Question Thrust Arms question

Domotron · 04-16-2021, 01:22 PM

Hi All,
i recently took my car in for vibration/shaking at high speed when braking, i was told the usual brake rotors are bad and need to be replaced. i got all 4 rotors/pads replaced but the issues is still there. i took my car back and they want more money to diagnose it further (yes bmw stealership). i didn't take them on that offer and got my lazy ass outside, jacked up the car and took the wheels off to see what's up. Once thing i noticed is that Thrust Arms are loose.. meaning i can twist them side to side. I'm assuming that the bushing is bad, from my experience all of the suspension components need to be tight as in not be able to move them by hand. What you guys think am i on the right path? car has 90k miles on it and its 2014 328 xdrive. how likely is it for them to go bad ?

brigade24 · 04-16-2021, 02:37 PM

Those bushings fail more frequently than not. You shouldn't be able to rotate the arm as you describe so the bushing has failed. Those bushings are gel-filled iirc so I would be very hesitant to install factory bushings since they will just fail again. it may depend how long you plan on keeping the car.

You have a few replacement options, you can go with a poly bushings (powerflex) or Monoball bushings. You can also purchase the thrust arms with the monoballs already installed so you would just need to replace the arm...no need to press the new bushings in or out.

frchdragon · 04-16-2021, 02:48 PM

As stated by brigade24 the OEM bushings are liquid filled, usually they start leaking and you can see a streak below the bushing. (brake job at the dealer... ouch...)

The monobal is a great option but an expensive one. Tighten up the front end beautifully.
You can get another Lemforder arm with liquid filled bushing already pressed in.
Or you can get a Meyle HD arm with a beefed up bushing already installed that should last longer.

FCP Euro has amazing prices on the arms (bought all 4 with axle bolts for $300)

This is a DIY if you are handy with a wrench, your car is Xdrive so you will need 2 new axle bolts.

Domotron · 04-16-2021, 05:20 PM

Thank you for the info guys brigade24 frchdragon ! 300 bucks in not bad at all i may just tackle this during one of my weekends

04-16-2021, 01:22 PM	#1
Domotron Captain 150 Rep 757 Posts Drives: 2014 BMW 328xi M-Sport Join Date: Feb 2013 Location: St. Louis iTrader: (2)	Question Thrust Arms question Hi All, i recently took my car in for vibration/shaking at high speed when braking, i was told the usual brake rotors are bad and need to be replaced. i got all 4 rotors/pads replaced but the issues is still there. i took my car back and they want more money to diagnose it further (yes bmw stealership). i didn't take them on that offer and got my lazy ass outside, jacked up the car and took the wheels off to see what's up. Once thing i noticed is that Thrust Arms are loose.. meaning i can twist them side to side. I'm assuming that the bushing is bad, from my experience all of the suspension components need to be tight as in not be able to move them by hand. What you guys think am i on the right path? car has 90k miles on it and its 2014 328 xdrive. how likely is it for them to go bad ? __________________ 2014 Estoril Blue II BMW 328i xdrive ///M-Sport
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04-16-2021, 02:37 PM	#2
brigade24 First Lieutenant 156 Rep 320 Posts Drives: 2013 335 X-dive Join Date: Jun 2018 Location: Canada iTrader: (0)	Those bushings fail more frequently than not. You shouldn't be able to rotate the arm as you describe so the bushing has failed. Those bushings are gel-filled iirc so I would be very hesitant to install factory bushings since they will just fail again. it may depend how long you plan on keeping the car. You have a few replacement options, you can go with a poly bushings (powerflex) or Monoball bushings. You can also purchase the thrust arms with the monoballs already installed so you would just need to replace the arm...no need to press the new bushings in or out. Last edited by brigade24; 04-16-2021 at 02:39 PM.. Reason: claritin clarity
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04-16-2021, 02:48 PM	#3
frchdragon Lieutenant 338 Rep 417 Posts Drives: 2016 BMW M4 Join Date: Feb 2021 Location: ON, Canada iTrader: (0)	As stated by brigade24 the OEM bushings are liquid filled, usually they start leaking and you can see a streak below the bushing. (brake job at the dealer... ouch...) The monobal is a great option but an expensive one. Tighten up the front end beautifully. You can get another Lemforder arm with liquid filled bushing already pressed in. Or you can get a Meyle HD arm with a beefed up bushing already installed that should last longer. FCP Euro has amazing prices on the arms (bought all 4 with axle bolts for $300) This is a DIY if you are handy with a wrench, your car is Xdrive so you will need 2 new axle bolts. __________________ '16 M4 bone stock '13 335ix Msport BM3 stage1 - MAD FMI - FTP CP - Bilstein B4 (SOLD) '85 635csi M30 turbo race car (SOLD)
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04-16-2021, 05:20 PM	#4
Domotron Captain 150 Rep 757 Posts Drives: 2014 BMW 328xi M-Sport Join Date: Feb 2013 Location: St. Louis iTrader: (2)	Thank you for the info guys brigade24 frchdragon ! 300 bucks in not bad at all i may just tackle this during one of my weekends __________________ 2014 Estoril Blue II BMW 328i xdrive ///M-Sport
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