Hard Spring, Soft Bar Vs Soft Spring, Hard Bar

[rcs_888]

Hey guys,

I guess this is the time old tale and i have been looking into a whole heap of different suspension packages for my R34 and i seem to be coming up with some wildly different setups.

I have noticed that the likes of MCA and BC seem to be going for the hard spring, soft ARB approach and then bilstein, Supashock are going for a softer spring firmer ARB. Obviously valving for each package is going to be different but dont really want to get into the nitty gritty of that (just yet).

I personally am going for the softer spring approach. In my opinion this gives more weight transfer F&R but then keeping roll seperate and having the bar do that for you. With the firmer spring i wouldnt think that you would get that initial squat/bite plus you are making your shock controll 2 aspects your F&R weight transfer and the roll.

What are your opinions? Like i said im just about ready to go down the path of shocks

[GTSBoy]

There are compromises and trade off each way. I think both approaches are faulty.

Stiff springs mean that the suspension is tuned for high speed bumps. It becomes much less pleasant at lower speeds. Also, particularly only feels good on smooth surfaces. The soft bars on that approach at least maintain as much independence from side to side, meaning that bumps that affect just one wheel will not unsettle the other side so much.

Soft springs + hard bars brings on another problem. The bars will resist a lot of roll, yes, but the springs are now not tuned for high speed bump inputs. You also lose a lot of side-side independence. This can be a horrible compromise.

The best approach is to go medium on each. But even that so much depends on the surfaces the car is going to be used on and the usage it will be put to. Street car? Go sensible, especially on Australian roads. Lots of bumps. Really stiff springs suck in that usage model. Track car? Smooth tracks only? Stiff as buggery and then add some more.

There is no such thing as one set up that works everywhere. That is why proper race teams have setups for every different track!

[_Wing_]

This debate has been going on since racing started, so just do what you think is the go. You'll know that hard bars will couple your lefts and rights and move you towards negating the benefits of your "independent" suspension.

[dr phil]

So just to chuck in another semi-related question - why does the v-spec have 4kg/mm front, 5kg rear spring rates, compared to say your "normal" MCA or other setup for a GTR, which would be biased the other way?

Assuming Nissan did this to get the car to turn (less understeer). Have also read that the damping on a v spec is biased soft on compression in rear, harder at front, to change the balance back a bit.

Anyway would like to hear any thoughts on the difference in spring rate front to rear, in a 4wd. I have a ENR34 sedan with a turbo stag motor and all stock R34 gtr suspension components at the moment, so 3.2kg/mm front and rear.

[rcs_888]

Potentially the v-spec may have also had different rear diffuser and wing combo than normal GTR?

[Roy]

So just to chuck in another semi-related question - why does the v-spec have 4kg/mm front, 5kg rear spring rates, compared to say your "normal" MCA or other setup for a GTR, which would be biased the other way?

Assuming Nissan did this to get the car to turn (less understeer). Have also read that the damping on a v spec is biased soft on compression in rear, harder at front, to change the balance back a bit.

Anyway would like to hear any thoughts on the difference in spring rate front to rear, in a 4wd. I have a ENR34 sedan with a turbo stag motor and all stock R34 gtr suspension components at the moment, so 3.2kg/mm front and rear.

I guess they have the active dff so perhaps they try to help dial out understeer by running a higher rear spring rate

I used to grab bits off a V8 Supercar guy and when he was at Kmart Racing he told me there was a big difference to how Rick Kelly and Greg Murphy set up their cars. If memory serves me correctly Murphy loved as much bar as they could throw at the car whilst Kelly liked more spring.

I ran big bars at one point in time and whilst the car was generally about as quick as it was with the other smaller bars I have run it did handle and feel very different. Not sure porpoising is the ride word but it seemed to feel as though it crabbed around fast corners..just felt odd. With smaller bars it just feels like the car handles what I would say is more natural

Russman now runs my old mega bars in his Time Attack GTSt and its friggin quick for a basic car so they obviously work well with the Tein RS setup he runs. But for me I ended up with my ARC bars that generally felt the same at the off the shelf Whiteline offering but are larger diam and hollow so lighter but still adjustable in the rear.

[dr phil]

Potentially the v-spec may have also had different rear diffuser and wing combo than normal GTR?

Yes for R34. However R33 v spec had same spring rates and no diffuser (but you could put a lot of wing on the rear from what i have seen).

[djr81]

Forget aero it is a non event on any road car.

You usually run a soft rear spring for traction. If your GTR has a properly functioning attesa system (Which can exclude 32's) you won't struggle for traction and can then use the front/rear springs to alleviate under steer which all gtr's do in spades. SO who's right - MCA or Nismo? IMHO Nismo by a long way. WHich doesn't mean I wouldn't ask MCA what a decent Spring rate would do to their shock setup.

Bar choice comes down to chucking the hardest you can find at it - I bought mine a long while ago so am no longer sure what is still available. Hard springs with soft bars leaves you with wheel hiking ugliness like Mark Skaife circa 1995 and generally a car that feels unsettled in the corners. Running too hard sway bars reduces your grip and the suspensions independence so isn't to be recommended either. FWIW I run 5.5kg/mm front, 5 rear with a Cusco rear bar and a whiteline front on soft with heaps of front -Ve camber. Balance changes with tyre age from mildly tails (and quicker) on new to under steer on old. This on a 32 GTR.

[rcs_888]

Yeah well thats the thing for my application MCA is reccomending a 16kg front and 6kg rear but i will have aero and it is purely track but from what i have seen he runs stock bars.

[hardsteppa]

in my discussion with MCA yes, he said runs stock/soft swaybars and did not seem keen on using a stiffer swaybar in most applications. While I also have stiffer and adjustable swaybars myself, I prefer a stiffer spring to control the majority of body roll - in fact recently had first a front swaybar link, then a swaybar bracket break, and the subsequent loss of working front swaybar has only mildly affected the handling, and mostly in a stability sense rather than any affect on controlling body roll. To some degree I find left and right being able to operate independently of each other rather than being linked by the swaybar to be better, although not to the extent I will not be linking it up again.

Overall though when I first fitted stiffer swaybars on stock springs the handling improved but not to the same extent as moving to a stiffer spring, and of the choice between the 2 I'd say stiffer spring (relevant to the given application) is far more beneficial any day, with the ideal result being the right balance of both of course.