you'd done it the other way around though (i.e coiled the front first) a 4 link rear will have very low roll stiffness and the car will behave worse than if you'd left leaves in it. I knew this would be case with my car, and it is, even with the added roll stiffness of radius arms. (I had other reasons to do coil rear first though)

I'd seriously do the front first. Once you have the front sorted the rear will be easy.

Steve.

PS Joe, what's the problem with Jimny front springs?

[V.W.Dave]

I am doing the rear first for a few reasons. The front as it is right now is very strong and has plenty of flex. The front as it is has a great approach angle. I am doing the rear first for these reasons in this order.

1) I need drive line space for the twin transfers and still have a decent length drive shaft without crazy angles.
2) The wheel base is only 90in I want it at 105 without making the chassis longer
3) I am building a custom rear tray and I don't want to have to build it twice.
4) I want more flex
5) because I can

[Gwagensteve]

The front as it is right now is very strong and has plenty of flex.

That's all true now I'm sure with a leaf rear with higher roll stiffness than the front.

4 link/Coil the rear and front won't flex at all unless you reverse up every obstacle.

Steve.

[redzook]

The front as it is right now is very strong and has plenty of flex.

That's all true now I'm sure with a leaf rear with higher roll stiffness than the front.

4 link/Coil the rear and front won't flex at all unless you reverse up every obstacle.

Steve.

stupidest thing i have ever heard

lucky i used to drive every obstacle in reverse

[BlueSuzy]

The front as it is right now is very strong and has plenty of flex.

That's all true now I'm sure with a leaf rear with higher roll stiffness than the front.

4 link/Coil the rear and front won't flex at all unless you reverse up every obstacle.

Steve.

stupidest thing i have ever heard

lucky i used to drive every obstacle in reverse

I can see your reverse lights on..

[V.W.Dave]

The front as it is right now is very strong and has plenty of flex.

That's all true now I'm sure with a leaf rear with higher roll stiffness than the front.

4 link/Coil the rear and front won't flex at all unless you reverse up every obstacle.

Steve.

Steve your normaly fairly spot on with everything but I dont understand your thinking here.....

If this was true why do most of the Hilux boys do the rear first? Are they all wrong as well?

I am doing the rear first because I have to. The front is ok for the momment but the rear is not. When I have a few weeks I will do the front at a later date but for now I am doing the rear. The front will be done in time.

[GRPABT1]

I find the extra weight over the front of a zook compared to the rear tends to bring the most out of front suspension unlike other, heavier rigs. Hence I think you can have a potentially flexier setup rear and still match it to the front easily. I had to go 3/4 elliptic to match the front flex on my zook with 3 leaves front and 4 rear. The rear leaves are longer and have longer shackles yet still don't flex as well without the 3/4 elliptic setup due purely to the wieght distribution IMO

[V.W.Dave]

Mine is no normal zook have a look at my build up. I thought about a 3/4 but that still will not fix the problem I have with to short of a drive line.

[V.W.Dave]

stupidest thing i have ever heard

lucky i used to drive every obstacle in reverse
[/quote]

Hey do you have some better pics of your set up????

[Gwagensteve]

If this was true why do most of the Hilux boys do the rear first? Are they all wrong as well?

Yes, they are wrong.

They're doing the rear first because they're trying to deal with axlewrap and coiling the rear is 487564847 times easier than doing the front.

Here's two photographs of my car to prove my point about the effect of low rear roll stiffness on balance.



This is the "money shot" - it looks cool (if you like the hektic flex look) and it's exactly the kind of result you should be able to expect from a 4 link rear. I'm running N76 shocks and stock SWB vitara rear springs in this shot and the coil is unseating in this shot. like lots of people's rear coil conversions.

However, the car is terribly badly balanced in this shot. Have a look at the front end - it's hardly flexing at all.

This is how I drive it - with the radius arm bolts all in, I have much less flex, but the car is far more balance - note how much harder the front is flexing. These photos were taken in the same place, on the same day. The ONLY variable was roll stiffness. You want to drive the car like this VVV not like that ^^^^^ sure, with a much lower front spring rate, it would balance better in the photo above, but I'd never lower the roll stiffness as much as I could in the rear. When you are climbing in difficult terrain, you want rear roll stiffness to keep the car as level as possible and keep the front wheels on the ground.



It is possible to achieve good balance with a 4 link rear and leaf front, but it will involve increasing roll stiffness in the rear with spring rate and generally a rear sway bar to force the front to work and the car to balance. Often, this will involve loosing some rear travel in order to make the front work, and that seems totally counter hektic, so it's rarely done.

There's been plenty of threads about this in the past, including a thread where the owner was unhappy with balance, added a rear sway bar, overall articulation INCREASED and the car was far more stable and was more capable as a result.


I was so adamant I was going to coil the front first (notice that Nissan and toyota offer leaf rear coil front cars but nobody has ever offered a coil rear leaf front car?) but my dying rear end led me to do the rear first.
Steve.

[redzook]

Hey do you have some better pics of your set up????

try my members http://forum.outerlimits4x4.com/viewtop ... 16&t=22277" onclick="window.open(this.href);return false;

[V.W.Dave]

Hmmm very interesting Steve..... Now that you explained it that does make sence. I can't see in the picture but is it a 4 link or 3 link ? Could you or have you tried to over come that problem by using a progesive spring? or even a taller spring in the rear? I have also seen on a comp truck back in the states they put a small heavy spring inside the first springthat was only about 2in tall. crazy idea but it worked.

Hey Joeblow do you have any input on what Steve is saying or how to better over come it?

[lay80n]

Steve runs rover radius arms.

Layto....

[Gwagensteve]

If I converted my rear end to three link+ panhard (which I am planning to do as it's pretty easy) The resulting drop in roll stiffness would see it behave as per the 1st photo.

VW - the primary road springs (i.e the coils) don't have very very much effect on roll stiffness. (yes, really) You'll notice that in the highly articulated picture, the axle is pivoting off of the bumpstop on the compressed side and the drooped side spring is now hanging free, so the springs are really having no effect on suspension performance at this point. Adding a progressive or taller spring will just make the car behave the same but bouncier and sitting higher overall - not desirable for the driving I do.

The ideal position would be to move the springs further outboard towards the wheels, but that's not possible unless you run short springs under the chassis, making the car too tall an the springs too short for good articulation if you try to run the car low (or low enough to match a SPUA leaf front)

I chose radius arms for my rear suspension because it has inherent roll stiffness - and I genuinely believe that in an off road application, rear roll stiffness should be higher than front roll stiffness.

If you design an effective three or 4 link suspension and run a leaf front you'll need some means to add roll stiffness and you won't want to do that with the coils as it will make the spring rate too high for a harsh ride and/or poor articulation.

The real key is designing a functional suspension with a realistic amount of travel. It's easy to chase the big flex but it's a better solution to be realistic with overall travel and focus on a more balanced result.

Steve.

[dad]

Steve, are you using a knuckle as your spare tyre carrier?

[Gwagensteve]

Not a whole knuckle, just a spindle/hub assembly.

Steve.

[shakes]

VW - the primary road springs (i.e the coils) don't have very very much effect on roll stiffness. (yes, really) You'll notice that in the highly articulated picture, the axle is pivoting off of the bumpstop on the compressed side and the drooped side spring is now hanging free,

Have you played with having the coil fully captive? From my small experience uncaptive coils are the equivelant of drop shackles.

[Gwagensteve]

I don't need to shakes. Because I run the radius arms fully bolted (as in the second picture) my springs can't go loose. If/when I go three link I'll limiting strap the suspension to stop the coils unloading.

I agree that loose coils are the equivalent of drop shackles. I posted the photos only to highlight the effect of roll stiffness.

Steve.

[V.W.Dave]

Sorry upping a old post.

Steve,
Going back to this. What are your thoughts on doing the rear first but with coil over air-shocks? Would a 4 link or 3 link be better? After reading your brake down of how it works I have been looking at different rigs and how the rear end affects the front. Its interesting if you watch the rigs that are great on a ramp are not always good on the rocks because of this.
That said I still need to do the rear first. All because I need drive line room. (I wish I started with a LWB)

If I dropped it all the way down to about 2" off the bump stops all around and ran coil over air-shocks in the rear with a link system would this keep the front end working the way it is now? In your apinion would a 4 link with pan hard or 3 link with A frame be best???

Blowjoe, Evil-11, Red zook I wouldn't mind your input on this either