[Bim20k]

Last night while driving I went through few potholes and bumps. I later heard a rubbing noise at low speeds and a burnt rubber smell. I didn’t connect the dots at the time but when I checked today I saw that my strut went through the knuckle. There’s this very thick grease all over the fender and wheel well. I made it home safely and the car was driving normal even at freeway speeds.







There’s some thing I suspect that caused this to happen. I recently installed emd m4 springs (on factory struts). This car is also an xdrive. When I installing my springs I didn’t use knuckle spreader and just opened it with a chisel.

Can someone help me pinpoint what exactly happened and what I’m going to need to replace and repair now ?

[Charles B]

Looks like the strut slipped downward in the knuckle, and it touched the CV boot, ripped the boot, and the grease inside spun out while driving the car. You probably didn't tighten the knuckle enough around the strut. So you need to reset the strut, make sure the bolt is tight enough and now you have to have the CV boot repaired (replaced) which is cheaper than a new axle.

[casualDIYer]

Charles B +1

That must have be quite a pot hole for the strut to slip through the knuckle. Here would be my list of checks:

1) Take off the wheel and check for cracks or bends. Check for loss of tire pressure.

2) To be through, I'd take off the strut and check the knuckle for cracks. It's a aluminum. If it's cracked or bent , it's pretty much un-repairable. It controls camber and caster so if it's out of wack, you'll find it now becomes a full time tire killer. A new one probably runs $400 but I'd check your local wrecker.

3) Your anti-sway/anti-roll bar end link? That might be bent. Check it.

4) When putting the strut back into the knuckle, use a new bolt and tighten according to BMW torque specs

5) When you get the car in the air, before taking the wheel off, turn the wheel and listening for clicks in the CV shafts. If it is smooth, then you can get a repair kit for it. You will need grease as well. Does BMW sell a convenient $25 repair kit? Well, no. They sell $1200 CVs shafts. The death of $1.25 piece of rubber definitely requires a $1200 repair. If you hear click, a bearing might be dead here. Check local wrecking yards for a new-to-you CV shaft

5) I would also check the wheel bearing. Again, listen for the dreaded click of death. You will need to disconnect the CV shaft as there is no way to tell which of the two are clicking, unless they both click.

Good luck

[E90lova]

Funny how BMWs Rival Audi never has this problem.

[mmm-five]

Originally Posted by E90lova

Funny how BMWs Rival Audi never has this problem.

[space_2001]

I’m pretty sure the designers deliberately had this knuckle design to avoid failure in the strut towers. It’s just unfortunate that it can wipe out a lot of other components, but then again it must have been a really bad pothole.

[freakystyly]

Originally Posted by space_2001

I’m pretty sure the designers deliberately had this knuckle design to avoid failure in the strut towers. It’s just unfortunate that it can wipe out a lot of other components, but then again it must have been a really bad pothole.

Reminds me of this from a Porsche...

[cfm56d7b]

Originally Posted by Bim20k

Last night while driving I went through few potholes and bumps. I later heard a rubbing noise at low speeds and a burnt rubber smell. I didn’t connect the dots at the time but when I checked today I saw that my strut went through the knuckle. There’s this very thick grease all over the fender and wheel well. I made it home safely and the car was driving normal even at freeway speeds.

Attachment 3390911

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There’s some thing I suspect that caused this to happen. I recently installed emd m4 springs (on factory struts). This car is also an xdrive. When I installing my springs I didn’t use knuckle spreader and just opened it with a chisel.

Can someone help me pinpoint what exactly happened and what I’m going to need to replace and repair now ?

Is there a reputable indy shop in your area? Through inspection is recommended at this point to ensure that any other problems are discovered and addressed at the same time.

[toxik]

Originally Posted by freakystyly

Reminds me of this from a Porsche...

this was actually a huge problem on the BMW Z8, bmw released some official upgrades to reinforce strut towers as they were getting damaged from hitting potholes. I believe they released steel plates to reinforce them and strut tower brace.