Prominent "clunk" when braking at very low speeds *SOLVED*

[Eric SS]

Solved

Hello all. I have a new to me 2018 M4 CZP with 25k miles. It was recently lowered on KW HAS (minimally) and has Dinan tension strut ball joints. Also some small wheel spacers.

When I'm below about 10mph and barely tap (or press harder) the brake there is a very prominent "clunk" coming from the front end that you can actually feel in the steering wheel or if you put your hand on the dash. If I release the brake and tap it again it's the same clunk. Again this happens if I just barely tap the brake and I can get it to do it over and over again if I tap the brake repeatedly. It's not coil bind because I'm not even tapping the brake hard enough to make the front end dive at all. Does anyone have any theories of what that might be or has anyone else experienced this? I don't seem to experience it at higher speeds. It couldn't be the pads moving in the calipers right? I have had multiple other cars with Brembo 4 pots and have never experienced this. I'm unsure if the pads are OEM or not.

I hear what I think is the same "clunk" when I am pulling into my driveway slightly sideways as the first wheel goes over curb and puts tension on the sway bar.

As a side note (but maybe related) I also have the noisiness coming from the front end that I have heard others have after adding HAS to their vehicle when in a parking lot. kind of rattley and clunky at slow speeds.

At first I thought maybe it was an end link but I checked and those all seem to be tight. I'm more of a GM know how than a BMW know how so would like some additional insight. Thanks all!

[Eric SS]

Here's a pic of a part of the pad. Based on pics I've seen these appear to be OE pads.

[Keebin]

i have the same exact issue as you and its worse for me because im running all spl arms up front and i cant find the the clunk. one thing we have in common is the sway bar endlink maybe? but at angle to in drive way i can here it make a loud clunk nothing at high speeds but at hard brake at a light i can hear it.

[Eric SS]

Originally Posted by Keebin

i have the same exact issue as you and its worse for me because im running all spl arms up front and i cant find the the clunk. one thing we have in common is the sway bar endlink maybe? but at angle to in drive way i can here it make a loud clunk nothing at high speeds but at hard brake at a light i can hear it.

I checked the end links and they were all tight. That was my initial thought as well

[aswy6]

I have everything stock and have the same clunk. It first started when i swapped brake pads from street to track and clunk was pretty loud. When swapping back to stock, clunk came back after a while but its somewhat quiet and only when i change braking direction.

[Eric SS]

Originally Posted by aswy6

I have everything stock and have the same clunk. It first started when i swapped brake pads from street to track and clunk was pretty loud. When swapping back to stock, clunk came back after a while but its somewhat quiet and only when i change braking direction.

I just looked closer at my pads and they are OEM pads.

My clunk doesn't just happen the first time I use the brakes when changing braking direction. It happens every time I hit the brakes below 10mph. I wiggled my fingers in there and the retainers are on and I don't feel any movement in the pads just trying to wiggle them with my fingers. Pads appear to have almost full life on them still.

[jshahm]

did this clunk happen immediately after installing the HAS? i've been experiencing a "clunk" (i would describe mine more as a "snap") situation similar to you recently as well, but is a little variated in how i arrived here.

i have MP HAS (full drop) with vorshlag camber plates and dinan monoballs, and have a "snap" sound when turning the steering wheel (more so clockwise), braking at low speed (can also make the sound consistently happen from letting go of the brakes and letting the car roll, then applying the brakes again) and bumps. i have had the MP HAS + camber plates installed on my car for over 3 weeks now, but my sound just started showing a couple days ago (i had a separate strut clunking sound right after i installed MP HAS and camber plates, but resolved it).

also, i changed my brake pads yesterday, and the sound has remained exactly the same.

today, i attempted to replace the wheel studs on my car in hopes it would cure the sound (i only managed to replace the driver side today), and the sound hasn't changed.

[Eric SS]

Originally Posted by jshahm

did this clunk happen immediately after installing the HAS? i've been experiencing a "clunk" (i would describe mine more as a "snap") situation similar to you recently as well, but is a little variated in how i arrived here.

i have MP HAS (full drop) with vorshlag camber plates and dinan monoballs, and have a "snap" sound when turning the steering wheel (more so clockwise), braking at low speed (can also make the sound consistently happen from letting go of the brakes and letting the car roll, then applying the brakes again) and bumps. i have had the MP HAS + camber plates installed on my car for over 3 weeks now, but my sound just started showing a couple days ago (i had a separate strut clunking sound right after i installed MP HAS and camber plates, but resolved it).

also, i changed my brake pads yesterday, and the sound has remained exactly the same.

today, i attempted to replace the wheel studs on my car in hopes it would cure the sound (i only managed to replace the driver side today), and the sound hasn't changed.

I don't know if it was there before the drop because I purchased the car right after HAS and Dinan monoballs were installed. It has been there since the drop though. I don't get any sort of "snap" when turning. Mine seems to be from either hitting bumps at slow speeds (clunks or rattles) or tapping the brakes at slow speeds).

[Eric SS]

I see in another thread that people are curing a clunk by tightening the steering rack bolt about 3 tic marks. I'm going to try that to see if it helps anything.

[c0nrad]

having this issue and bringing my car to the dealer at the end of the month. oem suspension and pads. tried cleaning the pads, didn't help. seems to be coming from under the center console + rear

[c0nrad]

Originally Posted by c0nrad

having this issue and bringing my car to the dealer at the end of the month. oem suspension and pads. tried cleaning the pads, didn't help. seems to be coming from under the center console + rear

they tell me the pins are loose and the sensor is hitting the wheel. replacing pins, spring clips, and sensor.

seems to be my error while swapping the pads, but i've done it several times before without an issue, so i'm not really sure what went wrong. i'm thinking the plastic clip on the sensor broke or the spring got bent

[Eric SS]

Originally Posted by c0nrad

they tell me the pins are loose and the sensor is hitting the wheel. replacing pins, spring clips, and sensor.

seems to be my error while swapping the pads, but i've done it several times before without an issue, so i'm not really sure what went wrong. i'm thinking the plastic clip on the sensor broke or the spring got bent

Thanks for the update. I'll check into that.

[mattylmbr]

Just had a front end clunk/noise diagnosed and fixed yesterday. It was a loose thrust bolt lock nut. It sounded like the front end was going to fall off at low speeds over bumps. They replaced the lock nut with a new one and torqued - and it's like a brand new car now.

Note - the thrust arm had previously been replaced when I looked at the service history and the thought was that the lock nut had been reused instead of replaced - which is why it may have backed off.

[Eric SS]

Originally Posted by mattylmbr

Just had a front end clunk/noise diagnosed and fixed yesterday. It was a loose thrust bolt lock nut. It sounded like the front end was going to fall off at low speeds over bumps. They replaced the lock nut with a new one and torqued - and it's like a brand new car now.

Note - the thrust arm had previously been replaced when I looked at the service history and the thought was that the lock nut had been reused instead of replaced - which is why it may have backed off.

I have the Dinan monoballs installed so I will check that as well. I believe that's the part you're talking about.

[Eric SS]

Update!

I finally put the car up on jack stands and searched around. Turns out that the place that installed the Dinan monoballs and HAS didn't tighten the tension rod to knuckle bolt at all. It was loose and sloppy. I tightened it up and now we're good to go!

[nrubenstein]

Originally Posted by Eric SS

Update!

I finally put the car up on jack stands and searched around. Turns out that the place that installed the Dinan monoballs and HAS didn't tighten the tension rod to knuckle bolt at all. It was loose and sloppy. I tightened it up and now we're good to go!

If they didn't tighten the balljoint going into the knuckle, I'd be scared that the seat is ovalized. If they didn't tighten at the subframe, no biggie.

[Eric SS]

Originally Posted by nrubenstein

If they didn't tighten the balljoint going into the knuckle, I'd be scared that the seat is ovalized. If they didn't tighten at the subframe, no biggie.

I'll keep an eye on it and replace if needed which I DON'T want to do. In addition to being a $400 part I really don't want to tear apart the entire front corner of the car. Thanks.

[TouringM3]

This thread just saved me a lot of heartache.
I was experiencing identical symptoms (low speed clunk, and clunking over speed bumps / pot holes)

Turns out my passenger front control arm was not at all tight, likely either from my own work, or some shop work I had done.

After getting in there with a wrench and a torx bit it's solid and silent.

Thanks Eric SS