How much further can you go once the brake wear sensors go off?

[quattro PETE]

I know this is very subjective. My "check brake linings" message just came on. I will have to do about 300-400 more miles of relatively easy mixed city/hwy driving before I can get those brakes taken care of. I'm assuming BMW has built in some buffer in there so that when the warning comes on, you still have some pad material left? I tried to visually inspect them, but couldn't really tell without getting the wheels off.

[JackEatsEmoKids]

3mm of pad are left....you should be fine for 400 miles, but be aware of how they are!

Keep on downshifting when you stop, save the brakes. It would be wise(if you have mechanical experience to just buy the parts and do it yourself.

How many miles on the car?

[thejlevie]

In normal driving you should have about 1000mi to go before there's no pad material left. The distance will be a bit greater if the majority of the driving is highway use and can be quite a bit less in a purely urban scenario. So you should be okay.

[quattro PETE]

Thanks guys.

Jack, I've got 44k miles on the car. I bought it at 30k and haven't had any brake work done, so I don't know when was the last time the pads were installed. Dealer records from the previous owner don't specifically show any brake work either (apart from brake fluid change). Would it be possible that at 44k miles I would still have the original pads? I'm guessing it they were replaced at some point.

[ViolinARC]

Change em asap...nothin worse than hittin your brake pedal and NOT stopping. Just want you to be safe and sound...oh yeah, you already drive a BMW. LOL

[quacktoduck]

i knew a guy that drove with the brake light for about 2 months+ he was fine... its just the fact that you might not be able to use the rotors due to uneven wear....

[chiefwej]

Thanks guys.

Jack, I've got 44k miles on the car. I bought it at 30k and haven't had any brake work done, so I don't know when was the last time the pads were installed. Dealer records from the previous owner don't specifically show any brake work either (apart from brake fluid change). Would it be possible that at 44k miles I would still have the original pads? I'm guessing it they were replaced at some point.

That sound about right, depending on how much was highway and how hard the previous owner was on the brakes. I swapped my pads out at 30k (couldn't stand the brake dust any more) and there was pad left.

[ViolinARC]

i knew a guy that drove with the brake light for about 2 months+ he was fine... its just the fact that you might not be able to use the rotors due to uneven wear....

So you're saying it's ok to continue to drive with thin brake linings but you're gonna have to replace the rotors if you do. Sounds like it'd be more cost effective to just replace the pads now to preserve the rotors (unless they're already beat of course)...agreed?

EDIT: Yeah, these OEM rotors are soft in comparison to aftermarket or performance.

[quacktoduck]

yes.... thats what the stealership tech said... one of my buddies... he said it not necissary to put new rotors every brake change... but pads overexcesivly used can cause uneven wear

[quattro PETE]

One more question: when you get this "check brake linings" message, is there a way to tell which brakes (front or rear) triggered the warning without actually pulling the pads out?

[jamesdc4]

One more question: when you get this "check brake linings" message, is there a way to tell which brakes (front or rear) triggered the warning without actually pulling the pads out?

I think you have to pull the pads to find out.

[racerx0911]

how long should pads last?

[MGW540i6]

I would highly recommend changing them ASAP. Do not trust the sensor!

The sensor is only on one side and not both. You do not know what the other side looks like.

[ViolinARC]

One more question: when you get this "check brake linings" message, is there a way to tell which brakes (front or rear) triggered the warning without actually pulling the pads out?

Yes but you're still gonna have to pull the wheels so you can get a good look at the pads. Then you're gonna have to measure the thickness of the pads, one at a time. I believe that 3mm is the MINIMUM before having to replace. I remember something on the http://www.bavpros.com site and the owner, Mike, in the video interview, tells you exactly what to look for when it's time for a brake job. Let me know if you found this helpful...

EDIT: Oh yeah, you'll most likely find that most of the wear is on the front pads since they carry about 70% of the stopping power for your ride. Peace...

[Steve530]

I'm surprised that the pads have worn that quickly. Undoubtedly the front pads. They seem to wear about twice as fast as the rear.

It is entirely possible that the pads are not worn parallel to the disc. Since the sensor is in the middle of the pad that 3 mm thickness is in the center. One edge could be getting really thin. Of course, if the brake backing pad starts contacting the rotor, it will wear a groove in the disc quickly. Then you'll have to replace the rotor, too.

[quattro PETE]

So, my shop is telling me I need new front rotors in addition to the pads. Visually, the rotors do have a noticeable groove in them already. I'm a bit surprised that the rotors only lasted 44k miles. But then again, it's a heavy car, so these brakes do have a lot of work to do. Is this about normal life of e39 rotors? How many miles did you guys get out of your OEM rotors?

[Petes540i6]

It is likely that 3mm is what is required to pass your state's inspection (if your state has one). Theoretically, so long as there is pad material left, the brakes should be fine, no matter how thin the pad material is. You will hear it when there is no pad material left, because it will make a metal-to-metal "grinding/scraping" sound from the wheel. You should of course replace the pads before that occurs.

The conventional wisdom is that the rotors need to be replaced when the pads are replaced on BMW's. True or not, if you can see or feel a lip on the edge of the rotor, and you have that kind of milage on the same set of rotors, I strongly suspect you will need to replace the rotors as well.

I sispect you can go a couple of thousand miles on 3mm of pad, assuming normal driving conditions, and assuming you have that much on each pad.

[PeterZ]

I was looking at my wife's 318i last night while replacing the fender well. Her light has not gone off, but she is nearly there. I think the 3 mm includes the metal backer, meaning there is about 1 mm of pad left. That is the way hers looked. I ordered pads this morning. Miked the rotors yesterday - .825". Replacement point is .803" for her 318i, so I will just do the pads this time around.

[ViolinARC]

Man...you guys are really willing to "push it" with a highly critical component. What's a couple mm's of pad and a few dollars compared to crashing your incredible machine? Remember...no brakes, no stop. A rather simple principal IMHO. Change 'em before you can't stop your 4000 lb. machine and you kill yourself or someone else. Just my $.02+ some

[quattro PETE]

Take it easy, 12CoolDude. I'm getting new brakes on Wed.

[ViolinARC]

Take it easy, 12CoolDude. I'm getting new brakes on Wed.

Sorry Pete...I've been in the "no-stop" situation before so I speak from experience (f'in shop didn't replace the master cylinder on my '84 Z28 and it failed). I can't help being slightly emotional about it. I mean if it's a fan clutch or radiator, no problem. Put it off til you're stranded on the side of the road but brakes?!? How're you gonna apologize to the guy you smash into? Uh...sorry man, thought the .825 mm of pad was gonna do the trick. I was also thinking about the thread discussing 120+ mph. Does anyone really think a couple mm of pad will hold up if you have to stop fast at such speeds (c'mon...you KNOW we all break triple digits with these cars)? Braking failure is the most likely scenario IMO. Well...you get the idea.

No personal attacks or flaming intended, just responding to some of the "put-it-off as long as you can" posts cause I don't wanna get sandwiched on my motorcycle by some guy who was testing the limits of his brake pads. Peace and have a Happy and safe Holiday everyone...

EDIT: To clarify my title...change the brake pad at 3mm. After the sensor alarm goes off, don't wait another 3mm...LMAO!

[Steve530]

Sorry Pete...I've been in the "no-stop" situation before so I speak from experience ...

Not being able to go is annoying, but not being able to stop is a real bad experience.

[quattro PETE]

EDIT: To clarify my title...change the brake pad at 3mm. After the sensor alarm goes off, don't wait another 3mm...LMAO!

I understand. I just don't think one should panic and necessarily replace the pads the minute the brake warning light comes on. BMW is not dumb and they must have built a reasonable buffer. That buffer being 3 mm.

Let's be reasonable... when new, the pads have 11 mm thickness. Assuming they now have 3 mm, that means I was able to do 44k miles on 8 mm of pad material. By proportion, the remaining 3 mm should be good for another 17k miles. Now, I do realize that wear may not be linear throught the pads' life and that wear may not be exactly even across the pads' surface. But still, it's not like you suddenly lose all your braking power... you normally hear some strange noises as you get to the end of the pad. I think I'm far from it. I do agree with you that I will have to get it done sooner or later, and in this case it's probably better to do it sooner than later.

Happy holidays to you, too!