Question Re: Front Struts

[LarryM]

I'm trying to diagnose a slight "clunking" noise coming from my front struts that's noticeable at low speeds.

If you remove the cap (item #5) and turn the top nut (item #4), should the strut rod freely turn with it? When I try to turn mine, it feels like it's binding up against the rubber portion of the upper strut mount (item #1); I'm suspecting that either item #6 or #7 is missing and the bearing inside the mount can't do its job.

http://www.realoem.com/bmw/enUS/showpar ... Id=31_0083

[dsmith]

Not knowing the history of your struts, I would first check condition of sway bar links for good movement, then check that the strut nut that holds it in the housing is tight. Sometimes that is not torqued to spec and loosens. If you can turn it with channel locks, that is a problem. You will need to disassemble to check 6&7.

[Shawn D.]

Question Re:

You don't need to put that in a title. Both are implied. That leaves "Front Struts," which is not a very descriptive title. Next time, make it something like "What is causing this low-speed front strut clunking?"

[Federico]

If you remove the cap (item #5) and turn the top nut (item #4), should the strut rod freely turn with it?

No.

The rod turns with the strut as a unit.
To see it more clearly, mind that said nut is clamping the bearing's inner race against the spring perch. Therefore, the rod turns with the spring and the rest of the strut.

[Mike W.]

Federico's got it.

I would just add that the bearings in the upper mount can be a problem too. Mine were all red and rusty when I got the car, noisy and crunchy and surely contributed some added friction to the assembly. Cleaning and new grease revived them.

[LarryM]

OK, thanks for all the replies. First of all, sorry for the the vague title of my OP. I'm usually much more specific in my posts, but it was 2 AM and had been a long day, including recovery from anesthesia. I know better than that.

I should have also mentioned that the struts and mounts are relatively new; a few years ago I installed M-Tech springs and shocks with Bilstein Sports, including new strut mounts, spring pads, and all new hardware. I seriously doubt that I would have left out either item #6 or 7 during reassembly; it was just a thought. Federico's post helped clear things up for me so I don't think that's the issue here.

The sway bar links are also new, but I'll check their movement during compression of the suspension. I'll also check the tightness of the strut housing nuts.

It's also possible that something else is worn in my front suspension, so I've got some more diagnosing to do.

[ElGuappo]

A clunk at low speeds is usually going to the the sway bar link, as mentioned.
2 years is plenty of time for the cheaper brands to fail, like Karlyn.
You can easily test this by disconnecting the links from the bar, and slowly going over some bumps and see if it persists.

That being said I have also experienced the gland nut being loose, allowing the actual strut insert body to move just a bit inside the housing, causing a clunk noise.

[thrty8street]

OK, thanks for all the replies. First of all, sorry for the the vague title of my OP. I'm usually much more specific in my posts, but it was 2 AM and had been a long day, including recovery from anesthesia. I know better than that.

I should have also mentioned that the struts and mounts are relatively new; a few years ago I installed M-Tech springs and shocks with Bilstein Sports, including new strut mounts, spring pads, and all new hardware. I seriously doubt that I would have left out either item #6 or 7 during reassembly; it was just a thought. Federico's post helped clear things up for me so I don't think that's the issue here.

The sway bar links are also new, but I'll check their movement during compression of the suspension. I'll also check the tightness of the strut housing nuts.

It's also possible that something else is worn in my front suspension, so I've got some more diagnosing to do.

Hello! Did you ever resolve your issue? Ifo so, what was the remedy?

[LarryM]

OK, thanks for all the replies. First of all, sorry for the the vague title of my OP. I'm usually much more specific in my posts, but it was 2 AM and had been a long day, including recovery from anesthesia. I know better than that.

I should have also mentioned that the struts and mounts are relatively new; a few years ago I installed M-Tech springs and shocks with Bilstein Sports, including new strut mounts, spring pads, and all new hardware. I seriously doubt that I would have left out either item #6 or 7 during reassembly; it was just a thought. Federico's post helped clear things up for me so I don't think that's the issue here.

The sway bar links are also new, but I'll check their movement during compression of the suspension. I'll also check the tightness of the strut housing nuts.

It's also possible that something else is worn in my front suspension, so I've got some more diagnosing to do.

Hello! Did you ever resolve your issue? Ifo so, what was the remedy?

A couple years ago I installed new upper and lower arms plus new tie rods, center link, and idler arm. I no longer have the knocking issue. The old UCA bushings were cracked and worn, I believe that was the problem. I used 750i bushings from Korman in the new arms. According to the maintenance records the UCA bushings had been replaced only about 20K miles previously; possibly whoever installed them didn't follow the proper procedure when torquing them down.

[williamtii]

Came here to say check UCA's as well. I've been trying to figure out a similar low speed clunk all year. I've replaced everything in the front end the past couple years and checked and rechecked again and again with nothing to show for it. The only thing I did not suspect were the UCA's since they were freshly replaced with the Aluminum kind when I bought it. The bushings looked absolutely fine and ball joints were good when I did strut housings last year.

Well 5 years and 100k has passed since I bought it, silly me. Replaced them and the clunk is gone, though the old ones do not look bad at all

[Aldo525]

That being said I have also experienced the gland nut being loose, allowing the actual strut insert body to move just a bit inside the housing, causing a clunk noise.

As said by ElGuappo in 2019, a loose insert into the strut can made a lot of clunking noise but also the lack of oil added into the strut housing when a new shock absorber is fitted.