Brake shudder at the track

[Andrew]

A week before Christmas, I got to the track with the 1098R (for the first time) - in summary the bike steers nicely and the power is quite good - this is a fun track day ride.

The day was a bit of a trial though with the first 3 sessions having me fighting with an overzealous DTC, each session starting at a lower setting (finally at setting 2, I got the DTC where I was happy).

However the biggest issue for the day was a seemingly random brake shudder - it was a violent high frequency shudder that didn't seem reduce the effectiveness of the brakes - but is sure shook my confidence in the brakes. A check of the bike in the pits revealed no brake issues and as stated it was random, I couldn't deliberately make the shudder happen so eventually I resigned myself to leaving plenty of space before a corner.

When I bought the bike, the previous owner stated that he had replaced the pads and the currently fitted pads seem to be quite coppery in colour (compared to OEM units).

Last week when I finally had time to clean-up the bike properly, I measured the disc thickness and run-out (all good) and during this time I noticed the front discs have pad material smeared around the drill holes - see the picture that is copper coloured pad material not rust.

I suspect the bike has been fitted with harder pads and I simply wasn't getting them hot enough (I rarely win braking duels at the track), however on occasion I was heating them to a point where they were beginning to become efficient (thus the shudder) and the rest of the time the disc holes were simply shaving the pad surfaces*.

Anyway since I've never had concerns with OEM pads at the track before; I'll clean the disc surfaces and refit OEM pads and see if this cures the problem.

Andrew...

* the actual purpose of the holes drilled in discs is to allow steam and water trapped between the disc surface and the pad to escape. Super performance discs will sometimes have radial groves on the disc surface designed to treat the pad faces - not common on bikes.

[desmo_pt]

Check the torque of the triple clamp bolts. I had the middle bolt from the top triple not thigh and that gave a shudder when braking.

Pedro

[Andrew]

Originally Posted by desmo_pt

Check the torque of the triple clamp bolts. I had the middle bolt from the top triple not thigh and that gave a shudder when braking.

Pedro

I'll check the triple clamps, the bike vibrates like a Harley until 4,000rpm and so far I've had to replace a few minor bolts on the fairing and rear guards

Andrew...

[moto]

Originally Posted by Andrew

When I bought the bike, the previous owner stated that he had replaced the pads and the currently fitted pads seem to be quite coppery in colour (compared to OEM units).

Anyway since I've never had concerns with OEM pads at the track before; I'll clean the disc surfaces and refit OEM pads and see if this cures the problem.

.

Cleaning the discs may solve the problem.
I used one of these on one of my bikes and it solved the problem.
I clean the discs every time I swap out the pads.


Rotor Hone Tool

-M

[ducati_750]

Originally Posted by moto

Cleaning the discs may solve the problem.
I used one of these on one of my bikes and it solved the problem.
I clean the discs every time I swap out the pads.


Rotor Hone Tool

-M

+1 on the above.. it's very likely that the previous owner didn't bed the new pads in and left some deposits on the rotors.... this is a common problem in the ST world and I've dealt with it first hand...

do a search in the ST forum for this problem and you'll find a fair bit of wisdom there...

[Slower than you]

Yup. Rotor hone the discs. $40 usd at your auto parts house. Get the finer grit. Note that perhaps the pads you're running may not be compatible with the rotor material. Just an idea but it won't hurt to find out if they are the right choice.

I've also heard horror stories about bikes with the high speed high freq shudder. Some have had to go to extremes replacing parts to rectify it. First try the rotor honing then swap out the disks if you still have it.

The other prob we encounter is low speed pulsation under sat 40 mph. This is 90% of the time pad gunk buildup. I refer to it as poor mans ABS. Does yours do this also?



I made this setup on my drill press and motorized the table for rotation. Works like a charm.

[johnnie27]

Originally Posted by Andrew

A week before Christmas, I got to the track with the 1098R (for the first time) - in summary the bike steers nicely and the power is quite good - this is a fun track day ride.

The day was a bit of a trial though with the first 3 sessions having me fighting with an overzealous DTC, each session starting at a lower setting (finally at setting 2, I got the DTC where I was happy).

However the biggest issue for the day was a seemingly random brake shudder - it was a violent high frequency shudder that didn't seem reduce the effectiveness of the brakes - but is sure shook my confidence in the brakes. A check of the bike in the pits revealed no brake issues and as stated it was random, I couldn't deliberately make the shudder happen so eventually I resigned myself to leaving plenty of space before a corner.

When I bought the bike, the previous owner stated that he had replaced the pads and the currently fitted pads seem to be quite coppery in colour (compared to OEM units).

Last week when I finally had time to clean-up the bike properly, I measured the disc thickness and run-out (all good) and during this time I noticed the front discs have pad material smeared around the drill holes - see the picture that is copper coloured pad material not rust.

I suspect the bike has been fitted with harder pads and I simply wasn't getting them hot enough (I rarely win braking duels at the track), however on occasion I was heating them to a point where they were beginning to become efficient (thus the shudder) and the rest of the time the disc holes were simply shaving the pad surfaces*.

Anyway since I've never had concerns with OEM pads at the track before; I'll clean the disc surfaces and refit OEM pads and see if this cures the problem.

Andrew...

* the actual purpose of the holes drilled in discs is to allow steam and water trapped between the disc surface and the pad to escape. Super performance discs will sometimes have radial groves on the disc surface designed to treat the pad faces - not common on bikes.

it could also be the one or both rotors have a slight warp..my sps did , i did not really notice it at road speeds( slowing from around 20kmph using a light finger to slow you get here a very very slight choock choock noise as the pad found the warp), but at philip island i did! got some new disks from the usa at 1 billion less than they wanted here, and whalla my prob was solved..just another thought mate..

[pjonte]

On the track I rate brake and tire safety about equal, both are consumable components. If you don't know what they are and they are giving you trouble replace them at the same time you recondition the rotors. Brake pads are cheap and not worth the risk.

[metalhead]

Aside from anything technical, may I ask a question? You said it was the 'first' time You took Your bike to a track. I remember my first time at a track. My bike did WAAAAY different stuff than I was used to in My regular 'twisty' riding. Could it be that You were hearing and feeling stuff that You had never felt before due to More aggresive riding and pushing the bike hard?

I'm just askin.

[davy.j]

Also have a look at the headstock bearings as any looseness there will make it shudder at times under brakes.

.