MZ4 Front Brake Discs Reversed

wyshyvanuk · 04-16-2025, 07:11 PM

So, I've just discovered that the front discs on my 2008 MZ4 are reversed right to left. My best guess is that they've been that way for the last 12k miles, when they were probably replaced to repair some accident damage. They appear to still be in excellent condition with no detectible "ridge" on the outside edge. So....

1. Close my eyes. and swap them side to side?
2. Swap them side to side and replace the pads with OEM?
3. New rotors and new pads?

I'm not cheap, but I am thrifty ;~). Thanks!!

gaseosx · 04-16-2025, 07:45 PM

Get them resurfaced and put new pads.

XMetal · 04-16-2025, 09:14 PM

Quote:

Originally Posted by gaseosx

Get them resurfaced and put new pads.

You can't resurface drilled rotors.

mmm-five · 04-18-2025, 09:05 AM

Just swap them around!

cbpip · 04-18-2025, 01:19 PM

Quote:

Originally Posted by XMetal

You can't resurface drilled rotors.

Not true. Can be done and have had it done by a reputable shop.

XMetal · 04-18-2025, 01:51 PM

Quote:

Originally Posted by cbpip

Not true. Can be done and have had it done by a reputable shop.

I've asked a few shops around my area a while back when I tried to sort out a shimmy while braking and they all told me the same thing - can't resurface drilled rotors, and no one would do it. Maybe it's not just drilled rotors, but because they're floating as well?

pungo · 04-18-2025, 02:15 PM

I'd just swap them side to side and go for a few good braking sessions and be done.

wdb · 04-22-2025, 11:37 AM

Quote:

Originally Posted by mmm-five

Just swap them around!

Quote:

Originally Posted by pungo

I'd just swap them side to side and go for a few good braking sessions and be done.

I third the motion. New pads would not be a crazy thing to do but if there really is no discernible ridge and the surfaces are clean looking, just swap them around.

Quote:

Originally Posted by XMetal

I've asked a few shops around my area a while back when I tried to sort out a shimmy while braking and they all told me the same thing - can't resurface drilled rotors, and no one would do it. Maybe it's not just drilled rotors, but because they're floating as well?

The caliper 'floats', not the rotor. Floating rotors are two-piece items.

wyshyvanuk · 04-22-2025, 12:28 PM

Thanks, guys!! Swapping tomorrow.

XMetal · 04-22-2025, 02:17 PM

Quote:

Originally Posted by wdb

The caliper 'floats', not the rotor. Floating rotors are two-piece items.

The M rotors are indeed floating - it's made from two separate pieces, even though you can't separate them like conventional aftermarket floating rotors.

Here are a couple pictures of said rotors.

wdb · 04-22-2025, 06:42 PM

Quote:

Originally Posted by XMetal

The M rotors are indeed floating - it's made from two separate pieces, even though you can't separate them like conventional aftermarket floating rotors.

Wow. I never knew that! The previous owner of my (former) car had done the brakes not long before I bought it, so I never had to explore that aspect of it. I guess those are the CSL brakes, which might explain their complexity.

XMetal · 04-22-2025, 07:24 PM

Quote:

Originally Posted by wdb

Wow. I never knew that! The previous owner of my (former) car had done the brakes not long before I bought it, so I never had to explore that aspect of it. I guess those are the CSL brakes, which might explain their complexity.

Yes, Z4M gets the CSL brakes.

wdb · 04-23-2025, 07:37 AM

Quote:

Originally Posted by XMetal

Yes, Z4M gets the CSL brakes.

And the quicker CSL steering rack. I do remember a few things...

belcom · 04-23-2025, 12:31 PM

OP, in case you decide on new rotors I would gladly pay shipping for you to send the old ones to me for a project I am working on

Consider SHW Performance rotors

Right side:
https://www.bimmerworld.com/Brakes/B...2-282-446.html

Left side:
https://www.bimmerworld.com/OEM-Repl...2-282-445.html

SHW is the company that makes these rotors for BMW. They go way back with BMW and helped develop these rotors for BMW Motorsport division.

The only difference is when you get them from dealer with BMW logo stamped, they come coated in grey anti-rust coating. SHW do not have that coating. But the hat is aluminum so it won't rust and the ring... who cares, they will rust eventually anyway from inside if you daily drive in the winter and rain all the time (which most people don't do with these cars).

The dealer price may vary of course but as an example here is the price tag for one rotor from a dealer:
https://parts.bmwofsouthatlanta.com/...or-34112282445

SHW makes sense as it is the same product. You get both for the price of one BMW stamped one.

wyshyvanuk · 04-23-2025, 12:49 PM

Thanks, belcom. I'll try flipping these rotors, but that's excellent information.

04-16-2025, 07:11 PM	#1
wyshyvanuk First Lieutenant 757 Rep 310 Posts Drives: 2008 Z4 MR Join Date: Apr 2018 Location: Tucson AZ iTrader: (0)	MZ4 Front Brake Discs Reversed So, I've just discovered that the front discs on my 2008 MZ4 are reversed right to left. My best guess is that they've been that way for the last 12k miles, when they were probably replaced to repair some accident damage. They appear to still be in excellent condition with no detectible "ridge" on the outside edge. So.... 1. Close my eyes. and swap them side to side? 2. Swap them side to side and replace the pads with OEM? 3. New rotors and new pads? I'm not cheap, but I am thrifty ;~). Thanks!!
	Appreciate 0 Tweet Quote

04-16-2025, 07:45 PM	#2
gaseosx Private 11 Rep 55 Posts Drives: E85 Z4 3.0i Join Date: May 2024 Location: Bay Area, CA iTrader: (0)	Get them resurfaced and put new pads.
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04-18-2025, 09:05 AM	#4
mmm-five Captain 434 Rep 705 Posts Drives: Z4MC + 335xD M-Sport Touring Join Date: Aug 2017 Location: Liverpool, UK iTrader: (0)	Just swap them around!
	Appreciate 4 XMetal1362.50 3798j17929.50 wdb5543.50 Efthreeoh22235.50 Quote

04-18-2025, 02:15 PM	#7
pungo Colonel 1210 Rep 2,907 Posts Drives: Z4MC, X3-35i,525i, Corrado G60 Join Date: Nov 2007 Location: MD iTrader: (5) Garage List 2007 BMW Z4 M Coupe [9.01] 2011 BMW X3 x35i [10.00] 2001 BMW 525i [9.50]	I'd just swap them side to side and go for a few good braking sessions and be done.
	Appreciate 4 XMetal1362.50 3798j17929.50 wdb5543.50 Efthreeoh22235.50 Quote

04-22-2025, 12:28 PM	#9
wyshyvanuk First Lieutenant 757 Rep 310 Posts Drives: 2008 Z4 MR Join Date: Apr 2018 Location: Tucson AZ iTrader: (0)	Thanks, guys!! Swapping tomorrow.
	Appreciate 1 3798j17929.50 Quote

04-23-2025, 12:31 PM	#14
belcom Lieutenant 247 Rep 507 Posts Drives: '18 540i, '06 Z4si, '07 Z4MC Join Date: Nov 2014 Location: Toronto iTrader: (1)	OP, in case you decide on new rotors I would gladly pay shipping for you to send the old ones to me for a project I am working on Consider SHW Performance rotors Right side: https://www.bimmerworld.com/Brakes/B...2-282-446.html Left side: https://www.bimmerworld.com/OEM-Repl...2-282-445.html SHW is the company that makes these rotors for BMW. They go way back with BMW and helped develop these rotors for BMW Motorsport division. The only difference is when you get them from dealer with BMW logo stamped, they come coated in grey anti-rust coating. SHW do not have that coating. But the hat is aluminum so it won't rust and the ring... who cares, they will rust eventually anyway from inside if you daily drive in the winter and rain all the time (which most people don't do with these cars). The dealer price may vary of course but as an example here is the price tag for one rotor from a dealer: https://parts.bmwofsouthatlanta.com/...or-34112282445 SHW makes sense as it is the same product. You get both for the price of one BMW stamped one.
	Appreciate 0 Quote

04-23-2025, 12:49 PM	#15
wyshyvanuk First Lieutenant 757 Rep 310 Posts Drives: 2008 Z4 MR Join Date: Apr 2018 Location: Tucson AZ iTrader: (0)	Thanks, belcom. I'll try flipping these rotors, but that's excellent information.
	Appreciate 2 belcom246.50 AK72315.50 Quote