help me track down a suspension rattle

[LightlyToasted]

Would worn engine mounts clunk when tap braking, and over stutter bumps? My clunk is definitely coming from the driver's side. I'll see if I can get an inspection camera in there to take a look at it. I may also hook up a remote microphone to it.

In the meantime, I'm going to replace the hub/bearing assembly this weekend. I can make a fainter version of the clunk happen by quickly rotating the wheel back and forth, similar to tap braking. Previous microphone tests with a mic near the hub were very loud, but I've also learned that vibrations and sound travels through related parts.

[CLS70]

I believe you replaced a number of items already but below are some posts with similar 'clunking' issues that I researched when I was troubleshooting mine.....there is great material here - just read through those.....

https://xoutpost.com/bmw-sav-forums/...left-side.html

https://xoutpost.com/bmw-sav-forums/...ks-x5-e70.html

https://xoutpost.com/bmw-sav-forums/...-hit-bump.html

https://xoutpost.com/bmw-sav-forums/...ssemblies.html

https://xoutpost.com/bmw-sav-forums/...end-clunk.html

https://xoutpost.com/bmw-sav-forums/...build-diy.html

https://xoutpost.com/bmw-sav-forums/...ive-drive.html

Several threads pointed to the #8 and #10 as primary culprits as well as sway bar links and the lower control arm - engine mounts was my "last" item to test (less likely to be the cause)

1. #8 and #10
2. Sway Bar Links (and Sway Bar Supports)
3. Lower Control Arms
4. Loose Brake Pads
5. Front Axle / Bearing / Diff.
6. Loose radiator
7. Engine Mounts

.....

[LightlyToasted]

Originally Posted by CLS70

1. #8 and #10
2. Sway Bar Links
3. Lower Control Arms
4. Loose Brake Pads
5. Front Axle / Bearing / Diff.
6. Loose radiator
7. Engine Mounts
.....

I've eliminated 1-4. On to #5-2 now. Will replace bearing assembly tomorrow, and check 6 and 7 while I'm at it. I really hope it isn't the diff...

[LightlyToasted]

Replaced bearing and hub assembly today. The clunking remains. The bearing was dry and needed to be replaced, but really that's just what I'm telling myself to keep from pushing this thing off a cliff.

Thanks for the advice, and apologies to the forum, but I concede defeat. I'll take it in to an indy Monday morning.

For those of you who want to replace a front bearing assembly, a couple of tips:

• don't cheap out on the bearing. SKF and FAG are good brands
• you need to replace the 4 TTY bolts holding the bearing assembly to the swivel bearing. There's more than one variant of OE bolt for this purpose, so be sure to get the correct bolt which matches the thread pitch (either 1.25mm or 1.5mm) of the new bearing assembly. My SKF was 1.5mm. To remove the old bolts I needed an 12-point M12 "triple-square" male bit, and the new bolts required a T60 torx bit. There's not much room around the outer CV joint, so a long bit is preferable, and it helps to remove the sway bar end link to get to the forward ones.
• if the axle shaft doesn't go in far enough to get the axle nut on, you'll need an M27 axle puller. You can get a kit on Amazon for about $60.

[Nyc Dito]

Originally Posted by LightlyToasted

Replaced bearing and hub assembly today. The clunking remains. The bearing was dry and needed to be replaced, but really that's just what I'm telling myself to keep from pushing this thing off a cliff.

Thanks for the advice, and apologies to the forum, but I concede defeat. I'll take it in to an indy Monday morning.

For those of you who want to replace a front bearing assembly, a couple of tips:

• don't cheap out on the bearing. SKF and FAG are good brands
• you need to replace the 4 TTY bolts holding the bearing assembly to the swivel bearing. There's more than one variant of OE bolt for this purpose, so be sure to get the correct bolt which matches the thread pitch (either 1.25mm or 1.5mm) of the new bearing assembly. My SKF was 1.5mm. To remove the old bolts I needed an 12-point M12 "triple-square" male bit, and the new bolts required a T60 torx bit. There's not much room around the outer CV joint, so a long bit is preferable, and it helps to remove the sway bar end link to get to the forward ones.
• if the axle shaft doesn't go in far enough to get the axle nut on, you'll need an M27 axle puller. You can get a kit on Amazon for about $60.

Sorry to hear.


Please update when the solution is found, thanks

[LightlyToasted]

As a last gasp, I double checked a couple of things. I checked the brake pads for play. With the caliper removed and the pads hanging from the caliper mount, there is a very small amount of play, say 0.1mm, on both pads. I can make a slight rattle with this small amount of play. How much play is allowable? Do they basically need to be a slip fit? The inner pad fits snugly in the caliper piston. When I attach the caliper and anti-rattle clip there's zero play. The caliper slide pin rubber bushings are solid with no excess play. I really don't think this is it.

I was also able to hear a faint clunk from under the vehicle when rotating the front wheels back and forth. I traced the noise to the rear of the front drive shaft at the transfer case. There's quite a bit of play at the rear universal joint when I move the shaft up and down, and some radial play in the rear u-joint and a slight clunk when I rotate the front drive shaft. I kind of suspect this is the culprit - it seems like the rear u-joint has too much play, or perhaps the play is in the transfer case. Any way to tell for sure?

[ard]

Did someone hear or BF drop a front driveshaft looking for a noise? Just for a few hundred yards, to diagnosis. deroy? Im thinking it was someone in the Netherlands....

[LightlyToasted]

The TIS seems to suggest that any play at all is bad. Mine has significant play, especially laterally and radially.


I wonder if I can rig up a GoPro in that area...

[Badsmerf]

Would that make noise when tapping the brakes though? All the U joints I've replaced were identified by vibrating or a single clunk, not from small bumps.

We might not have the same problem, but it sounds very similar. I haven't replaced all the bump stop in the strut/shock assembly, but have replaced the tension arm, end links and both doughnut bump stops. The sound started on the drivers side only, but it is now very much on both sides. I ignored it for a while, but I will be actively chasing it this spring. Hopefully you can find the answer before I have to go through a bunch of parts lol.

[LightlyToasted]

Originally Posted by Badsmerf

Would that make noise when tapping the brakes though? All the U joints I've replaced were identified by vibrating or a single clunk, not from small bumps.

I can recreate the clunk by hand by rotating the front drive shaft through its radial play, so I'm confident that loading and unloading the drive train (via tapping the brakes) would do the same. As for the clunks caused by bumps, it clunks quite a bit by pushing it up and down (lateral play). I'll see about taking some video of this play.

At any rate, I'll know soon enough. In an effort to continue to throw money at this problem and single-handedly stimulate the economy, I'm picking up a front drive shaft today which by some miracle is in stock at a local parts store. The diagnosis procedure in the TIS is pretty clear about the u-joints not having play, so may as well replace this thing to see if it helps.