Help please - Brake discs - is this normal ?

Bastet · 01-20-2008, 11:50 AM

Could someone tell me if it's normal that one of the break discs is grooved (1st photo) ? All the others are really smooth (like in the second photo) but one has grooves. Should I be worried/take the car back to the dealer/just forget about it and enjoy driving ???

GregW / Oregon · 01-20-2008, 12:06 PM

No, it's not normal, but not unusual. Probably got some debris caught between the rotor and disc. It shouldn't have much effect on braking, but I''d show it to the dealer. They may well go away on their own in a few thousand miles.

On GM cars rotor grooves of up to .060 inch are acceptable if the rotor meets all other specifications. Not sure what BMW specs say.

Epacy · 01-20-2008, 12:07 PM

I do see the grooves in the first pic. I would say if no other brake discs have this scoring, you might want to take it in.

Bastet · 01-20-2008, 12:10 PM

Thanks guys ! I knew it

- I hate returning to the dealers for something like this !

Gearhead999s · 01-20-2008, 12:23 PM

Those brakes are not even broken in yet as the machining marks are still on the surface.Read this link about brake & rotor "bed in".I have been using the methods used here with very few braking problems in both street & race cars.

http://www.stoptech.com/tech_info/wp...contents.shtml

Bastet · 01-20-2008, 12:26 PM

Quote:

Originally Posted by Gearhead999s

Read this link about brake & rotor "bed in".

thanks !

heyimsexy · 01-20-2008, 05:55 PM

not normal. i would only be concerned if youre having vibrations or squeaking. if its not bothering you in any way, dont take it in, because you can be sure the dealer is gonna pile on the bullshit and youre gonna be spending $$$.

Epacy · 01-20-2008, 06:02 PM

Quote:

Originally Posted by heyimsexy

not normal. i would only be concerned if youre having vibrations or squeaking. if its not bothering you in any way, dont take it in, because you can be sure the dealer is gonna pile on the bullshit and youre gonna be spending $$$.

I would not follow this advice.

lucid · 01-20-2008, 06:04 PM

i don't think there is much downside here. it can make noise. it's not as if the groove is so deep that the rotor will crack. the dealer will want and love to replace the pads and the rotor, and that will cost dearly. if it starts vibrating, that would be problematic because that can affect performance, at which point i'd take it in, so i agree with the sexy member. or i guess the alternative would be to take it in and ask them to remove whatever is stuck on the pad, but they most likely won't want to do that saying they need to replace everything. if there is nothing stuck on the pad, one could argue the pad was defective.

Epacy · 01-20-2008, 07:37 PM

If there is something stuck between the pad and rotor, you would most likely hear it at all times. That space is fairly small. Also, it looks like you have three marks. Would be hard for three different pieces of debris to be there. Looks most likely your pad is the culprit.
If you don't hear it at all times, it seems like a problem with the pad scoring the rotor. Which the dealer would have to replace.

Stahlgrau · 01-20-2008, 08:14 PM

Quote:

Originally Posted by lucid

i don't think there is much downside here. it can make noise. it's not as if the groove is so deep that the rotor will crack. the dealer will want and love to replace the pads and the rotor, and that will cost dearly. if it starts vibrating, that would be problematic because that can affect performance, at which point i'd take it in, so i agree with the sexy member. or i guess the alternative would be to take it in and ask them to remove whatever is stuck on the pad, but they most likely won't want to do that saying they need to replace everything. if there is nothing stuck on the pad, one could argue the pad was defective.

Wouldn't replacement be covered under warranty?

lucid · 01-20-2008, 08:17 PM

Quote:

Originally Posted by Stahlgrau

Wouldn't replacement be covered under warranty?

If they attribute it something getting caught in the pad, they would probably argue that is not warranty related. If they attribute it to the pad itself, then they would have to cover it given it's a brand new car. In the US, it wouldn't be an issue as we have the 4 year warranty+free service deal, so it wouldn't matter what has caused it.

GregW / Oregon · 01-20-2008, 10:39 PM

Quote:

Originally Posted by Stahlgrau

Wouldn't replacement be covered under warranty?

That would most likely be covered under free maintenance in the US, but they don't get this in Europe, despite paying more.

OzStriker · 01-20-2008, 11:37 PM

+1 on those brakes not being broken in.
You can still see the diamond criss cross marks from original manufacturing.
Go bed them in on a freeway early morning and see what happens.

GregW / Oregon · 01-20-2008, 11:45 PM

Quote:

Originally Posted by OzStriker

+1 on those brakes not being broken in.
You can still see the diamond criss cross marks from original manufacturing.
Go bed them in on a freeway early morning and see what happens.

Good advice.

Bastet · 01-21-2008, 05:37 AM

Our warranty covers pretty much everything during the first year, so I'll probably go show the discs to the dealership anyway, just to be on the safe side...

GregW / Oregon · 01-21-2008, 09:26 AM

Quote:

Originally Posted by Bastet

Our warranty covers pretty much everything during the first year, so I'll probably go show the discs to the dealership anyway, just to be on the safe side...

I doubt this is technically a warranty issue (defective parts), but likely will be considered a wear issue. Good luck with the dealer. If they don't think it's important, just drive it and the rotor may even out.

Gearhead999s · 01-21-2008, 10:00 AM

I would not worry about it,because one of the problems with drilled discs is that the scoring of the disc face is pretty normal.I am not a fan of drilled discs as when used on track they tend to have cracks that start ot the holes,whether they are cast or machined after.On Porsches they are cast and they also do crack after a few hard days.A lot of the scoring on your discs might have been caused by rust particles coming out the holes and getting collected on the pads.On a lot of street Porsches I have noticed brake pad material actually filling up these holes.I prefer Slotted discs,much more servicable for hard use.

gblansten · 01-21-2008, 10:41 AM

I don't think that those disks are broken. Long-term if you have breaks instead of brakes you'll be in the shop a lot.

Dew yew sea what eye did their?

southlight · 01-21-2008, 11:37 AM

Quote:

Originally Posted by gblansten

I don't think that those disks are broken. Long-term if you have breaks instead of brakes you'll be in the shop a lot.

Dew yew sea what eye did their?

Nice attitude, n00b.

Best regards, south

gblansten · 01-21-2008, 12:54 PM

Quote:

Originally Posted by southlight

Nice attitude, n00b.

Best regards, south

Laugh a little there chief. Relax.

Minus whale because for all intensive porpoises life is two short.

Ultimate regards,

GBlansten

Bastet · 01-29-2008, 02:50 PM

Just thought I'd let all those who read this know that after a few days of working the brakes pretty hard the grooves are virtually gone. I'm quite surprised that they have reduced so much as i could easily feel them on the surface.

Makes me wonder how the discs and pads will wear the miles??? Only time will tell, but hopefully they'll last a good while.

01-20-2008, 11:50 AM	#1
Bastet Second Lieutenant Drives: M3 E92 aka 'Batmobile' Join Date: Nov 2007 Location: Brussels Europe Posts: 226 iTrader: (0)	Help please - Brake discs - is this normal ? Could someone tell me if it's normal that one of the break discs is grooved (1st photo) ? All the others are really smooth (like in the second photo) but one has grooves. Should I be worried/take the car back to the dealer/just forget about it and enjoy driving ??? Attached Images
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01-20-2008, 12:06 PM	#2
GregW / Oregon Commander-In-Chief Drives: 2008 M3 Coupe, 2006 ML350 Join Date: Nov 2005 Location: Lake Oswego, OR Posts: 6,051 iTrader: (1) Garage List 2006 M-B ML350 [0.00] 2008 E92 M3 Coupe [4.75]	Scored brake rotor No, it's not normal, but not unusual. Probably got some debris caught between the rotor and disc. It shouldn't have much effect on braking, but I''d show it to the dealer. They may well go away on their own in a few thousand miles. On GM cars rotor grooves of up to .060 inch are acceptable if the rotor meets all other specifications. Not sure what BMW specs say. __________________ Greg Lake Oswego, Oregon, USA 2008 M3 Coupe - Alpine/Fox Red/Carbon 2001 M3 Coupe - SOLD 3/08 2006 Mercedes-Benz ML350 (2012 ML350 BlueTEC on order) Last edited by GregW / Oregon; 01-20-2008 at 12:28 PM.

01-20-2008, 12:07 PM	#3
Epacy Reincarnated Drives: 02 Maxima SE Join Date: Mar 2007 Location: IL Posts: 4,227 iTrader: (0) Garage List 2008 M3 [0.00]	I do see the grooves in the first pic. I would say if no other brake discs have this scoring, you might want to take it in. __________________ Pearl Bliss

01-20-2008, 07:37 PM	#10
Epacy Reincarnated Drives: 02 Maxima SE Join Date: Mar 2007 Location: IL Posts: 4,227 iTrader: (0) Garage List 2008 M3 [0.00]	If there is something stuck between the pad and rotor, you would most likely hear it at all times. That space is fairly small. Also, it looks like you have three marks. Would be hard for three different pieces of debris to be there. Looks most likely your pad is the culprit. If you don't hear it at all times, it seems like a problem with the pad scoring the rotor. Which the dealer would have to replace. __________________ Pearl Bliss

01-20-2008, 12:10 PM	#4
Bastet Second Lieutenant Drives: M3 E92 aka 'Batmobile' Join Date: Nov 2007 Location: Brussels Europe Posts: 226 iTrader: (0)	Thanks guys ! I knew it - I hate returning to the dealers for something like this !

01-20-2008, 12:23 PM	#5
Gearhead999s Major General Drives: E93 335is(wifes)E92 M3 Join Date: Apr 2007 Location: Toronto Posts: 5,633 iTrader: (0)	Those brakes are not even broken in yet as the machining marks are still on the surface.Read this link about brake & rotor "bed in".I have been using the methods used here with very few braking problems in both street & race cars. http://www.stoptech.com/tech_info/wp...contents.shtml

01-20-2008, 05:55 PM	#7
heyimsexy Private Drives: e36 Join Date: Jul 2007 Location: bay area Posts: 65 iTrader: (0)	not normal. i would only be concerned if youre having vibrations or squeaking. if its not bothering you in any way, dont take it in, because you can be sure the dealer is gonna pile on the bullshit and youre gonna be spending $$$.

01-20-2008, 06:04 PM	#9
lucid Major General Drives: E30 M3; Expedition Join Date: Apr 2007 Location: USA Posts: 8,057 iTrader: (0)	i don't think there is much downside here. it can make noise. it's not as if the groove is so deep that the rotor will crack. the dealer will want and love to replace the pads and the rotor, and that will cost dearly. if it starts vibrating, that would be problematic because that can affect performance, at which point i'd take it in, so i agree with the sexy member. or i guess the alternative would be to take it in and ask them to remove whatever is stuck on the pad, but they most likely won't want to do that saying they need to replace everything. if there is nothing stuck on the pad, one could argue the pad was defective.

01-20-2008, 11:37 PM	#14
OzStriker Captain Drives: Ford Falcon Ute, Ducati 1198S Join Date: Sep 2007 Location: Melbourne Posts: 923 iTrader: (1) Garage List 2008 BMW E92 M3 [0.00] 2009 Ducati 1198S [0.00]	+1 on those brakes not being broken in. You can still see the diamond criss cross marks from original manufacturing. Go bed them in on a freeway early morning and see what happens.

01-21-2008, 05:37 AM	#16
Bastet Second Lieutenant Drives: M3 E92 aka 'Batmobile' Join Date: Nov 2007 Location: Brussels Europe Posts: 226 iTrader: (0)	Our warranty covers pretty much everything during the first year, so I'll probably go show the discs to the dealership anyway, just to be on the safe side...

01-21-2008, 10:00 AM	#18
Gearhead999s Major General Drives: E93 335is(wifes)E92 M3 Join Date: Apr 2007 Location: Toronto Posts: 5,633 iTrader: (0)	I would not worry about it,because one of the problems with drilled discs is that the scoring of the disc face is pretty normal.I am not a fan of drilled discs as when used on track they tend to have cracks that start ot the holes,whether they are cast or machined after.On Porsches they are cast and they also do crack after a few hard days.A lot of the scoring on your discs might have been caused by rust particles coming out the holes and getting collected on the pads.On a lot of street Porsches I have noticed brake pad material actually filling up these holes.I prefer Slotted discs,much more servicable for hard use.

01-21-2008, 10:41 AM	#19
gblansten Captain Obvious Drives: 2011 BMW M3 SSII/Black Join Date: Sep 2007 Location: Thick ascending limb Posts: 713 iTrader: (0)	I don't think that those disks are broken. Long-term if you have breaks instead of brakes you'll be in the shop a lot. Dew yew sea what eye did their?

01-29-2008, 02:50 PM	#22
Bastet Second Lieutenant Drives: M3 E92 aka 'Batmobile' Join Date: Nov 2007 Location: Brussels Europe Posts: 226 iTrader: (0)	Just thought I'd let all those who read this know that after a few days of working the brakes pretty hard the grooves are virtually gone. I'm quite surprised that they have reduced so much as i could easily feel them on the surface. Makes me wonder how the discs and pads will wear the miles??? Only time will tell, but hopefully they'll last a good while.