C6 brake pedal mushiness
#1
Le Mans Master
Thread Starter
C6 brake pedal mushiness
Okay, I cooked my Motul at COTA this past weekend after having to do the pump the pedal and open/close the bleed screw method with my Dad. So, I pressure bleed the system (finally bought a Motive) and take it for a drive and it's still a bit mushy. I nail the brakes a few time to engage ABS and the pedal firms up a bit, but still not that great. Guess a bit of air got in the ABS circuit I do a quick bleed again on 4 of the 8 bleed screws, a few bubbles come out and the pedal is pretty firm at this point.
Here's my question: After a few inches of travel, the pedal firms up nicely about mid-stroke. It's driving me crazy, but I think that is the way most/all of the C6 brake pedals are. Am I right? I drove my wife's RX350 Lexus and her pedal is the same way, not much going on the first few inches of travel and then it starts to bite progressively.
So, is that normal? Is there any way to have a firmer pedal within the first few inches of travel or is that not even desirable?
Okay, I know this is probably the dumbest thread in a while, but it's annoying me. I HATE having a mushy pedal.
For those guys who have stayed with me throughout my rambling post, I got a bonus for y'all. I swapped brake pads right before COTA, burnished them, everything, but guess what? On the passenger rear wheel, I didn't run the pins through one of the two pads, so it slid a bit into the rotor/caliper. Wonder if that contributed to my not confidence inspiring braking at COTA? It doesn't appear to have caused any damage besides a touch of uneven pad wear. It also let the rotor chew up the retaining bracket a little bit. Moral of the story: I'm stupid and make sure you run the pins through both pads on each wheel.
Here's my question: After a few inches of travel, the pedal firms up nicely about mid-stroke. It's driving me crazy, but I think that is the way most/all of the C6 brake pedals are. Am I right? I drove my wife's RX350 Lexus and her pedal is the same way, not much going on the first few inches of travel and then it starts to bite progressively.
So, is that normal? Is there any way to have a firmer pedal within the first few inches of travel or is that not even desirable?
Okay, I know this is probably the dumbest thread in a while, but it's annoying me. I HATE having a mushy pedal.
For those guys who have stayed with me throughout my rambling post, I got a bonus for y'all. I swapped brake pads right before COTA, burnished them, everything, but guess what? On the passenger rear wheel, I didn't run the pins through one of the two pads, so it slid a bit into the rotor/caliper. Wonder if that contributed to my not confidence inspiring braking at COTA? It doesn't appear to have caused any damage besides a touch of uneven pad wear. It also let the rotor chew up the retaining bracket a little bit. Moral of the story: I'm stupid and make sure you run the pins through both pads on each wheel.
#4
Le Mans Master
Thread Starter
Yeah, I guess you guys are right. Pedal is firm once the brakes engage, it'd just be nice to have a pretty firm pedal throughout it's movement.
#5
Race Director
It's designed so less then expert drivers can get on the brakes & not get rear ended because they got excited & pushed too hard. Generally (not talking track here) stock Vette brakes will whoa you down very fast if you put your foot in it hard - street driving - much better than your avg suv or mini van.
#7
Burning Brakes
QUIKAG
I have a Z07 and have experienced the exact same thing you are describing after swapping out the stock fluid for the first time. I thought it felt soft so I bled brakes again, better but still soft at first. Went out and worked ABS, bled again and got a few super small bubbles. Pedal is better but still just a slight amount take up before it really grabs. I think its normal. What froggy said in post #5 makes sense to me. I recently did a track weekend at Road Atlanta and didn't have any problems at all.
I have a Z07 and have experienced the exact same thing you are describing after swapping out the stock fluid for the first time. I thought it felt soft so I bled brakes again, better but still soft at first. Went out and worked ABS, bled again and got a few super small bubbles. Pedal is better but still just a slight amount take up before it really grabs. I think its normal. What froggy said in post #5 makes sense to me. I recently did a track weekend at Road Atlanta and didn't have any problems at all.
#8
Pull the rotors and check for a crack around the hub that centers the wheel. The crack is just a hair line and hard to see. Use a good lite. This might not be the problem but to be safe it's good to check.
#9
Tech Contributor
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All of my Vettes from the 86 on let the brake pedal drop to the level of the gas pedal on first application. I always thought it was designed that way to make it easier to heel/toe. With the pedals the same height it is a lot easier to roll the right side of your foot onto the gas pedal to blip the throttle.
Bill
Bill
#10
I need to double check my service manual again (but with that being said) I think the inner bleed screw is to be bled first which is somewhat unintuitive? Any chance you bled the outer screw first? Just a thought....
I agree that on my brake pedal there is a bit of travel to get the brakes engaged, but it should be rock solid once you get them engaged.
Ian
I agree that on my brake pedal there is a bit of travel to get the brakes engaged, but it should be rock solid once you get them engaged.
Ian
#11
Drifting
Next time you go out on the track/street, try tapping the brake pedal with your left foot just a smidgen before the next turn and then see if you have the same travel on initial brake application. I've read that a number of pro drivers will do this because of knock back so that the pedal is firm and bite aggressive when they get into the next corner. I've been meaning to try this but always forget.
#12
Le Mans Master
Thread Starter
QUIKAG
I have a Z07 and have experienced the exact same thing you are describing after swapping out the stock fluid for the first time. I thought it felt soft so I bled brakes again, better but still soft at first. Went out and worked ABS, bled again and got a few super small bubbles. Pedal is better but still just a slight amount take up before it really grabs. I think its normal. What froggy said in post #5 makes sense to me. I recently did a track weekend at Road Atlanta and didn't have any problems at all.
I have a Z07 and have experienced the exact same thing you are describing after swapping out the stock fluid for the first time. I thought it felt soft so I bled brakes again, better but still soft at first. Went out and worked ABS, bled again and got a few super small bubbles. Pedal is better but still just a slight amount take up before it really grabs. I think its normal. What froggy said in post #5 makes sense to me. I recently did a track weekend at Road Atlanta and didn't have any problems at all.
All of my Vettes from the 86 on let the brake pedal drop to the level of the gas pedal on first application. I always thought it was designed that way to make it easier to heel/toe. With the pedals the same height it is a lot easier to roll the right side of your foot onto the gas pedal to blip the throttle.
Bill
Bill
I need to double check my service manual again (but with that being said) I think the inner bleed screw is to be bled first which is somewhat unintuitive? Any chance you bled the outer screw first? Just a thought....
I agree that on my brake pedal there is a bit of travel to get the brakes engaged, but it should be rock solid once you get them engaged.
Ian
I agree that on my brake pedal there is a bit of travel to get the brakes engaged, but it should be rock solid once you get them engaged.
Ian
Next time you go out on the track/street, try tapping the brake pedal with your left foot just a smidgen before the next turn and then see if you have the same travel on initial brake application. I've read that a number of pro drivers will do this because of knock back so that the pedal is firm and bite aggressive when they get into the next corner. I've been meaning to try this but always forget.
#13
Burning Brakes
Exact same deal on all accounts. Glad it's normal, but I still think Motul 600 isn't enough, so I'm going SRF next time.
#16
Racer
QUIKAG I've got the same issue with my 07 base coupe.
I've even changed the master cylinder and still first pump is a little mushy. I even bought a long length of tubing to run from the bleeder back to the master cylinder and had my son pump the brake pedal for a very long time. During this process I could see super tiny (micro) bubbles. I don't know how to get rid of these tiny bubbles. I'm not sure but this may be my and your problem all so.
I did notice there's some flex in the fire wall when you really lay hard on a firm pedal.
I've even changed the master cylinder and still first pump is a little mushy. I even bought a long length of tubing to run from the bleeder back to the master cylinder and had my son pump the brake pedal for a very long time. During this process I could see super tiny (micro) bubbles. I don't know how to get rid of these tiny bubbles. I'm not sure but this may be my and your problem all so.
I did notice there's some flex in the fire wall when you really lay hard on a firm pedal.
#17
Le Mans Master
Member Since: Dec 2006
Location: Phoenix Arizona
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QUIKAG I've got the same issue with my 07 base coupe.
I've even changed the master cylinder and still first pump is a little mushy. I even bought a long length of tubing to run from the bleeder back to the master cylinder and had my son pump the brake pedal for a very long time. During this process I could see super tiny (micro) bubbles. I don't know how to get rid of these tiny bubbles. I'm not sure but this may be my and your problem all so.
I did notice there's some flex in the fire wall when you really lay hard on a firm pedal.
I've even changed the master cylinder and still first pump is a little mushy. I even bought a long length of tubing to run from the bleeder back to the master cylinder and had my son pump the brake pedal for a very long time. During this process I could see super tiny (micro) bubbles. I don't know how to get rid of these tiny bubbles. I'm not sure but this may be my and your problem all so.
I did notice there's some flex in the fire wall when you really lay hard on a firm pedal.
#19
Racer
Rustyguns, I did the bench bleed and bleed the master cylinder at the connections after I installed it on the firewall.
Wish I could get a cheap Tech 2 tool to do a proper bleed of the ABS unit.
I think I may have to bleed my calipers at a different angle? It looks like the bleeder valves aren't quiet at the highest point possible when I have the car jacked up at a high angle.
Wish I could get a cheap Tech 2 tool to do a proper bleed of the ABS unit.
I think I may have to bleed my calipers at a different angle? It looks like the bleeder valves aren't quiet at the highest point possible when I have the car jacked up at a high angle.
Last edited by V4kerker; 01-24-2013 at 01:46 AM.
#20
Le Mans Master
Member Since: Dec 2006
Location: Phoenix Arizona
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Rustyguns, I did the bench bleed and bleed the master cylinder at the connections after I installed it on the firewall.
Wish I could get a cheap Tech 2 tool to do a proper bleed of the ABS unit.
I think I may have to bleed my calipers at a different angle? It looks like the bleeder valves aren't quiet at the highest point possible when I have the car jacked up at a high angle.
Wish I could get a cheap Tech 2 tool to do a proper bleed of the ABS unit.
I think I may have to bleed my calipers at a different angle? It looks like the bleeder valves aren't quiet at the highest point possible when I have the car jacked up at a high angle.
if that does not work, take it to a Brake shop. ask them to replace your brake fluid. they will find whats wrong