[sinuosi]

Hello everyone,

I hope you're all doing well. I recently noticed a knocking sound coming from the rear of my F30 335XI when driving on rough roads. It sounds like someone is knocking on a door, and it's been bothering me for a while. I've decided to address this issue by upgrading to a new set of B12 Pro coilovers.

My question is, aside from replacing the B12 Pro coilovers, should I also consider replacing the bushings or control arms to potentially fix this issue? Has anyone experienced a similar problem, and if so, what was the solution?

Additionally, I'm curious about the expected cost of installing the B12 Pro coilovers. I live in Houston, so if anyone has had a similar installation done in the area, I would greatly appreciate any cost estimates or recommendations for reputable shops.

Thank you in advance for your assistance!

[casualDIYer]

I notice you have a 335xi, so it's been a while since the last one rolled off the assembly line. How much mileage do you have on it? If you are approaching the 70,000 mile (100,000 km) mark, typically one strut will either be dead or getting close. If the struts have never been changed since the car has been built, replace all. As for make and model of struts, take your time on this. Ask yourself these questions:

Do I want OE ride hide and damping?

Do I plan to use run flat tires? If you do plan on that, cancel those plans. Run flats are terrible in terms of comfort on a wide variety of roads in my opinion.
Of all things comfort, tires have the greatest impact in my experience.

Do I want the flexibility to change the damping?

Can I get the product I want in a timely manner? Believe it or not a lot of guys have had to pick their second choice over their first because of delayed delivery timelines. If your daily driver has a bad shock you don't want to wait 8 weeks to get a new set of coilovers.

As for bushings, they wear over time. If one wants to make a luxury car, the default is to use soft plushy bushings, great for comfort but not longevity. You can replace just the bushings but the issue comes down to cost. For a shop to remove and replace the bushing the cost is likely going to be the same as just replacing the bushing integrated control arm. FCP Euro has a complete set of control arms for the F30, including bolts. I believe the set is made by Lemforder, the OE for BMW suspension currently on your car. Fitment and performance will be up to OE spec and many on this forum have reported positive experiences with that brand.

As for shop, go with a BMW specific place. A dealer isn't required for this work. In general many cars are the same but I am always shocked when I see a friend's car that, while generally has the same parts as mine, has other quirks that can make disassembly and reassembly a challenge. You want a guy who isn't going to take 8 hrs on a 4 hrs job. Swapping bushing/control arms at the same time will save a lot of time and likely install cost overall.

[sinuosi]

Originally Posted by casualDIYer

I notice you have a 335xi, so it's been a while since the last one rolled off the assembly line. How much mileage do you have on it? If you are approaching the 70,000 mile (100,000 km) mark, typically one strut will either be dead or getting close. If the struts have never been changed since the car has been built, replace all. As for make and model of struts, take your time on this. Ask yourself these questions:

Do I want OE ride hide and damping?

Do I plan to use run flat tires? If you do plan on that, cancel those plans. Run flats are terrible in terms of comfort on a wide variety of roads in my opinion.
Of all things comfort, tires have the greatest impact in my experience.

Do I want the flexibility to change the damping?

Can I get the product I want in a timely manner? Believe it or not a lot of guys have had to pick their second choice over their first because of delayed delivery timelines. If your daily driver has a bad shock you don't want to wait 8 weeks to get a new set of coilovers.

As for bushings, they wear over time. If one wants to make a luxury car, the default is to use soft plushy bushings, great for comfort but not longevity. You can replace just the bushings but the issue comes down to cost. For a shop to remove and replace the bushing the cost is likely going to be the same as just replacing the bushing integrated control arm. FCP Euro has a complete set of control arms for the F30, including bolts. I believe the set is made by Lemforder, the OE for BMW suspension currently on your car. Fitment and performance will be up to OE spec and many on this forum have reported positive experiences with that brand.

As for shop, go with a BMW specific place. A dealer isn't required for this work. In general many cars are the same but I am always shocked when I see a friend's car that, while generally has the same parts as mine, has other quirks that can make disassembly and reassembly a challenge. You want a guy who isn't going to take 8 hrs on a 4 hrs job. Swapping bushing/control arms at the same time will save a lot of time and likely install cost overall.

Thank you so much for your patience in answering my questions, I followed your advice and purchased some new parts form FCP to work on my car.