Help with a Brake Squeal (BMW x5 3.0i)

[RbSX]

Hey guys,

I just got the the rear pads on my mom's BMW x5 replaced, I don't trust mechanics to give inspections that don't line their own pockets so I visually inspected the front and rear pads and discs it was pretty obvious to me that the front pads had ample life left in them and the rears needed to be replaced.

As well, the discs showed no abnormal grooves or striations and don't appear to need to be replaced.

Unfortunately the BMW is way more complicated than my Acura so I had to defer to my mechanic.

Well, after the change the brake squeal is still there, and the brake lining light has shown up since I took it to my mechanic to get the pads changed. I blame this on the fact that he broke one of the brake sensors.. anyways..

He says I need to get a full BMW brake kit complete with new discs, sensors and pads. From my research I'm aware that the ratio of pads to discs is roughly 2:1 for every two sets of pads the discs need to be replaced.

Now, I know my mechanic is a sales person, which is why I inspected the car first, but is there any validity to this statement? I think it's a load of shit on his part. I find it hard to believe that you have to replace the entire set at one time, and that you can't replace the pads without breaking a sensor.

Now I'm curious, the mechanic would not take any responsibility to breaking one of my sensors during pad replacement. Is it common for the sensors to break?

What should I do next since there wasn't anything obvious to me that would cause the brake squeal..

 

[Vette73]

There is nothing special about BMW brakes then any other.

If the brake light is on then the sensor is being hit. Take the front wheel off and look at the INSIDE pad to make sure it is not down to the sensor. I have seen many cars wear the inside faster then the outside. Its either due to bad slides(or to dry) and/or a bad design.

After that look at the rear to see if the sensor is broke. It is just a single wire that runs from the brake pad to another connection to the car. Very basic and easy to check.

Report back what you see.

 

[RbSX]

Originally posted by: Marlin1975
There is nothing special about BMW brakes then any other.

If the brake light is on then the sensor is being hit. Take the front wheel off and look at the INSIDE pad to make sure it is not down to the sensor. I have seen many cars wear the inside faster then the outside. Its either due to bad slides(or to dry) and/or a bad design.

After that look at the rear to see if the sensor is broke. It is just a single wire that runs from the brake pad to another connection to the car. Very basic and easy to check.

Report back what you see.

Well here's the thing, the brake light only came on after my mechanic destroyed the sensor.

I will take a look this week as my no one is driving the car and my mom is on vacation.

 

[rh71]

what year is it? I don't know if that matters, but on my E70 (2007+) this will happen and all you need to do is brake very aggressively a few times and the squeal will disappear. Mine was only a few weeks old when the squeal started but has gone away on its own after some "brake-in". BMW forum guys recommended it as it had happened to them as well. At least give that a try as it's free.

 

[AMCRambler]

If the pads really aren't worn down (check the inside pads, my GTO eats pads that way), you could try the bedding in procedure. Basically get the brakes up to operating temp and then do a couple of real hard stops from like 60-0 on em. If that doesn't cure it, there's a product called Brake Quiet made by Permatex. I did my GTO brakes and even after bedding in the pads, they were squealing like stuck pigs. My pops had a spray can of that Brake Quiet stuff. You spray it on the metal backing of the pads and let it dry till it's tacky. Then you put the pads back on. Worked like a charm. Just make sure you don't accidentally get it on the compound side of the pads. That would be bad, very bad. If the sensor is busted, you're gonna have to get the part to fix that but the mechanic should fix it if it he broke it.
My guess is your brakes are fine and the mechanic is trying to gouge you for new brakes all around. They'll tell you all kinds of BS like the rotors are too thin to be turned, the pads are down to the metal, etc. Check them yourself before you let them do anything. Brakes are one of the easiest ways for mechanics to make some fast money. It's also one of the easiest things to replace yourself.

 

[Engineer]

Originally posted by: AMCRambler
If the pads really aren't worn down (check the inside pads, my GTO eats pads that way), you could try the bedding in procedure. Basically get the brakes up to operating temp and then do a couple of real hard stops from like 60-0 on em. If that doesn't cure it, there's a product called Brake Quiet made by Permatex. I did my GTO brakes and even after bedding in the pads, they were squealing like stuck pigs. My pops had a spray can of that Brake Quiet stuff. You spray it on the metal backing of the pads and let it dry till it's tacky. Then you put the pads back on. Worked like a charm. Just make sure you don't accidentally get it on the compound side of the pads. That would be bad, very bad. If the sensor is busted, you're gonna have to get the part to fix that but the mechanic should fix it if it he broke it.
My guess is your brakes are fine and the mechanic is trying to gouge you for new brakes all around. They'll tell you all kinds of BS like the rotors are too thin to be turned, the pads are down to the metal, etc. Check them yourself before you let them do anything. Brakes are one of the easiest ways for mechanics to make some fast money. It's also one of the easiest things to replace yourself.

This. Don't leave home (or change your brakes) without it!

 

[PlasmaBomb]

Originally posted by: RbSX

Originally posted by: Marlin1975
There is nothing special about BMW brakes then any other.

If the brake light is on then the sensor is being hit. Take the front wheel off and look at the INSIDE pad to make sure it is not down to the sensor. I have seen many cars wear the inside faster then the outside. Its either due to bad slides(or to dry) and/or a bad design.

After that look at the rear to see if the sensor is broke. It is just a single wire that runs from the brake pad to another connection to the car. Very basic and easy to check.

Report back what you see.

Well here's the thing, the brake light only came on after my mechanic destroyed the sensor.

I will take a look this week as my no one is driving the car and my mom is on vacation.

I guess it is a fail safe then.

A quick look at the BMW forums (Bimmerfest, Bimmerforums) suggests that if the brake light is on you need a sensor, and that the tolerances of the X5 discs are tight and that turning them is likely to leave them out of spec and prone to warping.

Since I am nice - next time you need to change the brakes read this -

BMW X5 Complete Brake Job DIY

 

[RbSX]

Originally posted by: PlasmaBomb

Originally posted by: RbSX

Originally posted by: Marlin1975
There is nothing special about BMW brakes then any other.

If the brake light is on then the sensor is being hit. Take the front wheel off and look at the INSIDE pad to make sure it is not down to the sensor. I have seen many cars wear the inside faster then the outside. Its either due to bad slides(or to dry) and/or a bad design.

After that look at the rear to see if the sensor is broke. It is just a single wire that runs from the brake pad to another connection to the car. Very basic and easy to check.

Report back what you see.

Well here's the thing, the brake light only came on after my mechanic destroyed the sensor.

I will take a look this week as my no one is driving the car and my mom is on vacation.

I guess it is a fail safe then.

A quick look at the BMW forums (Bimmerfest, Bimmerforums) suggests that if the brake light is on you need a sensor, and that the tolerances of the X5 discs are tight and that turning them is likely to leave them out of spec and prone to warping.

Since I am nice - next time you need to change the brakes read this -

BMW X5 Complete Brake Job DIY

Thanks for your help.

I haven't had the chance to remove the wheels yet to take a look at the inside pads on the front.

However, I've noticed that the brakes only squeak if I am braking while making a turn. I know it seems silly to ask but would this be any sort of clue as to what is going on?