"Pulsing" brake pedal
Thread Starter
Retired & lovin' it!
Joined: Mar 2005
Posts: 4,475
Likes: 549
From: Jackson NJ
"Pulsing" brake pedal
'05 C6/Z51 with 25K miles...."pulsing" in pedal from hard stops. Initial thought was warped rotor, although car has never been tracked & mileage is low (weekend driver). Pulled a wheel & found the rotor to be smooth as a baby's butt with plenty of material left on the pads. I don't have a run-out gauge, but spun the rotor & didn't feel anything odd with finger pressure on the swept surface (admittedly not very scientific). Only thing I noticed was that when I had installed Cray wheels several months ago, I had not removed the factory rotor retainers & they both (2 on opposite studs) appeared crushed. Apparently, the OEM wheels must have a machined relief on the inner side while the forged wheels do not. I've removed the retainers, but thunderstorms started up & I didn't have the opportunity for a test drive. Will do that later this week. Only thing I can think of is that the few thousandths thickness of the retainers was somehow creating an imbalance under braking. Anyone experience anything similar? I sure don't want to cut or replace the rotors unless I'm sure of the fix.
Tolero Apto Victum
Joined: Jul 2007
Posts: 9,669
Likes: 37
From: Woodlands TX
'05 C6/Z51 with 25K miles...."pulsing" in pedal from hard stops. Initial thought was warped rotor, although car has never been tracked & mileage is low (weekend driver). Pulled a wheel & found the rotor to be smooth as a baby's butt with plenty of material left on the pads. I don't have a run-out gauge, but spun the rotor & didn't feel anything odd with finger pressure on the swept surface (admittedly not very scientific). Only thing I noticed was that when I had installed Cray wheels several months ago, I had not removed the factory rotor retainers & they both (2 on opposite studs) appeared crushed. Apparently, the OEM wheels must have a machined relief on the inner side while the forged wheels do not. I've removed the retainers, but thunderstorms started up & I didn't have the opportunity for a test drive. Will do that later this week. Only thing I can think of is that the few thousandths thickness of the retainers was somehow creating an imbalance under braking. Anyone experience anything similar? I sure don't want to cut or replace the rotors unless I'm sure of the fix.
Race Director
Joined: Oct 2007
Posts: 11,367
Likes: 211
From: Edgewood Washington
St. Jude Donor '11-'12-'13-'14-'15
Leaving those tabs on with aftermarket wheels usually shows up as a high speed vibration.
If it's not 'normal' ABS action, is there anything loose in the suspension or calipers?
If it's not 'normal' ABS action, is there anything loose in the suspension or calipers?
Safety Car
Joined: May 2006
Posts: 4,289
Likes: 129
From: Providence Forge, VA
St. Jude Donor '08-'09-'10-'11-'12
'05 C6/Z51 with 25K miles...."pulsing" in pedal from hard stops. Initial thought was warped rotor, although car has never been tracked & mileage is low (weekend driver). Pulled a wheel & found the rotor to be smooth as a baby's butt with plenty of material left on the pads. I don't have a run-out gauge, but spun the rotor & didn't feel anything odd with finger pressure on the swept surface (admittedly not very scientific). Only thing I noticed was that when I had installed Cray wheels several months ago, I had not removed the factory rotor retainers & they both (2 on opposite studs) appeared crushed. Apparently, the OEM wheels must have a machined relief on the inner side while the forged wheels do not. I've removed the retainers, but thunderstorms started up & I didn't have the opportunity for a test drive. Will do that later this week. Only thing I can think of is that the few thousandths thickness of the retainers was somehow creating an imbalance under braking. Anyone experience anything similar? I sure don't want to cut or replace the rotors unless I'm sure of the fix.
Melting Slicks
Joined: Sep 2005
Posts: 2,670
Likes: 134
From: merritt island fl
C1 of Year Finalist (stock) 2019
2016 C1 of the Year Finalist
2015 C2 of the Year Finalist
C'mon!
The OP didn't mention anything about engaging the ABS. You have to get on the brakes pretty hard to do that.
The first thing to do for a pulsing pedal is a few hard stops from about 60 to 10 mph.
My brake pedal pulses every time after I wash the car- probably due to rust on the rotors. A few hard stops fixes everything.
The OP didn't mention anything about engaging the ABS. You have to get on the brakes pretty hard to do that.
The first thing to do for a pulsing pedal is a few hard stops from about 60 to 10 mph.
My brake pedal pulses every time after I wash the car- probably due to rust on the rotors. A few hard stops fixes everything.
Drifting
Joined: Apr 2006
Posts: 1,276
Likes: 5
From: Ambler Pa.
'05 C6/Z51 with 25K miles...."pulsing" in pedal from hard stops. Initial thought was warped rotor, although car has never been tracked & mileage is low (weekend driver). Pulled a wheel & found the rotor to be smooth as a baby's butt with plenty of material left on the pads. I don't have a run-out gauge, but spun the rotor & didn't feel anything odd with finger pressure on the swept surface (admittedly not very scientific). Only thing I noticed was that when I had installed Cray wheels several months ago, I had not removed the factory rotor retainers & they both (2 on opposite studs) appeared crushed. Apparently, the OEM wheels must have a machined relief on the inner side while the forged wheels do not. I've removed the retainers, but thunderstorms started up & I didn't have the opportunity for a test drive. Will do that later this week. Only thing I can think of is that the few thousandths thickness of the retainers was somehow creating an imbalance under braking. Anyone experience anything similar? I sure don't want to cut or replace the rotors unless I'm sure of the fix.
Thread Starter
Retired & lovin' it!
Joined: Mar 2005
Posts: 4,475
Likes: 549
From: Jackson NJ
Thanks guys....I doubt that it's the ABS....I'm pretty familiar with that feel & I'm feeling the pulsations on dry roads with no apparent wheel slip under braking.....and everything is tight. I'm traveling on business this week, but when I get home, I'll do a test drive to see if removal of the retainers has any effect. And yes, I have felt a slight vibration at 90/100+ so even if the retainers have nothing to do with the brake pulsing, removal may cure the high speed vibration. Will post more at end of the week.
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Burning Brakes
Joined: Nov 2008
Posts: 940
Likes: 1
From: Long Island NY
It could be uneven pad deposits on the rotors. Like was mentioned above a few hard stops (no need to stop hard enough to engage the abs) from 60 to 10 will clean the rotors. Do not come to a full stop and then also drive about 15 minutes if you can without using the brakes to let them cool. There's a lot of good information on I believe it's Stoptech's site.
