View Full Version : 'juddering' front brake.
Not on an SV, but a cbr600rr. Under heavy braking, typically at lower speeds in the 40-0mph range the front will judder a bit, feels like a rattle through the forks. If I release and reapply it goes away usually but is pretty odd.
I've not had the brakes off yet but pads are fine (tyres changed recently and they had a look) and discs don't appear to be warped.
I had exactly the same, my forks were bottoming out.
What weight are you? I weight 12.5st and my preload had to be wound 15 clockwise of it's 16 adjustments before it was right.
Forgot to say that's on a 600rr too.
Other things I did at the same time were clean all the brakes up including caliper pistons and making sure the floating discs are actually floating by cleaning the washers.
99% put my money on the forks bottoming like mine were though.
Thanks buddy. I'll check they're not bottoming out but I don't think they are. I'm about the same weight as you but my suspension settings are all stock, unless someone wound them all the way around? Don't know if that's even possible.
It's about time I had the brakes off anyway so I'll check preload first and then give the brakes a clean up.
If it's still on stock settings then it probably is lacking preload for your weight by a fair bit.
Stick a cable tie on the stanchion and after hard riding with heavy braking it need to finish at 33mm, at 27mm from the bottom the forks are bottoming out.
warrenhewitt10
11-10-10, 08:39 AM
can you get the RR with abs?
can you get the RR with abs?
I guess it would depend on how much time it spent in the gym.
warrenhewitt10
11-10-10, 01:11 PM
I guess it would depend on how much time it spent in the gym.
very true, just thought it would be worth a say :)
Apparently after a quick Google search, ABS has been available on the RR since last year.
warrenhewitt10
11-10-10, 02:56 PM
reason i suggest this, have a friend whos dad has one of the new tiger 1050's it has abs, and when it kicks in it sounds awfully like what sauluk has described
http://www.gostar-racing.com/club/motorcycle_suspension_set-up.htm
Have a quick look there, may help with setting up your suspension
And yup, both 600RR and Blade now come with optional ABS :thumright:
yorkie_chris
11-10-10, 05:42 PM
If it is gentle braking suspension setup won't make much difference at all. You have to try quite hard to get chattering unless it's absolutely miles out or some retard took springs out or something.
Check headstock bearing for play.
skidmarx
11-10-10, 07:01 PM
What exactly happens? Is it a juddering you can feel through the bars, or a vibration you pick up through your fingertips? Reason I ask is my 09 abs does this, definately nothing to do with suspension, it usually happens at lower speeds and is more pronounced under moderate breaking when pulling up. Can be felt through the lever as a weird vibration, nothing thru the bars. No idea what it is though... It's done it for last 8k miles. Issue never arises when brakes are used at higher speeds or heavy breaking. It was fine on track no hint if it.
If the headstock bearing check shows up no play and you have also checked the tightness of the steering stem nuts etc then I'd bet it is the discs producing headshake through either warpage or wear. Have you wacked the front end in anyway?
Milky Bar Kid
11-10-10, 07:43 PM
AFAIK the ABS has only been available on the CBR600RR and Blade since last year, don't think it was available in the 2008, I may be wrong though.
Certainly not an issue I have with my RR.
I don't have ABS, forks could be bottoming out as it's set up pretty soft. I was going to have it set up professionally anyway for £30 so I'll just do that. Front end has definitely not been whacked in any way. Not sure how to check for play in the headstock bearing?
It only happens under heavier braking
Holdup thanks for posting that article, really handy.
Also I fell the judder through the brake lever although I think through the forks too, can't be sure as it doesnt happen all the time!! Might just be suspension settings are wrong for my weight. Bike handles great but stock settings are pretty soft
Why have we got to the end of page 2 without someone suggesting warped discs. which is by far the most logical conclusion?
But I think its a parrot stuck in the rear left indicator.
C
Milky Bar Kid
12-10-10, 09:55 AM
Berlin...I think that was suggested some time ago...
Milky Bar Kid
12-10-10, 09:56 AM
If the headstock bearing check shows up no play and you have also checked the tightness of the steering stem nuts etc then I'd bet it is the discs producing headshake through either warpage or wear. Have you wacked the front end in anyway?
See Berlin....:smt019
Suggested as an extra option in reply 14.
"My brakes are juddering and I can feel it through the lever..."
Warped discs. Not suspension, not ABS, not headstock, not parrots not martians.
Warped discs.
If its the one with Honda's super duper ABS then the brakes are completely ride by wire and so pulsing in the brakes *could* be electrical gremlins. Especially if its felt via the lever (but i don't think this bike has that) Even with ABS If felt generally then it'd still be warped disks.
I've changed my answer to three day old custard blocking the oil way just underneath the exhaust exup valve on the 5th cylinder.
.
I think it may be because in the very first post he suggests it's not warped discs. ;-)
He also suggests it does not happen every time he brakes and with warped discs it would happen every time he braked.
So what gives a warped disc without the discs being warped?
Sticky disc rivets. If it happens then doesn't happen the disks aren't floating freely. 1st application of brake doesn't shift it, then a second does. Also the forces at higher speeds usually shift it first time out. at slower speeds and gentle braking the disks can stick on the rivets giving pulsing.
Check the rings between the discs and the disk mounts.
Simples :)
... and being able to see a warped disc is a special skill. :) If the disk has a high point of just 0.2mm it could lead to pulsing. So without going over them with a vernier and a set of feeler gauges, on a known flat surface, its impossible to tell if they are warped. Having a quick look isn't going to tell you.
C
I'm kinda with Berlin on this. I had the same issue on my 600RR. Changed the discs and the problem went away. Not sure if it was warped discs or sticky disc buttons, but it was definitely a disc issue.
I don't disagree with you Carl, but if it WAS a warped disc, you'd feel it every time you braked, not intermittently. That's why I and probably everyone else has not suggested it IS a warped disc.
On the topic of replacing discs. My YZF does have a warped disc and I have the discs to replace them. However I have noticed one of the disc bolts has been butchered by someone (no not me) before I have a go with the alan key to get it out, anyone got any suggestions on how to remove the offending bolt should I find the alan key will not do the job?
yorkie_chris
12-10-10, 03:35 PM
Couple of options.
For a start don't even touch the allen keys, they are the devil. Get some allen sockets instead.
Get some fire on it first to break any loctite off. Add some penetrating oil.
If that rounds it out you can hammer in the next size up imperial or torx bit.
If that doesn't shift it you can weld a nut to it to turn it.
Tried to isolate it today. It comes through the brake lever under constant medium / heavy pressure at around 30mph. The constant bit is important, a stab or varying pressure and it's fine but if I hold it at the same point I'll get it.
Now wheres that 5th cylinder?!
yorkie_chris
12-10-10, 10:55 PM
You checked those head bearings yet? Get a mate to lift front end off floor on sidestand and push and pull bottom of forks... if there is a knock and front to back play that is your problem.
If there is no play here then start looking at discs and other stuff.
barwel1992
13-10-10, 06:45 AM
exactly the same problem i have
but i know my disc's are warped..
Warped discs. (or a high spot on the discs, same difference)
Light pressure allows the warp to show itself and heavier pressure keeps the pads in the same place and the judder transfers through the disc pins.
Bear in mind it might only one of the discs that's warped. Take the wheel out, remove one of the disks and put the wheel back in and check for the judder. If its gone you got it. If not, Drop the wheel and prise the bads back and remove the other disc and replace the one you took off. Try again. Gone?
Temember to pump the pads with the lever before you move the bike each time to push the pads out .
Or its a poodle under the seat, scratching as you brake :)
C
Unfortunately my paddock stand is in work so haven't checked headstock bearing. Will warped discs be covered by warranty since they're defective? I'll give the garage a call they're decent people so I'm sure they'll replace if they're dodgy. Will check headstock first and then look for the poodle / custard
Will warped discs be covered by warranty since they're defective?
Worth a punt but doubtful I would suspect.
Berlin please repeat your last post with the added advise to make sure there is always enough brake fluid in the reservoir. Thanking you kindly.
Make sure there's enough brake fluid in your reservoir.
There should be, because you've only removed one disc and therefore only one set of pads will come together. This is a movement of about 4-6mm to take up the space left by the missing disc. Or the same as the thickness of one pads worth of brake material. As, with 4 pads in the front calipers, there's approx 16-20mm of pad material to wear away during the life of the pads then there should be enough to handle 4-6mm of movement.
But check anyway.
... and check there aren't any penguines in there too. They can block the cables. :D
C
Very good point but you never know!
Any news? Was it the penguins?
C
No news, I'm going out tomorrow to take the brakes off and get some brake cleaner on discs and service the caliper. If it still does it after that I'll book it in so they can check the discs! (and penguin based issues)
Serviced brakes today and cleaned everything up. Pads looked like this:
http://i7.photobucket.com/albums/y258/saul_uk/MobilePhoto24Oct2010205459.jpg
So don't look great and are pretty mirrored, don't know if they're glazed or not though. I had the bike from 600 miles so the prev owner could have glazed them when new?
Also the pins looked a bit corroded:
http://i7.photobucket.com/albums/y258/saul_uk/MobilePhoto24Oct2010205409.jpg
(don't worry, that's after wiping the copper slip off them, they weren't dry!) Would that stop the pads moving freely?
Everything else seemed fine, one of the discs had a slight score in it but nothing severe.
yorkie_chris
25-10-10, 11:53 AM
You need to get the wheel in the air and spin the wheel to check the discs for wobble.
Pins look fine
custard
25-10-10, 12:27 PM
something else to check for (although this is second hand info) have a check of the buttons on the disc. if they get gunged up the disc cant float and you can get juddering. make sure you can turn the buttons, if not get a rubber mallet and brake cleaner and see if you can free things up.
Well after the general cleaning yesterday everything seems fine. No judder on my commute at all and I tried a good few times where it would usually do it.
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