french_connection Posted March 2, 2009 Report Share Posted March 2, 2009 97 Blade with recently stripped and cleaned calipers with new seals. Carbone Lorraine non race compound pads fitted. Symptom: from about 80mph under hard braking all is well, smooth, no judder until speed drops to about 10mph when the front end suffers from really heavy judder. The judder is so harsh you don't want to keep the pressure ont he brakes and back off jkust to stop the judder. The other oddity is that from 130mph (on track) again braking pretty hard the judder was there intially then disappeared. Thinking that it's down to warped dics I've tried super light and light braking at 55ish mph and can't detect any judder at all. So what to do? An article from PB some time back mentioned that there may be a judder effect if the pads have bound onto the disc when parked up over winter with a resultant difference in braking surface finish and that running some wet n'dry over the disc surface should sort it out. Has anyone suffered this and therefore might be able to point me in the right direction? Any help gratefully received. Cheers, French Link to comment Share on other sites More sharing options...
lorenzo Posted March 2, 2009 Report Share Posted March 2, 2009 I can't help with any kind of technical explaination here, but I had a realy similar thing on my old TRX some years back. A truck then pulled out in front of me and I had to do a proper emergency stop and all was well after that! Link to comment Share on other sites More sharing options...
sparx55 Posted March 3, 2009 Report Share Posted March 3, 2009 This sounds daft, but check that the wheel is round. Sometimes an egg shaped wheel will do this as the juddering matches the natural frequency of the your beer gut . I only know this as the same thing happened to me on Saturday......braking from 18Mph would set it juddering, once the speed dropped below 12 the suspension absorbed the shaking from the buckled wheel and all was well After winter riding, salt can start corrosin in the space between the disc and the carrier, this effect is worsened due to disimilar metals, sometimes a bit of harsh braking can remove the worst of the white furring, but often the bobbins lock up and a th disc gets hot, it warps, or dishes, My geuss is that a phone call to ebc is on the cards,. ( prolites and HH sintered ) Mark Link to comment Share on other sites More sharing options...
french_connection Posted March 3, 2009 Author Report Share Posted March 3, 2009 Thanks for the ideas/advice. I've got a list I'm going to work through of: Wet & dry disc surfaces check discs are true (they may be slightly warped) Check on wheel bearings I will check the wheel is round After that I'll consider getting on the phone to EBC... Cheers for the help, French Link to comment Share on other sites More sharing options...
lorenzo Posted March 4, 2009 Report Share Posted March 4, 2009 Get a tiny dab of WD40 on the bobbins on the disc too, so that they've got a fighting chance of being able to work properly, also making sure that any spills onto the disc are wiped off with brake cleaner. The final bit is quite important when trying to avoid death. Link to comment Share on other sites More sharing options...
scwirral Posted March 4, 2009 Report Share Posted March 4, 2009 I'd get the pads and pins out before spending any money. Sometimes the pins can get themselves in a right old state over winter. Give them a good clean, refit and see what happens. What have you got to loose? Link to comment Share on other sites More sharing options...
chancho196 Posted March 4, 2009 Report Share Posted March 4, 2009 Does sound like a warped disc to be fair. Have the discs been removed from the wheel? I take it the steering head bearings aren't notchy or loose? Has this only happened after the caliper strip down? If so, it's definitely worth cleaning the discs and pads up with 80 grit paper and try it again. Link to comment Share on other sites More sharing options...
ZXRarrgh Posted March 5, 2009 Report Share Posted March 5, 2009 Does sound like a warped disc to be fair. Have the discs been removed from the wheel? I take it the steering head bearings aren't notchy or loose? Has this only happened after the caliper strip down? If so, it's definitely worth cleaning the discs and pads up with 80 grit paper and try it again. +1 on the checking your steering head bearings. Warped discs are usually, but annoyingly not absolutely always, at their worst around 55-60 in my experience. Link to comment Share on other sites More sharing options...
Jay Posted March 5, 2009 Report Share Posted March 5, 2009 Get a tiny dab of WD40 on the bobbins on the disc too, so that they've got a fighting chance of being able to work properly, also making sure that any spills onto the disc are wiped off with brake cleaner. The final bit is quite important when trying to avoid death. +1 Link to comment Share on other sites More sharing options...
french_connection Posted March 5, 2009 Author Report Share Posted March 5, 2009 I'm not too hot at this forum thing just yet so pls excuse the lack of quotes which I'm sure would make this easier... Head bearings absolutely fine. Calipers stripped, split & cleaned, seals changed, new pads and all was well (discs were not removed). Some 500 miles later and the effects started. Will also try the 'lubing' of the floater bobbins. Christ I'm getting a lot of stuff to do! Thanks for all the help guys. Will feedback how I get on. Cheers, French Link to comment Share on other sites More sharing options...
sparx55 Posted March 9, 2009 Report Share Posted March 9, 2009 Take care mate, Trying not to die is better than Dying by not trying Link to comment Share on other sites More sharing options...
french_connection Posted April 3, 2009 Author Report Share Posted April 3, 2009 Update for those patient enough fo rme to get some int he garage......... Head bearings - OK Wheel bearings fine Disc run out (off bike) within spec Disc run out (wheel in forks) exactly the same Disc wear absolutely even Pad wear even No pulsing at the lever with the gentlest of braking. I'm of the opinion it ain't the brakes! So... Next thoughts are that perhaps this is front end chatter?? Next set of things to try: Vary front tyre pressure Max rebound damping just to see if the zone changes then at least I'll know it's tuneable. BUt I'm going to buy a new tyre 'coz it's past it's best. If any of you are still reading, don't hold your breath for the next installment but any advice on how to tune out chatter would be mucho appreciated. Cheers, French Link to comment Share on other sites More sharing options...
french_connection Posted April 3, 2009 Author Report Share Posted April 3, 2009 Oh yeah. and the wheel is perfectly balanced. Cheers, French Link to comment Share on other sites More sharing options...
french_connection Posted May 1, 2009 Author Report Share Posted May 1, 2009 Oh yeah. and the wheel is perfectly balanced. Cheers, French Seems to be fixed with nothing else but a new tyre. (BT016). Thanks for the help all. French Link to comment Share on other sites More sharing options...
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