Measuring brake pads
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Road Master
Joined: Sep 2009
Posts: 787
Likes: 6
From: Charlotte NC
Measuring brake pads
I have a bit of a squeal coming from my rear pads. As I look at the pads how can I tell if the are shot? The HD tech at inspection said they were fine but I notice the rotor is a bit rough also. These pads have about 15K on them and have yet to change the front.(30k) The plate looks to be at least 1/8 " or more from the rotor.
Road Warrior
Joined: Mar 2010
Posts: 1,422
Likes: 278
From: USA
Rear pads have less material on them compaired to the fronts when both are new.
15k and 1/8" of pad material tell me your pads are like new.
If the squeal is from a glazed rotar, you could sand the glaze off your rotar with some sand paper. 180 grit works well, just put bike on lift and spin the wheel and hold sandpaper on rotar. Do both sides of rotar. It doesn't take much to sand the glaze off.
Another cause of brake squeal is from not using anti squeal on the back of the pads when installed. HD has a kit that has templates you put on the back of the pads (rear pads only), then smear the anti squeal paste on, then remove the template. This way you only get the paste where needed.
15k and 1/8" of pad material tell me your pads are like new.
If the squeal is from a glazed rotar, you could sand the glaze off your rotar with some sand paper. 180 grit works well, just put bike on lift and spin the wheel and hold sandpaper on rotar. Do both sides of rotar. It doesn't take much to sand the glaze off.
Another cause of brake squeal is from not using anti squeal on the back of the pads when installed. HD has a kit that has templates you put on the back of the pads (rear pads only), then smear the anti squeal paste on, then remove the template. This way you only get the paste where needed.
Last edited by timbo141; May 20, 2017 at 02:23 PM.
Seasoned HDF Member
Joined: Aug 2011
Posts: 11,814
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From: SW Ohio
I have a bit of a squeal coming from my rear pads. As I look at the pads how can I tell if the are shot? The HD tech at inspection said they were fine but I notice the rotor is a bit rough also. These pads have about 15K on them and have yet to change the front.(30k) The plate looks to be at least 1/8 " or more from the rotor.
I don't have my newer Touring SM handy, but the Brembo OEM pads are thin to start with. I want to say they recommend replacement at 1mm or something like that.
Club Member
Joined: Jun 2007
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From: Bedford UK
There was a time in the distant past when brake rotors didn't work well until they looked like ploughed fields! If yours look a bit rough they are probably fine and will last until they go below the minimum thickness specified in your FSM. It also sounds as if your pads have plenty of life left, so to solve the squeal follow timbo's suggestion.
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Road Master
Joined: Sep 2009
Posts: 787
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From: Charlotte NC
I took them off and looked at them. one side was pretty worn so I just went ahead and replaced them. Kinda foolish to have the job half done and put the old ones back on. Running like new again. Thanks
Extreme HDF Member
Joined: Jun 2011
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From: Mountain Top, Alabama
With a mirror underneath the caliper, you can easily see the pad thickness.
A dime is approx. 1 mm, a nickel is approx 2 mm (depending on coin condition). You can slide the coin up to the pad and compare. Stack coins, if you like. I have heard of folks using a deck of plastic coated playing cards, they will reveal the thickness of the pad as some will stop at the pad backing plate. In time, just a peek will tell you what you want to know.
To some dealers, most of them "Need Replaced", BTW...
A dime is approx. 1 mm, a nickel is approx 2 mm (depending on coin condition). You can slide the coin up to the pad and compare. Stack coins, if you like. I have heard of folks using a deck of plastic coated playing cards, they will reveal the thickness of the pad as some will stop at the pad backing plate. In time, just a peek will tell you what you want to know.
To some dealers, most of them "Need Replaced", BTW...
Club Member
Joined: Jun 2007
Posts: 45,429
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From: Bedford UK
If they have worn unequally it is worth checking the functioning of your caliper, to make sure both pistons are moving freely. If one is stuck that may explain your squeal, also the uneven wear. I also bleed my brakes and replace the fluid every time I replace pads.
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Road Warrior
Joined: Mar 2010
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From: USA
It was good to post your findings as it reminds us all that the inner and outer pads don't wear at the same rate.
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Stellar HDF Member
Joined: Jan 2008
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From: Earth
What worked for my rear brake squeal was to grind or sand a 45 degree angle on the leading edges of both the inner a and otter pad. I now do this with all new pads. Never have any squeals since.
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