Brake rotors.... need help

[scott_araujo]

Even with new pads, be sure to scrub the rotors down with brake cleaner and a ScotchBrite pad.

Scott

[uclabiker06]

Ok, so I just took the bike to Nick from Valley Ducati Service.  He said the wheel spins freely enough and the drag wasn't excessive.  He doesn't think the rotor is bent.  He didn't even make me wait to make an appointment...  Just took me right in....(THANKS) 

Anyways we decided the best thing to do for now is to hit it with the scotch bright and brake cleaner.  I went to home depot and got scouring pads.  I don't know what scotch bright pad is but Nick showed me and the pads I got from home depot look the same.  I should have some brake parts cleaner lying around the house.

So how hard to i need to scrub the rotors?  Like for hours or what ?  Never done this before

[Ddan]

And go through the process to properly bed them in.  It's a waste of time if you don't.

edit:

You shouldn't have to spend too much time cleaning.  The key is to get an even deposit of pad material on the rotors.

[junior varsity]

i think for braking performance that a proper bed-in is more important than the cleaning. You want as much friction material all over that-there rotor as possible.

[uclabiker06]

Scrubbed the rotor w/ scour pad and brake cleaner then took out for a test and still pulsates just like i thought it would.    

Don't know what else to do so I will install new pads to see if that helps but don't think pulsing has anything to do w/ the pads.  Maybe i'll try the scour pad again and rub harder.  Thanks anyways to all for the suggestions.  

[scott_araujo]

Scotch Brite is a brand name from Scotch brand products.  It really is very different from the cheap knock offs that look exactly the same.  The pad has a microscopic abrasive (aluminum oxide I think) embedded in the plastic that is amazingly hard and works worlds better than one that's just scrungey plastic.   It's hard enough to scratch chrome, ask me how I know

The first time I cleaned my rotors it didn't make a difference even though I had a real Scotch Brite pad and brake cleaner.  Then I did it again and scrubbed my heart out.  Then worked on every disc button to make sure they moved freely.  That and a quick sanding to break the glaze on the stock pads and it was all better.

Cleaning the buttons is obvious, that frees the rotor to move which is what a semi-floating rotor should do.  If they stick then you might get some pulsing or other odd vibes.  There's some weird science behind all the scrubbing and bedding in. 

When you properly bed in brake pads you take a perfectly clean rotor and perform a series of hard braking exercises.  These repeated brakings get the pads hot and when they get nice and hot (but not too hot) they start to actually leave a thin coating of material evenly over the rotor.  It's this thin even coating that the pads grab and really take hold of, not the steel surface.  Getting that coating nice and even takes a series of hard stops followed by a nice long run to cool the discs evenly.  If you don't get a nice, thin, even coating then some spots on the rotor have more friction than others and you can get pulsing.

Getting back to cleaning before new pads...

If your pulsing is caused by a warped rotor cleaning won't help.  If your pulsing is caused by uneven brake pad deposits on your rotors dropping new pads in may not help.  Even if you try to bed them in properly you're doing it over a spotty coating and not on a dead clean rotor surface.  You get another uneven coating and pulsing.  But now you're convinced the rotors are warped so you order two new ones, drop in your new pads, bed int, and things are fine.

What's the point of all this rambling?  Maybe it's the pads, maybe the rotors are warped.  Either way, seriously cleaning the rotors, really scrubbing, with the right pad and brake cleaner will take an hour of your time and cost about $10.  Pads are usually around $100 and up, discs around $300 and up. 

My brakes pulsed so bad I could sweat the rotors were warped.  But with those kind of prices I scrubbed the crap out of the discs before I was going to drop that kind of coin.  Turned out a good cleaning was all I needed and the braking performance was much improved to boot.

Scott

[uclabiker06]

Don't mean to ramble.  I got a used rotor from ebay and installed it to replace the rotor i thought was warped after taking off w/ the disc lock on, yet there is still some pulsing. Thought that was clearly stated.  

The scour pads I got are green ones made by 3M.  I'll give it another shot and scrub the crap out of them.  Didn't scrub to hard initially cuz didn't want to take too much off the rotors and thin them out.  I didn't really scrub the buttons though.

[Howie]

The rotors are stainless steel if they are stock.  The most you will do is scratch them up a bit, which would be good for bedding.  To clean them effectively you should remove them from the wheel.  The only resistance in the rotors should be the springs.  You might want to search the board for Norm's method to turn semi floaters into full floaters if you don't have a fear hitting expensive parts with a big hammer and like the clang clang of a full floater.

[Ddan]

The theory:
http://www.stoptech.com/tech_info/wp_bedintheory.shtml

The procedure:
http://www.stoptech.com/tech_info/wp_bedinperformance.shtml

[uclabiker06]

Thing is I had more than 8K miles on the bike w/ no problems so I don't think bedding is the issue w/ the current current setup. It was after the disc lock hit that the pulsing started.  Thanks for the tips.  I know what bedding is and I will definitely bed in the new pads when i instal them.  I want my rotors to function w/ out pulsing before I worry about turning them into fully floating...

[scott_araujo]

The green scrubby pads from 3M are the ones you want.  Again, cleaning is cheaper than replacing.  Even if you don't want to turn them into full floaters cleaning the buttons and making sure they can move and turn is part of this.  If all that doesn't work, try the new pads.  If it's still  pulsing, yeah, you may have a bent/warped rotor

Scott