Front brake judder

[mellowyellow]

RE warped gs 1200 discs

I have a 12 month old 1200gs with almost 12000 miles on the clock. Both front and rear discs were replaced at 5500 miles due to warping/ uneven wear, causing a judder at both ends of the bike. I now notice that the front engine plate is starting to corrode from under the plastic cover and the top box is cracked underneath. Both will have to be addressed at the 12k service.

I have also noticed a slight seeping of gear oil at the gearbox/ engine joint.
I am really looking forward to the rear drive bearing and ews failure .

I have 12 months of warranty left and have no intention whatsoever of keeping the bike after this expires.

Crying shame, cos in every other respect the machine is fantastic.

 

[John Gates]

Warped discs - front

18K miles, on 3rd set of discs all under warranty from Jefferies at Shipley no quibble. Hopefully by now bad stock will have worked its way through the pipeline and some decent ones will have come along.

From experience judder starts at v low speed but quickly develops. My advice is don't delay in getting them replaced.

 

[whitegloss]

Here you go, a quick search has revealed this: Brake warping

M

Thanks-interesting read, as it says dispels myths

 

[RickG]

My GS has brake judder too. It's had it from new. I'm not convinced about this warping idea due to heat for two reasons, one it's done it from brand spanking new, virtually before the brakes were even applied let alone made hot, and two I've had Brembo disks bright turn blue with heat before now without any consequential warping. The only time I've seen certifiable disk warp is on a mate's Laverda (brembos) after he foolishly fitted sintered pads. The disks warped so much he developed a series very visible blue 'hot spots' where the pads were catching on the resulting high spots.

Right, so purely in the interests of science of course, I've had a play about with mine. I can brake from 130mph with various amounts of judder taking place and control it according to how hard I brake. For me it tends to go away the harder I squeeze (I bit like bad constipation).

The fundamental thing is the frequency of the judder is NOT speed dependent. It's constant at about 5 judds (that's a scientific measurement you know) a second. Now, if it were a warped disk the warps would create a pulse in the system dependent on speed, so as you slowed the juddering would fall in frequency, as it would if there were lumps of some sort of deposit on the disk. I've had the latter on cars that have been parked up for months so there's a big blob of rust where the pads were sitting. Take it for a drive and it judders, but again it's frequency related to road speed and as you brake and slow, so does the rate of juddering. As the rust wears off all returns to normal

And no way is it the ABS kicking in as I'm way, way off the point of lock up, unless of course the ABS is somehow fecked but magically rights itself as I brake harder..I think not

Just before anyone complains, I'm not suggesting that you are all wrong about your own instances of warping, pad deposits or whatnot, just that in my case I'm betting it's something else. But what? I'd take a guess it could even be the forks juddering and is something set off by the initial braking but continues until you alter the dynamics by changing the braking force. It seems worse if you grab a sharp handful of brake rather than gradually easing them on

So, my question is: did you all have judder that was at constant freqency or was it speed related? If the latter, did BMW actually bung a dial guage on the disks to check for out-of-true. Or did they just change them and not bother to argue about the real underlying cause?

Who knows, I bet BMW do though.

 

[Pipster]

Bike booked in sat morning will let you know what they find.

As to holding bike on brakes when Waiting at lights, as i said in previous post
yes i do sometimes rear sometimes front sometimes both not always front
Considering that most of the stop start riding i do is in city centre at speeds of up to 30mph maybe 40mph if i'm lucky i don't think my discs would generate enough heat to warp

Maybe if i rode a sports bike and had just done an emergency stop from 170mph

Mark as to always using rear brake when stopped that how its done on bike test,just wondered if you drive your car with hands on steering wheel at ten to two thats how its done in car test

 

[Gog yn y De]

So, my question is: did you all have judder that was at constant freqency or was it speed related? If the latter, did BMW actually bung a dial guage on the disks to check for out-of-true. Or did they just change them and not bother to argue about the real underlying cause?

Mine was speed related.

After 6,000 miles, BM' didn't bother to measure the disks the first time around - just replaced them and the problem was solved.

6,000 miles later the judder returned. BM' confirmed that they were 'out' but within tolerance so they wouldn't change them. Put a set of EBC brakes on which helped. Sold the thing after that. Just hope it doesn't happen on my GSA.

 

[camel_landy]

...just wondered if you drive your car with hands on steering wheel at ten to two thats how its done in car test

I'm sorry to say that actually I do... I also don't cross my hands when turning. On top of that, I always drive with my thumbs outside of the wheel (it's an off-roader thing...).

...I know what you're saying though.

M

 

[Pipster]

Problem solved...

The guys at williams have found cause of judder ,The discs are not warped they oscillate up and down due to bolt holes being slightly of centre, maybe a bad batch of discs!

 

[(RIP) Bin Ridin]

Pipster,
Sorry to say I would have a hard time agreeing with what Williams have told you. As far as the pad is concerned, it sweeps a circular track. All you would get is an eccentric wear-pattern on the off-centre disc. Where does the judder come from?
Bin

 

[Pukmeister]

The guys at williams have found cause of judder ,The discs are not warped they oscillate up and down due to bolt holes being slightly of centre, maybe a bad batch of discs!

Thats funny, if you remove the disks you will find the 'holes' are actually oval shaped slots to allow the disks to expand radially outwards from the centre due to thermal expansion. If your disks oscillate that means there is wear in the sides of the slots (holes).

Mine has slight judder, made better by removing the disks and cleaning the mounting faces on the alloys. Maybe my holes are worn too ??

 

[Pipster]

New discs are being fitted week after next , I'll let you know if it cures judder

 

[duds]

Pipster I had exactly the same problem at 6000 miles after the bike had been in to have the mod done to eliminate brake squeal. No judder at high speed but could feel it at about 20 – 30 mph especially when slowing for traffic lights. BVM found a problem with the disc bolts and replaced the discs, pads and front wheel. Needless to say it’s now cured.

 

[Pipster]

Big thank you to Williams

New discs fitted on warranty problem solved thanks to all at Williams