Member
Hello, I am having a problem with my E46 2003 320d. It bounces irregularly while driving - it won't happen all the time but happens at all speeds. It comes from the back, a quick succession of bounces. On the highway it is pretty crazy as the bounces happen so quickly - I would say it feels like my rear tire axle is detaching from the car. 2 mechanics looked at it, put it up and said they couldn't see anything wrong in the back. I thus believe it is not a normal problem. A BMW mechanic looked at the shocks and struts and concluded it is not them.
Has anyone had this problem before? I look forward to you responses, thank you for your time.
Also, the reason I started a new thread is because I've looked through dozens of bouncing problem threads and haven't found what could be causing this.
Member
Occasional bouncing suggests (to me anyway) that some moving part(s) have a harmonic that is sometimes in phase (producing the bounce) and other times not (no bounce). Wow that says little, but read on.
You should consider the major moving masses at the back of the car (assume your diagnosis of the problem being caused there is good). The major masses are the tires and much less, the halfshafts and driveshaft. Try rotating your tires and see if the problem stays with you, or moves to the front. This should confirm/eliminate the largest masses...
Next check that the halfshafts are secure to the diff and to the rear axle hubs. Also that there is no untoward play at the CV joints, but you should be able to hear them during a sharp turn, if they're bad.
The driveshaft must straight and not have dents or bends. Visually inspect it, all around. The giubo (rubber donut at the front) must not have cracks or other damage.
Charlie
Your mission, should you decide to accept it, is to add value to these threads, either by pictures or by descriptions, so the next person with the same or similar problem stands on your shoulders.
Member
Thank you for your response, I will do what you asked me to do
Could I ask which of these would be ruled out if my car has been looked at twice by 3 different mechanics - they put the car up and tried to shake the back parts around.
Member
Mikola, Charlie is not suggesting that parts are loose but that they are harmonically out of balance to each other. If your shocks check out (not leaking) then try rotating your tires and see if the 'bouncing' follows the tires or stays the same. That process will be diagnostic and cost you nothing but some time...
Johnny Murray
Posting Permissions
Reply With Quote
Bookmarks