Knocking sound AUDI A4 Avant (8K5, B8)

AUDI A4 Saloon (8K2, B8) 2.0 TDI

c. f.

17.09.2023 23:53

Member

Hi dave , i got a knocking sound coming from front left- center when braking you can hear a knock when the car is almost stoped and then on road with bumps you can hear multiple knocks , is funy if i go forward and keep braking you can hear the knock but if i go backwards and brake nothing, you can hear it going forwards and backwards on roads with bumps but not braking which I find it very weird, don’t feel anything in the steering no problem steering no noise no nothing i had a look and other people but nobody did a very deep check, just bushings, tie road like what usually everybody would check, it’s only on the left cuz if o take bumps only with the right side nothing but immediately i take bumps on the left side you can hear the knocks , this year i did a lot off work on the car , some myself some with a fried some a mechanic, I changed the brakes disc , pads and everything, got brand new tires, change the lower arm , control lower arm , ball joint, tier road ( after when for wheel alignment) , sway bars and just days ago the shock absorber, coil spring, and the mounting on top , all of this is done on front both side excluding brake with is done in the rear as well, honestly i dont know exactly what to do anymore everybody is checking the bushings and that but nobody finds anything weird cuz everything is brand new and they suggest to leave it and when is going worse i will be able to figure it out but the thing is i have this for months and is driving me crazy, i got this nice car with a very annoying noise , the car is an audi a4 b8 2.0 tdi with 100k , most off the thing i hand to change on the car cuz of the mileage and the noise is for half an year bugging me, i don’t know is there is anything lose or the cv axle is going bad or the steering rack cuz those are the only things I didn’t change so far, my mind is telling me to take the brake caliper off and have a good look there but to be honest this noise is such a nightmare that even with that i have doubts, can you help me with any suggestion any tip , anything will be helpful

I gone leave a link with the noise I’m having https://youtube.com/shorts/BuxLiCfQLUs?si=vOqFxZq-hpnbuDcZ

Started

17.09.23

Latest reply

02.10.25

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678

@Prionsprould

18.09.2023 11:27

Member

Hello, there could be many reasons that causes this sound, such as a non-working shock absorber, a steering rack, or even a brake caliper. You need to contact a qualified service so that they can tell you exactly what the problem is.
@Ethan.Knight.

02.10.2025 21:05

Member

Hey, that knocking noise on the front left of your Audi A4 B8 2.0 TDI sounds like the automotive version of a ghostly whisper driving you nuts—almost there but playing hard to find! Since you’ve already thrown a laundry list of fresh parts at it (brakes, tires, ball joints, lower arms, sway bars, shockers, springs…), it’s definitely time to think a bit deeper.

Here’s a couple of suggestions beyond the usual suspects:

1. Brake caliper and hardware: You’re right to consider removing the caliper for inspection. Sometimes the brake caliper slides, pins, or the anti-rattle clips can wear or not sit properly. A slightly loose caliper or missing/old shim can cause knocking especially when braking and driving over bumps. Give those a close look and apply some copper grease on the back plates or shims—noise killers.

2. CV joints and axle shafts: Since it’s only on the left and related to bumps/braking, a worn or damaged CV joint might be the culprit. They can knock under load or change of torque, often when driving forwards and over uneven surfaces. Jack up the car, grab the axle near the CV boot and try moving it aggressively; if it moves or clicks, it’s a suspect.

3. Steering rack mounts and bushings: Even if steering feels fine, the rack mounts or subframe bushings could be worn or cracked. They soften vibrations but if damaged, can cause noises that change depending on braking or road surface.

4. Front strut mounts or top mounts: Sometimes the new mounts aren’t seated properly or are faulty, which causes noises only when there are changes in suspension load — like braking and bumps.

5. Brake disc runout or warped rotor: Even new discs can sometimes be warped or installed incorrectly, causing knocking or pulsation.

Your mention that the noise is only when going forward and braking but silent going backward is a classic symptom of something moving or under tension in one direction only, such as caliper slider pins or axle joints.
@Ethan.Knight.

02.10.2025 21:09

Member

Since it’s driving you bonkers, here’s a plan:
- Start with the brake caliper, remove it, clean/lube the pins and anti-rattle clips.
- Check the CV joints by manually manipulating them.
- Inspect the steering rack mount bushings for cracks or wear.
- If all else fails, a suspension specialist’s stethoscope or a mechanic experienced with Audi’s front end can isolate it quicker.

Bottom line: this noise is a diva who only shows her face under certain conditions. But with your detective skills and methodical approach, you’ll pin the knockout punch soon—you’ll go from knocking to knocking 'em dead at the next service! 🔧😎🎯

And cheers for the link! That knock sound is clear as day—definitely mechanical, not a ghost. If you want I can help you with step-by-step caliper removal or CV joint inspection instructions. Just say the word!