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BMW 3-Series (E90 E92) Forum > BMW E90/E92/E93 3-series General Forums > General E90 Sedan / E91 Wagon / E92 Coupe / E93 Cabrio > How necessary are the rear brake dust shields?



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      06-25-2024, 09:40 PM   #1
Boston4
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How necessary are the rear brake dust shields?

Car is a 328, does not see the track and most of its trips are either in the city or road trips. Just discovered that my LR dust shield is loose and just rattling around.

Replacement of the shield requires removing the hub, which is tough to justify (either DIYing or paying a shop to do it). Plenty of cars don't have this part at all. My intuition is that in track driving, the rear brakes will get hot enough to necessitate a heat shield to protect the suspension components, which is why they were installed at the factory. It is difficult for me to imagine a daily-driver scenario that will produce enough heat to cause problems, except for bedding in new rotors/pads.

Will I torch my suspension bushings if I just cut it out with tin snips and throw it away or do I actually need to replace it?
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      06-26-2024, 12:11 PM   #2
Yngvejos
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Quote:
Originally Posted by Boston4 View Post
Car is a 328, does not see the track and most of its trips are either in the city or road trips. Just discovered that my LR dust shield is loose and just rattling around.

Replacement of the shield requires removing the hub, which is tough to justify (either DIYing or paying a shop to do it). Plenty of cars don't have this part at all. My intuition is that in track driving, the rear brakes will get hot enough to necessitate a heat shield to protect the suspension components, which is why they were installed at the factory. It is difficult for me to imagine a daily-driver scenario that will produce enough heat to cause problems, except for bedding in new rotors/pads.

Will I torch my suspension bushings if I just cut it out with tin snips and throw it away or do I actually need to replace it?
The parking brake shoes attaches to the dust shields.
You can cut them open with pliers to replace them without removing the hub.
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      06-27-2024, 08:28 AM   #3
Efthreeoh
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Originally Posted by Yngvejos View Post
The parking brake shoes attaches to the dust shields.
You can cut them open with pliers to replace them without removing the hub.
There is a separate part that locates the parking brake shoes for the rear brakes. The OP is talking about the big dust shield.

OP I'd inspect the shield and see if you can add some fender washers if the shield is rusting at the bolt holes. If the part eventually falls out, I doubt it will affect anything.
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      06-27-2024, 07:28 PM   #4
Yngvejos
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Quote:
Originally Posted by Efthreeoh View Post
There is a separate part that locates the parking brake shoes for the rear brakes. The OP is talking about the big dust shield.

OP I'd inspect the shield and see if you can add some fender washers if the shield is rusting at the bolt holes. If the part eventually falls out, I doubt it will affect anything.
What's the part number?
On the cars I have owned E91 325i, E90 320d and E87 118d, the brake shoes have been attached to the big dust shield.
That have also been the case for E30, E34, E39 and E61.
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      06-27-2024, 11:29 PM   #5
Efthreeoh
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Originally Posted by Yngvejos View Post
What's the part number?
On the cars I have owned E91 325i, E90 320d and E87 118d, the brake shoes have been attached to the big dust shield.
That have also been the case for E30, E34, E39 and E61.
Dust shield - 34216792239 & 40

Backing plate - 34216771429
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      06-28-2024, 03:06 AM   #6
Yngvejos
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Originally Posted by Efthreeoh View Post
Dust shield - 34216792239 & 40

Backing plate - 34216771429
That's interesting. Must have fused together with the dust shield as a single piece of rust on the car I've replaced them on. Are they installed on the outside of the dust shields or the inside?
I can confirm that the parking brake fits and works great without the backing plate, so I guess that it will work the same with backing plate only.
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