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Brake pad replacement questions

Started by 1.21GW, June 21, 2015, 07:52:43 AM

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1.21GW

June 21, 2015, 07:52:43 AM
I replaced my front brake pads yesterday.  First time doing it.  Very simple job it turns out.  Anyway, I have a few follow up questions:

- the old pads had groves through the friction material.  My replacement pads (EBC Double H) have no grooves and are one contiguous surface.  What's the difference?  My guess is that the grooves allow better cooling and perhaps allow brake dust to vent away better.  Meanwhile, grooveless would have relatively more grip, since they have slightly more surface area.  Are these assumptions correct?

- what is everyone's favorite way to set the new pads?  I haven't gone out to set them yet because it has been raining all weekend.  I've read three methods: (1) do a couple of heavy stops at 20mph, then 30mph, etc. all the way up to 60mph; (2) ride 250 miles of urban riding with an emphasis on strong braking; (3) 25 heavy stops at 25 mph.

- I elected to replace the front pads because I've owned the bike for 3 years and have not replaced them, while I'm not sure if/when the PO did.  Upon removal, the old pads had plenty of material left, about 3-4mm (I've read that you should replace at 2mm).  I decided to replace regardless.  Here's the thing, the right caliper had both pads at ~3.5mm thickness remaining; the left had one pad ~3mm and one ~4mm.  Why would two pads on the same caliper wear at different rates?  Is there something I should check regarding the operation of my left caliper?

- I took the opportunity to clean my calipers using soapy water.  They are now much cleaner, but still have some stubborn gray brake dusty splotches.  Any suggestions on how to remove these?

"I doubt I'm her type---I'm sure she's used to the finer things.  I'm usually broke. I'm kinda sloppy..."

ducpainter

#1
June 21, 2015, 07:59:02 AM
I bed in pads like this.

Clean rotors with brakleen and a scotchbrite to remove the old pad material.

On a straight stretch of road with relatively light traffic accelerate to 60 and brake hard 7 or 8 times down to about 20mph.

Then ride home without using the front brake...it needs to completely cool.

Done.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


koko64

#2
June 21, 2015, 10:28:47 AM
Could it have been a wear indicator groove that you saw?

2015 Scrambler 800

DarkMonster620

#3
June 21, 2015, 10:47:34 AM
Quote from: koko64 on June 21, 2015, 10:28:47 AM
Could it have been a wear indicator groove that you saw?


there are none . . . that's "normal". . . at least here where there is a lot of grime even cars are  marked like that
Carlos
I said I was smart, never that I had my shit together
Quote from: ducatiz on March 27, 2014, 08:34:34 AMDucati is the pretty girl that can't walk in heels without stumbling. I still love her.
"When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth."

Howie

#4
June 21, 2015, 10:57:36 AM
Most aftermarket pads do not have the groove.  It's purpose, besides making it real easy to see when your pads are worn is to help prevent gas fade* during high speed braking,  Totally not needed since your bike has cross drilled rotors.

If you can follow Nate's advice on bedding, do. It works, but is difficult in New York Silly.  If you can't, avoid very hard or very light braking for the first 100 miles or so and all will probably be good.  Since your rotors are used expect a less than perfect lever until they bed in.

As long as the pistons moved in easily I would not be concerned with the .5mm wear difference




*Gas brake fade occurs the brake pad is actually skidding on a film of gas and brake dust created by the over heating.

1.21GW

#5
June 21, 2015, 12:55:56 PM
Quote from: koko64 on June 21, 2015, 10:28:47 AM
Could it have been a wear indicator groove that you saw?


No, because they went as deep as all the way to the metal, so wouldn't make sense as a wear indicator.


Quote from: howie on June 21, 2015, 10:57:36 AM
Most aftermarket pads do not have the groove.  It's purpose, besides making it real easy to see when your pads are worn is to help prevent gas fade* during high speed braking,  Totally not needed since your bike has cross drilled rotors.

If you can follow Nate's advice on bedding, do. It works, but is difficult in New York Silly.  If you can't, avoid very hard or very light braking for the first 100 miles or so and all will probably be good.  Since your rotors are used expect a less than perfect lever until they bed in.

As long as the pistons moved in easily I would not be concerned with the .5mm wear difference




*Gas brake fade occurs the brake pad is actually skidding on a film of gas and brake dust created by the over heating.


I was in the burbs visiting my father for Father's Day, so I was able to find some unoccupied roads to do Nate's method.  I thought I did it right, but I think maybe I didn't go hard enough.  I let them cool for a little over and hour and then road back into the city.  Since it was highway, I didn't need the brakes until I hit traffic in da Bronx.  Then they started acting funny---grunting with not effect, then suddenly biting hard.  So I laid off them and used engine/rear braking until I got home.  I'm letting them cool now and will test them tonight or later this week.

Didn't think I could, but I may have screwed up the bedding process.  Nate's instructions were pretty clear, and jibed with stuff I read online, so this is 100% human error on my part.
"I doubt I'm her type---I'm sure she's used to the finer things.  I'm usually broke. I'm kinda sloppy..."

ducpainter

#6
June 21, 2015, 01:52:19 PM
HH pads do have a strong initial bite, but I've never experienced a 'delay'.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


oldndumb

#7
June 21, 2015, 03:57:01 PM
The HH rating is an SAE designator for cold and hot coefficient of friction. Far as I know, they are the highest rating available for street machines, but there could be some now available which I am not aware of.

As stated, there should not be any "delay".

If it were me, since they are new, I would remove them and clean them with denatured alcohol. Then clean the rotor surfaces, inner and outer. There are tools available for this, so do not try to improvise and use something which might be excessively aggressive. Not having the correct tool, you could safely use some ScotchBrite or BearTex, essentially the same material. Then thoroughly clean the rotor surfaces with denatured alcohol before reinstalling the calipers.

I suggest using alcohol because certain solvents are not universally available in all localities. If Methyl Ethyl Ketone or Acetone is available, use that.

Back in the drum brake days, spray brake cleaner was fine. When the changeover to discs happened, some of the older brake cleaners actually caused material deposits (cementite) on the new discs. Far as I can tell, the safest spray brake cleaners to use on disc brakes now are the ones based on tetrachloroethylene. Once again, those products are not universally available.

Once that is done, go through the bedding process again. It really should not be that difficult.

And that is the long winded version of ducpainter's advice.  :)

ducpainter

#8
June 21, 2015, 04:09:20 PM
If you use MEK...which I doubt you can buy in NY...use gloves and do it outside or wear a respirator. I'm not very sensitive to most chemicals anymore, but MEK will give you a buzz you won't really enjoy.

"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


oldndumb

#9
June 21, 2015, 06:20:17 PM
I'm in Fl so can find MEK at some suppliers. When I do, I stock up. I use quite a bit of it, and should know better.
I won't even mention my other favorite solvent, trichloroethylene.  [evil]

ducpainter

#10
June 21, 2015, 06:28:30 PM
I worked at a shop that had a trich soaking 'vat'. Great cleaner.

I can buy MEK in NH, but I only used it for one purpose, and I won't do that job anymore.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


1.21GW

#11
June 21, 2015, 06:38:50 PM
Quote from: ducpainter on June 21, 2015, 06:28:30 PM
....
I can buy MEK in NH, but I only used it for one purpose, and I won't do that job anymore.

"I doubt I'm her type---I'm sure she's used to the finer things.  I'm usually broke. I'm kinda sloppy..."

ducpainter

#12
June 21, 2015, 06:55:04 PM
Nowhere...

near that much fun. ;D
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


Howie

#13
June 21, 2015, 09:34:34 PM
Sounds to me like it just might have taken a while for the pads to bed since they need to conform to your previously used rotors.  If your old pads with the groove look like these  https://www.bing.com/images/search?q=oem+ducati+brake+pad&view=detailv2&&&id=FED5753E53A6FC9204177C467C276A14E03D225C&selectedIndex=0&ccid=vqvViMSe&simid=608032421858184567&thid=JN.TqSqpzcAji26lOXsngb06A&ajaxhist=0  (sorry, no tiny URL on this computer yet)  they were probably OEM, and definitely have less initial bite than your EBC HH pads, a much less wooden feel too.  You should never need more than two fingers with those pads.  Do keep in mind I am guessing at what you felt.  On used rotors first thing I do is measure the rotors to assure they are still in spec.  Yes, even stainless wear.  Then, particularly if changing brake pads material clean the rotors as described by oldndumb.  CRC BRAKLEEN original (tetrachloroethylene) formula is still available in NYC.  I also put a slight bevel on the bottom and leading edge of the pad to help bedding. 




Howie

#14
June 21, 2015, 10:00:10 PM
OEM are FF. 
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