Do I need swaybars / what to they do exactly ?

[MvM]

My NSX is lowered by about 1". It was that way when I bought it four months ago. In general I'm very happy with the way the car behaves. However, we have a lot of speed-bumps and sometimes the nose of the car just dives down a bit too much so the airdam hits the road. Also, when cornering fast, the car rolls a bit than I would like.
I was thinking of getting stiffer swaybars but I'm not exactly sure how they would help. Doesn't a swaybar take away a bit of the independent suspension effect ?
I went to a (small) track last Saturday and had lots of fun turning rounds on the oval. Screeching tires but the car was pretty stable. Would stiffer bars help me atain higher cornering speeds as well?? I would say yes from the top of my hat but since this is all very new to me I would like to hear it from the (NSX)pros.
Thanks in advance.

 

[Carguy!]

Anti-sway bars help keep the car and tires level when cornering. I have a set of Dali's track/street bars and it helped a lot. On very rough corners it can cause you to bounce more and not keep the tires as well planted, but on most corners (especially on tracks) it helps quite a bit.

Good Luck!

 

[Number9]

With respect to speed bumps, and assuming that your direction of travel is perpendicular to the long axis of the speedbump, the [anti]sway bars will not have any useful effect. The front and rear [anti]sway bars are just a torsion bar spring that couples the left and right sides of the respective front and rear suspensions together. You really need higher spring coefficient springs and matching dampers to stop the nose dive thing...

 

[MvM]

Number9,
So you are saying I should first get stiffer springs instead of swaybars?
In that case, with stiffer springs, would I get any of the benefits of swaybars as well (less roll in corners)?
And what if I would do both (springs and bars). Or would it be better to combine stiffer springs with shockbreakers instead of springs and bars ??

 

[Hrant]

Number 9 drives a Zanardi, while I drive a tamed 98-T

Sway bars help in reducing the body roll.
Springs help lower the car and give it some further stifness.
Dampners help your issue of too much lunging forward upon breaking and also helps in cornerning.

I installed the Comptech sway bars first (should be simialr to Dali strret/track sway basr), and noticed more steering responsiveness, considerable straight line tracking not to mention less body roll (which you will notice more when you drive on the track or twisties). After a few months I added Bilstein on lower perches and the car really came to life; upon hard breaking, the nose did not dive as much as before, frankly very little ... the ride is definitely more sporty and less "touring" .... I have been told this is closer to a fresh non-targa ride (perhaps a tad stiffer) ..... so if you have a coupe you many more levels that you can go to .........

 

[DutchBlackNsx]

MvM,

I'll say, give my car a try. I've got the yellow Koni's and the Dali street/track ones.

Though less roll and dive, i found the car to be more unpredictable. Nearly drove it in the barriers at the Nordschleife (nurburgring) last weekend

Maybe i still have to get used to it.........


Mich

 

[Number9]

MvM, stiffer (than stock) antisway bars will reduce lateral body roll but will not help with fore and aft dive/squat. Getting higher spring coefficient springs will help with the latter. If you get the stiffer springs, you'll need new shock absorbers with higher damping force to match the new springs. As Hrant noted, you can also just get shock absorbers with higher damping force alone, which will help somewhat with reducing dive/squat, though I prefer matched (for the particular vehicle) spring/shock absorber sets.

P.S. Look at the related thread entitled "What Suspension Is Everyone Running On Their NSX?" for further thoughts on suspension stuff.

[This message has been edited by Number9 (edited 05 August 2002).]

 

[docjohn]

The original issue of bouncing or bottoming out on bumps sounds like a shock or damper issue.The shock can not controll the ocilation as the compressed springs disipates it's stored energy.Worn shocks can be tough to diagnose because it is a slow inssideus proccess.Try to get a ride in another car for a contrast.The sway-bars reduce some body lean but do more to promote better tire ground contact under lateral load by changing roll stifness,I'll leave that exp. to the enginears.

 

[Andrie Hartanto]

Originally posted by docjohn:
The sway-bars reduce some body lean but do more to promote better tire ground contact under lateral load by changing roll stifness,I'll leave that exp. to the enginears.

Actually the sway bars reduced body roll but with expense of tie-ing up the suspension. This mean more lateral load transfer which is bad, and reduce total tractive capacity of the car.

Sway bars can help handling by reducing dynamic camber change.

On modern race cars, more and more engineers shy away from rear bars.

 

[docjohn]

Thanx for chiming in Andrie,I figured my explanation was suspect.From what I remember the realtime nsx dos'nt use swaybars as an example.

 

[Hrant]

Since I am not an engineer, I try to apply common sense ......... if I am not convinced, then I let the engineers argue it while I watch in amazment from the sidelines ......

If you have very stiff suspension (springs and dampners) and aggressive track alignment, then I would see why you might get away without sway bars; they will do most of the work.

But with 70% street driving and with some of the simpler aftermarket mods such as moderately stiff dampners like (Bilsteins), or progressive Eibach/Comptech springs or even both combined, the sway bars presumably should still play a role if one looks at Type S, Type R as reference points ......... having said this, my next mod is the non-compliance toe link once Comptech starts cutting the price on this one as well

........ and no I am not investing in the beam that ......


[This message has been edited by Hrant (edited 05 August 2002).]

 

[Andrie Hartanto]

Hrant,

I agree for street use the sway bars make more sense, and will do it's job.

I still use them too. (stock one though)

 

[Number9]

Originally posted by Hrant:
Since I am not an engineer, I try to apply common sense ......... if I am not convinced, then I let the engineers argue it while I watch in amazment from the sidelines ......

Common sense(?!) - you mean it wasn't necessary solve the damped oscillation differential equation to find the critical damping coefficient for NSX shocks? Darn, yet another afternoon gone to waste...

Seriously though, the shocks and springs work together as a system and changing either the damping coefficient (by changing shocks) or the spring constant (with stiffer springs) alone is not generally a good idea (of course if your shocks are shot, then, yes go ahead and replace them). As an exercise for the reader, how do you optimize the shocks for progressive springs?

In summary MvM, if you get slightly stiffer springs and appropriate shocks first, you will mitigate some of the dive/squat that you are experiencing, whether through braking or driving over speed bumps. It will also have the collateral effect of reducing body roll. After that, if you wish to reduce body roll even further, then get stiffer antisway bars too.

[This message has been edited by Number9 (edited 05 August 2002).]