Hi all ive read that the most common cause of brake judder is dirty disc bobbins and poor brake transfer film, can anyone elaborate, I can't seem to get rid of my judder. paul
plus check worn pads, discs , fork legs not aligned , incorrectly fitted wheel spacers, calipers not seated on fork bottoms properly , bleed system, new fluid ?
My old Aprilia RSV used to suffer from brake judder a lot, and it was always down to clogged up bobbins. I just put a long bolt through the bobbins, tightened with a nut and spun anticlockwise with a cordless drill to spin the crap out (anticlockwise cos the nut will undo itself otherwise). Never had a problem with pad material transfer, but I don't suppose it would hurt to give the braking surfaces a quick going over with scotchbrite or emery. Make sure the caliper pistons move freely too.
which bike and what kind of discs Paul? as said above there could be many reasons. If discs are fully floating with worn bobbins then judder inevitable at slow speeds. If you carefully study the braking surface of each disc for irregularities in the surface and colour it might give you a clue. A lot of fuss has been made of brake transfer film and it's nothing to really think or worry about unless you are going racing imo. The pad will either produce it or it won't depending on pad compound and disc type. If you are bedding-in new pads and particularly if you have changed to a different compound then this could also be a factor.
As I understand it, when you brake some of the pad material initially transfers onto the brake disc as a thin covering or 'film'. Thus the pads are not actually pressed onto the discs themselves, but onto the 'brake transfer film'. This reduces wear etc. and makes the pads more effective. Clever huh!?! I guess that if the brake transfer film covering was uneven then it could be a cause of judder.
It's a standard 04 749, newly cleaned and rubbed down with fine emery semi floaters and new bendix mrr pads went in only about 200 miles ago. But I've had this issue before these pads when I was using brembo sc compound pads and noticed it then too. The colour of the disc is normal and regular with no major scores or unevenness, I do have radial play on the bobbins, imagine the movement as if brakes are applied and rock the bike forward and back, it moves the disc on the carrier, it is more movement than my dads st4 discs and brothers monster discs. It's a noticeable judder at speeds less than 15mph and light pressure on the lever.
I know it's hard to quantify in words but if you have let's say, easily-noticeable play with brakes locked up on semi-floaters then it sounds like you've found it right there. Sometimes standing corrosion can cause early play like this - i say early as it sounds as though the discs have many more miles in them without ridges even?
paulm You mention that the pads have only done 200miles. They probably haven't fully bedded in yet. Give em' a chance, and things could improve.
cripes, 200 miles is plenty unless you never used them - I remember bedding in some pads on the way to Silverstone once - 70 miles if that.
