When are front rotors & pads too thin

Mercutos · 09-08-2009, 01:50 PM

I needed new rear brakes bad, pads & rotors.

I got new front pads, just pads, 50k mile ago, so I figured I would just change the front pads & rotors in the front too. Well, they look good, the pad & rotors. The rotors seem to have lots of material left in them. The Pads aren't even worn down past the bevel in the pad material. The car stops great w/ no vibration.

I'm thinking I will just leave the fornts on there for a while. Now that I know how to change those parts I realize it is not big deal to lift up the front & change the brakes, as long as you have a sledge hammer for the rotors.

Not sure how long it will be till I need new pads/rotors up front, trying to figure out whether I should just return the front pads & rotors.

What are the thickness specifications at which pads and rotors are recommended replaced?

rhm325i · 09-08-2009, 01:54 PM

factory rotors come 23mm thick and min. thickness is 21mm
and bmw recommends replacement of rotors every time you replace pads

mbreeden · 09-09-2009, 10:22 AM

Rotors for front and rear have different thickness. Front minimum thickness is thicker than rear (20.4 vs 18.4). Also replacing rotors each time you replace pads is the wrong way around (even though the stealerships may think differently): changing pads when you change rotors is more efficient ;-) BMW does recommend that, because BMW pads seem to be more abrasive and therefore put a more heavy burden on the rotors. If you take the time and effort to measure the rotors now and then: feel free to replace just pads. If not and you want to be better safe than sorry: spend the extra bucks.

Mercutos · 09-09-2009, 10:44 AM

Well, I have a lip on each side of the rotor that is at least 1mm, so I'll keep the set of pads & rotors I have and replace them relatively soon. I'll keep and eye on them every 5k mi when I rotate my tyres.

hummer · 09-09-2009, 11:44 AM

If the car stops Ok, why would you throw away good pads. If the bevels are still visible they are less than half gone! Use them up! Use them until the pad material is at least the same thickness as the backing plate. The warning lite doesn't go on until they are very thin!

09-08-2009, 01:50 PM	#1
Mercutos Registered User Join Date: Nov 2006 Location: FL Posts: 111 My Ride: 99 323i View My Garage	When are front rotors & pads too thin I needed new rear brakes bad, pads & rotors. I got new front pads, just pads, 50k mile ago, so I figured I would just change the front pads & rotors in the front too. Well, they look good, the pad & rotors. The rotors seem to have lots of material left in them. The Pads aren't even worn down past the bevel in the pad material. The car stops great w/ no vibration. I'm thinking I will just leave the fornts on there for a while. Now that I know how to change those parts I realize it is not big deal to lift up the front & change the brakes, as long as you have a sledge hammer for the rotors. Not sure how long it will be till I need new pads/rotors up front, trying to figure out whether I should just return the front pads & rotors. What are the thickness specifications at which pads and rotors are recommended replaced? Last edited by Mercutos; 09-08-2009 at 02:07 PM.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread:

09-08-2009, 01:54 PM	#2
rhm325i Registered User Join Date: Jul 2009 Location: Atlanta, GA Posts: 33 My Ride: 02 BMW 325i View My Garage	factory rotors come 23mm thick and min. thickness is 21mm and bmw recommends replacement of rotors every time you replace pads

09-09-2009, 10:22 AM	#3
mbreeden Registered User Join Date: Sep 2007 Location: Holland Posts: 3 My Ride: 325Ci 2001 (E46) View My Garage	Rotors for front and rear have different thickness. Front minimum thickness is thicker than rear (20.4 vs 18.4). Also replacing rotors each time you replace pads is the wrong way around (even though the stealerships may think differently): changing pads when you change rotors is more efficient ;-) BMW does recommend that, because BMW pads seem to be more abrasive and therefore put a more heavy burden on the rotors. If you take the time and effort to measure the rotors now and then: feel free to replace just pads. If not and you want to be better safe than sorry: spend the extra bucks.

09-09-2009, 10:44 AM	#4
Mercutos Registered User Join Date: Nov 2006 Location: FL Posts: 111 My Ride: 99 323i View My Garage	Well, I have a lip on each side of the rotor that is at least 1mm, so I'll keep the set of pads & rotors I have and replace them relatively soon. I'll keep and eye on them every 5k mi when I rotate my tyres.

09-09-2009, 11:44 AM	#5
hummer Registered User Join Date: Apr 2003 Location: Haverhill, MA Posts: 2,508 My Ride: 2001 330CI View My Garage	If the car stops Ok, why would you throw away good pads. If the bevels are still visible they are less than half gone! Use them up! Use them until the pad material is at least the same thickness as the backing plate. The warning lite doesn't go on until they are very thin!