BACONMOTORSPORT

Ive owned 40ish cars in the last 20 years. Half of which have been brand new. My wifes new GL350 is one of the hardest (roughest) riding vehicles I have ever been in. I drive a 2006 Dodge Ram 3500 diesel everyday for work and personal use. The MB is worse. I feel like it really tosses your head left to right. This is with the air springs set to standard ride default mode. When its in lifted mode its unbearable. Any thoughts??

Fourdiesel

Something is wrong! Go to a dealer and finagle a ride in another GL (it shouldn't really matter if it is a 350 or not) and compare the ride quality on a variety of road surfaces.

BACONMOTORSPORT

The test drive we had originally was in a different GL than the one we bought. I thought that ride was rough as well but I was blaming it on the rough secondary roads around Boston. Oh well. Was wondering if the lowering mods softened things up a bit as there would be less pressure in the bags for the lower height

mdadgar

Something is definitely wrong. I drove a GMC 2500HD Duramax daily for 6.5 years and my new GL350 is light years beyond that.

- Mark

jimmyp

Make sure the tire pressure is 32 psi. Mine rides very good for run flats, I have them on my GTR andthey ride a little rough but worth it.

BACONMOTORSPORT

What could be "wrong"? I have a better than average understanding of suspension dynamics. Short of wrong swaybars etc... what are you guys thinking it might be. Good luck with the smuck at the dealer figuring that one out!

BACONMOTORSPORT

The roads in New England are extra bad right now so that could be part of it

BACONMOTORSPORT

I did check the pressures. I do think the 20" run flats make things worse but its more of the left to right bob that gets me.

mdadgar

If it was a BMW (or, heck, anything with coil springs), I would guess that the dealership forgot to remove the shipping spacers from the springs (that happens occasionally and is immediately followed by "gee, my new BMW sure rides like crap!" posts in various BMW forums ).

There's probably some equivalent for air springs. Worth checking.

- Mark

Max Blast

Lowering mods?

StevethePilot

I don't know how lowering mods can make things smoother? Some shorten the throw of the springs/struts and therefore both tighten the suspension and make it possible for the suspension to bottom out due to less available wheel travel.

When you say the ride is "rough", do you mean it's harsher or more active? You feel more of the road or you're being thrown around inside the cabin more? (Were all of your other cars Cadillac Fleetwoods? )

The general consensus on this board is the ride to those who've complained the most is too soft, wallowy, and boaty. Those who've moved from the original to run-flat tires are fairly evenly split on whether the ride is better or worse (and road noise, etc.)

What could be wrong is (like was already said) something used in shipping not removed. You could also have some kind of malfunction in your air ride system, missing or broken parts, all kinds of possibilities. It'll take a mechanic peering around under there to tell you if something's wrong. But if the ride's the same with any same-model-year 450 or 350, then nothing is wrong with the car mechanically, it's just not to your liking.

Brocktoon

I agree with Bacon, if he is describing what I think he is. If you drive into a driveway, for example, not completely perpendicular, then you will be tossed about quite violently. This, i think, is inherent in the design of Airmatic, and there is not much you can do about it. Unlike earlier air and hydro-pneumatic suspensions (think Citroen), there is no direct cross linage between the bladders or reservoirs at each corner, they all act independently via a central compressor. I think this is a design compromise that was likely made when developing Airmatic for cars, but now that the same system has wound up on SUVs, as Bacon rightly points out, you will feel the effect more the higher the centre of gravity is from the wheel hub centre lines, and the greater the difference between the road height of the wheels.

When I try to enter the local Home Depot underground parking garage, I know to have all my passengers brace themselves, as I know this particular spot can cause the effect to the degree that people have hit their heads on the door glass or b-pillar in the past.

That being said, I would not consider that a "rough ride", just an unforunate dynamic characteristic. I can see how if you had to drive over ramps and curbs like that all day, it would be too much!

mdadgar

This is pretty inherent in the design of SUVs and is much worse with rigid rear axle designs. It's known as "SUV head toss".

What basically happens is that you have a tall vehicle, so it sways a lot. The engineers compromise with stiff sway bars, with are really just a torsion spring that connect the two sides of a vehicle together. When you hit a single-wheel bump (like entering a driveway diagonally), it twists the sway bar. When the suspension unloads, the sway bar twists back. Since the vehicle is tall, it acts like a lever arm and you get tossed sideways a lot.

- Mark

Brocktoon

Right, and if Airmatic was a closed, crosslinked system, the compression on the lifting wheel would cause the opposite strut to push down, leveling, and mitigating the head-toss. I personally think this trait is more pronounced in Airmatic equipped SUVs than anything else I have have owned, but I have not had a full-sized, live axle SUV, either.

43221B

I agree with mdadger. Maybe your roads are just really bad. There is an intersection where I make a left hand turn across a lane that is deeply grooved from heavy truck traffic. When I go diagonally accross those grooves the GL does rock side to side in an uncomfortable manner that I don't notice in my other SUV that has a softer suspension. Fortunately, that intersection is really the only place I experience that.

mdadgar

I think that's basically just a stiff swaybar, if I understand what you're saying correctly. Which means it would be the same end result.

You're welcome to buy my Escalade.

- Mark

TamZ

Mark, you are still pimping out that Escalade!

I live in a town that spends zero money on their roads, so we have potholes galore...I did find the ride a bit more "harsh" than I had anticipated at first, but even in my problematic GL, I have very little complaints about the smoothness of the ride, especially on the open road. Run flats wouldn't be my #1 choice, but they did win me over on the freeways. But I also agree with Brocktoon on the perpendicular thing...I have noticed that it goes a little 'back and forth' more if you don't hit things head on. There is a speed bump right on the 90 degree corner going into my banks ATM and it sends my car a little "wonky" everytime I drive over it. I wouldn't say it tosses us 'violently' back and forth but it's a good "jostle."

BACONMOTORSPORT

Brocktoon gets it exactly. Its the left to right sway on off camber bumps and the frost heaves right now. Our 2006 E320 CDI road much much smoother. Car vs suv with 7500# towing cap. is not fair. I understand. Guess I was just curious to see what other people thought. The stuff that seems to upset the chassis on this GL I do not think would be affecting a solid axle truck as much. Again my 3500drw dodge cruises through the same sections of road with out a complaint. Perhaps the only time the GL is worse than the truck in all fairness. I do think it is perhaps a weak point of the airmatic where a crosslink setup like the new Infiniti QX56 has may shine.

The way a lowering mod would soften things up would be through the air pressure in the bags. The lower the pressure in the air springs the lower the ride height. Lower spring pressure equals softer ride and so goes the opposite. Jacked up height equals stone like suspension feel. Although its cool for cruising around town and being able to see over the snow banks

Max Blast

Re: the SUV head toss- Brock nailed describing it. I can tell you my 2006 Kia Sportage was ATROCIOUS in that regard.

StevethePilot

Oh, your Killed-In-Action had nothing on the first generation Lexus LX-450. Besides the huge weight and rather high center of gravity, when it first was released (as basically a Land Cruiser with rear A/C) they put too-soft coil springs on with the air ride. It was like riding a drunken elephant built by Cadillac! (No offense to you poor, sad, lonely Escalade drivers. I mean the old Caddys, like from a year or two ago, before they were suddenly stylish and well-built.)

Brocktoon

I agree, I have driven a Tundra several times over the same spot, and had no issues, but I did not want to start arguing about suspensions again on here.

So, does the Q have a closed cross linked system? or is it open like airmatic? I think an open cross linked system is possible with the right valving. That must give a very nice ride indeed.

Brocktoon

Just found this :

http://www.justcar.org/2011-infiniti...walkaround.php

The Qx56 suspension looks boss! No sway bars, cross-linked hydro-pneumatic, with an open air system for load leveling at the rear! That must ride like a dream!

BACONMOTORSPORT

I liked the QX alot but my wife did not. A few problems.

1. its a Nissan
2. not diesel
3. thought the ride sort of wallowed, but I guess that it may have been better than the GL just to the opposite end of the scale.
4. the wife didnt like it
5. its a Nissan
6. first year for the model, although its built on the Patrol platform which has been around awhile
7. its a Nissan. Nissan engineers are all the Toyota and Honda flunkies

StevethePilot

You only mentioned your wife not liking it twice, and it wasn't #1 on the list. Was that in error?

Brocktoon

Compelling reasons, without a doubt, although I think a Patrol is pretty robust no matter who engineered them.