e46 330 sport brake judder
Discussion
Car runs smooth, its only when braking. I think that the problem is the warped discs, caused through movement in both arms. This would account for why when discs were replaced all was ok, yet the problem came back for previous owner. Maybe I am just trying to justify the £500 laid out today. Still need the tracking done as wheel off centre now
After 4 hours labour, both n/s and o/s wishbones £72 each and bush set £72, track rod ends £9 each and track rods £30 each were all replaced. I can only think that as these were faulty that they were causing the discs to warp. Is this a possibility as discs were not replaced and problem still there
I had a similar problem with my E36. I replaced all the discs only to have the problem return very quickly. It turned out to be some cheap brake pads which were wearing in a strange way, giving the impression that the discs were warped - pads were changed to EBC items and problem solved.
Worn suspension bushes are not likely to cause the disks to warp. The problem is an inherent one due to the sensitivity of the suspension and steering. Several BMW's are prone to the same symptoms.
The problem can be caused by worn wishbone/control arm bushes, worn steering linkage, warped disks, alloy wheels fitted without hubcentric spacers (if required) and wheels running out of true due to pothole or kerb damage.
Usually the presence of just one of these faukts, if minor, will not cause an issue but if more than one is present then the problem will occur.
Thats why replacing disks may remove the problem temporarily until they become ever so slightly warped again, then the problem returns - whereas a small amount of disk warp would not normally be an issue.
Alloy wheels are often not perfectly true and with larger sized wheels (17", 18", 19", 20" etc) this is a real issue. They can sometimes even be balanced but a slight buckle amy still be present.
Hubcentric spacers are often omitted, meaning that the wheel doesnt sit perfectly true on the hub. Not all wheels need them but if they are required, they really do need to be there!
THe problem often only occurs under braking because that is when the suspension bushes are under a good deal of load in a specific plain. If the bushes are a bit soft, they will move enough to create a problem.
THe vibration is caused when the whole wheel/hub/suspension assembly comes close to its natural resonant frequency, often induced by a bump or irregularity in the road surface. The vibration starts and the amplitude increases. Often, releasing the brake momentarily will stop the vibration and the brakes can be re-applied.
So, first things to check are a)the wheels for trueness b)hubcentric spacers if required c)steering joint play d)brake disk warp e)suspension bushes f)front shock absorbers
Just some ideas gained through experience but by no means a comprehensive list!
The problem can be caused by worn wishbone/control arm bushes, worn steering linkage, warped disks, alloy wheels fitted without hubcentric spacers (if required) and wheels running out of true due to pothole or kerb damage.
Usually the presence of just one of these faukts, if minor, will not cause an issue but if more than one is present then the problem will occur.
Thats why replacing disks may remove the problem temporarily until they become ever so slightly warped again, then the problem returns - whereas a small amount of disk warp would not normally be an issue.
Alloy wheels are often not perfectly true and with larger sized wheels (17", 18", 19", 20" etc) this is a real issue. They can sometimes even be balanced but a slight buckle amy still be present.
Hubcentric spacers are often omitted, meaning that the wheel doesnt sit perfectly true on the hub. Not all wheels need them but if they are required, they really do need to be there!
THe problem often only occurs under braking because that is when the suspension bushes are under a good deal of load in a specific plain. If the bushes are a bit soft, they will move enough to create a problem.
THe vibration is caused when the whole wheel/hub/suspension assembly comes close to its natural resonant frequency, often induced by a bump or irregularity in the road surface. The vibration starts and the amplitude increases. Often, releasing the brake momentarily will stop the vibration and the brakes can be re-applied.
So, first things to check are a)the wheels for trueness b)hubcentric spacers if required c)steering joint play d)brake disk warp e)suspension bushes f)front shock absorbers
Just some ideas gained through experience but by no means a comprehensive list!
Guys, this is really getting not funny. Eventually discovered that problem was only on n/s/f with warped disc. Replaced disc and caliper yet problem has just come back after 2500 miles. I have now had 3 discs on this hub in 5k miles.
It now looks like hub is warped or could a buckled wheel warp the hub or disc.
It now looks like hub is warped or could a buckled wheel warp the hub or disc.
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