Author Topic: Brake pads wear  (Read 587 times)

julio

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Brake pads wear
« on: February 16, 2019, 10:26:44 PM »
My brake pads seems to be worn irregularly (12000 kms)

What do you think ?


« Last Edit: February 16, 2019, 10:31:56 PM by julio »

jags

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Re: Brake pads wear
« Reply #1 on: February 16, 2019, 11:19:23 PM »
thats normal wear .you should change to koolstop salmon easier on the rims and netter stopping in rain.

mickeg

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Re: Brake pads wear
« Reply #2 on: February 17, 2019, 12:40:09 AM »
When mine start to wear that way, I usually re-adjust them so that the wear is more even.  But you do not have much more life in them so is it better to replace them?

The two photos here are my pads after I did my Pacific Coast trip, I replaced them immediately after I took the photos.  I do not have an end view like in your photo, but I am sure from an occasional adjustment that mine had more normal wear.


B cereus

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Re: Brake pads wear
« Reply #3 on: February 17, 2019, 10:04:09 AM »
What width rims do yo have?

Apologies if you already know this. The matching pairs of concave/convex washers differ in thickness to allow for different rim widths so that  the pad contacts the rim as close to parallel as possible.
Use whichever pair adjacent to the brake shoe that gives the best compromise.

Its also important that you assemble the conical washers correctly to allow setting of toe-in.

Here are Koolstop instructions.

http://www.koolstop.com/english/pdf/Inst_VBrakeThreadedthin.pdf

julio

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Re: Brake pads wear
« Reply #4 on: February 17, 2019, 08:24:50 PM »
Today i did as Mickeg, i re-adjusted the orientation, if i can get some thousand kms more, i will see...

And thanks B Cereus for the pdf, i did a mistake, mounting error at the back.
« Last Edit: February 17, 2019, 08:29:33 PM by julio »

rafiki

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Re: Brake pads wear
« Reply #5 on: February 18, 2019, 06:57:21 AM »
What width rims do yo have?
The matching pairs of concave/convex washers differ in thickness to allow for different rim widths so that  the pad contacts the rim as close to parallel as possible.
Use whichever pair adjacent to the brake shoe that gives the best compromise.

http://www.koolstop.com/english/pdf/Inst_VBrakeThreadedthin.pdf

Sorry, I'm a novice at this so could you explain please what you mean by rim width? Which measurement are you referring to? How does one choose which washer combination to use with a particular rim width?
« Last Edit: February 18, 2019, 07:06:18 AM by rafiki »

B cereus

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Re: Brake pads wear
« Reply #6 on: February 18, 2019, 11:15:15 AM »
What width rims do yo have?
The matching pairs of concave/convex washers differ in thickness to allow for different rim widths so that  the pad contacts the rim as close to parallel as possible.
Use whichever pair adjacent to the brake shoe that gives the best compromise.

http://www.koolstop.com/english/pdf/Inst_VBrakeThreadedthin.pdf

Sorry, I'm a novice at this so could you explain please what you mean by rim width? Which measurement are you referring to? How does one choose which washer combination to use with a particular rim width?


Refering to the Koolstop illustration that I linked to earlier.

http://www.koolstop.com/english/pdf/Inst_VBrakeThreadedthin.pdf

The rim width is the distance between the braking surfaces of the rim.

In the head on view you can see that the brake pads are set to contact the rim parallel to the braking surface. A substantially wider  or narrower rim would see the brake shoe making contact with the rim at a slight angle. The brake shoes are supplied with  matched pairs of convex/concave washers which when paired together are of differing overall thickness. One pair goes on either side of the brake arm. The thickness of the washer pair fitted immediately adjacent to the shoe governs the geometry of the set up. With the thicker pair fitted adjacent to the shoe it will space the shoe away from the arm and will generally suit a narrower rim. Similarly the narrower pair will better suit a wider rim.

In practice the exact geometry is dependant on a number of factors. Most notably the exact height and distance apart of the brake mounting bosses. Also, despite initial set up, the pads will wear increasingly unevenly as the brake shoes wear down, as in julio's illustration.


The other purpose of the convex/concave washers is to allow the brake shoe fixing bolt to swivel in relation to the brake arms. This allows  for precise alignment and in particular the setting of toe-in, whereby the leading edge of the shoe contacts the rim ahead of the trailing edge.
 
For a good explanation of all of this, including the setting of Toe-in, see this park tools web site.

https://www.parktool.com/blog/repair-help/linear-pull-brake-service
« Last Edit: February 18, 2019, 11:20:10 AM by B cereus »

rafiki

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Re: Brake pads wear
« Reply #7 on: February 18, 2019, 01:28:39 PM »
Thank you very much B cereus. I have bookmarked this for future reference.