not long had an S4r on an 03 plate and its not been without a few issues but generally a good ride with a full history. Under higher speed (65+) heavy braking i have a front end judder. slower speeds and gentle braking its not there. had a few bikes and a few track bikes - so not completely inexperienced-- and am now at a bit of a loss ..bike only has 14k on it-- is it a characteristic in the bike? So to detail what i have done - front wheel off replaced bearings as they rattled ( not impressed as just went through mot) problem better but still there had front wheel re-balanced(slightly out) and run out done on discs - they are good sanded down pads to remove any deposits/glazing- pistons in calipers move freely enough problem still there had front end off inspected headbearings cleaned and regreased --- have taken to 2 dealers both agree nothing wrong with head bearings and no play in the fork bushes problem still there have tinkered with suspension settings - a more comfortable ride but problem still there. I'm not talking a major judder - just a judder that i know shouldnt be there -- so where the hell do i now look? front tyre is good (not squared off and running 30 psi up front and 33 rear obviously not looking to spend where i dont have to but something isnt right so as i've done my money buying it - where should i be looking tyre? pads? head bearings? fork service? or the rear ??-- but no play in swing arm or rear wheel
Mine does it as well (04 S4R) and I'm not convinced it's not the head bearings. These bikes are easy to wheelie, and if one of the previous owners liked to spend time with the front end off the ground this would put strain on the head bearings on landings. I'm not too sure if there is a taper conversion for the bike as this would be a good upgrade, failing that it has to be the forks bushes. You've checked run out on the disks haven't you, even a few though run out will show it's self at higher speeds. Just a matter of setting a dial gauge up off the calliper bolts.
I'd say it's discs. Has the same problem with my S1000RR track bike. Had Maidstone Motorliners check the discs and they came back as all ok, however they weren't, they had a very slight run out. Defo discs mate
Just a thought, not too sure if you've had the disks off but it could be worth removing them, giving the bolt holes a light de-bur (should be done but worth a check), check the bolting holes in the back of the disks are bur free, then make sure the bolts go fully home and don't bottom on any thing and then give the mating surfaces a good clean (as in clinical). Reassemble with loads of care, slowly build the bolt torque settings up and see how you go. Could save you a call to these chaps: Motorcycle Brake Disc Straightening - Maidstone Motoliner Ltd (though see above) or http://www.blackshadow-uk.co.uk/Ducati.html (been told only good things about these chaps)
cheers guys ... will try taking discs off first and re-seat them- think based on Russell's comment would leave MM ltd alone , seen black shadow stuff on the dreaded bay but have not heard of em before and dont want to replace rubbish with unknown - so disc reseat then headrace bearings then pads then discs then forks had similar on YZF750 track bike and was a cracked disc hence why i had run out done on them ... would lose my confidence in the fella if it turned out that was the case as he been doing my bikes for years now when i get stuck on something as an aside though is there a tapered bearing replacement for the head or would i have to go the all balls route?
I had a set of discs that were replaced under warranty. There was no measurable run out but they were jerky at low speed and juddery at high speed. Cleaning and deglazing helped slightly but with the new disc the problem was completely solved.
Nothing wrong with Maidstone Motoliner...... ........been in the business of straightening bike wheels and frames etc for years........ I took three front wheels and a swingarm down there for sorting......... They took one tyre off and discs off one wheel; straightened wheel and refit tyre and discs, plus balanced it. Straightened two more wheels and checked and slightly 'trued' ally swingarm. £150 and done in two hours max........I'm not moaning.
Definitely discs. I was told mine were ok too. Tried the lot then changed the discs and the wobble went. I'm a really fussy now.Always clean the brake pistons, and turn the discs bobbins as I was told this is where the problem starts?
decided to bite the disc bullet .. set of discs came up on the bay last night so nabbed em as price wasnt too bad ... just hope i havent bought a wobbly pair... hopefully have em on the bike by the weekend so will report back
Mate had an issue where cold discs were fine, riding terrible. Turned out bobbins were locking in place under heat and creating a warped disc affect which when cooled down you couldn't notice
find something somewhere about using a nut n bolt through the bobbins and turning them and blasting them with brake cleaner so i know mine spin as they should but whether they bind or not when hot?
HAPPY DAYS FOLKS .... purchase of second hand discs turned out good ... on and tested as of about 10 mins age ... no more front end judder ... all i gotta do is sort the front suspenders out and the bike may go where i want to go.. so as to what the issue was with original discs i know not... so may turn em into a couple of clocks.. unless someone on here wants to take a punt on them?
