QUIKAG

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.

naschmitz

Sounds like pad taper or pad knock back, right? As soon as the pistons travel far enough to re-engage the pad with the rotor everything is good.

froggy47

It's normal to have about 1 inch of "not much" before you get stopping power (except my bmw's seem less so).

QUIKAG

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.

froggy47

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.

QUIKAG

That makes perfect sense. Thanks, Froggy.

phipp85

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.

1ED1

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.

Bill Dearborn

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

isnider

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

crease-guard

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.

QUIKAG

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.

That makes sense. It is easy to heel-toe this car.

They are solid once it engages, but it's that little bit of initial travel. I think I bled outside to in, but honestly how big of a difference would that make? I wonder why they recommend inner first?

Good idea. I'll try that next time I take her out for her weekly workout around town.

phipp85

I use SRF. Many believe it's overkill but I like knowing it's highly unlikely that I will boil my fluid.

rustyguns

stuff is bullet proof! Also i would bench bleed your master cylinder. I had same issue, that fixed it G/L

MarkDFW

I am going with SRF. I have boiled Motul 600 a couple times. Makes for a quick way to end a session when your pedal is a sponge.

V4kerker

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.

rustyguns

you both need to bench bleed using a master cylinder bench bleed kit. Ask your local auto parts store. They are cheap

QUIKAG

Thanks, rustyguns. I'll check into bench bleeding.

V4kerker

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.

rustyguns

i like to bench bleed it on the car, then when you remove the bleeder lines hook up the brake lines snug but loose enough so they leak a little bit. have someone push the pedal slowly as you tighten the brake lines. then bleed all of you brake lines. be sure to do it in the order the manual tells you

if that does not work, take it to a Brake shop. ask them to replace your brake fluid. they will find whats wrong