Braking Shudder

Just had the 1199S in for 7500 mile service at 7000 miles. Has been running well. 5 track days so far this year and she needed new brakes pads and tires too. Replaced both with OEM pads and stock supercorsas resp. Flushed brake and clutch hydraulics. Had to replace left fork seal-noted some leaking after last track day, so replaced the right as well. Some new flash ( on top of the full Termi up map), and turning signal gadget recall thing. Also noted the front drive sprocket retainer bolt nearly falling off-got that cleaned up and replaced

First track day back all seemed back to usual. Braking from highest speed, 135ish, was strong and smooth as usual. Those are god's own brakes!

Next track day, Labor Day, braking from high 160s (had the full track at Utah Motorsports Campus-used to be Miller), and there is a high speed low amplitude shudder, still braking hard, that seems to resolve if I ease off and reapply the brakes at 130. Tracked true. Running Race mode, don't think I was setting off ABS as there was no light flashing (isn't it supposed to??) Started with 28/28PSI cold, was at 132F/136R when hot. Put 2 more PSI in front and it may have been a little less shuddery.

The one day last year when braking from those speeds, I don't think that happened.

Anyone have any thoughts about what to check? Thanks, paul

Hey Paul,
3 things I would recheck since you made all these changes at the same time.
Verify that the wheels are still balanced. Riding hard on fresh rubber can cause the tires to shift on the wheel and throw the balance off.
Do a runout measurement to verify that the rotors are straight.
Also do a rotor thickness measurement in multiple spots to verify rotor thickness is the same all around.
Check the new pads for grease contamination and other defects.

To add to that do you know what they set the fork oil level to after? Do you have a fork guide on the tube? If not put a zip tie on and make sure you're not bottoming out on the straight. Bikes really squat the front hard at the high mph braking. Just a thought.


Sent from my iPhone using Tapatalk

Brake Shudder

Interesting thought. I didn't have a zip tie on the forks and now they don't leak so there are absolutely no oil lines. But it does seem to fit that less hard braking seemed to be not a problem. thanks, paul

I was out there all weekend. Next time talk to Scott Rybarik (69), Shane Turpin (14), or Scott the tire guy. Boulder motorsports is sometimes out there too. It was a pretty mild day and temps werent getting too hot. It was pretty hard to keep my 250s tires warm.

and you'd know if ABS kicked in. Sounds like your bike is breaking into pieces. Horrible sound. Also you'd be up over your handlebars pretty quick haha.

Desmophile said:

Interesting thought. I didn't have a zip tie on the forks and now they don't leak so there are absolutely no oil lines. But it does seem to fit that less hard braking seemed to be not a problem. thanks, paul

Click to expand...

Right, next time if the zip tie does bottom out than add 5mm of fork oil and repeat the process. I'm sure someone can chime in with an ideal fork oil level with your suspension. If you do some research you can probably find numbers with the spring and preload tube till inside so all you have to do is loosen the cap set the new level. Maybe take it back to the shop if you don't work on your bike a lot and tell them to check it and that you are running trackdays.


Sent from my iPhone using Tapatalk

Shuddering or front tire hopping? I experienced it once under very hard braking in my pre-tire warmer days earlier this year - it's front tire hopping. I was told by another Panigale rider that it went away completely for him when he went to slicks.

If it is high frequency low amplitude, it may be air trapped in brake system triggering hydrolock but countered by abs, resulting in pulsing feeling on the lever. I had this on an 899 that had very old brake fluid on a fast track. Flushing the system resolved this.
The fact you said it goes away if you reapply brake lead me to suspect this is the most likely cause.
No, abs does not trigger warning light like tc does. Abs trigger that pulsating and knocking feeling at the brake lever.
Sometimes brake flush or bleeding wasn't done perfectly, or banjo bolt wasn't tightened enough (happened with my clutch, letting air in and had to re-bleed), although be careful tightening those banjo bolts, don't gorrila it as my brothet has wrecked two calipers and one master from gorrilaing them.

It could also be warped rotor, which can be machined out at relatively low cost. Or pads mismatch to the rotor when reassembled, which could go away by itself with proper bedding in exercise.

If it is suspension issue, it would more likely be juddering (not shuddering) low frequency high amplitude under hard braking as the front tyre grip-not-grip-not, most likely due to suspension bottomming out or locking, and would feel quite unnerving. I had this a few times in one race (i think I have a video in my youtube channel showing this, but cant remember which). Some extra preload solved that one so it may be worth a shot. Would be easier to diagnose if you know whether you are bottomming out when that happens. Put a camera on your side fairing recording the suspension leg and watch the video.
If the rider sag is correct (but what is "corect sag"?? It varies!), 5ml extra fork oil in each leg may help.

Thanks for all the thoughtful replies guys.

I did some more close inspection on the front fork travel and with a bright flashlight, I can see a dust line which is 25mm above end of lower suspension leg. I don't know how close this is to mechanical limits of travel as determined by internal mechanisms. I have a 1999 900ss which I could bottom the forks on until adding heavier/more oil and it doesn't feel like that. Is it possible to bottom the electronic Ohlins? Any help here?

Thanks for the info on the ABS. I am pretty sure I have never triggered it because I have never felt the pulsations. Boggles my mind that the tires can handle more braking than I have had the guts to try. Two track seasons on, and my mind still hasn't fully made the transition from 1982 GS1100 brake/tire capacity to current Brembo/Supercorsa level.

I am inclined to replace the brake rotors and nothing else as a first attempt as this sensation seems most like what I have experienced in cars with warped rotors, just higher frequency because of the speed involved. Dealer has advised that front rotors cannot be machined, but just replaced. Since I have a month to next track day I may have a go at replacing them myself (and introduce all sorts of variables into the problem, HA!).

Any comments about replacing rotors with stock Brembos vs EBC rotors? thanks, paul