Vibration while coasting

[captainmorgan702]

Hey guys,

My parents dropped off their 2004 X5 4.4i with me to do a window regulator fix. I have been driving it for the past couple days and there is a pretty heavy vibration/shimmy above 30 mph while coasting. The vibration goes away when under acceleration and braking and only occurs while coasting. It also varies between the front (steering wheel) and rear (drivers seat). I have checked the tire pressure and that is fine. All of the other threads are for vibration under acceleration so I am stumped. I have asked various guys that worked on the E53 at BMW Plant 10 in Spartanburg SC but they all were stumped as well. They mentioned motor mounts, transmission mounts and of course tires. However the symptoms dont really match any of those since the vibration is at 30+ and is not constant.

Tried coasting in neutral and still has the vibration.

Car only has 87k miles.

Any ideas? Thanks in advance.

[captainmorgan702]

Would mismatched tires on the rear cause this issue? They are both the same size but they have different load ratings. When my parents got new tires they got the same as the spare so they could use the spare as the 4th tire. However the spare is load rated 103H and the 3 new ones are 104H.

Could this cause a vibration while coasting?

[captainmorgan702]

anyone?

[TriX5]

Why not start by have a tire shop check balance and wheel/tire roundness? I have my own balancer and find that higher quality tires usually spin perfectly round (porsche N0 fitments are excellent). Bridgestone often have problems and pirellis are unpredictable.

[captainmorgan702]

I have an appointment on Thursday with the goodyear place. They have the Hunter Road Force so hopefully they will fix the issue. The tires are michelin's.

[jst2878]

lugnuts loose? rear tire not balanced? check those two. wobble all tires while jacked and check hub bearings. could also be a loose swing arm bolt

[jdd]

Not sure about the X5 but I’ve seen this in other vehicles where one or more wheels is slightly out of balance and/or round, combined with worn suspension components.
When there is load on the driveline it loads up various suspension components, when the driveline is unloaded it allows more movement in some, potentially worn suspension components. If there is a slight vibration there to start with (eg out of balance wheel) the worn suspension might exaggerate this problem making it appear far worse when the driveline is unloaded.

[captainmorgan702]

Took the car to goodyear this morning and they put all 4 tires on the road force balance machine. All of them were pulled from lower 30's to under 20 lbs (max acceptable). Drove out of the place hoping that the matching would fix the issue but it did not.

Now all 4 tires matched to rims and fully balanced and still have the vibration only while coasting. I have a pair of front control arms on order but I am getting married this weekend so it will be a while before I get those installed.

@jst2878 - Swing arms look good and there is no noise. Need to check the hub's. I should have done that while the car was up at the goodyear place this morning.

It seems the issue only occurs in a free rolling state. When under power or braking the issue does not occur. It also got worse as the fuel level got lower (probably because of less weight).

[captainmorgan702]

Any ideas guys? The car is getting worse and my parents are afraid to drive it so that they don't cause any more damage.