Vehicle Rocking Back and Forth

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  #1  
Old 07-29-14, 09:41 AM
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Vehicle Rocking Back and Forth

My newly acquired 2008 Acura MDX rocks left to right when going over uneven road surfaces. I know for a fact that the sway bar links are bad. The boots are torn and they often make a clicking noise when turning and going over bumps. I know a sway bar helps prevent body roll when cornering, but would worn links cause the vehicle to rock left to right when driving straight?
 
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  #2  
Old 07-29-14, 07:42 PM
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Yes and struts too. But definitely links. Sway bar has much to do with side roll.
 
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Old 07-29-14, 08:05 PM
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I was thinking struts as well, but it doesn't bounce up and down like the struts are worn, just side to side over more prominent uneven surfaces.
 
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Old 07-30-14, 03:58 AM
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Is the movement predominately in the body or the steering wheel? The latter could indicate worn front end parts.
 
  #5  
Old 07-30-14, 05:31 AM
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Its in the body, like a boat rocking. Let's say you were sitting stationery in a boat, then the wake from another boat collided with your boat parallel to the left side. The left side would rise then fall, then the right side would rise and fall as the wake passed underneath. This is the same feeling when driving over uneven road surfaces. The steering wheel does seem to be overly sensitive as well, but I think that may be an alignment issue. Hopefully replacing the worn links and getting and alignment will resolve things. BTW, I just had both front control arms replaced, and this issue existed prior to that.
 

Last edited by mossman; 07-30-14 at 07:09 AM.
  #6  
Old 07-30-14, 04:39 PM
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Well, that's exactly what sway bars are for. I fixed my 1st boss Explorer, when he couldn't figure why the shad rolls to the side so badly. All it took was to glance underneath and notice a hanging down link.
Buy ones with zirks. Pack with grease and be happy.
For 08, I doubt your struts are bad. My 09 Ridgeline is basically same parts, and is rock solid.
If I were you, I'd have done SB bushings same time. They do have much to say with this too, as SB moves inside the bushing up/down a little bit, but because it's angular change, at the wheel it turns to be accentuated.
 
  #7  
Old 07-30-14, 06:01 PM
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I ordered new links and bushings today. Hopefully that does it.
 
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Old 07-30-14, 07:45 PM
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Keep us posted. I am always curious about suspension improvements.
PLEASE, do NOT buy polyurethane bushings!!!!! They compress too much. They do last longer, yes, but compress like mush.
 
  #9  
Old 07-30-14, 08:08 PM
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Nope, got the OEM rubber ones. Poly bushings tend to be noisy too and that would drive me nuts. I'll keep you posted. Probably will have them installed by next weekend.
 
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Old 07-31-14, 06:23 PM
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I simply pack them with GM PTFE grease. Also, you can install zirks on bushing brackets.
 
  #11  
Old 07-31-14, 07:23 PM
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Im confused. Why would you want/need to grease the sway bar bushings? The links, sure, but the bushings that hold the bar to the chassis?
 
  #12  
Old 07-31-14, 07:59 PM
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This has to be the most expensive "good deal" used car I ever heard of Mossman.
 
  #13  
Old 07-31-14, 08:16 PM
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Because:
1. the sway bar rotates inside and rubs off rubber
2. squeaks.
Don't be confused. Also helps reduce cracks in rubber.
Haven't you noticed that factory SB is lubricated inside bushings? Some white stuff.
 
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Old 08-01-14, 07:52 AM
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This has to be the most expensive "good deal" used car I ever heard of Mossman.
"Good deal" with respect to monetary cost, bad deal with respect to all the repairs. I've decided to view it as an act of charity--I rescued a vehicle from further punishment and rehabilitated it so it can continue on for hopefully another 100k. Makes me feel better about the situation.

Haven't you noticed that factory SB is lubricated inside bushings? Some white stuff.
Haven't noticed, but that's because I haven't even looked yet. Assuming the new OEM bushings don't have zirk fittings, do I simply lather some general purpose grease (NLGI 2) on the inside of the bushings?
 
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Old 08-01-14, 08:24 AM
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I've decided to view it as an act of charity--
Good way to look at it! Doubt I'd be so philosophical about it.
 
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Old 08-01-14, 08:30 AM
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I was thinking more of the way a politician will put a spin on the facts

But whatever it takes to make your mind handle adversity works
 
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Old 08-24-14, 07:38 PM
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New sway bar links and bushings did not help. In fact I think it may have made it worse. I'm beginning to think its the tires. It feels like the sidewalls are weak. Iw as experimenting the other day on the highway and when I would jerk the wheel abruptly, I would get a similar sensation as if the tires were made of jello.
 
  #18  
Old 08-25-14, 04:21 AM
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Unless the tires are worn out, try swapping the front and back and see if that changes anything. I assume you've checked the air pressure.
 
  #19  
Old 08-25-14, 12:16 PM
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They are only a little over a year old, so they aren't worn out per se, but I just think they are poor quality, or maybe just not suitable to my vehicle. I'm thinking of buying a pair of used Michelins and putting them on the front to see if the handling improves.
 
  #20  
Old 08-25-14, 04:25 PM
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I'm beginning to think its the tires.
Inflate the tires to max cold PSI.. Drive it and report back the results..
 
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Old 08-26-14, 09:49 AM
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Inflate the tires to max cold PSI.. Drive it and report back the results..
It occurred to me yesterday evening to give that a try. Max PSI stamped on the tire is 51 psi. Is that cold?
 
  #22  
Old 08-26-14, 10:17 AM
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Sounds about right. How hard do you have them inflated now?

FWIW, this would be a test - you typically get uneven wear (more in the center of the tire) when you pump them up to max like this and keep them that way. As an example, many cars say 32 psi for the tires but I like a stiffer ride so I keep mine at more like 36. There was a time when I had them at 40 but that's when I got the uneven wear.
 
  #23  
Old 08-26-14, 05:21 PM
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They were at 32 and I pumped them up to 46. No improvement. Could max'd out rear toe in (max manufacturer spec) and zero toe in front cause this odd behavior?
 
  #24  
Old 08-26-14, 06:22 PM
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Mossman, you got me on this one. I have never ever heard of tires causing anything of this nature. I am afraid, you are not quite well describing the symptoms. But this is very straightforward:

The left side would rise then fall, then the right side would rise and fall as the wake passed underneath.

and there are only 3 components that can cause this:
1. sway bar
2. sway bar links
3. struts

Unless you have air suspension, which you don't, and it's causing all this havoc. Or, you have very normal response from - now - well functioning suspension and you simply over react. Or terrain is like wave.
As a last straw, check on crossmember bolts. And control arms. Outside of strong side wind gusts causing lateral lean, there is nothing else that will cause this.
 
  #25  
Old 08-26-14, 06:33 PM
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I have never ever heard of tires causing anything of this nature.
Sure I tow a trailer and if the tires are not inflated to max I get sway.. Although these are 31" tall tires... ( I was suggesting mossmans tires may have been under inflated)


Mossman, you got me on this one.
I had this happen before on a car and the frame was bent... That was the issue....
 
  #26  
Old 08-26-14, 08:29 PM
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Yeah, that's why I suggested checking on subframe/cross member bolts. Also, that is trailer, and towing, and this is SUV.
Donno. Maybe man happened to be out of luck completely, and has an out of round tires - on both sides. Chances slim to none, but who knows.
 
  #27  
Old 08-27-14, 04:08 AM
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Wouldn't a bent frame show up on an alignment? And what about excessive toe in on the rear with zero toe in the front? Wouldn't this cause the rear wheels to steer the car a bit when going over uneven surfaces? Perhaps this is what I am feeling. It's like the rear is trying to steer the car and the front brings it back straight so you get this rolling/twisting sensation. I apologize for the description, but this is something I have never encountered before so it is hard to describe. I'll be replacing the tie rod ends this weekend (because one of them is bad) and then taking it to the shop to have it diagnosed and aligned.

A quick recap for those that may be reading this for the first time:

Issue: 2008 Acura MDX with squirrely handling, especially over uneven road surfaces
Vehicle alignment (toe only): Front toe: 0.0 total, Rear toe: 0.26 total (0.13 left and right)
Other known issues: Passenger's side tie rod end has free-play.
Work thus far: Replaced front sway bar links and bushings and both lower control arms (vehicle does not have upper control arms).
Work to be completed: Replace both tie rod ends and get four wheel alignment.
 

Last edited by mossman; 08-27-14 at 06:59 AM.
  #28  
Old 08-27-14, 01:58 PM
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Is this a plausible depiction of what may be occurring (toe angles exaggerated for illustrative purposes)?

Name:  Alignment.jpg
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  #29  
Old 08-27-14, 07:50 PM
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Moss, you need to finally determine WHAT is it that you are feeling. It either tilts like a boat on waves, side to side, or snakes down the road, left-right.
Your alignment picture will cause snaking. Not tilting.
 
  #30  
Old 08-27-14, 08:28 PM
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To ask an obvious question: Was the vehicle ever hit or messed up with a serious off road surface impact, before you bought it? Just wanted to confirm that there could be nothing related to poor frame repair or other bent suspension parts that were minor and not noticed and replaced. It can happen.
 
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Old 08-27-14, 09:08 PM
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Was the vehicle ever hit or messed up with a serious off road surface impact, before you bought it?
Of course from what I know from a previous post. This is why I stated frame issues...

The car was rear ended from what I read....


http://www.doityourself.com/forum/bu...-out-deal.html

Let the buyer beware....!!!!!!!!!!!
 
  #32  
Old 08-28-14, 12:38 AM
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A tire starting to separate will cause a low speed sway, May not feel anything above 25, Have to look at tires very close for a worn spot usually in one place in tire. Rotating will usually make the car feel different but will still sway.
 
  #33  
Old 08-28-14, 06:16 AM
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I believe it is a bad alignment and I am feeling the car steer itself as shown in the diagram, which is causing a left to right swaying motion, which I initially described as a rocking back and forth.
 
  #34  
Old 08-28-14, 01:26 PM
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Unless I'm mistaken, there is no "frame" on this vehicle. It is, of course, what Acura and Honda call a "unit-body" (otherwise know as "uni-body"). No big deal, but sometimes it's best to use the correct terminology.

Anyway, I'm starting to wonder if you might consider searching out another 2008 MDX that you can test drive (i.e. at a used car lot or dealership).

I say this because you seem to have experienced far more problems and issues with this vehicle than what I'd consider beyond average (for an Acura anyway). Therefor, I'm wondering if you might be "over-thinking" things a bit (I too have done this to some degree with used vehicle purchases).

Also keep in mind that some 4 wheel and all wheel drive vehicles tend to "hunt" somewhat while going down the road (especially older 4x4s). Not sure if this is the case here, but it's something to consider.
 
  #35  
Old 08-29-14, 06:01 AM
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I'll also mention that the 2008 MDX has an "Active (suspension) Damper System that might be causing what you're describing.

Active Damper System | 2008 Acura MDX | Acura Owners Site


You probably already know about this system tho...
 
  #36  
Old 08-29-14, 06:22 AM
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I'll also mention that the 2008 MDX has an "Active (suspension) Damper System that might be causing what you're describing.
The active damper system is only on the Sport models. I have the Tech/Entertainment model.
 
  #37  
Old 09-02-14, 07:37 AM
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UPDATE: Turns out it was the alignment after all. I had the shop set the rear toe to dead center of spec. and equal left to right, which also corrected the thrust angle to essentially 0.0. The front toe was corrected as well and the steering wheel is now nice and straight. No more odd behavior--it feels stable and straight now.
 
  #38  
Old 09-13-14, 04:38 PM
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Spoke too soon. Although the alignment helped, it still feels unstable. I believe it has to be the shocks. It does feel like I'm just riding on springs. Maybe I'll start with replacing the rears first since it is extremely easy and cheap--they are not coil overs.
 
  #39  
Old 09-20-14, 05:58 PM
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Okay, so I replaced the rear shocks this evening and there is a definite improvement. I'll therefore be doing the fronts as well in the near future. I'm wondering if it's a good idea to replace the strut bearings and/or mounts as well, or are these typically lifetime parts? Also puzzling is that the bump stops on the rear suspension (located inside springs) appear to rest against the bottom of the lower perch/basket/whatever it's called. Is this normal or are my springs sagging? Perhaps they are supposed to touch and compress with the suspension.
 

Last edited by mossman; 09-20-14 at 06:56 PM.
  #40  
Old 09-20-14, 06:23 PM
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Yes, replace the bearings.......
 
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