Doing a pad swap, what is this white stuff?

[darkrabbit]

Don't understand what this is, never seen it before. I am taking it out best I can but it's really in there... shouldn't affect anything in terms of vibration or braking, but it might be preventing proper cooling.

Not on the outside but on the inside.... weird... Anyone know what it is? Some factory paste or something?

-J

[Mpire]

cocaine?

[lemetier]

Originally Posted by darkrabbit

Don't understand what this is, never seen it before. I am taking it out best I can but it's really in there... shouldn't affect anything in terms of vibration or braking, but it might be preventing proper cooling.

Not on the outside but on the inside.... weird... Anyone know what it is? Some factory paste or something?

-J

Have you changed the pads before and used anti-squeal paste or had a service write up concern for squealing brakes?

[JNoSol]

Originally Posted by Mpire

cocaine?

That's a genius place to hide cocaine.


OP: Your dealer must have applied anti-squeal paste on it.

[darkrabbit]

Originally Posted by Mpire

cocaine?

.... LOL that would be an awesome spot

Originally Posted by miamiten

Have you changed the pads before and used anti-squeal paste or had a service write up concern for squealing brakes?

Nope. These havent been opened since the car was made.

If this isn't normal I wont worry about it and just tear it out.

Thanks!

-J

[lemetier]

Originally Posted by darkrabbit

.... LOL that would be an awesome spot



Nope. These havent been opened since the car was made.

If this isn't normal I wont worry about it and just tear it out.

Thanks!

-J

Doesn't seem like a very convenient hiding spot if you're doing it right...


Anyway, what do the pads from the cruddy side look like? I've never seen anything quite like that before and it looks as if there has been uneven contact with the pistons. Whatever it is, I'd suggest using distilled water (de-ionized on the rare chance it's accessible) in a kettle steamer and blast the Pistons clean.

[darkrabbit]

Originally Posted by miamiten

Doesn't seem like a very convenient hiding spot if you're doing it right...


Anyway, what do the pads from the cruddy side look like? I've never seen anything quite like that before and it looks as if there has been uneven contact with the pistons. Whatever it is, I'd suggest using distilled water (de-ionized on the rare chance it's accessible) in a kettle steamer and blast the Pistons clean.

That's what I thought as well but the pads look the same on either side with significantly less wear on the inboard pad, by a few mm. The contact surface has that white shit on it. It must be some sort of antisqueal but why fill the entire piston with it?

I am going to take it out, I have de-ionized distilled, a few jugs, at my disposal. Thanks!

[darkrabbit]

Well this sucks. The white stuff might actually be some corrosion from the pistons! The inboard pistons on both sides are chipped / corroded a little on the contact surface and some on the inside. There's still a solid contact surface but.. wow. You can see it a little in the pics above.

Cheap Brembo garbage....

Looks like I am going to have to rebuild the calipers in the coming months. I am not certain whether there's paste which caused the corrosion eventually, or the pistons corroded causing the white stuff. Either way... not good.

-J

[lemetier]

Originally Posted by darkrabbit

Well this sucks. The white stuff might actually be some corrosion from the pistons! The inboard pistons on both sides are chipped / corroded a little on the contact surface and some on the inside. There's still a solid contact surface but.. wow. You can see it a little in the pics above.

Cheap Brembo garbage....

Looks like I am going to have to rebuild the calipers in the coming months. I am not certain whether there's paste which caused the corrosion eventually, or the pistons corroded causing the white stuff. Either way... not good.

-J

I messaged a friend at Brembo and he responded quite quickly.

The tension springs can become encrusted with gunk and as the pad wears down, the pistons are unable to maintain contact with the pad. Magnesium/Sodium Chloride makes its way in and at 150c and high moisture content, becomes reactive enough to destabilize the stainless and starts galvanic corrosion. The aluminum caliper then acts as an anode and begins to pit as well. The sodium, other electrolytes, and all the reactive metals in the brake dust are in a perfect environment with lots of surface area in a small space, creating a nasty mess. They'll need a complete rebuild and refinish at minimum, though it appears the caliper corrosion might have penetrated into the bores. If you're under warranty, it's something a dealer should look at and cover. It's impossible to clean the tension springs without removing the wheels so this really shouldn't fall back on the customer.

[darkrabbit]

Thanks for the detailed response and thank your friend at Brembo for me. Yep I'll have to do a rebuild. They should be covered by warranty but I wonder what BMW will say when I worked on my own brakes? Hopefully not a problem.

Unbelievable.

-J

[TrevorM3]

put back on the stock pads, take it to dealer and tell them you have a vibration. let them see for themselves. that way they can't say u messed with the brakes. that is some fugly stuff for sure though. and quite frankly unacceptable on a 100k car.

[darkrabbit]

Originally Posted by TrevorM3

put back on the stock pads, take it to dealer and tell them you have a vibration. let them see for themselves. that way they can't say u messed with the brakes. that is some fugly stuff for sure though. and quite frankly unacceptable on a 100k car.

I did rotors as well. Brand new everything. Had to (rotors were toast). I still have everything though and will simply tell them I found this during the swap along with the pics. I have lots of evidence

To be fair, my dealership is pretty good. I'll talk to them and work something out I am sure.

There's no WAY I am the first person with this issue. I'm pissed too because I clean my brakes every time I switch wheels for season change. If it is indeed the tension spring causing this, I wonder if you can run without it?

-J

[lemetier]

Originally Posted by darkrabbit

Thanks for the detailed response and thank your friend at Brembo for me. Yep I'll have to do a rebuild. They should be covered by warranty but I wonder what BMW will say when I worked on my own brakes? Hopefully not a problem.

Unbelievable.

-J

That's the $4k question. I asked him if it was common problem and he stated that it isn't with BMW's, certain Porsches had a slightly higher occurrence, but it's most prevalent in US brands that specify a bargain version with a very crude design that use a shimmed piston face and wedge pad shims to align the pad to the rotor so the the same pad and caliper can be used on different vehicles.

If you have a good relationship with a service advisor and only one caliper had the issue or both did and you've cleaned the residue off both, it could be worthwhile to go with the car and show the photos. If you don't have a comfortable relationship, it still may be worth it, but I wouldn't take the car. It really is a situation where cleaning is a problem, but more from the point that it's a location that is almost impossible to get any effective cleaning action into without an unreasonable amount of effort. If they deny the claim for any reason, you'll be stuck with a dealer rate rebuild minimum and possibly full caliper replacement. They wouldn't reinstall those Pistons and they'll have to come out to check.

It's difficult to really gauge what's happening with the caliper, but there are spots that look as if they might have corrosion under the electroplated protective and finish layers. If it hasn't entered the bores,(rubber is an effective insulator but has varying capacity depending on the decay rate and its own composition). A bath in de-ionized, ph neutral, hydrophobic for the disassembled caliper, followed by a high-temp nano clear coat will do a sufficient job of sealing it off.

If there is pitting in the bores, this particular caliper is right at the limits and reboring/sleeving isn't recommended. It's also not a huge cost savings compared to the deals that can be had from vendors/members on here.

[lemetier]

Originally Posted by darkrabbit

I did rotors as well. Brand new everything. Had to (rotors were toast). I still have everything though and will simply tell them I found this during the swap along with the pics. I have lots of evidence

To be fair, my dealership is pretty good. I'll talk to them and work something out I am sure.

There's no WAY I am the first person with this issue. I'm pissed too because I clean my brakes every time I switch wheels for season change. If it is indeed the tension spring causing this, I wonder if you can run without it?

-J

The worn rotors most likely set it up perfectly (especially if you didn't have the dampened pads) and it probably didn't occur too long ago. It also might not have been very noticeable and alkaline or acidic cleaners can make the electrolytes go rampant. We see it occasionally with Magnesium wheels that have been installed without the insulating pad or refinished/touched up improperly.

If that buildup had been there long term, Pistons would have begun to seize in retracted and extended positions. The sound and feedback through the wheel would have been noticeable. The tension spring is necessary and the dampened pads help since they vibrate the spring to harmonically balance out squeal.

[darkrabbit]

Originally Posted by miamiten

That's the $4k question. I asked him if it was common problem and he stated that it isn't with BMW's, certain Porsches had a slightly higher occurrence, but it's most prevalent in US brands that specify a bargain version with a very crude design that use a shimmed piston face and wedge pad shims to align the pad to the rotor so the the same pad and caliper can be used on different vehicles.

If you have a good relationship with a service advisor and only one caliper had the issue or both did and you've cleaned the residue off both, it could be worthwhile to go with the car and show the photos. If you don't have a comfortable relationship, it still may be worth it, but I wouldn't take the car. It really is a situation where cleaning is a problem, but more from the point that it's a location that is almost impossible to get any effective cleaning action into without an unreasonable amount of effort. If they deny the claim for any reason, you'll be stuck with a dealer rate rebuild minimum and possibly full caliper replacement. They wouldn't reinstall those Pistons and they'll have to come out to check.

It's difficult to really gauge what's happening with the caliper, but there are spots that look as if they might have corrosion under the electroplated protective and finish layers. If it hasn't entered the bores,(rubber is an effective insulator but has varying capacity depending on the decay rate and its own composition). A bath in de-ionized, ph neutral, hydrophobic for the disassembled caliper, followed by a high-temp nano clear coat will do a sufficient job of sealing it off.

If there is pitting in the bores, this particular caliper is right at the limits and reboring/sleeving isn't recommended. It's also not a huge cost savings compared to the deals that can be had from vendors/members on here.

Thanks, I will send them pics and see what they can do. I will tell them right off I am not paying for a rebuild. I can buy new calipers for that price. The problem is there's no piston P/N so I need to buy a new caliper most likely, or see if I can run the P/N of the caliper and find replacement pistons.

Originally Posted by miamiten

The worn rotors most likely set it up perfectly (especially if you didn't have the dampened pads) and it probably didn't occur too long ago. It also might not have been very noticeable and alkaline or acidic cleaners can make the electrolytes go rampant. We see it occasionally with Magnesium wheels that have been installed without the insulating pad or refinished/touched up improperly.

If that buildup had been there long term, Pistons would have begun to seize in retracted and extended positions. The sound and feedback through the wheel would have been noticeable. The tension spring is necessary and the dampened pads help since they vibrate the spring to harmonically balance out squeal.

The rotors were still above minimum thickness so there's no good reason for this. I'd get it if the car wasn't maintained but a brake caliper from a "reputable" brand should not do this if taken care of properly. I take better care of this car than most who own it do, and it's frustrating that a part from what's supposed to be a quality product deteriorated so badly.

It may not have been there long term, but I've noticed a slight deterioration of braking performance over the last few months.

I am wondering if I should get the vibration dampers... Might be worthwhile.

I'll let you know what happens. Thanks!

EDIT: I should mention as well I just have stock wheels. Everything stock, until now as I've put on Carbotech pads, SS lines, RBF600 fluid. Sucks that I'll probably lose a L of that stuff re-bleeding :/

-J