Ride quality? - SE vs. SL

[Enforcer]

Originally posted by hfelknor
to the only place around here where they have a concrete road with expansion joints. This is a common road in the NE, but not down here.
And the roads are so good down here, I literally could not tell the difference on a "bumpy" road.
I had to drive back and forth a couple of times to find the "worst" speed (About 48MPH it turned out).

The car was HORRID on expansion strips. It set up an oscillation and the bounced all over the road.

The suspension has little compliance. And yes, you can have compliance and handle well.
So the only thing the car can do is bounce in the air.

And that was the SL!
The SE was worse.

Same with the Z BTW, just not 48mph, forget the worst speed.

The problem is that every single fixed suspension system will naturally oscillate at some frequency of bumps at some bump height at some speed. The trick is shifting something to get it out of the region you normally drive...which is also different depending on the person. In the Z forums, there were lots of complaints about bouncing and porpoising on concrete expansion joint roads.

[Kris]

Every system, be it electrical, be mechanical has a natural or resonance frequency. The same applies to suspension. It means that when you drive at a certain speed on certain roads you excite this resonant frequency. The trick is to pass this speed/frequency quickly. This is a well-known phenomena and there is nothing unusual about it.

Solution – do not drive with that critical speed.

[hfelknor]

Right. Do not drive at that speed.

But DO test a car at that speed.


Homer

[Kris]

What for? It you did it with a trubine ...no I will not even think what would happen!

[Enforcer]

Yep, your both dead nuts on Kris and Homer.

BLUF: Drive it and see what you think for yourself.

I will say though, there is plenty of aftermarket gear for the Z. Haven't seen any for the MO. So, that has to be part of the equation too. Make sure you test drive both the SL and the SE and decide for yourself before you buy.

On one hand I can see where Nissan missed the mark on both the MO and the Z, on the other hand, it's really a matter of personal preference. I've made 2 1200 mile round trips from Bama to OH10 in the MO and I am pleased. If anything, I wish the SE were stiffer. I've made that same trip countless times in my other stiff suspensioned vehicles and once in the Z and once in my fathers cushy roadmaster. It's a trade-off. Cushy ride versus stiff ride.

You have to be carefull about saying stiff suspension though. There are two "stiffs". One is sway and body roll/flex in corners and the other is bumps and dips. The way I think of it, stiff sway is determined mostly by body flex and sway bars and bump stiffness is determined mostly by shocks and springs. Tires affect both but mostly bump stiffness.

And when you talk about this stuff from a controls perspective, there is a plethora of terms. There is the natural resonant frequency, rise and fall times, overdamped, underdamped, critically damped, high frequency and low frequency response. And I'm sure I missed a few. And shocks historically have had a non-linear vertical velocity. Then there is the capacity determined by the piston and valve sizes. But I digress...

The reason you want a stiff ride is for road feedback. The reason you want a cushy ride is for comfort. The two are mutually exclusive to a great degree, but not totally. I do believe the shocks on the Z don't have enough capacity. I like the stiff ride but it shouldn't bounce. The same may be true of the MO, but I don't think so.

You also have to consider towing. All of these responses are also determined by weight. There is the weight of the stuff you cram inside the vehicle and then there is the tongue weight of something you are towing. I'm sure there will be a difference between the SE and the SL in ride quality when towing at max capacity tongue weight. Without thinking about this long and hard, extra mass of a laden SE towing max tongue weight would probably shift the response closer to an unladen SL.

Anyhow, great discussion.

[hfelknor]

I wonder if the Murano uses Gas charged Struts? It should for the price.

It doesn't feel like it, but you never know.

Considering that the SE is supposed to be the sporty version,and the SL the luxury version, I am also surprised that the sway bars are the same on both.

The only difference is the rear springs and the front struts.
UNLESS, without telling us, they have used Urathane bushings on the SE and "rubberized" bushings on the SL. But I don't think so. You can feel the difference in bushings.

IF I was designing the SL I would have put more compliant struts on it. Gas for sure. And I would have seriously considered a 70 series tire, even If I had to drop to a 17" wheel. And definitly softer bushings.

And if I was designing the SE, I would have done just about what they have done!
After all, with an SUV, car based or not, your CG is not conducive to absolute handling. Of course, I "might" have gone with an even fatter swaybar front or rear to promote more understeer or oversteer, Probably could use a bit more oversteer.
But it's nice that they have both front and rear and the car doen't push as bad as many. Although I have not pushed the Murano, i have a funny feeling it is going to be basically neutral with a bias toward understeer as most FWDs are.

BTW, ot would probably be a handful without swaybars, but without swaybars, it would definitly be a softer ride. Although Swaybars are not used to harden or soften a ride, it still has that affect to a degree.

But someday, some of this stuff will be available in the aftermarket if the sales accelerate.
Right now, with about 50-60K units, there may not be enough sales to incent the aftermarket boys. Especially since with a Zcar, there might be 10% or 20% of the drivers interested in mucking about with the supspension and with an SUV that interest would drop considerably.

Anyway, by the time "I" got done, ther would be a definite difference in the handling and ride.


As it is, I'm happier than a pig in mud, or somesuch , with my Murano and likely will never modify the suspension as I have on sevral other cars. (Vette, Miata, Mustang)


Homer

[Eric L.]

I had KYB AGX's on my 97 Maxima and they were absolutely fantastic. I would not hesitate to install those on the Murano if they ever become available.

[Mike TX]

Originally posted by Enforcer

** snipped for brevity **

Without thinking about this long and hard, extra mass of a laden SE towing max tongue weight would probably shift the response closer to an unladen SL.

Yep ... kinda like when my pickup (which rides a lot like a pickup) has something heavy in the bed it rides like a car (which is generally better than a pickup).

[Enforcer]

Mike, exactly. My Dodge gets real skiddish without a load, but boy does it do well laden.

Homer, I hear you:

Front Suspension
Independent Strut Design
• To provide car-like handling and response, Murano’s front suspension features an independent strut design that’s similar to Altima’s.

• The Strut design uses fewer parts, reduces weight and helps provide greater durability than many other front suspension designs.

• A new type of pinch-bolt knuckle attachment is used on the lower joint for added strength and durability in an SUV application.

• Due to Murano’s weight and higher center of gravity, thicker stabilizer bars are used to achieve the target roll motion.

• The front stabilizer bar is attached to the struts to help increase roll stiffness.

• New rubber mounts positioned between the upper and lower spring mounting points help to reduce NVH.

• Paint marks located on the top coil of the front spring are designed to prevent unintentional reversal of the spring during front suspension assembly.

Rear Suspension
Independent Multi-Link Rear Suspension
• Murano’s sophisticated multi-link rear suspension is rare in an SUV application.

• Use of multiple suspension links between the wheels and chassis and rubber mounts enhances control of wheel movement, combining excellent handling with a smooth and comfortable ride.

• Separation between springs and shock absorbers improves suspension

performance by reducing friction and allowing components to perform without compromise.

• Use of lightweight aluminum-alloy upper control arms reduces the weight of the suspension.

• Weight Distribution (%) Front/Rear

— 2WD 60/40

— AWD 59/41

• GVWR (lbs.)

— 2WD 4,858

— AWD 5,053

[1_Mean- mo]

Right off i saw the mo as 350z on steroids and when i read

about the power she had it was only natural for me to choose

the SE`s suspention package to match HP.


MY 2 cents

[mikehussey]

In retrospect, I think you go to the SE as well. Too late now. I love SL anyway!