Those pad-sized shims on brake pads... they do what?

I ask because the other weekend I had to grind down some pads to make them fit in my front calipers. (Not the pad material, just the 1/4" thick backing plate.) As the old ones were _totally_ shot, I didn't have much choice other than 'make 'em fit'. And I figured not having them wouldn't kill me. But grinding them to fit removed the little tabs where that metal shim clips on, so no metal shim.

Well, actually, I only needed to do this on the outside pads, not the inside, so it's the pad against the piston that doesn't have the shim.

Anti-squeak?

Thermal insulation?

Physical wear?

I'm not afraid to say I don't know something, so there it is, I don't know what those _really_ do. Does anyone else?

Cheers,
Anders

---

Grassroots rally. It's what I think about.

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Anders Green
Physical wear?

ding ding ding. they squeak when your pads wear down.

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Anders Green
I ask because the other weekend I had to grind down some pads to make them fit in my front calipers. (Not the pad material, just the 1/4" thick backing plate.) As the old ones were _totally_ shot, I didn't have much choice other than 'make 'em fit'. And I figured not having them wouldn't kill me. But grinding them to fit removed the little tabs where that metal shim clips on, so no metal shim.

Well, actually, I only needed to do this on the outside pads, not the inside, so it's the pad against the piston that doesn't have the shim.

Anti-squeak?

Thermal insulation?

Physical wear?

I'm not afraid to say I don't know something, so there it is, I don't know what those _really_ do. Does anyone else?

Cheers,
Anders

Anti-squeal and if they're stainless, a bit of heat blocking since stainless transmits heat so poorly.



Edited 1 time(s). Last edit at 09/13/2010 03:41PM by john vanlandingham.

its not a real racecar unless the brakes squeak really bad at slow speeds...

I would ask why you had to grind them down, wrong pads, weird brake combination or calipers sticking in the bore and going to sieze up in a week?


I had to grind pads to fit the Audi Gt. We got Quattro pads from EBC and they were a tad thick for GT calipers but I ground the pad down on a belt sander. A bit stinky and actually caught fire under the belt sander! I didn't notice that until a couple months later btw, could have lost the whole shop....

Anders,

Is this a race pad or street pad? I take it that its a street pad or else it wouldnt have that shim. What that does on street pads is to dampen the resonance of the backing plate against the pistons or anchors.

There wouldnt be much thermal barrier if it was indeed intended for that because even though SS has a slow heat transfer, then it would still quickly reach its thermal capacity and transfer the same amount of heat into the caliper. (steady state heat is still the same)

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DirkaDirkaJack
its not a real racecar unless the brakes squeak really bad at slow speeds...

Thats right. Because if the brakes arent "resonating" then you're leaving performance on the table. Just like trying to quiet down a race motor.

Paul: This is for a street car.

Gene: Simultaneously the right and wrong pads. Correct according to the database at autozone (and actually the same as some that I had sitting around as a backup for the rally car (which is the same) a couple years ago) so I'm sure that going back to any auto store would get me the same ones again. However, still the wrong shape. Correct ears, but needed about 2-3 mm removed to fit in the calipers.

So the shim is like a damper to remove high pitched vibrations that cause noise? I guess that then makes it interesting because OEMs can mess with the shim as well as the compound. Now, why do some compounds vibrate more or less? Is that the gasses escaping from under the rotor?

Anders

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Grassroots rally. It's what I think about.

those anti-squeal shims scare me on cars that don't have a way of keeping them 100% captive , after a customer came in and said they felt some vibration during braking, took a look and one of the stick on shims had come loose, dropped down and cut the rotor off of the hat. i'll try and dig up the pictures of it.

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fidel
those anti-squeal shims scare me on cars that don't have a way of keeping them 100% captive , after a customer came in and said they felt some vibration during braking, took a look and one of the stick on shims had come loose, dropped down and cut the rotor off of the hat. i'll try and dig up the pictures of it.

I toss the shims as well. We do several to lots of brake jobs a week or month and just haven't had a squeal issue for many years. The new ceramic pads seem pretty good most days.

The brake pads should fit a stock application without modification. I have had to sometimes 'touch' the ears with a grinder but not the back of the pad. I would worry that you'll have a caliper sticking issue.

If one is looking at the pad and the ears are, well, ears, I ground off the chin, not the nose. That is, neither the the pad side, or the side opposite the pad side.

Anders

---

Grassroots rally. It's what I think about.

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Anders Green
So the shim is like a damper to remove high pitched vibrations that cause noise? I guess that then makes it interesting because OEMs can mess with the shim as well as the compound. Now, why do some compounds vibrate more or less? Is that the gasses escaping from under the rotor?

Anders

Compounds "vibration" depends on the aggressiveness of the material, its like running your nails on a chalk board. Another thing in place to stabilize the vibration is the angle and shape of the chanfers on the leading and trailing edge of the pad. Most pads dont outgas that much for it to be an issue.

What car is it and I will check it out.

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Anders Green
If one is looking at the pad and the ears are, well, ears, I ground off the chin, not the nose. That is, neither the the pad side, or the side opposite the pad side.

Anders

So you had to grind an edge off the backing? That happens as I mentioned. Cheap offshore manufacturing I'd guess.

I think the word "auto zone" explains ever thing about the brake pads.

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Anders Green
If one is looking at the pad and the ears are, well, ears, I ground off the chin, not the nose. That is, neither the the pad side, or the side opposite the pad side.

Anders

Come on Anders your embedded programing skills can't be that far gone. It should be neither ... nor ...

Pretty much ALL pads from autozone or oriellys for Subarus (at least in the south) have that same problem.

I always end up taking a grinder to the ears to make them fit. Blah!