The upgrade to the front brake on the YZ250 for hill climb use was going swimmingly this morning. EBC 280mm floating disc and MX-S sintered pads. Took me a while to figure out how the new caliper mounting bracket is fitted and I'm more used to Brembo than Nissin, but I got there in the end. So the moment of truth. Spin the front wheel (the original 21 inch at the moment until I have one rebuilt to 17 x 3.50). Clackety-clack-clack, like the days when you used to attach a lolipop stick in the forks of you push bike to make a motor noise as it twanged the spokes. Careful examination reveals that a few of the lobes on the wavy disk are making light contact with the pin on the caliper that one pad locates on and also allows the caliper to move from side to side a bit. 6 out of the 18 lobes. Marked the offenders with a dry marker to find them randomly distributed - so not an obvious oval disc. I could send it back and get a replacement, but there is every chance another may be the same. It's only a gnat's cock too much metal on the offending lobes. I could grind a slot on the pin (not a good move I suspect) or fettle the disc to ease the tight spots. One has already succumbed to the merest hint of dressing with a fine file, but before I let rip on the other 5 with an angle grinder, "nothing could possibly go wrong", could it oh FOAK? -- +-------------------------------------------------------------------+ | Pete Fisher at Home: | | Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" | | Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" | +-------------------------------------------------------------------+
I'd probably start with some sandpaper on a flat surface (a piece of planed timber) myself rather than jump right in with the angle grinder. And if removing a gnats whisker from the offended pin is even remotely possible, that's where I'd start. A pin is a midge cheaper than a disc after all. -- Beav VN 750 Zed 1000 OMF# 19
Too late. I reckoned it shouldn't be too risky as long as I didn't mark the braking surface. I took it very carefully and kept checking after each smidgen of metal was removed from the offending lobes, then checked for rough edges once the clattering was eliminated. Spinning smooth as silk now and the new pads don't seem to grab on gentle application. First run up Hartland then braking hard after the finish could be the proof of the pudding. I'm hoping, however, to get some time on the Haynes test track before then to sort out suspension, gearing and jetting on both the YZs and also give the lad a feel for riding his 85 with sticky tyres on tarmac. I'll give the date sometime in February or March on here in case anyone else wants to come along for a a bit of fun. If we can sign up 15 bikes it becomes quite a good deal to have exclusive use of the circuit (such as it is) for a day. -- +-------------------------------------------------------------------+ | Pete Fisher at Home: | | Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" | | Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" | +-------------------------------------------------------------------+
