Parking Brake Pad Separation

[brantse]

I've had an occasional, but pretty consistent metallic sound coming from my right, rear wheel for some time now. I actually believe it began the last time my car was at the service center, in which they replaced my brakes with the "cold weather" version. The sound was a very hollow, sheet metal type sound that would occur when hitting bumps. I thought it likely had something to do with the brake backing plate, but wasn't quite sure exactly what was causing it. Last night, when changing back over to my summer wheels, I found that the one parking brake pad lining had separated from it's backer and got stuck between the rotor and backing plate. I've seen this happen on conventional brake pads, but am very surprised that this happened on a parking brake. Not sure if the pad had got hung up at some point or if it wore after falling apart, but there wasn't a whole lot of it left.

 

[Tennisballer]

Are you sure it separated it looks like the slides may be rusted and caused it to get into a bind and wear that pad out. When they get rusted and the brake applies it is supposed to relax back after it is disengaged. This would cause the pad to wear prematurely. How many miles I am surprised your range has not fallen off looking at that.

 

[brantse]

Are you sure it separated it looks like the slides may be rusted and caused it to get into a bind and wear that pad out. When they get rusted and the brake applies it is supposed to relax back after it is disengaged. This would cause the pad to wear prematurely. How many miles I am surprised your range has not fallen off looking at that.

The brake lining is sitting on top of the caliper in the second picture. It's hard to see, but you can see that the inside pad's metal backing is tight against the rotor. I'm also very surprised by this, especially considering that parking brakes are really only used at a stop. I agree that the slides look to be very corroded and likely aren't letting the pads slide very freely. You gotta love our NE winters .

The car has 35k miles and I haven't noticed any drop in range since I picked it up as a CPO at 24k.

 

[Tennisballer]

That is strange I see now it's laying right there lol. That pad should literally last forever I would think because it's only used for parking like you said. It had to be defective.

 

[mspohr]

That is strange I see now it's laying right there lol. That pad should literally last forever I would think because it's only used for parking like you said. It had to be defective.

Looks like the pad is completely worn out to 0 thickness. You also have an amazing amount of corrosion of the pins which is probably the source of the problem. If the calipers can't move freely, you'll get a constant rubbing and wear of the brake pad.
The whole assembly needs to be removed, cleaned and corroded/worn parts replaced. It shouldn't be difficult for a qualified brake mechanic. Check the rotor for scoring... it might need to be replaced. Also check all the other brake calipers. They probably are corroded also.
Brake job all around!

 

[Brass Guy]

A couple of us were discussing parking brake pad separation on this thread. I figured it deserved its own thread so I woke this one up when I found it.
My brakes don't look corroded like these pictures at all, but 3 of my parking brake pads have separated.

Tesla lists $220 for pads, they can be found under $50 online. Wagner MX971 are a fit. In my case anyway, the new pads where shorter by maybe 1/4 inch.

We both have some problems getting all the pins out. On each caliper, one pin came out without too much trouble, and on one caliper one pin got really beat up without budging. I had the 2 halves of the caliper apart and it's the inside end that's stuck. It has the most surface area in contact with the aluminum.
I eventually had to drill mine. Replacement pin sets from Tesla are listed at $18 per caliper (pair of pins and a replacement spring). The package had a Brembo "instruction" booklet (nearly useless) with a part number 98.8248.60 which may or may not prove useful.

In case anybody's interested in the process I used:
I cut through the stuck pin and separated the caliper halves. I shimmed it on a drill press using the empty hole to get the angle right. The hole is counter bored, the larger diameter goes most of the way through. Make sure you don't drill too deep from that end - I set the stop on the drill press using the empty hole. Lastly I had to clean out the holes; I intentionally drilled slightly under size as I was afraid of destroying the aluminum caliper. A hammer and nail helped peel out the remaining crescent, still stuck to the wall of the hole. I will say I did not like the prospect of drilling out a steel pin from an aluminum casting, but with a decent setup all worked out in the end.