Brake Job

[CrazyOneToo]

Originally Posted by racingbmwm3

etched/stamped on the rotor hat is the minimum thickness. use a caliper to measure the disc thickness at the thinnest area. generally, if there is a raised lip at the very edge of the disc, you need to replace them. My experience has shown that the front discs need to be replaced everytime with the front pads. The rear discs generally can get two sets of pads before needing to be replaced. But, that is all dependent on driving style.
Don't turn your discs as you lose even more disc material and will definitely be under the minimum thickness at that point. This also puts you at having higher chance of getting warped rotors. Cheap new rotors also have a very high risk of warping (if not a guarantee of it).
I'll bet that none of your previous vehicles could stop as fast or with as much control as a BMW either. Think of your chassis/suspension as a whole. To be at the highest level of safety (or grip/traction) you suspension, brakes, and tires all need to be in good condition. Your DSC system relies on all 3 parts to work effectively; or if driving with DSC off, You need all 3 parts for maximum control. All 3 are only as good as the worst component. If you don't care, might as well be driving a Hummer or Escalade...ok, rant over.

My other ride is a 328i sedan and when I changed all the brake pads on it there was no lip on the outer edge or grooving at all. I don't drive or accelerate fast or brake hard 98% of the time. But will check them thoroughly ASAP. Will replace the rotors if I feel they need it but I just don't see paying an extra $400 to do the brakes if they are still in good shape. Thanks for the info.

[bcredliner]

I didn't say they are not cool tools. I am saying they are not necessary for the toolbox in a personal garage to monitor brake pad wear properly. I don't want anyone to think they need to spend any money on pad measurement tools to get it right.

This forum is an E53 forum. Comparisons to other vehicle, even BMWs, confuse issues the vast majority of the time.

I don't know how often you change the oil but I might take a gander after a set has been on there for 30,000 miles. It would just be for grins as it is very unlikely they would be near worn out.

X5 rotors are built to last about as long as pads. They are intentionally no thicker than they need to be when new. I am not for spending on parts just because. However, on an X5, I think the rotors should be replaced every time the pads are replaced. As far as the back will last through two sets of pads?--the pads take longer to wear out on the back but when the pads do wear out there has been just about as much rotor wear as the front.

[TiAgX5]

Getting away from semi-metallic pads and going with a rotor friendly carbon/ceramic/brass pad compound will allow for 3 sets of pads prior to worn out rotors.

Semi-metallics and OE/OEM eat rotors.

[X5Cat]

Originally Posted by StephenVA

"I trashed my car but did not notice"

Just a weekend ago I had to put my son's front disc brake system back together (I won't give the name of the non-BMW vehicle here, lest we confuse someone). The steel backing plate for the left outer pad was GONE. I mean there was no trace of the pad or plate left, save for some dust. HOW do you not notice?? He only slowed down from running around having his fun when the pistons were completely ejected from the caliper, due to nothing left for them to push against, and all the fluid, pressure, and braking power was lost. Thank God that occurred in our driveway! The rotor and caliper were of course beyond hope. Adding to my misery was the fact that on that vehicle the wheel bearing hub had to be pulled in order to change out the rotor (oops -- sorry if I just confused some bimmer folks).

Life is so much easier if you don't ignore such things.

[admranger]

Originally Posted by StephenVA

Baum Tools - brake thickness measurement tool. No need to remove the wheel, just insert the tip into the back of the brake pad and see the measument in MM. Yes, it is pricy but it beats the heck out of pulling multiple wheels on my stable of of BMWs. 5 mins of effort beats pulling wheels each quarter. Those of you who do this for a living already own one. After seeing one in action, I added it to my Christmas list and ordered it!
Multiple tool vendors sell it, all at the same $$$. Welcome to special tools...
For gauging brake lining thickness w/o wheel removal, PN: 341260
Tool Listing

$90 worth of cleverness there. Wow. As heavy as the X5 wheels are, it is tempting though!

I always measure the rotor thickness when I'm doing the semi-annual summer/winter wheel/tire change (or doing a track pad swap on one of the M3's). Surprising how long these rotors last with ceramic pads.

[CrazyOneToo]

How much pad is left when the sensor activates the dash brake light and the cluster info center?
I am needing to drive my X5 due to weather conditions. Is it safe to drive it for a little while?
Have not had a chance to remove the wheels and physically check the pads yet.



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[racingbmwm3]

3mm remaining, which is 20-25% pad remaining. I'd at least do a visual inspection through the wheels to try to judge which brakes (front or rear) are worn by looking at the outer brake pad. Say your pads were last changed 30,000 miles ago and they are currently 80% worn out (20% remaining), you theoretically have 7000ish miles of life left in the pads. But, the lower you go with pad remaining, the more likely you are to start getting uneven wear on the pads and rotors, and possibly separation of the pad material from the backing plate. They are also more susceptible to brake fade during hard stopping from high speed.

Personally, I wouldn't go more than 1-2k miles after the light comes on. This is similar to the tread wear indicators on your tires, those show when you have 2/32" tread left. I try to replace my tires at or just before I get to that low of tread, or go waste the rest of the tread auto-crossing.

[CrazyOneToo]

Originally Posted by racingbmwm3

3mm remaining, which is 20-25% pad remaining. I'd at least do a visual inspection through the wheels to try to judge which brakes (front or rear) are worn by looking at the outer brake pad. Say your pads were last changed 30,000 miles ago and they are currently 80% worn out (20% remaining), you theoretically have 7000ish miles of life left in the pads. But, the lower you go with pad remaining, the more likely you are to start getting uneven wear on the pads and rotors, and possibly separation of the pad material from the backing plate. They are also more susceptible to brake fade during hard stopping from high speed.

Personally, I wouldn't go more than 1-2k miles after the light comes on. This is similar to the tread wear indicators on your tires, those show when you have 2/32" tread left. I try to replace my tires at or just before I get to that low of tread, or go waste the rest of the tread auto-crossing.

Oh OK thanks. I was just going to drive back and forth to work because of the icy roads we have here now and its AWD. My E46 isn't. Its less than 5 miles to work so I just need to make it until its a little warmer outside to check and change the brakes if needed. I'm hoping its a screwy sensor but if not I'll change them out. I'll look and see if I can view the pads thru the wheel tomorrow. Is there a difference between the dash panel brake light illuminating yellow and red? Read something about that somewhere. Mine is showing red.

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[TiAgX5]

Anyone else here think it's odd the OPs X is wearing out brakes/rotors every 30k miles?

The OEM set installed on my X (by BMW, prior owner, at 100k miles) lasted 70k miles before needing replacement. The rotors were still above min thk'ness, and I tow a lot.

Does the OP track his X?

[Ricky Bobby]

If you haven't noticed by most of the threads about how fast some drive in the X, and how fast they go stoplight to stoplight in the 3 ton SAV racing kids, a lot of the newer E53 drivers here don't surprise me that they wear out brakes often, most are friends with this guy: