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Discussion Starter #1
So randomly out of nowhere it seems like all my pads suddenly stuck to my rotors just as I was just turned into my drive to park up.

My discs are relatively new and same with the pads. Both Brembo and I wore them em slowly over 500 miles before I started to use them a bit more properly.

I also had a recent brake fluid change (about 6000 miles ago, 6 months ago)

Last weekend I went for a run on some country roads, and did use the brakes quite a bit, and on one occasion some vibration occurred through the steering wheel.

And then today that same vibration appeared randomly as I braked a bit hard on one occasion.

Everything was fine until I turned into my parking spot and felt very light jolt, usually I coast my car into the parking spot but this time it didn’t roll as easy.

I got out and notice all the pads are stuck to the rotors.

I thought I’d pump the brake pedal to no avail and then went for a short drive around the block, and brakes a few times to see if the pads came unstuck. Even though I could brake harder, the car does feel like it was dragging a tiny bit, even though there were no noises from brakes. When I parked up they were still stuck.

It’s also been cold recently, below zero Celsius so not sure if that has something to do with it.

What should I do next?


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If the brake pads were actually stuck to the rotors the car wouldn't move. Sound like what you're actually describing is some caliper sticking. If you get enough guck packed into the rubber bushings the calipers slide on, the calipers won't move freely and the pads will drag on the rotors. A combination of road salt, condensation, and dirt can cause this.
 

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The Arkleyologist
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If a flexible brake line gets weak, and collapses, it will cause this condition. The fluid will go in from the master cylinder to the pads when the pedal is applied, but the collapsed line will not allow the fluid to return when the brake pedal is released. Having said this, after the car sits for a while the fluid will gradually seep back through the line and the wheels will roll easily...until the next time you apply the brakes.
 

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Hi, are you sure that all the pads are stuck to the rotors? Because on brakes which are functioning properly there should actually be zero clearance between the rotor and pad, and the pads should drag slightly at all times. If you have the means, try jacking up the front wheels one at a time and giving each a spin.You should clearly hear the pads contacting the rotors, but each wheel should spin freely. Same with rear but you may have to elevate both rear wheels to allow both sides to spin. If you find both rear brakes dragging heavily, you may have a sticking ebrake. At track schools one is advised not to set the handbrake after a track session until the brakes have sufficient time to cool.

The vibration you are feeling through the steering may simply be a front wheel balance weight you lost during your spirited drive. I recently had that happen to me at a track event, where my front brakes/wheels got so hot the adhesive in the stick-on weight melted and the weight fell off, leaving me with a lovely steering wheel shimmy for the 2 hour drive home. A simple rebalance of the wheel fixed it. It might be worth removing both of your front wheels and checking the inside and outside of each wheel for a missing weight. Look for a spot on the wheel that is cleaner than the area around it.

If the vibration is occurring only during moderate to heavy braking, it may be that one of your brake pad backing plates (which are normally bonded to the back of each pad), has come loose. If that happens (as it did to me), you will hear and feel vibration through the pedal. Left unchecked it shouldn't hurt anything, but it will require removal/replacement of the offending pad to correct it.
 

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Discussion Starter #5
Thanks everyone for your comments and advice.

So yeh managed to get car into my bmw specialist - basically the near side brake Caliper was sticking - so they lubed up the caliber and problem seems to have gone. But they’ve said it’s likely I’ll prob need a new Caliper if it happens again.

I also didn’t realise the pad is supposed to be touching the rotor - I was thinking the brakes work more like bike brakes.

So yeh it’s wasn’t all the rotors just the left front!

Hoping rotor hasn’t warped as I recently had discs replaced because of warping last time from when I bought car

Might look to getting both front callipers replaced with performance ones - any recommendations, shout out. I won’t be tracking the car - but I do push the car on runs out


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Glad you got it solved. :thumbup: Your rotor is likely not warped unless you drove through a puddle with the brakes smoking hot. I don't think you will need to upgrade your stock brake calipers either, the factory units are more than adequate for track or spirited mountain driving, but you may want to install upgraded pads and SS lines.

I don't know if there is a car brake manufacturer that has perfected a way to pull the pad completely off the disc during normal running. I think the negligible amount of drag saved is more than offset by the extra safety margin of having the brakes always at the ready.
 

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Sounds like that caliper has a piston sticking. Rebuilt calipers are relatively inexpensive so it would be worth it to do both.
The stock calipers are fine for anything you'll do on the road and as AndyZ4 indicated they'll do fine for general track day duty. Getting high temp fluid and good pads installed are the key thing.

I've done lots of track days at Daytona (short course and long course) and Sebring (short course and long course) with the stock 3.0si calipers and they've been fine. Had to move up to Hawk DTC60 compound though to get pads that would handle the heat.
 

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Discussion Starter #8
Yeh bit surprised the calipers sticking - never had this problem with any other car before. And same with the vibration... bought the car about 7 months ago, the previous owner had but new discs and pads on, a couple of months prior to selling to me.

anyway I discovered after a month or so of driving the discs were warped. So I replaced with brembo grooved discs and performance pads. anyway I seem to be able to feel a tiny tiny bit of vibration creeping in again - when I'm a proper run after a fair bit of use.

so yeh - just gotta wait and see if problem goes worse or not. I also suspect my alignment might be off.. maybe a combination of everything making it a bit more prominent. I'm at 80k miles at mo... so guess it's that time when things need replacing/servicing etc
 

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Yeh bit surprised the calipers sticking - never had this problem with any other car before. And same with the vibration... bought the car about 7 months ago, the previous owner had but new discs and pads on, a couple of months prior to selling to me.

anyway I discovered after a month or so of driving the discs were warped. So I replaced with brembo grooved discs and performance pads. anyway I seem to be able to feel a tiny tiny bit of vibration creeping in again - when I'm a proper run after a fair bit of use.

so yeh - just gotta wait and see if problem goes worse or not. I also suspect my alignment might be off.. maybe a combination of everything making it a bit more prominent. I'm at 80k miles at mo... so guess it's that time when things need replacing/servicing etc
With slotted rotors and softer pads you'll feel the slots under hard braking.
 

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I also didn’t realise the pad is supposed to be touching the rotor - I was thinking the brakes work more like bike brakes.
They don't actually touch but the clearance is miniscule and any warpage or high spot on the rotor will result in contact with each revolution.
 

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I recommend you also inspect the pistons and caliper bores for rust/crud/corrosion. Brake fluid is hygroscopic (absorbs moisture from the air) and can cause rust to form on the pistons or in the caliper bore causing the piston to jam. While driving in Okinawa (warm, wet, marine environment), I stabbed the brakes to avoid a knucklehead and the front right disc brake locked up tight and drug me to the curb on a 4 year old car. Although brake service was current (fluid, pads and rotors), the issue was nonetheless caused by a rusted piston which stuck in the caliper bore necessitating a rebuild.
 

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Silverseal, that sucks and good thing nothing bad happened. I'm surprised that by now brake manufacturers are not making caliper pistons and bores out of ceramic, especially since they are already using the material on pads and rotors. It is much harder than steel or iron and virtually impervious to corrosion, which is what ended your day.
 

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Silverseal, that sucks and good thing nothing bad happened. I'm surprised that by now brake manufacturers are not making caliper pistons and bores out of ceramic, especially since they are already using the material on pads and rotors. It is much harder than steel or iron and virtually impervious to corrosion, which is what ended your day.
Ceramic has to be ground to the final dimensions and finish. while steel can be turned on a lathe. Grinding is a much slower and more expensive process than turning.
 

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And now that it can be done, the Chinese will figure out how to get it done cheap.
They're already doing the cheap steel pistons. The raw materials for ceramic pistons cost less than steel. If there was a way to do it for less cost, they would be doing it.
 

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Silverseal, that sucks and good thing nothing bad happened. I'm surprised that by now brake manufacturers are not making caliper pistons and bores out of ceramic, especially since they are already using the material on pads and rotors. It is much harder than steel or iron and virtually impervious to corrosion, which is what ended your day.
Calipers are a commodity item in the auto industry. As such, low cost is the key to keeping market share unless the end use is not cost-sensitive (e.g., Ferrari). Phenolic pistons were pretty popular for a while due to being corrosion-proof but they had other issues and many applications returned to steel. For 95%+ of the auto industry, (low) cost is king which is why we're still using cast iron calipers with steel pistons 50 years after disc brakes went into mass production.
 

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Spinning rotors have what's called a boundary layer of air which rotates with them. The pads ride on top of this layer rather than actually contacting the rotor.
 

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You might consider just keeping great brakes that are stock and dot 4 brake fluid... unless bmw has gone to dot 5, I doubt it but it's possible. Keeping good calipers and newer pads and fresh discs provides excellent braking unless your really running fairly advanced at the track.

Running stock parts but keeping the parts in great shape is what my friends do that drive fast and like occasional track work.
 
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