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Replace brake cotter pin with screw?

Old 08-10-20, 08:18 PM
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Ryan_M
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Replace brake cotter pin with screw?

I'm having some minor brake issues and want to pull the pads out to have a look at them, they're M6000 Calipers and have a cotter pin. I get the pin does the job just fine but I dont like them for removal and installation. With the best I can get my calipers in there I measure the pin diameter at 2.65mm. The pin seems kind of loose so maybe the hole is 3mm or close to, I was thinking I could either use a 3mm through bolt with a nylock on the other side or machine the threads off most of a 4mm bolt and tap the caliper on one side (depending if the existing hole size is appropriate). Option 1 seems better for nothing vibrating loose and will take no or minimal modification to the caliper, option 2 seems more elegant. Anyone done either?
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Old 08-10-20, 10:08 PM
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Pads are sitting in their shoes under compression. Both because of the clamping pressures the arms provide and the rim rotational force. For decades open ended pad shoes have worked very well, only recently as liability concerns have increased has the pad being better secured in the shoe become a need.

Have you found that your pads extract themselves form their shoes during use? If not the I suspect you're seeking a solution to a problem that isn't happening. Andy
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Old 08-10-20, 10:18 PM
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I'm not saying the way the pads are "secured" are a problem, I just don't like it. I, want to remove the pads to look at them so I thought while they were out I'd address that (very minimal) issue.

Bending a cotter pin back to its original shape so it slips out easily and not mar the hole on it's way out takes sone time, and that would be exasperated next time if I reused the same pin. I thought I can make a better solution.
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Old 08-10-20, 10:53 PM
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I like that idea. Not a fan of the cotter pins either. If you beat me to this project let me know how it went.
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Old 08-11-20, 12:36 AM
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The SLX, XT & XTR brakes use the following.......

https://www.nashbar.com/shimano-disc...z98010/p305110

I've seen a post where someone tapped a thread to use these 'pad axles' in Deore brakes, they said the thread is a 4mm x .7

https://forums.mtbr.com/fat-bikes/sh...l#post12697195


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Old 08-11-20, 03:41 AM
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Originally Posted by Ryan_M View Post
I'm not saying the way the pads are "secured" are a problem, I just don't like it. I, want to remove the pads to look at them so I thought while they were out I'd address that (very minimal) issue.

Bending a cotter pin back to its original shape so it slips out easily and not mar the hole on it's way out takes sone time, and that would be exasperated next time if I reused the same pin. I thought I can make a better solution.
I don't understand the cotter pin hate. I have bikes with SRAM brakes with a bolt, and Shimano brakes with a pin.

Invariably the bolts end up rounded after several pad changes and are somewhat difficult to find as they're not normal bolts. Moreover on a mountain bike they are a pain in the ass as they are small and the bolt head ends up filled with dried mud, and they tend to stick with time, which makes it easier to accidentally round the head.

Cotter pins on the other hand are cheap, you can find them anywhere, can be installed and removed with the pliers of a swiss knife, and are unaffected by dirt / mud, whatever.

Oh, I forgot to say that the SRAM brakes have a safety pin on the bolt (to avoid it coming loose, I suppose) which tends to break after a few removals. It would be easier to just us a big pin like Shimano "cheap" brakes to begin with.
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Old 08-11-20, 05:23 AM
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Last week while servicing a Sram brake caliper when attempting to remove the pad retaining or "safety" bolt the head broke off. Come to find out another mechanic had this happen as well. Looks like Shimano knows a thing or two and uses cotter pins on a few of their calipers. Makes sense to me.
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Old 08-11-20, 05:33 AM
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Originally Posted by TiHabanero View Post
Last week while servicing a Sram brake caliper when attempting to remove the pad retaining or "safety" bolt the head broke off. Come to find out another mechanic had this happen as well. Looks like Shimano knows a thing or two and uses cotter pins on a few of their calipers. Makes sense to me.
What I don't understand is why they don't use the cotter pins on high end brakes. Bolts rust, get stuck, heads get dirty and then rounded... it's a bad engineered system.
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Old 08-11-20, 06:42 AM
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Buy a box of cotter pins (cheap) and use a new one each time. I suspect that Nylok® nuts might not work well due to brake system heat, either coming loose or melting shut.
Perhaps the safety pins we use on aircraft could be used: https://www.aircraftspruce.com/catal...owlingpins.php

Here are some other locking pin ideas: https://www.mcmaster.com/lock-pins/cotter-pins/

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Old 08-11-20, 07:17 AM
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Originally Posted by Ryan_M View Post
IBending a cotter pin back to its original shape so it slips out easily and not mar the hole on it's way out takes sone time, and that would be exasperated next time if I reused the same pin. I thought I can make a better solution.
Indeed, one is not supposed to re-use cotter pins. Of course, everyone does. But in the classic applications (securing a castle nut with a split-pin through a hole drilled in a bolt, or securing a clevis pin) you're supposed to use a new pin every time you replace the nut. And I guarantee you that your car mechanics DO use a new pin on (for example) crown nuts in suspension service or wheel-retention service. Good ones do, at least! Reusing is probably not super critical as the pin doesn't take stress: the bolt or clevis does. But one uses new pins each time (partially to avoid a fatigued part that has been stressed past the yield point, partially for the fit/finish reason you state).

In this application I think that they use a pin to ensure there's no chance of loss (as can happen with a bolt and nut). And the design doesn't allow you to torque the nut: that would distort the two parts together. Frankly, I don't like the cotter pin in this application. A solid, rather than a split shaft would seem to better handle the significant shear force on this part. To tell you the truth, in this application I like a clevis pin. With a small cotter pin to retain it! I see that Cobba has a picture of such, above.

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Old 08-11-20, 08:50 AM
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Originally Posted by WizardOfBoz View Post
Indeed, one is not supposed to re-use cotter pins. Of course, everyone does.
I don't. It's just not worth it. They're extremely cheap and small, so you can store 10 years worth of pins for your brakes if needed. I replace them everytime I replace pads.
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Old 08-11-20, 08:54 AM
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I grew up on a farm. Seems like every time a cotter pin was used/broke it was replaced with a bent nail. Lol. I think that's where my dislike of them comes from. Every time I look and see that pin I think hmm i bet a 4d finish nail could replace that.
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Old 08-11-20, 09:19 AM
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Originally Posted by Amt0571 View Post
I don't. It's just not worth it. They're extremely cheap and small, so you can store 10 years worth of pins for your brakes if needed. I replace them everytime I replace pads.
You're a rare bird: doing things the way they are supposed to be done!
I still like a clevis pin for shear duty rather than a split-pin cotter. But I suppose Shimano knew what they were doing.
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Old 08-11-20, 10:18 AM
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I think the problem that OP is creating for which they are looking for a solution is the removal of the pads in the first place. There is no need to remove pads unless they are worn or you know them to need some other treatment, like filing off a lip or removing embedded metal rim leavings.

For a better look at the pads, just remove the wheel. If the pads are worn irregularly or have a lip, you might as well remove the pad and pad holder as it needs to be adjusted anyways to prevent recurrence of whatever necessitated the removal.
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Old 08-11-20, 11:53 AM
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https://bike.shimano.com/en-US/produ.../BR-M6000.html

with the cotter pin in your hand , go to an auto parts store and buy a bag of a dozen of them..

or Home Despot
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Old 08-11-20, 11:55 AM
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Originally Posted by Ryan_M View Post
I'm not saying the way the pads are "secured" are a problem, I just don't like it. I, want to remove the pads to look at them so I thought while they were out I'd address that (very minimal) issue.
Bending a cotter pin back to its original shape so it slips out easily and not mar the hole on it's way out takes sone time, and that would be exasperated next time if I reused the same pin. I thought I can make a better solution.
Buy more cotter pins and have them on hand, instead of reusing them.
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Old 08-12-20, 01:28 AM
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Originally Posted by ClydeClydeson View Post
I think the problem that OP is creating for which they are looking for a solution is the removal of the pads in the first place. There is no need to remove pads unless they are worn or you know them to need some other treatment, like filing off a lip or removing embedded metal rim leavings.

For a better look at the pads, just remove the wheel. If the pads are worn irregularly or have a lip, you might as well remove the pad and pad holder as it needs to be adjusted anyways to prevent recurrence of whatever necessitated the removal.
Correct. If everything is ok, pads don't need to be removed unless you have to replace them or you need to bleed the brakes for whatever reason.
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