Quick front brake question
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Nope, I got that clip, it's kind of important too!
The clip is in the picture in the original post. The flat metal thing to the right of the pad.
Later,
Chrome...
That's a shim. Some brake pad sets have them, some don't. Stock first gens didn't have them. Not a big deal. If your pad set doesn't have them, nothing to worry about.
Shims can be good (reduce squeal) or bad (make squeal worse). I wouldn't install shims unless they came with the pad set.
Shims can be good (reduce squeal) or bad (make squeal worse). I wouldn't install shims unless they came with the pad set.
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125 Posts
They can keep the pad from rattling around too much.
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799 Posts
no, they don't
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947 Posts
The stainless steel provides a hard clean surface for the pistons to contact and helps prevent some of the heat transfer from the pads to the pistons. There is a very very small amount of pad movement (sliding and rattling) against the pistons and the hard stainless provides a better surface for that than just the back or the pad alone.
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799 Posts
actually it is heat shield. stainless does not conduct heat as fast as steel used for pad backing or aluminum pistons or steel pistons (most are aluminum lately).
they have nothing to do with squeal, squeal is from pads moving which this plates don't stop. anti rattle is not either since they rattle anyway. anti rattle are wire clips like rear pads have or on front it would be plate on top of pads pushing down on pads. basically it is spring.
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563 Posts
I accidentally left those shims off another bike (rear brake) and it squealed like crazy. I'm not kidding: it was nuts. After I discovered my mistake and installed the shims, the noise completely disappeared. I'm not an expert; I'm not saying they aren't heat shields, but my personal experience was that they suppress vibration.
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If you look at the OP's pic you can see how they reduce the contact surface area between the pad and pistons which reduces heat transfer. The slots also allow for quicker cooling. Bearing is what they are doing. The pad has some amount of "squirm" on the pistons and the stainless is a better material to handle it. BTW, both my first gens certainly came with "shims".
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799 Posts
scroll down to bottom of this page and you will read what plate is for from manufacturer of plate and pads. most people are confusing heat shield with shim, anti-rattle shim or squeal shim. if you think about it you can figure out that plate that rattles itself can not stop rattling 
and as Marc said they do protect aluminum pistons from wearing out against steel pads.
http://www.ebcbrakes.com/mcoffroadpads.html
and as Marc said they do protect aluminum pistons from wearing out against steel pads.
http://www.ebcbrakes.com/mcoffroadpads.html
I agree that anti-rattle and anti-squeal claims are bogus. And stainless steels are generally softer than carbon steels, so the shim won't help as a bearing material.
It is true that stainless has a lower coefficient of heat transfer than typical steel plate (typical values around 8 vs. typical values around 26 BTU/(Hr*ft*deg. F)). However, the very thin shim material doesn't provide much of a thermal break. At best maybe 2 deg. F difference.
It is true that stainless has a lower coefficient of heat transfer than typical steel plate (typical values around 8 vs. typical values around 26 BTU/(Hr*ft*deg. F)). However, the very thin shim material doesn't provide much of a thermal break. At best maybe 2 deg. F difference.
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799 Posts
most pistons are aluminum. you don't want to rub aluminum against anything. stainless polished sheet metal is perfect in between.
same sheet is good to slow down temperature transfer from brake pad to piston when brake is in use.
really good stuff used lately for race car brakes is titanium.
same sheet is good to slow down temperature transfer from brake pad to piston when brake is in use.
really good stuff used lately for race car brakes is titanium.
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2,212 Posts
As Andy says, they're a 'anti squeal' shim; they help to eliminate high frequency vibration that we hear as squeal. They work well on some vehicles, and less so on others. There are some notable examples of vehicles where to remove them is to be bugged by a squeal any time the brakes are applied lightly. One would think that given that the piston is pushing the pad into the disc, they shouldn't do a **** thing, but it's a harmonics thing... suffice to say, if the factory has fitted them, you might as well refit them... if you've lost one, then only you in your particular cirumstances can decide whether replacement is justifable or not... some combintations of disc (wear also), pad squeal more than others as no doubt most of you have experienced at some stage.
Bottom line, they're not a safety item, you won't die without them.
Pad manufacturers over the last 10 years (longer than that actually, since asbestos was removed from their diet) have put a lot of effort into developing compounds that deal well with heat transfer, and a lot of effort has also been put into the ideal backing plates. Some of them... plenty of junky pads out there, although bikers are fortunately not as likely to run across those as car drivers.
Typically anti-rattle items are clips designed to give the pads tension in their mountings... some calipers have these, some do not. Again, not a safety item.
The shims won't do bugger all for heat transfer reduction.
One benefit they do provide is somewhere to put a little brake grease when installing new pads. Obviously any lubrication is the last thing you want on your friction surfaces, so having something to smear them between (the shim and the backing plate) is convenient. Again, the brake grease is designed to alter the harmonics of the sedtup, again reducing the tendency of brakes to squeal under light application. Without shims you're only option is to delicately smear grease on the face of the piston, where it touches the backing plate. IMHO it's worth doing if you have the right grease available.
Don't use any old grease for this, it's not designed for the heat load... I've had the pleasure of trying a good range of products, and I keep coming back to this. A small sachet will keep you going for 5-6 pad changes, and it's also good for lubing slides on sliding calipers (like the SV650 has).
Bottom line, they're not a safety item, you won't die without them.
Pad manufacturers over the last 10 years (longer than that actually, since asbestos was removed from their diet) have put a lot of effort into developing compounds that deal well with heat transfer, and a lot of effort has also been put into the ideal backing plates. Some of them... plenty of junky pads out there, although bikers are fortunately not as likely to run across those as car drivers.
Typically anti-rattle items are clips designed to give the pads tension in their mountings... some calipers have these, some do not. Again, not a safety item.
The shims won't do bugger all for heat transfer reduction.
One benefit they do provide is somewhere to put a little brake grease when installing new pads. Obviously any lubrication is the last thing you want on your friction surfaces, so having something to smear them between (the shim and the backing plate) is convenient. Again, the brake grease is designed to alter the harmonics of the sedtup, again reducing the tendency of brakes to squeal under light application. Without shims you're only option is to delicately smear grease on the face of the piston, where it touches the backing plate. IMHO it's worth doing if you have the right grease available.
Don't use any old grease for this, it's not designed for the heat load... I've had the pleasure of trying a good range of products, and I keep coming back to this. A small sachet will keep you going for 5-6 pad changes, and it's also good for lubing slides on sliding calipers (like the SV650 has).
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799 Posts
anti squeal shim is rubber glued to back of pad or rubber plug put inside piston.
purpose of this metal plate is not to stop squeal ( even tough it may help), it is to reduce heat transfer.
here is somebody that got it right, page 40.
http://books.google.com/books?id=u3U2xiPWWyQC&pg=PA37&lpg=PA37&dq=motorcycle+brake+pad+shim&source=bl&ots=bGlwIZIdZC&sig=U7hQ7nFJRBxLo_BggJSWt355BoA&hl=en&ei=YiHXSeWUJ6HqsgOztKmfCg&sa=X&oi=book_result&ct=result&resnum=7#PPA40,M1
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