T_PRO Posted January 18, 2006 Report Share Posted January 18, 2006 I was just wondering weather you would advise grinding the rotors of disc brakes, would this make them even more powerfull? Quote Link to comment Share on other sites More sharing options...
Siders77 Posted January 18, 2006 Report Share Posted January 18, 2006 No, it would muck up the pads. Quote Link to comment Share on other sites More sharing options...
T_PRO Posted January 18, 2006 Author Report Share Posted January 18, 2006 No, it would muck up the pads. So does grinding a rim but people still do it Quote Link to comment Share on other sites More sharing options...
Siders77 Posted January 18, 2006 Report Share Posted January 18, 2006 Yes, but a rotor isn't supposed to be ground. Grinding a rim doesn't really muck up the pads as such, it just makes them wear down fast. Quote Link to comment Share on other sites More sharing options...
Greetings Posted January 18, 2006 Report Share Posted January 18, 2006 think about it this way - discs need to be bed in. once they have done so, the disc is smoother than when it was just after mounting it onto your bike. grinding a disc would reduce its braking power substantially. DONT do it Quote Link to comment Share on other sites More sharing options...
T_PRO Posted January 18, 2006 Author Report Share Posted January 18, 2006 think about it this way - discs need to be bed in. once they have done so, the disc is smoother than when it was just after mounting it onto your bike. grinding a disc would reduce its braking power substantially. DONT do it I see what you mean, if i grind it the brake would have to bed it's self in again making it smooth really quickly. I won't do it. Cheers Quote Link to comment Share on other sites More sharing options...
matt rushton Posted January 18, 2006 Report Share Posted January 18, 2006 Don't be so stupid. the disc is only bout a mm thick so as soon as you put a grider to it the disc will go straight through. Quote Link to comment Share on other sites More sharing options...
monty rider Posted January 18, 2006 Report Share Posted January 18, 2006 think about it this way - discs need to be bed in. once they have done so, the disc is smoother than when it was just after mounting it onto your bike. grinding a disc would reduce its braking power substantially. DONT do it Good thinking. He's not thick is he. Phil Quote Link to comment Share on other sites More sharing options...
Simpson Posted January 18, 2006 Report Share Posted January 18, 2006 Don't be so stupid. the disc is only bout a mm thick so as soon as you put a grider to it the disc will go straight through. No...... a disk can b grinded as long as it is a fine grind, you know think of the width of your sidewall and how many different grinds that takes. but not a good idea some disks can stopwith a mm lever blade pull so you would be better of just buying a new disk if you are in despiration Quote Link to comment Share on other sites More sharing options...
Ben Geary Posted January 18, 2006 Report Share Posted January 18, 2006 I wouldn't even think of getting a grinder to a disk. Quote Link to comment Share on other sites More sharing options...
T_PRO Posted January 18, 2006 Author Report Share Posted January 18, 2006 I'm not going to do it, i aint even got my front disc brake yet, by the way i'm getting a Hope mono trial disc Quote Link to comment Share on other sites More sharing options...
Trials Dave Posted January 18, 2006 Report Share Posted January 18, 2006 I'm not going to do it, i aint even got my front disc brake yet, by the way i'm getting a Hope mono trial disctrust me mate. you wont need to do a thing to your rotor Quote Link to comment Share on other sites More sharing options...
T_PRO Posted January 18, 2006 Author Report Share Posted January 18, 2006 trust me mate. you wont need to do a thing to your rotor By that comment i take it that the discs are powerfull then? Quote Link to comment Share on other sites More sharing options...
Trials Dave Posted January 18, 2006 Report Share Posted January 18, 2006 By that comment i take it that the discs are powerfull then?yeah they are good. they are temperamental, so you have to play about with them a while to get them working nicely. but yeah they are really snappy due to the smaller piston.just look at the name, it is a trials specific brake by hope so its bound to be good. hahaa good investment mate Dave Quote Link to comment Share on other sites More sharing options...
chris222pher Posted January 19, 2006 Report Share Posted January 19, 2006 if you rind you do need more power on a disc the thing to do is take the pads out and roughen them up a little. maybe take a craft knife to them or something like that and roughen up the face of the pad.cheerschris Quote Link to comment Share on other sites More sharing options...
flange Posted January 19, 2006 Report Share Posted January 19, 2006 Sorry lad but I have to disagreeAnything that causes more friction between the pads and the disc means greater stopping power. The old way of getting hopes to work (e2's, c2's and the like) was to throw the rotor in a dirty puddle or cover it with coke and let it dry, simply because it causes more friction. Ride through a muddy puddle and stick your brakes on - what happens, you stop a lot quicker. Brake discs being smooth is something transfered from the motor industry. Brake discs must be smooth in order to have a consistant braking effect and prevent vibration/judder. When you hit the brakes at 70mph the last thing you want is an uneven braking surface - something similar to warped discs (which in itself is a myth but I'll not bore you with that). Braking from 70mph is not something your python/echo/zoo/onza is going to experience on a regular basis and therefore having a consistent (smooth) contact surface is not paramount. The bedding in period is there to take the surface resin off the pads and apply a (fine) coating of pad to the disc, not make the disc smoother. Think about it - a new brakes bedding in period won't be enough to file away imperfections on a disc. To summerise, yes, you could grind your disc and its certainly not a stupid idea. Plus a disc is resiliant enough to allow a light/medium grind although one or two is probably its limit. But if it fails its going to be nasty. I'd probably get some better pads before I start grinding anything. Quote Link to comment Share on other sites More sharing options...
011001000110010101110010 Posted January 19, 2006 Report Share Posted January 19, 2006 It doesnt work. Fact. The disc brake relys on having two smooth surfaces. Friction is heat, the heat comes from two surfaces rubbing. You are correct when you say something that increases the friction will improove the braking, but in this case it doesnot. By grinding the disc you are reducing the surface area which the pad can use to slow you down. Trust me, it will not work, unless you use soft pads which can compress into all the little ridges created by doing the grind. And since these do not exist... Quote Link to comment Share on other sites More sharing options...
flange Posted January 19, 2006 Report Share Posted January 19, 2006 Sorry, still not sure I agreeThere are two types of friction acting between disc and pada)Abrasive friction - brakes with this charateristic have a high wear rate and operate at a low('ish) temp and would be the result of a 'rough surface'b)Adherent friction - where some of the pad material diffuses across the interface between the pad and the disc and forms a very thin, uniform layer of pad material on the surface of the disc. As the friction surfaces of both disc and pad then comprise basically the same material, material can now cross the interface in both directions and the bonds break and reform. More common on a smooth surface where the depositing of brake pad material is consistant, thus preventing judder when the brake is appliedor in otherwordsa) for low speed (cooler) applications with a high wear rateb ) for high speed applications with a longer wear rateIn terms of a bicycle disc brake we're referring to both of the above, especially as theres no such thing as pure adherent or pure abrasive friction. Ideally you want one greater than the other depending on the application - in this case trials where application a) (low speed and concequently a low temperature) would be more beneficial. In DH, high friction would result in high temps and therefore a pad that worked at higher temps would be more suitableAs for the surface area issue, would this not also be the case on a grind on a rim brake? And if not, the same pressure over a smaller surface are would result in a better lock?(Its at this point that I tell you I'm an IT consultant and you tell me you are a Brake technician working for Brembo or something and I'll go into a corner and face the wall) Quote Link to comment Share on other sites More sharing options...
011001000110010101110010 Posted January 19, 2006 Report Share Posted January 19, 2006 (edited) I am a brake technicion, and I work for Brembo Its to do with the pad being soft enough to "mould" into the grinds you have made. If you have a pad which can do this (like a rim brake) it will be loads better because the total braking surface is increased. But on a disc (with hard pads) they will not "mould" into the grinds so the total braking surface is decreased, therefore decreasing the overall firction, and reducing the braking power.Also there is a good reason why every car disc is smooth. Edited January 19, 2006 by derf Quote Link to comment Share on other sites More sharing options...
flange Posted January 19, 2006 Report Share Posted January 19, 2006 and I'm an IT consultant... 'Also there is a good reason why every car disc is smooth'Yes there is - to allow uniform braking surface at speed to a) prevent judder and b )reduce friction by a certain degree to prevent fade. This isn't a consideration on a trials bike - if it were then water bleeds wouldn't work on maggies because of the heat Quote Link to comment Share on other sites More sharing options...
011001000110010101110010 Posted January 19, 2006 Report Share Posted January 19, 2006 Its getting harded and harded to explain this now! I know someone that has tried it, and it didnt work. Magura used to make an aluminuim disc rotor for the lousie, which was rough to touch. They where still rubbish as disc brakes, even with extra soft Jagwire pads. Quote Link to comment Share on other sites More sharing options...
Synergy Posted January 19, 2006 Report Share Posted January 19, 2006 (edited) just go for it and find out.other things to try:maybe smear tar on it monty spray Edited January 19, 2006 by Synergy Quote Link to comment Share on other sites More sharing options...
011001000110010101110010 Posted January 19, 2006 Report Share Posted January 19, 2006 All three of your suggestions will not work. And they are a good way of needing to buy a new disc and pads. Quote Link to comment Share on other sites More sharing options...
flange Posted January 19, 2006 Report Share Posted January 19, 2006 (edited) know what you mean. I'm going to conduct an experiement tonight on an old hayes brake I've got in the garage - I'll return with my findings (hopefuly, unless grinded discs really don't work) Edited January 19, 2006 by flange Quote Link to comment Share on other sites More sharing options...
Matt_Tupman Posted January 19, 2006 Report Share Posted January 19, 2006 It doesn't work with normal disc pads just except it I've tried it friends have forum users have and it doesn't!!! workBut if you have rubber paz like the plazmatic ones for the marta and louise then you could grind the disc and have an increase in power because the braking compound would be soft enough to mould into the grid unlike the harder compound or standered disc padsEnd of Quote Link to comment Share on other sites More sharing options...
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