gregtrx Posted March 29, 2012 Report Share Posted March 29, 2012 I've got a cb250rs with standard rubbish brakes and a solid front disk which sort of aquaplanes in the wet. I think drilling holes in it would make it look awesome and might increase performance by 0.0002% which is vital in the blast home from the chip shop. I've got a spare disc to try/waste, does anyone know anyone who has drilled discs in the past and knows what they are doing? Link to comment Share on other sites More sharing options...
VanWinkle Posted March 29, 2012 Report Share Posted March 29, 2012 I had it done way back in the dark days of my yoof..Me Uncle who was an engineer did the conversion for me so I cant offer up a "how to". Link to comment Share on other sites More sharing options...
gixerboy1 Posted March 29, 2012 Report Share Posted March 29, 2012 Use lots of coolant and a sharp drill. Link to comment Share on other sites More sharing options...
scrappy600 Posted March 29, 2012 Report Share Posted March 29, 2012 You can't/shouldn't do this without balancing the disc. Link to comment Share on other sites More sharing options...
ssray Posted March 30, 2012 Report Share Posted March 30, 2012 Have you tried a cb250n superdream disc and caliper first? diffrent pad material? what type have you in there at the moment? Ray Link to comment Share on other sites More sharing options...
heds954 Posted March 30, 2012 Report Share Posted March 30, 2012 Have you considered other options such as Galfers or Brembos? Link to comment Share on other sites More sharing options...
wavydavy Posted March 30, 2012 Report Share Posted March 30, 2012 Have you considered that Honda carefully balanced the power of the front brake with the spring rate in the forks and the choice of tyres for those rims so as to prevent the crappy biro springs from not bottoming out at the first sign of pad/disc interaction and, thus, forcing more braking effort onto the front Cheng Shin Teflonmax? I don't recall either of my 2 CB-RSs being under-braked, just that you had to juggle braking (both front *and* rear) with judicious down-shifting in a proper emergency, otherwise they were more than adequate for all but the most serious of stopping requirements. If you're that worried about the state of the brake, I'm quite happy to swap your CB and four grand (that's GBP not Turkish lira) for my GSXR.......... Link to comment Share on other sites More sharing options...
gregtrx Posted March 30, 2012 Author Report Share Posted March 30, 2012 While these are all good and valid points, they don't address the fact that drilled discs look way cooler. I also have a spare disc so I can try it with no loss. I'd quite like to swap the caliper at some point for a three-rib ap/lockheed one as the current swinging thingy is shite (and pretty knackered). Sadly I know from my last one that the ally the standard calipers are made out of is pretty soft some stripping out bleed nipples etc. I'll have a look at more modern pad compounds but I don't think there's too much available. Link to comment Share on other sites More sharing options...
gregtrx Posted March 30, 2012 Author Report Share Posted March 30, 2012 I'll admit the forks are shite, I'm replacing the front sava tyre with what's hopefully a stickier Michelin this weekend. Link to comment Share on other sites More sharing options...
Mahatma Posted March 30, 2012 Report Share Posted March 30, 2012 You can't/shouldn't do this without balancing the disc. This.And make sure there's no metalic edges standing out after drilling.Only do this if you have a spare you can waste-which is like on the other scale of the percentage scale you posted in probability of going wrong Why not buy a whole front end from an RVF 400? Link to comment Share on other sites More sharing options...
gregtrx Posted March 30, 2012 Author Report Share Posted March 30, 2012 RVF 400? It'd not suit the bike at all, it needs tall skinny wheels. I wasn't planning to do the drilling myself, wondered if anyone offered it as a service? I suppose it'll always be a risky thing. Link to comment Share on other sites More sharing options...
gixerboy1 Posted March 30, 2012 Report Share Posted March 30, 2012 I can do it if you cant find anyone to do it, but I have quite a lot on at the moment. Link to comment Share on other sites More sharing options...
gregtrx Posted March 30, 2012 Author Report Share Posted March 30, 2012 I can do it if you cant find anyone to do it, but I have quite a lot on at the moment. Cheers, I'll PM you, no rush for it at all it's only me being a tart. Link to comment Share on other sites More sharing options...
alexp5 Posted April 2, 2012 Report Share Posted April 2, 2012 Greg - this might be of interest to you. If it fits... http://www.ebay.co.u...d=p5197.c0.m619 Link to comment Share on other sites More sharing options...
gregtrx Posted April 2, 2012 Author Report Share Posted April 2, 2012 It should fit. I should also really spend the money on a new/reworked caliper as mine has stripped out one of the theads which hold it together I need to take it somewhere local and get it fixed or find a time-sert kit (bloody hell they are expensive, might try a helicoil kit first) I suppose.. Link to comment Share on other sites More sharing options...
chrisexup Posted April 3, 2012 Report Share Posted April 3, 2012 Greg, i've got M6,M8 and M10 Helicoil kits if you want to try the cost free approach.....? Link to comment Share on other sites More sharing options...
lorenzo Posted April 3, 2012 Report Share Posted April 3, 2012 Greg, get yourself a nice 4 pot caliper off a half decent modern bike, just the one'd be fine, I bet you can pick a bluespot up off ebay for about £25 on its own. Then get busy on a cad package, and get an adaptor plate made up. This will not only get you a better caliper by design, you'll get one that's got fairly healthy seals and is in all round better condition, plus you'll get access to all sorts of pukka pads too. A 3 way win and I'd say you could have it all sorted and get change out of a ton if you play your cards right. You might want a master cylinder off a CB500 or something, something that takes a single 4 pot as standard, and has a built in reservoir so it looks neat, and that might take you into 3 figures, but you will end up with stopping power that is more than enough for you and your trusty steed. Link to comment Share on other sites More sharing options...
kaighn80 Posted April 3, 2012 Report Share Posted April 3, 2012 i've drilled disks, i've also grooved disks, i have the advantage of having an engineering firm right next door who dont mind if i load up the odd program on their 3 axis mill, if your going to do this then i would not take the whole drill by hand approach, its a recipe for a&e. you will never get the disk drilled equally, which will lead do vibration eventual warping and overall crap brakes. do it right do it once or do the hospital food. Link to comment Share on other sites More sharing options...
chrisexup Posted April 3, 2012 Report Share Posted April 3, 2012 Greg,i also have a couple of shitty old four pot calipers you're welcome to use (iirc one is off a 'blade) looks like they have 61mm mounting bolt centres, they were for a ZXR400 front end i had on an ER5 and only used one disc. one of these calipers has 10mm bolts, the other 8mm (and i have a pair of bolts with m10 shank, M8thread) Link to comment Share on other sites More sharing options...
gregtrx Posted April 3, 2012 Author Report Share Posted April 3, 2012 Hi Chris, thanks for the offers, when I get back home I'll measure some stuff up and let you know. Link to comment Share on other sites More sharing options...
abos Posted April 9, 2012 Report Share Posted April 9, 2012 Drilling discs is ok as long as you do it symmetrically either on a CNC M/C or on a mill/drill with a rotary table this will ensure that the disc is balanced after the drilling do not over drill the disc as you will weaken it. As mentioned above use a fresh drill and flood cool the Job to prevent local hot or indeed soft spots which will potentially cause warping or failure, however as mentioned a modern caliper/MC with new pads and fresh fluid will have the desired effect. Link to comment Share on other sites More sharing options...
gregtrx Posted May 14, 2012 Author Report Share Posted May 14, 2012 Well I was forced into fitting the drilled superdream disk by caliper issues (could only get a superdream one) and it seems to work ok, no vibration at all really. It's a larger diameter than standard too. Link to comment Share on other sites More sharing options...
lorenzo Posted May 15, 2012 Report Share Posted May 15, 2012 Pics of a one handed stoppy while doing a silly face towards the camera or you're a liar. Link to comment Share on other sites More sharing options...
ricey3 Posted May 15, 2012 Report Share Posted May 15, 2012 enter it in the next british supersport round and outbrake everyone at Snetterton! Link to comment Share on other sites More sharing options...
AllanE Posted May 15, 2012 Report Share Posted May 15, 2012 Find a picture of a drilled disc you like, then print it out at a scale that matches your disc. Stick it over your disc with tape (clear is best as you can see through it). Spot through the centre of all the holes with a small drill bit, preferably in a bench/pillar drill. Remove paper, then drill with a 6mm or 1/4" -ish drill. Countersink - important this, as it lessens any stress raisers. Should be equivalent of at least 0.000003bhp... Link to comment Share on other sites More sharing options...
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