Mystery Clunk under Hard Braking

[kbecks13]

Alright i need some expert opinions...took the car autocrossing and heard a weird clunk under heavy braking right as i started to turn the wheel. I definitely took this turn a bit hot

Based on the fact that i'm running 265 tires and definitely have minimal clearance, i'm leaning towards this being fender on tire contact - but wanted to get some other opinions.

After taking a close look i didn't see anything immediately wrong and couldn't find any signs of contact on the fender. Car drove the rest of the day just fine and seems OK.

Thoughts on what caused this noise?

 

[buttershrimp]

Dude, you didn't see that you just hit a grandmother on a lime scooter?

 

[TrumpetTitan]

I heard a clunk when my 3 was under hard braking at an autocross as well. It sounded to me like the clunk my Elantra used to make and the S2000 still makes when I first take the car for a drive after it sits for a couple days. The clunk on the S2000/Elantra would occur when either car started to move for the first time, and I figured out those cars were clunking because there was a light layer of rust buildup on the brake discs (sometimes a harmless amount collects from moisture in the air, especially if the either car sits for days).

I had never touched the brake pedal in my Model 3 until this autocross (only used regenerative braking) so I think the sound is the rotors settling into place, since they hadn't been used prior.

OP, did you regularly use the brake pedal before this video was taken?

 

[kbecks13]

OP, did you regularly use the brake pedal before this video was taken?

Yea i had, i think this was my tire bumping the fender since i'm running 265's which are pretty wide. Haven't had another incident like this since though.

 

[DrZoidberg]

Did you ever figure this out? I just had this exact problem yesterday. What was you wheel setup? Wondering if this is a fitment issue? M3P?

 

[kbecks13]

Yea it was almost certainly my tire hitting the fender since i was braking really hard and had some steering input at the same time. Haven't heard it since then, but i almost have some more negative camber to tuck the upper part of the tire inside the fender now.

 

[DrZoidberg]

Are you lowered or on coils? If so how low and what did you do to gain camber?

 

[ZOMGVTEK]

Maybe it was the cones screaming.

 

[kbecks13]

Are you lowered or on coils? If so how low and what did you do to gain camber?

I wasn't lowered at the time, but i am now and it's about 1.25" or so lower. Camber is around -1.8 and i used UP camber arms, but lowering the car will naturally add some negative camber that gets you fairly close to that anyway.

 

[usofrob]

I've heard that clunking issue a few times autocrossing my car. I have 19x9.5" +35mm offset wheels, but 235mm tires. So, it's unlikely the tires hitting. Or more specifically, it's unlikely to be caused by wider tires.

 

[DrZoidberg]

I've heard that clunking issue a few times autocrossing my car. I have 19x9.5" +35mm offset wheels, but 235mm tires. So, it's unlikely the tires hitting. Or more specifically, it's unlikely to be caused by wider tires.

Thanks for the comments.
It doesn't sound like tires hitting to me and I see no evidence of it on the fender or liner. It sounds more like something knocking to me.

 

[MountainPass]

Double-check your lower control arm bolts where the arm mounts to the subframe, we had those back off at Laguna Seca! It turns out with frequent tracking those bolts need to be retorqued after each weekend. I would also pop out the frunk and remove the rubber cover on the strut tower to inspect the front upper control arm, it can hit the chassis if you are bottoming out the suspension. There will be marks on the arm if this is happening. - Jesse