RKCRLR

I've had a rattling noise from my front suspension for a while now that would go away under slight braking. I removed my front wheels today to see if I could determine where the noise was coming from. I noticed a couple of things:
The plastic air deflectors mounted on the lower control arms flops around enough to contact the upper control arm.
The mass dampers on the Powerstop Z26 pads were loose. I pulled out my OEM pads and verified that the mas dampers were not loose on the original pads.

I called Powerstop to ask about this. They said their pads were warrantied for 3 years for cracks but rattles are not covered under warranty.

When I removed the pads I noticed that the stainless shims had walked on the pads (see pictures below). I suspect that gravity pulls the pads to the bottom of the calipers. The pads then attempt to migrate to the top of the caliper under braking. The friction between the shim and piston is greater than the strength of the adhesive between the shim and the pad (especially at temperature) and causes the shim to migrate to the bottom of the caliper over repeated cycles. This is all conjecture.

I used a ball peen hammer to tighten the rivets that hold on the mass dampers. I contemplated re-positioning the shims but have no idea what kind of adhesive to use so I left them alone.

I reinstalled the pads and took the car for a test drive. The rattling noise that went away under braking is gone. There is still some noise on rough surfaces - perhaps the deflectors.

Just thought I'd throw this out there for other Powerstop pad users.

2019GSTX

RKCRLR

They also have a 60 day satisfaction guarantee (or something like that). You may want to wait until that 60 days is up until you do something like I did in case there are other problems, they may not like hammer marks on their brake pads.

Adam@Amp'dAutosport.com

Good info..

2019GSTX

Quick question as I have not done a brake job on a C7 yet....do they recommend brake grease for the back of the pads? I have always used it on my Silverado SS brakes.....thanks!

Mayor111

Can you post a picture and circle where you had to bang in pins on the pads - you provided great information, and Im installing these pads (and rotors) in the spring - but Im just not clear on what needed to be done to resolve.

Thanks for any additional pictures and info you can share.

RKCRLR

The factory manual just calls for grease on the edge of the pads where they contact the calipers so that is what I did (I did put some lube on the pins where the pads contact). I did not put any lube on the back of the pads.

RKCRLR

@Mayor111
The mass dampers are the weights on the "ears" of the pads. You can see the dimple marks from the ball peen hammer on the rivet heads in the pictures I posted.
I recommend you check the weights to see if they are loose before you do anything. If they are loose contact Powerstop to see what they want you to do. This could be a limited manufacturing defect. You don't want to do anything that would void the warranty.
It was quite clear that they weren't going to do anything for me since I was past the 60 days and the pads weren't cracked. .

RKCRLR

Update:
I sent an email to Poweerstop tech support and asked them if these issues are normal for their brake pads. They said they are not normal and are covered under warranty. They are going to send me a replacement set of pads.

Adam@Amp'dAutosport.com

Yes, all they need is a lite coverage edge to edge on the backing plates. http://netwelding.com/Ceramic_Pads.pdf

okaythen

Thanks a lot I thought I was the only one with z26 that's making noises!

Before I did a semi emergency stop then after that there was a pretty loud rattling from left front brake pad. Took it out and put it back in and the rattling was gone, not sure what that was, pad looked fine but didn't check if shim and pad were loose. Anyways no rattle for awhile but recently at 15mph or so, when I turn right slightly there is a little "flapping" noise, if I brake slightly the noise will go away. (also the flapping have been there for awhile, it didn't get louder and I don't drive the Z06 that often so been ignoring it.)

Before I got the Z26 I did a lot of research and no one mentioned what you said, I tho I was the only one after I got them. Maybe it's not a common problem and we got a bad batch?

pad looks ok etc (without taking off wheel) But after seeing your thread I guess I should look into it.

What did you email powerstop to get new ones? That they make noises? thanks

KNSBrakes

Lots of pads have the shim go around the pin hole so if it comes unglued it cannot fall

bjones7131

I am thinking about going with the Z23 which I don't think has the shim that is there for heat transfer If I remember correctly.

RKCRLR

I sent Powerstop tech support a picture of the displaced shims and asked them if this was normal. They said no and sent me some new pads.

I had two noises coming from my brakes. The higher frequency rattle was from the loose brake pad mass dampers. A lower frequency rattle (went away when braking) was due to a loose rotor disk on the hat (I had the early 2 piece rotors). If you have an early car with the 2 piece rotors you may want to see if they are loose.

JMII

Correct. The shim helps isolate the pad from the caliper to reduce heat transfer. I used titanium shims on my last track car, but I've yet to see them offered for Z51 sized pads, only GS / Z06 pads in the aftermarket.

I have the Z23 pads on my car which has no metal shim and instead uses the more common rubber sticker like material as a backer. I could see where the shims on the Z26 might create noise as it wiggles between the pad and the caliper pistons. This product applied between the shim and the pad should help eliminate noise.

KNSBrakes

Shims on street pads are for noise isolation.

Titanium shims on track pads are to reduce heat transfer to brake fluid through AL pistons which are common on OEM Brembo's