Undercarriage rattle when driving over uneven surfaces at low speed

softsign · 06-13-2022, 10:13 AM

Can anyone identify the source of this rattle on a 2017 F25 (28i)? Video attached, sorry for the shot of my bare foot as I just took it driving around the block this morning.

The rattle sounds like it could be coming from just behind or just below the firewall. Possibly front driver's side of the car.

It's most noticeable at low speeds (when the cabin is quiet). Happens when going in a straight line as you see in the video. There's no obvious problem with the steering or suspension and I just did a 1200 km round trip over the past few days, with another 300 to go today.

Wondering if it's just something that's worked loose on the undercarriage or maybe a suspension component that's worn out?

Doing some digging around the forums had me wondering if maybe it's a strut mount bearing? Would that make this sound?

softsign · 06-13-2022, 05:44 PM

Some more digging leads me to think it's probably the thrust piece, which seems to be a common issue for BMW.

Found the video below on Youtube, and realized moving my steering wheel back and forth with the engine off definitely produces the same clicking/knocking noise from the steering rack. I guess driving at low speed achieves the same effect.

pungo · 06-13-2022, 07:33 PM

Quote:

Originally Posted by softsign

Some more digging leads me to think it's probably the thrust piece, which seems to be a common issue for BMW.

Lift the drivers side tire off the ground. Grab the tire at 3&9 o'clock, push/pull firmly and quickly like you're steering the vehicle left/right. If you feel play and hear clunking, the thrust piece may be worn. The play should be at the inner tie rod location at the rack.

I replaced mine with the revised part. The original part is susceptible to wear, therefore causing play in the rack. The new part has wear bars made from a more suitable material, plus has o-rings for less friction of the part

I'm not saying that will fix your rattle, but an easy way to tell is to simply turn the adjustment on the original part to remove the play and see if the rattle goes away.

There was a groove worn on one side of the old part from where the rack rubs:

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06-13-2022, 10:13 AM	#1
softsign New Member 8 Rep 15 Posts Drives: BMW X3 Join Date: Mar 2019 Location: Canada iTrader: (0)	Undercarriage rattle when driving over uneven surfaces at low speed Can anyone identify the source of this rattle on a 2017 F25 (28i)? Video attached, sorry for the shot of my bare foot as I just took it driving around the block this morning. The rattle sounds like it could be coming from just behind or just below the firewall. Possibly front driver's side of the car. It's most noticeable at low speeds (when the cabin is quiet). Happens when going in a straight line as you see in the video. There's no obvious problem with the steering or suspension and I just did a 1200 km round trip over the past few days, with another 300 to go today. Wondering if it's just something that's worked loose on the undercarriage or maybe a suspension component that's worn out? Doing some digging around the forums had me wondering if maybe it's a strut mount bearing? Would that make this sound?
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06-13-2022, 05:44 PM	#2
softsign New Member 8 Rep 15 Posts Drives: BMW X3 Join Date: Mar 2019 Location: Canada iTrader: (0)	Some more digging leads me to think it's probably the thrust piece, which seems to be a common issue for BMW. Found the video below on Youtube, and realized moving my steering wheel back and forth with the engine off definitely produces the same clicking/knocking noise from the steering rack. I guess driving at low speed achieves the same effect.
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