Pad contamination?

cookieMonster · Mar 27, 2022

Hey guys — I recently swapped my Codes for my old Saints. I put a new 220mm rotor up front as well as new MTX gold pads, and it’s working great after a trail ride.

I swapped the rear more recently, and kept the 200mm rotor that came with the bike (essentially it’s a brand new rotor; I only did a couple rides on snow with the Codes). Anyway, with the Saints and their old pads (about 1/2 life left), it immediately feels like they’re contaminated.

Just no real power or bite, and kind of squeals when I finally come to a stop. I know for a fact the rotor is clean because it had great power with the Codes (although the Codes don’t hold a candle to the Saints when they’re working properly). Additionally, the pads in my Saints had amazing power on my old bike.

Could it just be they don’t like the residue from the Codes? I could clean the rotor and sand them, but I’ve never experienced such a drastic change in performance going from one rotor to another. I also don’t know how they could possibly have gotten contaminated. I am very careful when handling braking components and use brake cleaner to clean all surfaces after bleeds before installing pads, etc.

Scratching my head on this one.

Stewiewin · Mar 27, 2022

cookieMonster said:
Hey guys — I recently swapped my Codes for my old Saints. I put a new 220mm rotor up front as well as new MTX gold pads, and it’s working great after a trail ride.

I swapped the rear more recently, and kept the 200mm rotor that came with the bike (essentially it’s a brand new rotor; I only did a couple rides on snow with the Codes). Anyway, with the Saints and their old pads (about 1/2 life left), it immediately feels like they’re contaminated.

Just no real power or bite, and kind of squeals when I finally come to a stop. I know for a fact the rotor is clean because it had great power with the Codes (although the Codes don’t hold a candle to the Saints when they’re working properly). Additionally, the pads in my Saints had amazing power on my old bike.

Could it just be they don’t like the residue from the Codes? I could clean the rotor and sand them, but I’ve never experienced such a drastic change in performance going from one rotor to another. I also don’t know how they could possibly have gotten contaminated. I am very careful when handling braking components and use brake cleaner to clean all surfaces after bleeds before installing pads, etc.

Scratching my head on this one.

clean rotor and get new pads

wschruba · Mar 27, 2022

None of us can guess from over here, but if you wipe the rotor with a paper towel and it comes away black, that's a usual sign of pad contamination. In which case, clean the rotor thoroughly with brake cleaner/buff with sandpaper, and replace your brake pads. Check the pistons of the caliper for any weeping (will show up as oily rings on the back of the brake pads).

Brad Pitted · Mar 27, 2022

I’ve had that as well even when I know I didn’t do anything to foul the pads. In my case it was first ride after the bike sat all winter. They say the shimano can leak a bit at the piston and oil weeps its way around to the pad surface.

No amount of cleaning has ever brought the pads back and I have a few sets I want to try baking at some point.

cwoodffr · Mar 27, 2022

Nothing to lose in cleaning the rotors and then hitting the pads with high heat from a torch. Get them good an hot and any oil will burn off. If they still are not good, replace the pads.

Mountainfrog · Mar 27, 2022

Check for leaking pistons. Cook pads at 400 degrees for ten minutes. Sand rotor. Bed in brakes. If no improvement replace pads.

dompedro3 · Mar 27, 2022

Brad Pitted said:
I’ve had that as well even when I know I didn’t do anything to foul the pads. In my case it was first ride after the bike sat all winter. They say the shimano can leak a bit at the piston and oil weeps its way around to the pad surface.

No amount of cleaning has ever brought the pads back and I have a few sets I want to try baking at some point.

Almost every set of Shimano disc brakes I have had (going on 5 or 6 now) have leaked at the pistons so that after a few months the brake pads would be contaminated. As a result I have a process.
1. always have an extra set of pads waiting on stand by so you can ride if you want
2. spray pads with brake cleaner/alcohol some sort of chemical that breaks down oils
3. quick sand on 80 grit sand paper to remove top layer
4. another spray with brake cleaner
5. hit them with a torch for a few minutes (I will some times use my gas stove, or butane torch, beware brake cleaner is flammable, I am not responsible for a burned down house, handle brake pads carefully as they will be hot)
6. sand them lightly one more time (after they have cooled, I usually just dunk them in water)
7. clean rotors until paper towel sprayed in isopropyl alcohol until paper towel comes off white
8. reinstall pads and re-bed them in

ride.
The whole process takes 5-10 minutes and I'll do two sets at a time so I always have another set. Honestly I can't stand the lower end shimano (Deore, SLX, Alivio, Etc.) because of this, but I'm too cheap and lazy to buy new ones.

AEyogi · Mar 27, 2022

They could also be glazed.

cookieMonster · Mar 28, 2022

I got it sorted out. I soaked some steel wool in brake cleaner and grabbed the rotor with it and spun for a while, then switched to scotch bright. New set of MTX Golds. At first it felt like even then it was contaminated, but after a few mild downhills dragging the rear brake in dusty conditions, it started to bite. I did a pretty big ride today and ended with a short but really steep DH trail. Brakes worked like a dream.

After the ride, I noticed a lot of dust stuck to the caliper — indicating an oily surface prior to the ride. I normally use the Syndicate method of gravity bleeding my Saints and Zees, and despite cleaning the caliper very well with brake cleaner and wiping every surface with dry paper towels, there must have been a residue left nonetheless which made it onto the old pads. They’re actually only about 25% used so I’m going to try to revive them.

Next time I have to do a full bleed I’m going to try blow torching the caliper before getting pads anywhere near it, lol.

cwoodffr · Mar 28, 2022

cookieMonster said:
I got it sorted out. I soaked some steel wool in brake cleaner and grabbed the rotor with it and spun for a while, then switched to scotch bright. New set of MTX Golds. At first it felt like even then it was contaminated, but after a few mild downhills dragging the rear brake in dusty conditions, it started to bite. I did a pretty big ride today and ended with a short but really steep DH trail. Brakes worked like a dream.

After the ride, I noticed a lot of dust stuck to the caliper — indicating an oily surface prior to the ride. I normally use the Syndicate method of gravity bleeding my Saints and Zees, and despite cleaning the caliper very well with brake cleaner and wiping every surface with dry paper towels, there must have been a residue left nonetheless which made it onto the old pads. They’re actually only about 25% used so I’m going to try to revive them.

Next time I have to do a full bleed I’m going to try blow torching the caliper before getting pads anywhere near it, lol.

Not sure I would torch the calipers! could harm seals and for sure will bubble the paint....maybe you are joking. Also, oil isn't going to magically jump from a caliper surface onto the pad surface...would take fingers or a surface to surface transfer....or dripping onto the pad face (which I have done when bleeding and being too lazy to remove pads first)

dompedro3 · Mar 28, 2022

cookieMonster said:
I got it sorted out. I soaked some steel wool in brake cleaner and grabbed the rotor with it and spun for a while, then switched to scotch bright. New set of MTX Golds. At first it felt like even then it was contaminated, but after a few mild downhills dragging the rear brake in dusty conditions, it started to bite. I did a pretty big ride today and ended with a short but really steep DH trail. Brakes worked like a dream.

After the ride, I noticed a lot of dust stuck to the caliper — indicating an oily surface prior to the ride. I normally use the Syndicate method of gravity bleeding my Saints and Zees, and despite cleaning the caliper very well with brake cleaner and wiping every surface with dry paper towels, there must have been a residue left nonetheless which made it onto the old pads. They’re actually only about 25% used so I’m going to try to revive them.

Next time I have to do a full bleed I’m going to try blow torching the caliper before getting pads anywhere near it, lol.

Yeah, don't torch the caliper. There are lots of little rubber and painted pieces. Just spray it down with brake cleaner and wipe it off.

cookieMonster · Mar 28, 2022

Yeah, I wasn’t really going to torch the calipers.

. Makes me wonder about dusting some oil-absorbent powder on them though, and then rinsing them off with water before installing the pads.

All I know is that I really tried to do a thorough job cleaning everything after the bleed with actual brake cleaner, and yet somehow oil still got onto the old pads…

jeremy3220 · Mar 28, 2022

Could have been fresh oil that leaked from the caliper.

Pad contamination?

cookieMonster

Stewiewin

wschruba

Brad Pitted

cwoodffr

Mountainfrog

dompedro3

AEyogi

cookieMonster

cwoodffr

dompedro3

cookieMonster

jeremy3220

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