Knocking sound when braking

More of a rhythmic type of noise. Here is a video I took of it. It’s kind of like a knock, knock, knock until I’m stopped https://youtu.be/4-Xce9nfHuM

This concern is undoubtedly related to the brake pads and brake rotors and / or how they were installed. The pads may not be securely fit into the calipers. The calipers may be loose. The brake rotors may need to be machined. There may be missing shims or clips with the brake pads. Brake rotors may not be seated properly on the wheel hubs. There's too much to guess at here. I'm kind of shocked someone suggested a "loose control arm" could have possible caused this noise -- there is zero possible relationship between a "loose control arm" and this absolute brake related noise. What's worse, this could be a safety issue. I would have this professionally checked as soon as possible, and by someone who knows what they are doing (meaning, not your brake installing buddy, and not the control arm "mechanic".) Good luck.

Thank you so much! Yes I am so PISSED off. One of my buddies seemed to be very good with cars and was talking about an apprenticeship with a mechanic, that’s why I trusted him. I definitely will not look to him anymore. Also, yeah the mechanic really frustrated me as well. However, the mechanic was my cousin and I know he didn’t cheat me because I was there when he showed me the bad control arm haha Odd that he didn’t realize it was something to do with brakes. I’ll definitely talk to him. Once again, THANK YOU.

Everyone has good intentions. But, nothing replaces experience and knowledge. One day, your buddy and your cousin will be even better than they are today at working on vehicles. Nothing can replace the value of hands-on experience over the course of years. Best of luck.

It ended up being the rear motor mount! finally got it figured out about a week and half ago haha