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No Fear
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Discussion Starter · #1 ·
Hello every body

My first question is that if a rotor is contaminated with brake fluid * mineral so much that cleaning it with alcohol 3 times didt wirk and the pads slip again

Bicycle tire Bicycle wheel rim Yellow Rim Bicycle part


maybe the riders braked hard during a long decent and the pressure of pads in the rotor made the leaked fluid make it like this

Is it any thing we could do with the rotor ??

Sand paper maybe a very very fine & smooth No.# ??

And the second question :

What is the difference between the rotors that indicate (resin pad only ) with the other ones ?

I mean whats the structural difference ? is it the way their produced or the material their made of ?

And what if we use non resin pads on them ? what happens the rotor is scratched ? or burned ?

Thanx to all
 

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Removing material from rotors to resurface them can work but there are 2 problems.
1. You’re removing material, keep an eye on the wear limits.
2. Be careful with the finish you leave. I’ve used 320 grit paper fairly successfully and I’ve bead blasted rotors that made it much rougher and I couldn’t get pads to settle in after that.
 

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From what I understand, the difference between the resin-only rotors and others is the heat treating of the metal. The resin-only rotors are a bit softer. If metallic pads are used on them, they'll most likely wear excessively. And since rotors all have a minimum thickness (how much depends on the rotor), you certainly don't want excessive wear.

If I've got a rotor giving me issues, I'll sand it and clean it with alcohol once (also take care of the pads at the same time), and if I'm still having problems, just replace the rotor. If you clean off the rotor, it has to be bedded in again, and until then, braking quality will stink. Usually I don't have too much trouble with this, and if it's a repeated problem, there's something going on with the caliper that's causing it to get contaminated again.
 

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Removing material from rotors to resurface them can work but there are 2 problems.
1. You're removing material, keep an eye on the wear limits.
2. Be careful with the finish you leave. I've used 320 grit paper fairly successfully and I've bead blasted rotors that made it much rougher and I couldn't get pads to settle in after that.
I have rotary sanded rotors for ears w/o any issue. Sanding is really just breaking the surface glaze. Rotor thickness is pretty easy to determine based on web thickness vs. brake track thickness. Hayes use to print minimum thickness just like some auto manufactures.
 

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No Fear
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Discussion Starter · #6 ·
From what I understand, the difference between the resin-only rotors and others is the heat treating of the metal. The resin-only rotors are a bit softer. If metallic pads are used on them, they'll most likely wear excessively. And since rotors all have a minimum thickness (how much depends on the rotor), you certainly don't want excessive wear.

If I've got a rotor giving me issues, I'll sand it and clean it with alcohol once (also take care of the pads at the same time), and if I'm still having problems, just replace the rotor. If you clean off the rotor, it has to be bedded in again, and until then, braking quality will stink. Usually I don't have too much trouble with this, and if it's a repeated problem, there's something going on with the caliper that's causing it to get contaminated again.
Thanx a lot
at first it was the caliper that leaked fluid

Tool Rotary tool Metalworking hand tool Hand tool Drill accessories


first i serviced the brake whole..........

then it leaked again and i changed the caliper & the leakage from the Square rings were sloved and the pads in the new caliper were new as well

i also alcohol cleaned the rotor too but it still had some contamination & and now i think the last solution is sanding it right ?

I have rotary sanded rotors for ears w/o any issue. Sanding is really just breaking the surface glaze. Rotor thickness is pretty easy to determine based on web thickness vs. brake track thickness. Hayes use to print minimum thickness just like some auto manufactures.
Thanx a lot to all members who helped :thumbsup::thumbsup:

Any suggestion for sanding the rotor if i havnt got the electrical sanding machine ?
 

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I've never found it too difficult to clean oil off a rotor. It's just a bit of metal. Brake cleaner does the job. New pads and burn the heck out of them on a long hill and it should be fine.
 

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Acetone is a powerful oil and grease remover, just use it outdoors.

Just keep on mind if you sand or grind the rotors to remove contamination, you'll have to repeat the bed in procedure with your pads to rebuild the layer of material that helps them grip. They'll feel weak until you do.

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EAT MORE GRIME
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^ be careful with acetone. it will melt any paint any plastic it touches... and even the vapors can weaken paint, plastics, possibly carbon fiber layups...etc. this means brake lines and cable housings too

if cleaning rotors with acetone it's best to remove rotors and clean them away from all other bike parts
 

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Very mild, if any. Like I say, it's just a piece of metal. Any good degreaser should remove all of the oil. Sanding shouldn't be necessary. What you do have to watch is the edges. If you just wipe the surface of the disk you can miss oil that's in the holes.
 

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thank you all very much i sanded the rotor but havnt tested it on the bike yet

By the way what grade of sandpaper do you think would be suitable for this job ?

Something around 1000 / 800 like these ??
Way too fine. Most rotary discs specifically made for rotors (automotive) are 80-120 grit. I have used these sanding discs on my mtb rotors w/ excellent results. As I mentioned earlier they will just break the glaze.
 

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If the pads are contaminated too (very likely) they'll just oil up the rotors again. I've had good luck using a propane torch on the pads till they smoke (don't get them too hot) and then sanding them for a fresh surface. Then bedding them in again like others have said. Or get new pads!
 

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No Fear
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Discussion Starter · #14 ·
Very mild, if any. Like I say, it's just a piece of metal. Any good degreaser should remove all of the oil. Sanding shouldn't be necessary. What you do have to watch is the edges. If you just wipe the surface of the disk you can miss oil that's in the holes.
Thanx good point sanding doesnt affect inside the holes

Way too fine. Most rotary discs specifically made for rotors (automotive) are 80-120 grit. I have used these sanding discs on my mtb rotors w/ excellent results. As I mentioned earlier they will just break the glaze.
I sanded the rotor by putting the wheel in a truing stand and spinning it & sanding with hand

If the pads are contaminated too (very likely) they'll just oil up the rotors again. I've had good luck using a propane torch on the pads till they smoke (don't get them too hot) and then sanding them for a fresh surface. Then bedding them in again like others have said. Or get new pads!
Good point thanx i always threw away those pads .... maybe this time try this method
 

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When bedding in, don't come to a full stop with the brake pads compressed to the rotor when they are anywhere near hot or warm.
When releasing the brake, the pads will lift the material off the rotor and there will be a bare spot, this will cause a slip/grab and most probably a squealing noisy rotor.
Wet and dry sandpaper 800 grit, circular motion or opposed to the direction of wear (cross grain) is the best method I've used.
Wash with methyl hydrate, (NOT Isopropyl Alcohol).

You can upgrade the caliper pistons with new seals, bleed valve, banjo bolt and main caliper bolt all in titanium.
Options for the BR in titanium is available as well.
https://www.aliexpress.com/wholesal...20190428184144&SearchText=shimano+xt+titanium
 

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No Fear
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Discussion Starter · #17 ·
Nice idea but I think sanding across the track would be better. The grinding on new disks is random, at least the ones I've payed attention to ;0)
hmmm as im not that much fluent in english i diddnt fully understand the patterns

By across the track or cross...does it mean like the green arrows ?

And also circular means like the blue ones ? right ?

Bicycle part Bicycle drivetrain part Auto part Gear Crankset


When bedding in, don't come to a full stop with the brake pads compressed to the rotor when they are anywhere near hot or warm.
When releasing the brake, the pads will lift the material off the rotor and there will be a bare spot, this will cause a slip/grab and most probably a squealing noisy rotor.
Wet and dry sandpaper 800 grit, circular motion or opposed to the direction of wear (cross grain) is the best method I've used.
Wash with methyl hydrate, (NOT Isopropyl Alcohol).

You can upgrade the caliper pistons with new seals, bleed valve, banjo bolt and main caliper bolt all in titanium.
Options for the BR in titanium is available as well.
https://www.aliexpress.com/wholesal...20190428184144&SearchText=shimano+xt+titanium
Well we dont have such luxuries here in iran maybe if i can find a brake with a broke lever we could use the caliper specially these days with this super hyperinflation we have 7 years ago a pair of B01 pads for shimano M series we payed 8 units of our currency not we have to pay 85 / 90

at that time maybe a minimum wage was 400 units now its 1400

Every thing has gone up by some thing like 1100/ 1200% but the income maybe 250 %
We are living in the county ruled by religion...... like we are n the dark ages.....but with internet....

:skep::skep:
 

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You can get good cheap pads from AliExpress, but there’s not much point if the caliper is still leaking. Cleaning a rotor with IPA is a 2min task, but you’ll have to figure out if the caliper is gonna leak all over the new pads again
 

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BOOM goes the dynamite!
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hmmm as im not that much fluent in english i diddnt fully understand the patterns

By across the track or cross...does it mean like the green arrows ?

And also circular means like the blue ones ? right ?

View attachment 1249243
The blue is what I do. Nice drawing!

Well we dont have such luxuries here in iran... :skep::skep:
Just ignore Penny's attempt to sell you something...been spamming the forum lately with aliexpress links and no one's done anything yet. :p
 
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