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 High Speed brake Stutter 
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Post High Speed brake Stutter
Last track day at NC bike last year I started to notice some high speed stutter while on the brakes hard. At first I thought it might have been head shake do the new steering stem bearings put in at the end of the year so I went through and re-torqued and make sure the bars were free side to side.

Work has been crazy so this weekend of the first time I really had a chance to look into it.

Caliper pistons were clean of debris and not leaking, pads were worn even but blueish along with the rotors. I hate to throw parts are it but I am signed up for NYST the 10th so I bought a known good set of calipers and oem rotors along with new pads. Thoughts ?

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Mon May 28, 2018 4:47 pm
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Assholio Supremo
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Post Re: High Speed brake Stutter
The blueing happens, that's not a problem. The shudder, however...

I'd do this on those new rotors since they're off the wheels, but your current ones are probably ok, they just have some brake pad material unevenly transferred onto it. They need to be cleaned up.

step 1: clean the shit out of the buttons on the brake rotors with degreaser. spray it in there and work the rotor side to side, then clean it out well with some brake cleaner and water. Watch getting it on your tire.
2: Do you have access to a glass bead blaster? you can bring the rotors back to a "virgin" state easily with that. If not, do your best to evenly scuff the rotors with sandpaper. I often use an air tool with one of those 3M Roloc sanding discs on it, 120 grit. Just make sure you do it EVENLY.
3: Bed in the new pads.
4: Profit.

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Tue May 29, 2018 8:28 am
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Post Re: High Speed brake Stutter
Eskimo wrote:
The blueing happens, that's not a problem. The shudder, however...

I'd do this on those new rotors since they're off the wheels, but your current ones are probably ok, they just have some brake pad material unevenly transferred onto it. They need to be cleaned up.

step 1: clean the shit out of the buttons on the brake rotors with degreaser. spray it in there and work the rotor side to side, then clean it out well with some brake cleaner and water. Watch getting it on your tire.
2: Do you have access to a glass bead blaster? you can bring the rotors back to a "virgin" state easily with that. If not, do your best to evenly scuff the rotors with sandpaper. I often use an air tool with one of those 3M Roloc sanding discs on it, 120 grit. Just make sure you do it EVENLY.
3: Bed in the new pads.
4: Profit.


Thanks, the more I thought about I think I slapped the pads on at the track and didnt bed them either, straight out onto the track. I have some vortex src pads on the way, picked up some scotch brite to clean and scuff the rotors.


Tue May 29, 2018 7:42 pm
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Sharp-Sighted Shooter of Substantially Separated Steels (but can't hear shit)
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Post Re: High Speed brake Stutter
If that doesn't cure it, my bet is the rotors are toast...they're warped.
By warped, I don't mean they look like a bent LP record. I mean they look, in micro-measurements, like they've been hammered all over the place. Sure, the run-out will spec good, but all that tight/loose gripping by the pads on the peaks and valleys that may only measure upwards of .004" is what's causing the stutter/shudder and eventual violent side-to-side vibration as they continue to grow. And they will. If the cleaning/proper pad bedding doesn't cure the problem, it only gets worse.
Done it to a Yamaha and a Honda. Pads and cleaning actually accelerated the process in both instances.
You don't feel it at lower speeds and/or lesser application of the brakes, but wick it up past 100 and squeeze 'em hard...it's like mechanical ABS, but it sucks worse cause it transfers all that oscillation through the forks, steering head and on to the grips. Es no bueno. Your fork bushings, seals and steering bearings are taking a beating at that point, and you're wondering when the front end is gonna break off.

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Tue Jun 19, 2018 1:23 pm
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Post Re: High Speed brake Stutter
funfred wrote:
If that doesn't cure it, my bet is the rotors are toast...they're warped.
By warped, I don't mean they look like a bent LP record. I mean they look, in micro-measurements, like they've been hammered all over the place. Sure, the run-out will spec good, but all that tight/loose gripping by the pads on the peaks and valleys that may only measure upwards of .004" is what's causing the stutter/shudder and eventual violent side-to-side vibration as they continue to grow. And they will. If the cleaning/proper pad bedding doesn't cure the problem, it only gets worse.
Done it to a Yamaha and a Honda. Pads and cleaning actually accelerated the process in both instances.
You don't feel it at lower speeds and/or lesser application of the brakes, but wick it up past 100 and squeeze 'em hard...it's like mechanical ABS, but it sucks worse cause it transfers all that oscillation through the forks, steering head and on to the grips. Es no bueno. Your fork bushings, seals and steering bearings are taking a beating at that point, and you're wondering when the front end is gonna break off.


new rotors and pads have cured the issue, NYST last weekend from 140 to around 60 they were fine.


Fri Jun 22, 2018 6:00 pm
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Sharp-Sighted Shooter of Substantially Separated Steels (but can't hear shit)
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Post Re: High Speed brake Stutter
Good deal!

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Sat Jun 23, 2018 4:55 am
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Post Re: High Speed brake Stutter
fz811 wrote:
new rotors and pads have cured the issue, NYST last weekend from 140 to around 60 they were fine.


Sweet!!

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Rich Q.
'07-08 Yamaha R6 - Race "the Tiger Bike"
'04 Aprilia Tuono - Street/coaching
'06 KTM XC-W 200 - braaap!
'14 Zuma 155 - Yeah, it's striped, too.
CCS Expert #128
EvolveGT coach #128

Thanks to my 2017 sponsors! METRIC DEVIL MOTO / PIRELLI TIRE | SCORPION | WOODCRAFT | VORTEX | PARTS CLUB | HAZARDOUS RACING
GET IT!!! http://www.richquinlan.com


Mon Jun 25, 2018 8:48 am
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