Steering wheel shakes under braking

XMetal · 02-04-2021, 02:51 PM

My MC had developed a shake in the steering wheel under moderate to heavy braking only. No shakes driving in any speed. Could a 2-piece floating rotor warp? If so, what can cause it to warp? If it is indeed warped, can the OE cross drilled rotors be turned/resurfaced?

I had already replaced the FCAB and got an alignment in an attempt to remedy the problem, but it still persist. Any insights or ideas would greatly be appreciated - thanks.

GuidoK · 02-04-2021, 03:46 PM

If you already replaced the FCAB in attempt to solve the problem, why didn't you place an indicator dial on the rotor in the process?
Takes 30 seconds or so (maybe remove the caliper with 2 bolts).And maybe measure thickness at the same time.
Everything can warp and cause is the usual.

XMetal · 02-04-2021, 06:20 PM

It didn't occur to me, at the time that the a 2-piece floating rotor could warp so easily under mild street use. With that said, if it is indeed warp, is it advisable to turn (resurface) a cross drilled rotor? Thanks.

Steeler · 02-04-2021, 06:42 PM

Can you recall a braking event that could have warped the rotor?
IE build up that much heat.

XMetal · 02-04-2021, 10:29 PM

I don't recall such event that could generated that much heat to have warped the rotor.

Michael9218 · 02-05-2021, 06:16 AM

Highly unlikely you’ve warped a rotor, especially on a street car. Pad buildup is more likely. To rule that out, do a brake bed in procedure to cook it off.
If replacing the FCAB did nothing, inspect the inner and outer ball joints.

Steeler · 02-05-2021, 06:54 AM

I have an upper strut mount going bad in my Cooper S.
Has been for a while.
I get shimmy in the steering wheel under braking.
FYI mount gets replaced tomorrow.

racerbruce · 02-05-2021, 08:22 AM

This happened to me on my Z4MR; after assessing with multiple professionals, I was advised to perform 3-5 very hard stops from 60 mph; I chose a safe location and performed multiple hard brake applications (about 3 of them); the shimmy went away; it was explained to me that rotor and/or pad buildup can cause the shimmy; I was preparing to replace the rotors but sources told me it is very highly unlikely that the Z4M rotors warp, especially under non-track driving.

XMetal · 02-05-2021, 10:26 AM

Thanks everyone for all the excellent comments and suggestions - definitely gives me some things to look at and try. Very much appreciate it

Quote:

Originally Posted by Michael9218

Highly unlikely you’ve warped a rotor, especially on a street car. Pad buildup is more likely. To rule that out, do a brake bed in procedure to cook it off.
If replacing the FCAB did nothing, inspect the inner and outer ball joints.

Will definitely inspect the inner/outer ball joints next if it isn't pad buildup. But I do believed pad buildup makes the most sense here

Quote:

Originally Posted by dbarton62

I have an upper strut mount going bad in my Cooper S.
Has been for a while.
I get shimmy in the steering wheel under braking.
FYI mount gets replaced tomorrow.

Please update us whether the upper strut mount fixed your shimmy issue on the Cooper.

Quote:

Originally Posted by racerbruce

This happened to me on my Z4MR; after assessing with multiple professionals, I was advised to perform 3-5 very hard stops from 60 mph; I chose a safe location and performed multiple hard brake applications (about 3 of them); the shimmy went away; it was explained to me that rotor and/or pad buildup can cause the shimmy; I was preparing to replace the rotors but sources told me it is very highly unlikely that the Z4M rotors warp, especially under non-track driving.

Thank you for your input and experience! Uneven pad deposit starting to make more sense since the shimmy varies - someday it's more pronounce than other and not very consistent.

inTgr8r · 02-05-2021, 02:20 PM

if you have access to aggressive track pads, that's a good way to grind off the existing pad transfer material.
Then do a bed in procedure with street pads

MZHammer · 02-06-2021, 08:30 AM

Had a similar issue with my M4. I took someone's advice to do some conservative driving, lightly apply the brakes (just to the point that I could start to feel them making contact), and coasting with them applied for several seconds at a time, over a 15-20 min drive. The theory was to "gently" remove the build up, at lower temps, rather than potentially baking more debris onto the rotors. I did this a few times, over the course of a couple of days and the problem went away. Hopefully it's an easy fix for you too.

racerbruce · 02-10-2021, 11:58 AM

Quote:

Originally Posted by XMetal

Thanks everyone for all the excellent comments and suggestions - definitely gives me some things to look at and try. Very much appreciate it

Will definitely inspect the inner/outer ball joints next if it isn't pad buildup. But I do believed pad buildup makes the most sense here

Please update us whether the upper strut mount fixed your shimmy issue on the Cooper.

Thank you for your input and experience! Uneven pad deposit starting to make more sense since the shimmy varies - someday it's more pronounce than other and not very consistent.

Greetings XMetal
Any cause/effect updates??

XMetal · 02-10-2021, 01:29 PM

Nothing concrete yet, until I replace the rear rotors/pads but it's pointing toward uneven pad deposit. If I do a few light brakings, then it shimmy less and won't be too pronounce for a few days. Right now, it's difficult for me to do proper bed-in for the front brake because the front pads are a bit less aggressive compound than the rear, so my bias is a bit out of wack at the moment and that could also contribute to my uneven pad deposit for the front.

XMetal · 05-07-2021, 02:21 PM

Apparently, you CAN indeed warp a 2-piece vented rotor on the street - I don't know how it happened, but it did

Had my mechanic do a runout measurement and the rotors are warped. Also found out that you can't "turn" a 2-piece rotor...so new pads and rotors went in and smooth sailing again.

racerbruce · 05-07-2021, 05:44 PM

Quote:

Originally Posted by XMetal

Apparently, you CAN indeed warp a 2-piece vented rotor on the street - I don't know how it happened, but it did

Had my mechanic do a runout measurement and the rotors are warped. Also found out that you can't "turn" a 2-piece rotor...so new pads and rotors went in and smooth sailing again.

Greetings XMetal -
Never knew this could happen w/street driving....have you had some significant negative G moments?? OEM pads or other?? I'm at 68K miles w/OEM pads and will have the Red Roadster serviced in the next month; how many miles on your OEM rotors before they were replaced?? If I may ask, what was the $ for parts and the $ for labor??

Regards
Racerbruce

XMetal · 05-07-2021, 07:09 PM

I guessed some of those "significant negative G moments" could had happened on one of the many road trips/drives lead by "m3dragon" on here

But I don't recall a moment where I was inhaling brake pads fumes

This issue is with OE rotors and Akebono ceramic pads. My Original pads/rotors were replaced with these at about 43k miles (currently sitting at about 64k miles). I wanted something that dusted a bit less than OE, so I went with the Akebono ceramic pads as I had great experience with them on my X5. The pads still have plenty of meat on them - free to anyone who wants them - local (Irvine CA) pick up only, though.

This time, I just went with what my mechanic can readily get from his supplier, which is Zimmermann rotors and Textar pads. Out the door cost (Labor/Parts/Taxes) is just a shade over $800 for the front brake job.

ToddBlack88 · 05-08-2021, 07:02 PM

Quote:

Originally Posted by XMetal

I guessed some of those "significant negative G moments" could had happened on one of the many road trips/drives lead by "m3dragon" on here

But I don't recall a moment where I was inhaling brake pads fumes

This issue is with OE rotors and Akebono ceramic pads. My Original pads/rotors were replaced with these at about 43k miles (currently sitting at about 64k miles). I wanted something that dusted a bit less than OE, so I went with the Akebono ceramic pads as I had great experience with them on my X5. The pads still have plenty of meat on them - free to anyone who wants them - local (Irvine CA) pick up only, though.

This time, I just went with what my mechanic can readily get from his supplier, which is Zimmermann rotors and Textar pads. Out the door cost (Labor/Parts/Taxes) is just a shade over $800 for the front brake job.

I didn’t know anyone made rotors for the MC except BMW and ECS

Have any part numbers for the rotors.

XMetal · 05-08-2021, 11:27 PM

Front Left => https://www.autohausaz.com/pn/34112282445
Front Right => https://www.autohausaz.com/pn/34112282446

I've used Zimmermann rotors on my X5 and they're good quality...so that's why I didn't hesitate to use them on the MC.

02-04-2021, 02:51 PM	#1
XMetal Colonel 1135 Rep 2,866 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	Steering wheel shakes under braking My MC had developed a shake in the steering wheel under moderate to heavy braking only. No shakes driving in any speed. Could a 2-piece floating rotor warp? If so, what can cause it to warp? If it is indeed warped, can the OE cross drilled rotors be turned/resurfaced? I had already replaced the FCAB and got an alignment in an attempt to remedy the problem, but it still persist. Any insights or ideas would greatly be appreciated - thanks.
	Appreciate 0 Tweet Quote

02-04-2021, 03:46 PM	#2
GuidoK #buildnotbought 10855 Rep 4,893 Posts Drives: Z4 3.0i ESS TS2+ Join Date: Jul 2012 Location: Tinkering in the garage iTrader: (0)	If you already replaced the FCAB in attempt to solve the problem, why didn't you place an indicator dial on the rotor in the process? Takes 30 seconds or so (maybe remove the caliper with 2 bolts).And maybe measure thickness at the same time. Everything can warp and cause is the usual. __________________ Z4 3.0i \| ESS TS2+ supercharger \| Quaife ATB LSD \| Brembo/BMW performance BBK front/rear \| Schrick FI cams \| Schmiedmann headers+cats \| Powerflex/strongflex PU bushings \| Vibra-technics engine mounts \| H&R anti rollbars \| KW V3 coilovers/KW camber plates \| Sachs race engineering clutch \| tons of custom sh#t
	Appreciate 1 XMetal1134.50 Quote

02-04-2021, 06:20 PM	#3
XMetal Colonel 1135 Rep 2,866 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	It didn't occur to me, at the time that the a 2-piece floating rotor could warp so easily under mild street use. With that said, if it is indeed warp, is it advisable to turn (resurface) a cross drilled rotor? Thanks.
	Appreciate 0 Quote

02-04-2021, 06:42 PM	#4
Steeler Colonel 2429 Rep 2,704 Posts Drives: Built not Bought 04 Z4 VF Join Date: Feb 2013 Location: Kitchener Ontario Canada iTrader: (2)	Can you recall a braking event that could have warped the rotor? IE build up that much heat. __________________ W2A Intercooled Vortech V3Si, custom ducting, Alpha N, 60# Bosch,2.62 pulley, multi port WMI, Severn Tuning(pokeybritches), Tial, magnaflow,SS race muffler, 42 design,3.91LSD, H&R, Hotchkis,ST coils,Konis, Megan camber arms, AKG SS, Nylon mounts, Poly bushings, Carbon interior, CF Aero.APEX
	Appreciate 0 Quote

02-04-2021, 10:29 PM	#5
XMetal Colonel 1135 Rep 2,866 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	I don't recall such event that could generated that much heat to have warped the rotor.
	Appreciate 0 Quote

02-05-2021, 06:16 AM	#6
Michael9218 Lieutenant 595 Rep 484 Posts Drives: 2007 Z4 M Coupe Join Date: Oct 2012 Location: Woodstock, GA iTrader: (0)	Highly unlikely you’ve warped a rotor, especially on a street car. Pad buildup is more likely. To rule that out, do a brake bed in procedure to cook it off. If replacing the FCAB did nothing, inspect the inner and outer ball joints.
	Appreciate 3 Steeler2428.50 XMetal1134.50 wdb4732.00 Quote

02-05-2021, 06:54 AM	#7
Steeler Colonel 2429 Rep 2,704 Posts Drives: Built not Bought 04 Z4 VF Join Date: Feb 2013 Location: Kitchener Ontario Canada iTrader: (2)	I have an upper strut mount going bad in my Cooper S. Has been for a while. I get shimmy in the steering wheel under braking. FYI mount gets replaced tomorrow. __________________ W2A Intercooled Vortech V3Si, custom ducting, Alpha N, 60# Bosch,2.62 pulley, multi port WMI, Severn Tuning(pokeybritches), Tial, magnaflow,SS race muffler, 42 design,3.91LSD, H&R, Hotchkis,ST coils,Konis, Megan camber arms, AKG SS, Nylon mounts, Poly bushings, Carbon interior, CF Aero.APEX
	Appreciate 1 XMetal1134.50 Quote

02-05-2021, 08:22 AM	#8
racerbruce Brigadier General 3854 Rep 3,004 Posts Drives: 21 X3 & 13 335is E93 Join Date: Dec 2009 Location: Seattle iTrader: (1)	This happened to me on my Z4MR; after assessing with multiple professionals, I was advised to perform 3-5 very hard stops from 60 mph; I chose a safe location and performed multiple hard brake applications (about 3 of them); the shimmy went away; it was explained to me that rotor and/or pad buildup can cause the shimmy; I was preparing to replace the rotors but sources told me it is very highly unlikely that the Z4M rotors warp, especially under non-track driving. __________________ Racerbruce
	Appreciate 2 Steeler2428.50 XMetal1134.50 Quote

02-05-2021, 02:20 PM	#10
inTgr8r Lieutenant General 2432 Rep 11,667 Posts Drives: M2 Comp Join Date: Mar 2006 Location: Toronto iTrader: (10)	if you have access to aggressive track pads, that's a good way to grind off the existing pad transfer material. Then do a bed in procedure with street pads
	Appreciate 1 XMetal1134.50 Quote

02-06-2021, 08:30 AM	#11
MZHammer Lieutenant 45 Rep 516 Posts Drives: E85 Z4M, F82 M4 Join Date: Sep 2010 Location: Hamilton, ON iTrader: (2) Garage List 2016 M4 [0.00] 2006 BMW Z4M Roadster [0.00]	Had a similar issue with my M4. I took someone's advice to do some conservative driving, lightly apply the brakes (just to the point that I could start to feel them making contact), and coasting with them applied for several seconds at a time, over a 15-20 min drive. The theory was to "gently" remove the build up, at lower temps, rather than potentially baking more debris onto the rotors. I did this a few times, over the course of a couple of days and the problem went away. Hopefully it's an easy fix for you too.
	Appreciate 1 XMetal1134.50 Quote

02-10-2021, 01:29 PM	#13
XMetal Colonel 1135 Rep 2,866 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	Nothing concrete yet, until I replace the rear rotors/pads but it's pointing toward uneven pad deposit. If I do a few light brakings, then it shimmy less and won't be too pronounce for a few days. Right now, it's difficult for me to do proper bed-in for the front brake because the front pads are a bit less aggressive compound than the rear, so my bias is a bit out of wack at the moment and that could also contribute to my uneven pad deposit for the front.
	Appreciate 0 Quote

05-07-2021, 02:21 PM	#14
XMetal Colonel 1135 Rep 2,866 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	Apparently, you CAN indeed warp a 2-piece vented rotor on the street - I don't know how it happened, but it did Had my mechanic do a runout measurement and the rotors are warped. Also found out that you can't "turn" a 2-piece rotor...so new pads and rotors went in and smooth sailing again.
	Appreciate 1 wdb4732.00 Quote

05-07-2021, 07:09 PM	#16
XMetal Colonel 1135 Rep 2,866 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	I guessed some of those "significant negative G moments" could had happened on one of the many road trips/drives lead by "m3dragon" on here But I don't recall a moment where I was inhaling brake pads fumes This issue is with OE rotors and Akebono ceramic pads. My Original pads/rotors were replaced with these at about 43k miles (currently sitting at about 64k miles). I wanted something that dusted a bit less than OE, so I went with the Akebono ceramic pads as I had great experience with them on my X5. The pads still have plenty of meat on them - free to anyone who wants them - local (Irvine CA) pick up only, though. This time, I just went with what my mechanic can readily get from his supplier, which is Zimmermann rotors and Textar pads. Out the door cost (Labor/Parts/Taxes) is just a shade over $800 for the front brake job. Last edited by XMetal; 05-07-2021 at 07:14 PM..
	Appreciate 1 ToddBlack88595.00 Quote

05-08-2021, 11:27 PM	#18
XMetal Colonel 1135 Rep 2,866 Posts Drives: Anything Join Date: Apr 2010 Location: SoCal iTrader: (0) Garage List 2008 Z4M Coupe [10.00] 2018 Audi S3 [0.00] 2004 X5 [8.50]	Front Left => https://www.autohausaz.com/pn/34112282445 Front Right => https://www.autohausaz.com/pn/34112282446 I've used Zimmermann rotors on my X5 and they're good quality...so that's why I didn't hesitate to use them on the MC.
	Appreciate 1 ToddBlack88595.00 Quote